Far-field cardiac event detection method and system

Abstract

The invention relates to a computer implemented method for far-field cardiac event detection in an implantable medical device (10), comprising the steps of providing (S1) the implantable medical device (10) being configured to operate using a first set of far-field sensing parameters (Auto1), monitoring (S2) a prevalence of AV synchrony by the leadless implantable medical device (10), identifying (S3) insufficient AV synchrony based on at least one predetermined condition (12), selecting (S4) a second set of far-field sensing parameters (Auto2) among a plurality of far-field sensing parameter sets (Auto1, Auto2, Auto3), and executing (S5) the selected second set of far-field sensing parameters (Auto2). In addition, the invention relates to a system for far-field cardiac event detection in an implantable medical device (10).

Description

[0001] Applicant: BIOTRONIK SE & Co. KG

[0002] Date: 02.04.2026

[0003] Our Reference: 23.060P-WO

[0004] FAR-FIELD CARDIAC EVENT DETECTION METHOD AND SYSTEM

[0005] The invention relates to a computer implemented method for far-field cardiac event detection in an implantable medical device.

[0006] Furthermore, the invention relates to a system for far-field cardiac event detection in an implantable medical device.

[0007] Traditional autosensing capabilities employ a set of parameters for balancing the need to detect true cardiac signaling while, at the same time, avoiding responses to input artifacts (e.g., T-waves). In leadless pacing systems implanted in the ventricle that aim to support AV (atrioventricular) synchrony, there arises a need to not only provision autosensing for near-field QRS complexes (i.e., VS, ventricular sensed events) but also autosensing support for far-field events indicative of atrial senses. With reliable knowledge of atrial events, the timing of ventricular paces can be coordinated to better optimize the heart’s pumping efficiencies while also avoiding regurgitation and its affiliate side-effects.

[0008] Because the atrial signaling is far-field in nature for VDD (V = pacing in the ventricle, D = sensing in the atrium and ventricle, D = inhibit and or trigger) leadless pacemaker systems, the configuration support needed for the atrium needs greater flexibility and adaptability than a “one size fits all” autosensing configuration utilized for near-field signaling. In addition, there is a temporal component to atrial sensing, and configuration at implant may not be appropriate after three months, six months, or several years. Changes in the heart anatomy, orientation, ingrowth of the implant, and other factors may influence sensing performance and subsequently AV synchrony overtime.

[0009] Between follow-ups adaptive algorithms are common in the active implantable medical device context. Perhaps most familiar to clinicians in CRM (cardiac rhythm management) are the offerings associated with 1.) capture control, 2.) mode-switching, and 3.) autosensing.For capture, clinicians can generally prescribe guard railing to lower the pace output overhead by setting pulse widths, search start amplitudes, and sometimes even controlling the regularity of capture search routines. Similarly, mode switching configuration gives clinicians an opportunity to specify “backup” behaviors applicable when tachycardias emerge that would prove undesirable to track. Last, autosensing settings configure limits for how true cardiac events can best be recognized in the context of surrounding signaling artifacts.

[0010] In more recent developments, some CRM device manufacturers have also expanded upon some of the adaptation schemes noted above to provision means for best configuring therapy output in service of cardiac re synchronization therapy.

[0011] Based on the above, it is therefore an object of the present invention to provide a method and system for better supporting AV synchronous pacing in leadless pacemakers.

[0012] The object is solved by a computer implemented method for far-field cardiac event detection in an implantable medical device having the features of claim 1.

[0013] Furthermore, the object is solved by a system for far-field cardiac event detection in an implantable medical device having the features of claim 14.

[0014] In addition, the object is solved by a computer program with program code to perform the method according to the present invention when the computer program is executed on a computer.

[0015] Moreover, the object is solved by a computer-readable data carrier containing program code of a computer program for performing the method according to the present invention when the computer program is executed on a computer.

[0016] Further developments and advantageous embodiments are defined in the dependent claims.

[0017] The present invention provides a computer implemented method for far-field cardiac event detection in an implantable medical device. The method comprises providing the implantable medical device being configured to operate using a first set of far-field sensing parameters, monitoring a prevalence of AV synchrony by the implantable medical device, identifying insufficient AV synchrony based on at least one predetermined condition, selecting at least a second set of far-field sensing parameters

[0018] 23.060P-WO / 02.04.2026among a plurality of far-field sensing parameter sets, and executing the selected second set of far-field sensing parameters.

[0019] According to an embodiment, the monitoring a prevalence of AV synchrony is performed between patient follow-ups.

[0020] Furthermore, the present invention provides a system for far-field cardiac event detection in an implantable medical device. The system comprises the implantable medical device being configured to operate using a first set of far-field sensing parameters.

[0021] Moreover, the system comprises a computing unit configured to monitor a prevalence of AV synchrony by the implantable medical device and an identifying unit configured to identify insufficient AV synchrony based on at least one predetermined condition.

[0022] According to an embodiment, monitoring a prevalence of AV synchrony is performed between patient follow-ups.

[0023] The system in addition comprises a selection unit configured to select a second set of far-field sensing parameters among a plurality of far-field sensing parameter sets and the implantable medical device being configured to execute the selected second set of far-field sensing parameters.

[0024] In addition, the present invention provides a computer program with program code to perform the method according to the present invention when the computer program is executed on a computer.

[0025] Moreover, the present invention provides a computer-readable data carrier containing program code of a computer program for performing the method according to the present invention when the computer program is executed on a computer.

[0026] Far-field cardiac event detection is known as monitoring for heart contractions occurring in chambers other than the one where the implanted device’s sensing electrodes reside, e.g. detection of ventricular electrical activity in the atrium. AV synchrony is defined as a QRS complex preceded by a P-wave within 300 ms.

[0027] 23.060P-WO / 02.04.2026According to an embodiment, the method further comprises monitoring of sequences of a sensed atrial activity followed by a ventricular (sensed or paced) activity. The monitored sequences are evaluated to which extent a VDD mode is operating in a state which is driven by the atrial rate.

[0028] An idea of the present invention is to optimize far-field sensing through the continuous monitoring of patient and / or patient / device conditions and, in turn, dynamically refining the prescription for atrial autosensing between follow-ups.

[0029] All of the known adaptive offerings establish a single set of boundary conditions for any of changes permissible between follow-ups. As such, while medical devices can monitor prevailing conditions and change their responses, the devices are never able to collect information between follow-ups that enables the wholesale revision of the boundary conditions for device response. Specific to the autosensing needs for far-field signaling, this historic limitation in adaptive support challenges the capacity for leadless therapies to access optimized AV synchrony subject to patient and / or patient / device interactions that emerge or change between follow-ups.

[0030] The present invention outlines a new approach to better leveraging this increased configuration support in ways that are not restricted to a single far-field parameter set prescribed at follow-up or programming at a single point in time during a remote of in-person follow up procedure.

[0031] In VDD leadless pacemakers, the invention offers a means for accessing improved AV synchrony responses across a broader set of the bradycardia population. The invention further simplifies a complex programming procedure. Often times a large number of parameters are involved in programming appropriate sensing, especially for VDD systems with a single implant. This invention describes selection of one setting among a plurality of settings, each setting comprising a plurality of parameters, wherein the system is configured to select the setting with the most beneficial parameters in terms of AV synchrony automatically, which allows it to achieve an optimum output without human interaction.

[0032] The invention also permits the automatic adjustment and optimization of the sensing parameters over time to address changing device conditions, physiologic condition, health status of the patient, or the wishes of the clinician to achieve a certain effect. Traditionally, parameters or parameter sets are not automatically adjusted by the device. Automatic adjustment of sensing parameters furthermore reduces the need for follow up procedures which can be expensive for the health care system, applying both to in person follow up and remote programming based follow up.

[0033] 23.060P-WO / 02.04.2026Remote follow-ups / remote programming as well as in person follow-ups also have an impact on battery usage and battery drain for the implant. Thus, an improved or optimized sensing solution reduces the need for these follow-ups and reprogramming and can thus extend the longevity of the implant. In AAI leadless pacemakers, the invention offers a means for better tracking conduction responses which, in turn, offers means for reporting on heart block conditions that may need further attention

[0034] According to an aspect of the invention, the plurality of far-field sensing parameter sets, in particular the plurality of atrial far-field sensing parameter sets, comprise user- and / or system-accessible groups comprising at least the first set of far-field sensing parameters, the second set of far-field sensing parameters and a third set of far-field sensing parameters. A specific set of far-field sensing parameters can thus be programmed during follow-ups as well as dynamically set between followups.

[0035] According to a further aspect of the invention, any one of the plurality of far-field sensing parameter sets comprises at least one of: a sense channel parameter for threshold settings, a filtering prescription, an adaptation time constant and / or a condition for certifying that subsequent samples are trending in predefined directions. Thus, AV synchrony can be more accurately determined.

[0036] According to a further aspect of the invention, if a currently executing set of far-field sensing parameters inadequately supports atrial tracking, in particular if atrial tracking is below a predetermined threshold value, another set of far-field sensing parameters among the plurality of far-field sensing parameter sets is selected. Hence, the implantable medical device is configured to operate using an optimal parameter setting at any time.

[0037] According to a further aspect of the invention, each of the plurality of far-field sensing parameter sets is consecutively selected and executed to test its relative performance and, to select a best set of far-field sensing parameters for ongoing use. In doing so, the best of the available parameter settings at a given time can be determined and executed by the implantable medical device.

[0038] According to a further aspect of the invention, the least one predetermined condition for identifying insufficient AV synchrony is a measurement of at least one predetermined output parameter of the implantable medical device, in particular AV-synchrony metrics such as ASVS (atrial sense, ventricular sense) and / or ASVP (atrial sense, ventricular pace) sequence counts in the implantable

[0039] 23.060P-WO / 02.04.2026medical device being outside a predetermined range. Therefore, an accurate determination of sufficient or insufficient AV synchrony can be made. In such an exemplary embodiment the AV-synchrony metrics would count the number of ventricular senses or ventricular paces within a predetermined AV interval (for instance within 200-300ms or 250 ms) after an atrial sense. A predetermined condition for identifying insufficient AV synchrony may be X% (percentage of ASVS / ASVP within the predetermined AV interval) AV synchrony during a given time interval, in particular hour, day or week. An additional or alternative predetermined condition for identifying insufficient AV synchrony may be a decline of AV synchrony by Y% (percentage of ASVS / ASVP within the AV interval less than a predetermined previous time interval, in particular hour, day, week). A specific example may be an AV synchrony of 85-95% or 90% (meaning for instance 90% of all ASVS / ASVP within the predetermined AV interval) or a decline of the AV synchrony by 8-3% or 5% (meaning for instance a decline of 5% AV synchrony compared to yesterdays AV synchrony).

[0040] According to a further aspect of the invention, further output parameters usable for optimization of far-field cardiac event detection comprise at least one of an area under the curve or a power density measurement during a P-wave measurement, a heart rhythm status, a diagnosis status of a patient, predominant and secondary sequence statuses or pacing modes, in particular VDD mode or VVI (V = pacing in the ventricle, V = sensing in the ventricle, I = inhibit) mode, a prevalence of a synchronous mode (as e.g. VDD) or an asynchronous mode (as VVI), a number of switches between modes, a percentage of detected P-waves, an amplitude of detected P-waves, a timing of detected P-waves and / or a morphology of detected P-waves, a number of cardiac cycles and / or a time in which an intrinsic atrial rate has been measured, i.e. where the VDD mode has been in atrial tracking state. Thus, an effective optimization of far-field cardiac event detection can be performed using one or more of a plurality of suitable parameters.

[0041] According to a further aspect of the invention, at least one sensing parameter within at least one programmed boundary condition is adjusted based on measurement and / or computation of statistics on sensing and pacing sequences to maximize / improve the detection of AS sequences and to minimize the prevalence of asynchronous non-tracking conditions using signal filtering properties, wherein at least a high pass filter is adjusted by the implantable medical device and / or wherein at least a T-wave blanking parameter is adjusted dynamically by the implantable medical device to optimize AV synchrony performance.

[0042] 23.060P-WO / 02.04.2026According to an embodiment of the present invention, if atrial senses AS are measured, followed by ventricular senses VS within a physiological AV delay, such AS VS state should be supported by the implantable device, e.g. by adding a hysteresis time to the AV delay. In a patient with permanent AV block, maximizing ASVP sequences is a goal, and a setting, comprising a plurality of parameters of atrial sensing, is selected automatically by the implant to maximize the ASVP count. As an example, the duration of blanking of the signal after the T-wave are adjusted to maximize the likelihood of detecting the far-field P wave and thus establishing an ASVP rhythm.

[0043] According to a further aspect of the invention, at least one other parameter associated with far-field sensing of a P-wave is adjusted, comprising at least one of a sensing threshold of any portion of a signal, a blanking time of any portion of the signal, a filtering property during an entire time window of the signal or during specific windows of time relative to the R-wave, T-wave or P-wave, an increasing or decreasing slope threshold of the signal, a threshold number of threshold crossings or zero crossings of the signal, a morphology or template matching parameter threshold. Thus, an effective far-field sensing of the intrinsic atrial event can be achieved.

[0044] According to a further aspect of the invention, atrial sensing parameters for a far-field P-wave, in particular a T-wave blanking time, filter comers, and thresholds are automatically and dynamically adjusted to achieve a greatest area under the curve for P-wave candidates. The area under the curve acts as a surrogate that indicates detection of a proper P-wave and not an artifact or interference. Atrial sensing parameters such as T wave blanking time, filter comers, and thresholds are dynamically adjusted to maximize the area under the curve of the P wave candidate and thus achieve best possible P wave detection.

[0045] According to a further aspect of the invention, re-optimization of the far-field sensing parameters is conducted on a periodic basis such as every hour, day, week or month or when a performance metric reaches a given threshold from above or below. For instance, when the area under the curve of the P-wave candidate decreases below a given threshold it is suspected that P-wave detection is no longer optimized, and the procedure would be automatically triggered and rerun to optimize P-wave detection. In another example when the duration of time in non-tracking mode substates exceeds a given threshold, P-wave detection optimization is triggered and remn to minimize non-tracking and / or mode-switching prevalence and maximize tracking behavior such as an ASVSASVS or ASVPASVP sequence.

[0046] 23.060P-WO / 02.04.2026According to a further aspect of the invention, wherein the re-optimization procedure is triggered by the measurement of a given property of the system, in particular a time spent in synchronized mode (as VDD) or asynchronous mode or in an asynchronous mode (as VVI), a number of switches between modes, and / or a property of the detected P-wave. Thus, the adjustment can be triggered using one of a plurality of measurement results.

[0047] According to an embodiment, the re-optimization procedure is programmable by a user.

[0048] According to a further aspect of the invention, the QT interval duration and / or the degree of saturation of the far-field signal may be monitored. The QT interval duration and / or the saturation of the far-field signal may be periodically monitored over a series of 2-16 cardiac cycles. The periodical monitoring may take place once per hour or in more energy constrained implants once or more per day. The QT interval duration and / or the degree of saturation of the far-field signal may be used to select the at least one second set of far-field sensing parameters among a plurality of far-field sensing parameter sets.

[0049] In an embodiment the QT interval duration may be determined by determining the time between the maximum amplitude of the ventricular signal (for instance the near-field signal) or the ventricular sense / ventricular pace event marker and the re-settling of the ventricular signal down to 5% of baseline (e.g. signal within a 5% deviation from the baseline amplitude of the ventricular signal). As an alternative embodiment the QT interval duration may be determined by a starting event trigger (threshold crossing, threshold slope or other onset criteria) and an end event trigger (zero crossing (positive-negative or negative-positive), target slope value or other means). The QT interval duration may therefore be determined between the earliest onset or any reference point of the QRS complex and any reference point or the end of the T-wave in the ventricular signal.

[0050] The saturation of the far-field signal may be determined by comparing the maximum signal amplitude with the maximum range of the far-field signal channel at the current parameter settings. A maximum signal amplitude within 1 %, 5 % or 10% of the maximum range may trigger the selection of a second set of far-field signal sensing parameters.

[0051] Moreover, according to a preferred embodiment of the present invention, the implantable medical device is a cardiac pacemaker which requires a far-field sensing to acquire an information from a chamber in which no sensing electrode is implanted. For instance, the implantable medical device

[0052] 23.060P-WO / 02.04.2026is a leadless cardiac pacemaker or a cardiac pacemaker having an electrode lead in the ventricle, but no lead in the atrium.

[0053] The herein described features of the computer implemented method for far-field cardiac event detection in an implantable medical device are also disclosed for the system for far-field cardiac event detection in an implantable medical device and vice versa.

[0054] For a more complete understanding of the present invention and advantages thereof, reference is now made to the following description taken in conjunction with the accompanying drawings. The invention is explained in more detail below using exemplary embodiments, which are specified in the schematic figures of the drawings, in which:

[0055] Fig. 1 shows a flowchart of a computer implemented method for far-field cardiac event detection in an implantable medical device according to the preferred embodiment of the invention; and

[0056] Fig. 2 shows a diagram of a system for far-field cardiac event detection in an implantable medical device according to the preferred embodiment of the invention.

[0057] The computer implemented method for far-field cardiac event detection in an implantable medical device 10 of Fig. 1 comprises providing SI the implantable medical device 10 being configured to operate using a first set of far-field sensing parametersAutol, monitoring S2 a prevalence of AV synchrony between patient follow-ups by the implantable medical device 10, identifying S3 insufficient AV synchrony based on at least one predetermined condition 12, selecting S4 at least one second set of far-field sensing parameters Auto2 among a plurality of far-field sensing parameter sets Autol, Auto2, Auto3,...AutoN and executing S4 the selected second set of far-field sensing parameters Auto2.

[0058] The plurality of far-field sensing parameter sets Autol, Auto2, Auto3, in particular the plurality of atrial far-field sensing parameter sets, comprise user- and / or system-accessible groups comprising at least the first set of far-field sensing parameters Autol, the second set of far-field sensing parameters Auto2 and a third set of far-field sensing parameters Auto3.

[0059] Any one of the plurality of far-field sensing parameter sets Autol, Auto2, Auto3 prescribes a variety of sense channel parameters for threshold settings, filtering prescriptions, adaptation time constants

[0060] 23.060P-WO / 02.04.2026and / or conditions for certifying that subsequent samples are trending in predefined directions. If a currently executing set of far-field sensing parameters Autol, Auto2, Auto3 inadequately supports atrial tracking, in particular if atrial tracking is above or below a predetermined threshold value, another set of far-field sensing parameters Autol, Auto2, Auto3 among the plurality of far-field sensing parameter sets Autol, Auto2, Auto3 is selected.

[0061] Each of the plurality of far-field sensing parameter sets Autol, Auto2, Auto3 is consecutively selected and executed to test its relative performance and, to select a best set of far-field sensing parameters Autol, Auto2, Auto3 for ongoing use. The least one predetermined condition 12 for identifying insufficient AV synchrony is a measurement of at least one predetermined output parameter of the implantable medical device 10, in particular AV synchrony metrics such as AS VS and / or ASVP sequence counts in the implantable medical device 10 being outside a predetermined range.

[0062] Further output parameters usable for optimization of far-field cardiac event detection comprise an area under the curve or power density measurements during a P-wave measurement, a heart rhythm status, a diagnosis status of a patient, predominant and secondary sequence statuses or pacing modes, in particular, VDD mode or VVI mode, a percentage of detected P-waves, an amplitude of detected P-waves, a timing of detected P-waves and / or a morphology of detected P-waves, a number of cardiac cycles and / or a time in which an intrinsic atrial rate has been measured, i.e. where the VDD mode has been in atrial tracking state..

[0063] Sensing parameters within programmed boundary conditions are adjusted based on measurement and / or computation of statistics on sensing and pacing sequences to maximize AS-VX (VX standing for VS or VP) sequences and minimize non-tracking and / or mode-switched conditions using signal filtering properties, in particular high pass filter comers adjusted by the implantable medical device 10 and / or T-wave blanking parameters are adjusted dynamically by the implantable medical device 10 to optimize AV synchrony performance.

[0064] Other parameters associated with far-field sensing of a P-wave are adjusted, comprising sensing thresholds of any portion of a signal, blanking times of any portion of the signal, filtering properties during an entire time window of the signal or during specific windows of time relative to the R-wave, T-wave or P-wave, increasing or decreasing slope thresholds of the signal, threshold crossings or zero crossings of the signal, morphology or template matching parameter thresholds.

[0065] 23.060P-WO / 02.04.2026Atrial sensing parameters for a far-field P-wave, in particular a T-wave blanking time, filter comers, and thresholds are automatically and dynamically adjusted to achieve a greatest area under the curve for P-wave candidates. Re -optimization of the far-field sensing parameters Autol, Auto2, Auto3 is conducted on a periodic basis such as every hour, day, week or month or when a performance metric reaches a given threshold from above or below.

[0066] An optimization procedure is ran as programmed by a user, and wherein the optimization procedure is triggered by the measurement of a given property of the system, in particular a time spent in synchronized mode VDD or asynchronous modes and / or a property of the detected P-wave.

[0067] The best mode of carrying out the invention is envisioned to be one where a multitude of atrial far-field autosensing configuration settings are binned into user- and system-accessible groups e.g., Autol, Auto2, Auto3, etc.

[0068] Any single autosensing parameter setting group e.g., Autol would serve to prescribe a variety of underlying sense channel parameters for matters as broad as critical integrated threshold settings, filtering prescriptions, adaptation time constants, conditions for certifying that subsequent samples are trending in intended directions, etc.

[0069] Instead of forcing clinicians to simply pick one of the binned groupings to operate as a set of static boundary conditions in effect till the next follow-up, the best embodiment offers support for users to insist that the Implant instead dynamically select the most fitting of the binned settings at any point between follow-up based on prevailing conditions.

[0070] In cases where just a single binned grouping is leveraged / accessible between follow-up i.e., Auto 1, the dependent leadless pacer is challenged in accessing the same degree of AV synchronous pacing that is available in contexts where a multitude of binned groupings are employable between followup i.e., Autol + Auto2 + Auto3.

[0071] Between follow-up, the Implant would survey the prevalence of AV synchrony and subject to conditions where it was found to be insufficient, a routine would execute to enable new “trial” binned groupings of atrial far-field settings.

[0072] If, for example, the Autol grouping had been underperforming in its capacity to support atrial tracking, the device would change to the Auto2 grouping / set and run an evaluation to test for

[0073] 23.060P-WO / 02.04.2026improvements. The process could be repeated, rotating through the full set of available preconfigured groupings to evaluate their relative performance and, in turn, choose a new, best option for ongoing use e.g., Auto3.

[0074] Specific thresholds could be used to drive how often this dynamic selection of binned groupings occurred - in best forms balancing appropriately between the likelihood that the changes themselves proves symptomatic against the challenges associated with therapies that lack intended synchrony conditions.

[0075] The automated process of adjusting parameters would be guided by the measurement of some desired output. A desired output includes AV-synchrony metrics such as AS VS or ASVP sequence counts in the implant.

[0076] When far-field performance is poor due to poor P-wave detection, P-wave synchronized pacing sequences will be lower. In this condition the device may revert to an asynchronous mode-switched pacing mode, and underserving the patient’s therapeutic needs.

[0077] Therefore, sensing parameters within programmed boundary conditions could be adjusted automatically to maximize the prevalence of ASVX sequences and minimize the risk for modeswitching. This could be accomplished using varying signal filtering properties such as high pass filter comers automatically adjusted by the device, or T-wave blanking parameters could be adjusted dynamically by the device to optimize AV synchrony performance.

[0078] As a concrete example, atrial sensing parameters for the far-field P-wave is automatically and dynamically adjusted to achieve the greatest area under the curve for the P wave candidates. The area under the curve acts as a surrogate that indicates detection of a proper P wave and not an artifact or interference.

[0079] Atrial sensing parameters such as T-wave blanking time, filter comers, and thresholds are dynamically adjusted to maximize the area under the curve of the P-wave candidate and thus achieve best possible P-wave detection. Re-optimization of these parameters is conducted either on a periodic basis such as every hour day week or month or when a performance metric reaches a given threshold from above or below.

[0080] 23.060P-WO / 02.04.2026For instance, when the area under the curve of the P-wave candidate decreases below a given threshold it is suspected that P-wave detection is no longer optimized, and the procedure would be automatically triggered and rerun to optimize P wave detection. In another example when the duration of time in a mode-switched, asynchronous condition exceeds a given threshold, P-wave detection optimization is triggered and rerun to try and minimize the prevalence of mode-switching and re-instate tracking behaviors wherein ASVS or ASVP sequences prevail.

[0081] Fig. 2 shows a diagram of a system for far-field cardiac event detection in an implantable medical device 10 according to the preferred embodiment of the invention.

[0082] The system comprises the implantable medical device 10 being configured to operate using a first set of far-field sensing parameters Auto 1 and a computing unit 14 configured to monitor a prevalence of AV-synchrony between patient follow-ups by the implantable medical device 10.

[0083] Furthermore, the system comprises an identifying unit 16 configured to identify insufficient AV-synchrony based on at least one predetermined condition 12, a selection unit 18 configured to select a second set of far-field sensing parameters Auto2 among a plurality of far-field sensing parameter sets Autol, Auto2, Auto3, and the implantable medical device 10 being configured to execute the selected second set of far-field sensing parameters Auto2.

[0084] In the following a specific example of the computer-implemented method and the system according to the invention is described. In this example the medical device is a leadless pacemaker configured to detect a far-field and a near-field signal. The leadless pacemaker may be configured for implantation within the ventricle of a heart. The far-field signal comprises the atrial signal and the near-field signal comprises the ventricular signal. The far-field sensing parameters may comprise at least the duration and starting time of the atrial detection window (ADW, e.g. the time window of the far-field signal analysed in the far-field channel for the expected atrial sense), the atrial sense gain (ASG, e.g. the gain of the far-field channel in which the far-field signal is processed) and the atrial sensitivity (e.g. the rectification and filtering settings of the far-field channel). All three far-field sensing parameters may be set to standard values corresponding to first set of parameters Auto 1. At least two alternative settings for each of the three parameters may be available and therefore corresponding to plurality of far-field sensing parameter sets Autol, Auto2... Auto27.

[0085] An exemplary decision tree for selecting the second set of far-field sensing parameters based on QT interval duration and the degree of saturation of the far-field signal will be described below, whereby

[0086] 23.060P-WO / 02.04.2026the AV synchrony metric, the QT interval duration and the degree of saturation of the far-field signal will be determined once a day.

[0087] If AV synchrony is < 90% (e.g., 90%) OR AV synchrony declines by >5%:

[0088] • Has the QT interval elongated to a degree that T-wave signaling is at risk for residing within the early portion of the ADW?

[0089] • If yes, select the “next” ADW setting that narrows the duration of the open window (e.g. later starting time and shorter duration of the ADW)

[0090] • If no, and there is enough margin to expand the duration of the ADW, select the “next” larger ADW configuration setting (e.g. earlier starting time and longer duration of the ADW)

[0091] • Else, leave the atrial detection window duration settings intact

[0092] • Is there evidence of substantial saturation within the ADW?

[0093] • If yes, change the ASG setting to the “next” lower available setting

[0094] • If no, leave as is

[0095] • Is there evidence of too small an atrial signal on cycles where AS events are seen (i.e., below the noise floor, or only using the + / - 25% of the range, or only 50% of the range)?

[0096] • If yes, change the atrial sense gain setting to the “next” higher available setting • If no, leave as is

[0097] • If any adjustments were made to the ADW or the ASG based on prior bullets in the algorithm, exit the algorithm, pause until next determination of AV synchrony, QT interval duration and saturation of the far-field signal, and then pick up with Part 2 the algorithm

[0098] • Else proceed to the next major bullet

[0099] • Is the mean signal within the ADW >30% (e.g., >30%) of the total available frequency range (as permitted by the ASG)?

[0100] • If yes, and the current setting of the atrial sensitivity is “Pwave enhancement” change the atrial sensitivity to the “Standard” rectification and filtering setting • If yes, and the current setting of the atrial sensitivity is “Standard” change the atrial sensitivity to the “Twave suppression” rectification and filtering selection

[0101] • If no, leave as is

[0102] • Is the mean signal within the ADW greater than the noise floor but still on average only <5% of the total available frequency range (as permitted by the ASG)?

[0103] • If yes, and the current setting of the atrial sensitivity is “T-wave suppression” change the atrial sensitivity to the “Standard” rectification and filtering setting

[0104] 23.060P-WO / 02.04.2026If yes, and the current setting of the atrial sensitivity is “Standard” change the atrial sensitivity to the “Pwave enhancement” rectification and filtering selection If no, leave as is

[0105] Part 2, only executed if adjustments according to the bullet points above were made to the ADW and / or ASG: ) Is AV synchrony >90& or improved by more than 5%?

[0106] • If no, and the mean signal within the atrial detection window >30% of the total available frequency range (as permitted by the ASG)

[0107] • If atrial sensitivity is “Pwave enhancement” change the atrial sensitivity to the “Standard” rectification and filtering setting

[0108] • If atrial sensitivity is “Standard” change the atrial sensitivity to the “Twave suppression” rectification and filtering selection

[0109] • Else, leave as is

[0110] • If no, and the mean signal within the atrial detection window is greater than the noise floor but still on average only <5% (e.g., 5%) of the total available frequency range

[0111] • If atrial sensitivity is “Twave suppression” change the atrial sensitivity to the “Standard” rectification and filtering setting

[0112] • If atrial sensitivity is “Standard” change the atrial sensitivity to the “Pwave enhancement” rectification and filtering selection

[0113] • Else, leave as is

[0114] Further expansions and / or alternative means for adjusting settings to explicitly avoid T-wave oversensing may be also feasible. The system could survey the commonality of AS events registering early within the ADW (e.g., within the front -10%) and the co-prevalence of Wenckebach (WKB) pacing within the ventricle. If such signatures ever present, the between-follow-up ADW duration should be narrowed by delaying its start till a point in time further after the VS or VP (i.e., a change from short ADW to standard ADW or a change from “Standard” ADW to long ADW). Conversely, an absence of this early AS detection within the ADW and the WKB paced terminations of the cardiac cycle, could serve as grounds for considering expansions in the duration of the atrial detection window (i.e., starting the ADW sooner after the VS or VP via either a change from long ADW to standard ADW or a change from standard ADW to short ADW). Subject to any reduction in the ADW to combat T-wave oversensing, a continued prevalence of AS events registering early within the ADW and cycles terminating in WKB paces, may be used to, in turn, drive the PVABP settings to be extended to further blank the front portion of the ADW and better cover any prevalent T-waves. Subsequent nested routines to then reduce the ASG to limit T-wave content within the window, and

[0115] 23.060P-WO / 02.04.2026even transition the atrial sensitivity to, especially, the ‘T-wave suppression’ type (or possibly other) would also land within the scope of what is disclosed herein. The target for completion would be the realization of regular ASVP or ASVS cycles rather than any that terminated in WKB paces.

[0116] Further expansions and / or alternative means for adjusting settings to explicitly combat QRS oversensing may also be feasible. In such contexts the system could purposefully assess the commonality of large, sudden upticks or values in the signal amplitudes at / toward the end of the ADW (i.e., especially cases where this “last” value is the highest within the ADW). If such signatures ever present, thebetween follow-up atrial sensitivity setting should be updated to a ‘P-wave enhancement’ configuration. The content within the ADW would then be re-evaluated after the change - confirming the mitigation of QRS oversensing by the absence of large-value content toward / at the end of the ADW.

[0117] A more simpler alternative to the above described exemplary decision tree may be a simple cycling through the respective far-field sensing parameter sets Autol, Auto2... Auto9, meaning cycling the ADW between standard ADW, long ADW, short ADW, the ASG between standard ASG (70-125 pV), high ASG (<75 pV) and low ASG (> 125 pV) and the atrial sensitivity between standard, “Pwave enhancement” and “Twave suppression”. In addition some parameter sets may be prioritized.

[0118] 23.060P-WO / 02.04.2026Reference Signs

[0119] 1 system

[0120] 10 implantable medical device

[0121] 12 predetermined condition

[0122] 14 computing unit

[0123] 16 identifying unit

[0124] 18 selection unit

[0125] Autol first set of far-field sensing parameters Auto2 second set of far-field sensing parameters Auto3 third set of far-field sensing parameters S1-S5 method steps

[0126] 23.060P-WO / 02.04.2026

Claims

Claims1. Computer implemented method for far-field cardiac event detection in an implantable medical device (10), comprising the steps of:providing (SI) the implantable medical device (10) being configured to operate using a first set of far-field sensing parameters (Autol);monitoring (S2) a prevalence of AV-synchrony by the implantable medical device (10); identifying (S3) insufficient AV-synchrony based on at least one predetermined condition (12);selecting (S4) at least one second set of far-field sensing parameters (Auto2) among a plurality of far-field sensing parameter sets (Autol, Auto2, Auto3); andexecuting (S5) the selected second set of far-field sensing parameters (Auto2).

2. Computer implemented method of claim 1 , wherein the plurality of far-field sensing parameter sets (Autol, Auto2, Auto3), in particular the plurality of atrial far-field sensing parameter sets, comprise user- and / or system-accessible groups comprising at least the first set of far-field sensing parameters (Autol), the second set of far-field sensing parameters (Auto2) and a third set of far-field sensing parameters (Auto3).

3. Computer implemented method of claim 1 or 2, wherein any one of the plurality of far-field sensing parameter sets (Autol, Auto2, Auto3) comprises at least one of: a sense channel parameter for threshold settings, a filtering prescription, an adaptation time constant and / or a condition for determining that subsequent samples are trending in at least one predefined direction.

4. Computer implemented method of any one of the preceding claims, wherein if a currently executing set of far-field sensing parameters (Autol, Auto2, Auto3) inadequately supports atrial tracking, in particular if atrial tracking is below a predetermined threshold value, another set of far-field sensing parameters (Autol, Auto2, Auto3) among the plurality of far-field sensing parameter sets (Autol, Auto2, Auto3) is selected.

5. Computer implemented method of any one of the preceding claims, wherein each of the plurality of far-field sensing parameter sets (Autol, Auto2, Auto3) is consecutively selected and executed to test its relative performance and, to select a best set of far-field sensing parameters (Autol, Auto2, Auto3) for ongoing use.23.060P-WO / 02.04.20266. Computer implemented method of any one of the preceding claims, wherein the least one predetermined condition (12) for identifying insufficient AV-synchrony is a measurement of at least one predetermined output parameter of the implantable medical device (10), in particular AV-synchrony metrics such as ASVS and / or AS VP sequence counts in the implantable medical device (10) being outside a predetermined range.

7. Computer implemented method of claim 6, wherein further output parameters usable for optimization of far-field cardiac event detection comprise at least one of an area under the curve or a power density measurement during a P-wave measurement, a heart rhythm status, a diagnosis status of a patient, predominant and secondary sequence statuses or pacing modes, in particular a prevalence of an VDD mode or an asynchronous mode, a number of switches between modes, , a percentage of detected P-waves, an amplitude of detected P-waves, or a timing of detected P-waves and / or a morphology of detected P-waves a number of cardiac cycles and / or a time in which an intrinsic atrial rate has been measured.

8. Computer implemented method of any one of the preceding claims, wherein at least one sensing parameter within at least one programmed boundary condition is adjusted based on measurement and / or computation of statistics on sensing and pacing sequences to maximize the detection of AS sequences and to minimize VVI mode behavior using signal filtering properties, wherein at least a high pass filter is adjusted by the implantable medical device (10) and / or wherein at least a T-wave blanking parameter is adjusted dynamically by the implantable medical device (10) to optimize AV synchrony performance.

9. Computer implemented method of any one of the preceding claims, wherein at least one other parameter associated with far-field sensing of a P-wave is adjusted, comprising at least one of a sensing threshold of any portion of a signal, a blanking time of any portion of the signal, a filtering property during an entire time window of the signal or during specific windows of time relative to the R-wave, T-wave or P-wave, increasing or decreasing a slope threshold of the signal, a threshold number of threshold crossings or zero crossings of the signal, a morphology or template matching parameter threshold.

10. Computer implemented method of any one of the preceding claims, wherein at least one atrial sensing parameter for a far-field P-wave, in particular a T-wave blanking time, a filter comer,23.060P-WO / 02.04.2026or a threshold is automatically adjusted to achieve a greatest area under the curve for P-wave candidates in the detected far-field cardiac events.

11. Computer implemented method of any one of the preceding claims, wherein re-optimization of the far-field sensing parameters (Autol, Auto2, Auto3) is conducted on a periodic basis such as every hour, day, week or month or when a performance metric reaches a given threshold from above or below.

12. Computer implemented method of any one of claim 11, wherein the re-optimization procedure is triggered by at least one of a time spent in VDD mode or asynchronous mode, or a number of switches between modes, and / or a property of the detected P-wave.

13. Computer implemented method of any one of the preceding claims, wherein the implantable medical device is a leadless cardiac pacemaker.

14. System for far-field cardiac event detection in an implantable medical device (10), comprising:the implantable medical device (10) being configured to operate using a first set of far-field sensing parameters (Autol);a computing unit (14) configured to monitor a prevalence of AV-synchrony by the implantable medical device (10);an identifying unit (16) configured to identify insufficient AV synchrony based on at least one predetermined condition (12);a selection unit (18) configured to select at least a second set of far-field sensing parameters (Auto2) among a plurality of far-field sensing parameter sets (Autol, Auto2, Auto3); and the leadless implantable medical device (10) being configured to execute the selected second set of far-field sensing parameters (Auto2).

15. System according to claim 14, wherein the implantable medical device is a leadless cardiac pacemaker.23.060P-WO / 02.04.2026

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