A method of pericardial thickness assessment

Abstract

This invention relates to a method for assessing pericardial thickness. The method involves: acquiring a standard 12-lead electrocardiogram of the subject and calculating the frontal plane QRS-T angle; comparing the frontal plane QRS-T angle with a preset threshold of 108°; matching the corresponding assessment strategy based on the comparison result; and determining the pericardial thickness level of the subject based on the matched assessment strategy. The correlation coefficient between the assessed thickness and the actual pericardial thickness can reach 0.89-0.52, which is much higher than the 0.17 of traditional echocardiography and also better than the 0.27 of CT measurement, significantly improving the accuracy of the assessment.

Description

Technical Field

[0001] This invention relates to the field of electrocardiogram signal analysis and cardiac physiological parameter detection technology, specifically to a method for assessing pericardial thickness. Background Technology

[0002] Pericardial thickness is a key physiological indicator for diagnosing cardiac pericardial diseases such as pericarditis and constrictive pericarditis. Currently, the quantitative assessment of pericardial thickness in clinical practice heavily relies on imaging techniques. Echocardiography, as the preferred non-invasive screening method, has low overall testing costs and is radiation-free. However, this method is highly dependent on the operator's technical experience, is subjective, and is limited by the patient's cardiac acoustic window and equipment resolution, resulting in limited spatial imaging accuracy and significant errors in pericardial thickness measurement. Clinical studies have verified that the correlation coefficient between echocardiographic results and actual pericardial thickness measured with calipers is only 0.17, which is not statistically significant, and the accuracy is insufficient to meet the needs of precise clinical diagnosis.

[0003] CT scans and cardiac MRI are both commonly used clinical diagnostic methods. However, CT scans involve ionizing radiation, making them unsuitable for repeated testing or for patients with specific health conditions. Cardiac MRI offers high precision and is radiation-free, but it is expensive and time-consuming, and has contraindications for patients with implanted metal devices or those whose conditions prevent them from tolerating prolonged examinations. The high purchase and maintenance costs of these two types of advanced imaging equipment hinder their widespread adoption in primary healthcare institutions, significantly limiting their broad clinical application.

[0004] The frontal QRS-T angle is a mature and readily available non-invasive electrocardiographic biomarker that effectively reflects the heterogeneity of ventricular depolarization and repolarization. It is currently widely used in the assessment and prognosis of cardiovascular diseases such as myocardial hypertrophy, heart failure, and myocardial ischemia. However, current technologies and related clinical studies have not systematically explored the correlation between the frontal QRS-T angle and pericardial thickness in patients with constrictive pericarditis, nor have they uncovered the threshold correspondence between the two. Furthermore, the industry has not yet developed a non-invasive quantitative assessment scheme for pericardial thickness based on this electrocardiographic indicator, which fails to overcome the many shortcomings of traditional imaging methods, such as strong reliance on traditional methods, high cost, limited accuracy, and limited applicability.

[0005] In conclusion, developing a non-invasive, low-cost, easy-to-operate, and universally applicable method for assessing pericardial thickness based on the frontal QRS-T angle threshold can effectively fill the gap in existing technologies and has extremely high clinical application value and market promotion prospects. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a non-invasive, convenient, low-cost, and highly accurate method for assessing pericardial thickness, filling a gap in existing technologies and effectively resolving their deficiencies.

[0007] The technical solution of the present invention is implemented as follows: a method for assessing pericardial thickness, the method being: acquiring a standard 12-lead electrocardiogram of the subject to be tested, calculating the frontal plane QRS-T angle; comparing the frontal plane QRS-T angle with a preset threshold of 108°, matching the corresponding assessment strategy according to the comparison result, and determining the pericardial thickness level of the subject to be tested based on the matched assessment strategy.

[0008] Furthermore, when the frontal QRS-T angle is ≤108°, the pericardial thickness assessment value of the subject is calculated based on the negative correlation between the frontal QRS-T angle and pericardial thickness, combined with a preset prediction model.

[0009] Furthermore, when the frontal QRS-T angle is >108°, the pericardial thickness of the subject is evaluated by combining the pericardial thickness parameters measured by CT.

[0010] Furthermore, the frontal plane QRS-T angle is the absolute angle between the QRS wave axis and the T wave axis in a standard 12-lead electrocardiogram.

[0011] Furthermore, the measurement results of the frontal QRS-T angle were cross-validated by at least two independent cardiologists, and the intragroup correlation coefficient (ICC) obtained was greater than 0.85.

[0012] Furthermore, the prediction model is a multivariate linear regression model. In the population with a frontal QRS-T angle ≤108°, the model input parameters include the frontal QRS-T angle, pericardial thickness parameters measured by CT, limb lead voltage, bundle branch block, left ventricular end-diastolic diameter, left ventricular ejection fraction, and diabetes status. The Pearson correlation coefficient between the model's predicted value and the actual pericardial thickness is 0.89. The model formula is: Pericardial thickness = 0.143 × pericardial thickness parameters measured by CT + 0.385 × limb lead low voltage + 0.716 × bundle branch block + 0.293 × left ventricular end-diastolic diameter - 0.042 × left ventricular ejection fraction - 0.009 × frontal QRS-T angle value + 0.523 × diabetes.

[0013] Furthermore, the prediction model is a multivariate linear regression model. In the population with a frontal QRS-T angle > 108°, the model input parameters include the absolute value of Ptfv1, the pericardial thickness parameter measured by CT, gender characteristics, ST segment changes, precordial lead voltage, and bundle branch block. In this case, the Pearson correlation coefficient between the model's predicted value and the actual pericardial thickness is 0.52. The model formula is: Pericardial thickness = -4.819 × absolute value of Ptfv1 + 0.167 × pericardial thickness parameter measured by CT - 0.299 × female gender + 0.228 × ST segment changes + 0.602 × precordial lead low voltage - 0.755 × bundle branch block.

[0014] The present invention has the following positive effects: 1. This invention is non-invasive, convenient, and low-cost. It can be used in conjunction with a conventional 12-lead electrocardiogram to make a preliminary assessment of pericardial thickness (when the frontal plane QRS-T angle is ≤108°). This examination is widely used in medical institutions at all levels. It has no ionizing radiation, no contraindications, and extremely low examination cost. It can be widely used in primary medical institutions and is also suitable for subjects who cannot tolerate CT / CMR examinations.

[0015] 2. The accuracy of the assessment using this invention is significantly better than that of traditional methods. In the core application population with a frontal QRS-T angle ≤108°, the correlation coefficient between the frontal QRS-T angle used in this invention and the actual pericardial thickness can reach -0.56 (P=0.006), which is much higher than the 0.17 of traditional echocardiography (P=0.084, no statistical significance) and also better than the 0.27 of CT measurement (P=0.006), thus significantly improving the accuracy of the assessment.

[0016] 3. The prediction model of this invention has excellent consistency. In the population with a QRS-T angle ≤108°, the prediction model has a correlation coefficient of up to 0.89 (P<0.0001) between the predicted value and the actual pericardial thickness measured by vernier calipers, which can realize accurate quantitative assessment of pericardial thickness. Attached Figure Description

[0017] Figure 1 This is a distribution map of the baseline clinical characteristics of the population enrolled in the study of this invention.

[0018] Figure 2 This is a correlation analysis diagram of age, gender, clinical characteristics, and pericardial thickness in this invention.

[0019] Figure 3 This is a graph showing the correlation between clinical parameters and the consistency of imaging methods in this invention.

[0020] Figure 4 This is a graph showing the correlation between the QRS-T angle threshold effect and subgroups in this invention.

[0021] Figure 5 This is a graph verifying the consistency between the regression analysis and prediction model of this invention. Detailed Implementation

[0022] A method for assessing pericardial thickness includes: acquiring a standard 12-lead electrocardiogram of the subject and calculating the frontal plane QRS-T angle; comparing the frontal plane QRS-T angle with a preset threshold of 108°; matching the corresponding assessment strategy based on the comparison result; and determining the pericardial thickness level of the subject based on the matched assessment strategy.

[0023] When the frontal plane QRS-T angle is ≤108°, the pericardial thickness assessment value of the subject is calculated based on the negative correlation between the frontal plane QRS-T angle and pericardial thickness, combined with a preset prediction model. When the frontal plane QRS-T angle is >108°, the pericardial thickness is assessed by combining the pericardial thickness parameters measured by CT with the prediction model.

[0024] The frontal plane QRS-T angle is the absolute angle between the QRS wave axis and the T wave axis in a standard 12-lead electrocardiogram. The measurement results of the frontal plane QRS-T angle were cross-validated by at least two independent cardiologists, and the intraclass correlation coefficient (ICC) of the measurements was greater than 0.85. The predictive model is a multivariate linear regression model. In individuals with a frontal QRS-T angle ≤108°, the model input parameters include the frontal QRS-T angle, pericardial thickness measured by CT, limb lead voltage, bundle branch block, left ventricular end-diastolic diameter, left ventricular ejection fraction, and diabetes status. The Pearson correlation coefficient between the model's predicted values ​​and the actual pericardial thickness is 0.89. The model formula is: Pericardial thickness = 0.143 × pericardial thickness measured by CT + 0.385 × limb lead low voltage + 0.716 × bundle branch block + 0.293 × left ventricular end-diastolic diameter - 0.042 × left ventricular ejection fraction - 0.009 × frontal QRS-T angle + 0.523 × diabetes.

[0025] The prediction model is a multivariate linear regression model. In the population with a frontal QRS-T angle > 108°, the model input parameters include the absolute value of Ptfv1, pericardial thickness parameters measured by CT, gender characteristics, ST segment changes, precordial lead voltage, and bundle branch block. In this case, the Pearson correlation coefficient between the model's predicted value and the actual pericardial thickness is 0.52. The model formula is: Pericardial thickness = -4.819 × absolute value of Ptfv1 + 0.167 × pericardial thickness parameters measured by CT - 0.299 × female gender + 0.228 × ST segment changes + 0.602 × precordial lead low voltage - 0.755 × bundle branch block.

[0026] In specific implementation, such as Figure 1-5As shown, a method for assessing pericardial thickness first obtains a standard 12-lead electrocardiogram within 24 hours of admission. The QRS and T-wave axes are calculated using IntelliSpace professional ECG analysis software, yielding the absolute angle between them, i.e., the frontal plane QRS-T angle. This measurement process is verified by two independent cardiologists to ensure consistency (ICC>0.85). Threshold scanning determines that when the threshold is 108°, the correlation between the frontal plane QRS-T angle and actual pericardial thickness differs significantly between subgroups (r = -0.56, p = 0.006 for the ≤108° group and r = -0.050, p = 0.647 for the >108° group; difference p = 0.0066). Based on the relationship between the frontal plane QRS-T angle of the subject and this threshold, a differentiated assessment strategy is adopted: when the frontal plane QRS-T angle is ≤108°, the strong negative correlation between QRS-T angle and pericardial thickness in this subgroup is used to input the prediction model based on multivariate linear regression to calculate the pericardial thickness assessment value of the subject; when the frontal plane QRS-T angle is >108°, the pericardial thickness parameters measured by CT are combined with the prediction model based on multivariate linear regression to calculate the pericardial thickness assessment value of the subject.

[0027] The predictive model was trained using the frontal plane QRS-T angle and related clinical parameters as input, with the actual pericardial thickness measured by calipers as the gold standard. In individuals with a QRS-T angle ≤108°, the model's predicted value showed a Pearson correlation coefficient of 0.89 with the actual pericardial thickness, demonstrating extremely high assessment consistency. When the frontal plane QRS-T angle >108°, the pericardial thickness parameters measured by CT were combined with the predicted model constructed based on multivariate linear regression to calculate the estimated pericardial thickness of the subject, which showed a Pearson correlation coefficient of 0.52 with the actual pericardial thickness.

[0028] The present invention will be described in detail below through specific verification embodiments: This retrospective study included 108 participants who visited our center between January 2018 and May 2025. Among them, 81 were male (75%) and 27 were female (25%), with a mean age of 57.75 ± 16.22 years. All participants underwent standard 12-lead electrocardiogram, echocardiogram, and CT scan, and participants with missing clinical data were excluded.

[0029] All subjects underwent a standard 12-lead electrocardiogram (ECG) within 24 hours of admission, with a sampling rate of 500 Hz, paper speed of 25 mm / s, and calibration of 10 mm / mV. The QRS and T-wave axes were automatically calculated using IntelliSpace professional ECG analysis software; the absolute angle between them is the frontal plane QRS-T angle. This result was manually verified by two independent, experienced cardiologists, with an intragroup correlation coefficient (ICC) > 0.85, ensuring measurement consistency. Other ECG parameters were also recorded.

[0030] Pericardial thickness measured with vernier calipers was used as the gold standard. A 256-slice CT scanner was used to measure the pericardial thickness at multiple sites, including the anterior wall of the right ventricle, the lateral wall of the left ventricle, and the inferior wall. The maximum value was taken as the actual pericardial thickness. At the same time, echocardiography was used to measure the pericardial thickness, and the average value of three cardiac cycles was taken.

[0031] Through threshold effect analysis, this embodiment determined the optimal threshold for the frontal QRS-T angle to be 108°, and divided the subjects into two subgroups: Group 1: QRS-T angle ≤ 108° subgroup (n=23): In this subgroup, the frontal plane QRS-T angle was significantly and strongly negatively correlated with the actual pericardial thickness, with a correlation coefficient r = -0.56, P = 0.006, which was highly statistically significant; while the correlation coefficient between the traditional echocardiogram measurement and the actual thickness was only 0.17, P = 0.084, which was not statistically significant, and the correlation coefficient between the CT measurement and the actual thickness was 0.27, P = 0.006, all of which were significantly weaker than the indicators of this invention.

[0032] Group 2: QRS-T angle > 108° subgroup (n=85): In this subgroup, the QRS-T angle was not significantly correlated with pericardial thickness (r=0.05, P=0.647), but the CT measurement was significantly positively correlated with the actual thickness (r=0.31, P=0.004). Therefore, this subgroup can be evaluated in conjunction with CT parameters.

[0033] A predictive model was constructed based on multivariate linear regression, using the frontal QRS-T angle and related clinical parameters as inputs and the actual pericardial thickness as output. Validation results showed that in the subgroup with a QRS-T angle ≤108°, the Pearson correlation coefficient between the model's predicted value and the actual pericardial thickness was as high as 0.89 (P<0.0001), indicating extremely high consistency between the two. In the subgroup with a QRS-T angle >108° and the entire population, the correlation coefficients were 0.52 and 0.41, respectively, both of which were statistically significant, validating the excellent performance of the model.

[0034] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method of pericardial thickness assessment, characterized by, The method is as follows: a standard 12-lead electrocardiogram of the subject is collected, and the frontal plane QRS-T angle is calculated; the frontal plane QRS-T angle is compared with a preset threshold of 108°. When the frontal plane QRS-T angle is less than or equal to the preset threshold, the corresponding evaluation strategy is matched according to the comparison result, and the pericardial thickness level of the subject is determined according to the matched evaluation strategy.

2. The pericardium thickness evaluation method according to claim 1, characterized by: When the frontal plane QRS-T angle is ≤108°, the pericardial thickness assessment value of the subject is calculated based on the negative correlation between the frontal plane QRS-T angle and pericardial thickness, combined with the preset prediction model; when the frontal plane QRS-T angle is >108°, the pericardial thickness of the subject is assessed by combining the pericardial thickness parameters measured by CT.

3. The pericardium thickness evaluation method according to claim 1, characterized by: The frontal plane QRS-T angle is the absolute angle between the QRS wave axis and the T wave axis in a standard 12-lead electrocardiogram.

4. The pericardium thickness evaluation method of claim 1, wherein: The measurements of the frontal QRS-T angle were cross-validated by at least two independent cardiologists, and the intraclass correlation coefficient (ICC) was greater than 0.

85.

5. The pericardium thickness evaluation method according to claim 2, characterized by: The prediction model is a multivariate linear regression model. In the population with a frontal QRS-T angle ≤108°, the input parameters of the model include the frontal QRS-T angle, pericardial thickness parameters measured by CT, limb lead voltage, bundle branch block, left ventricular end-diastolic diameter, left ventricular ejection fraction, and diabetes status. The Pearson correlation coefficient between the model's predicted value and the actual pericardial thickness is 0.

89. The model formula is: pericardial thickness = 0.143 × pericardial thickness parameters measured by CT + 0.385 × limb lead low voltage + 0.716 × bundle branch block + 0.293 × left ventricular end-diastolic diameter - 0.042 × left ventricular ejection fraction - 0.009 × frontal QRS-T angle value + 0.523 × diabetes.

6. The method for assessing pericardial thickness according to claim 2, characterized in that: The prediction model is a multivariate linear regression model. In the population with a frontal plane QRS-T angle > 108°, the model input parameters include the absolute value of Ptfv1, pericardial thickness parameters measured by CT, gender characteristics, ST segment changes, precordial lead voltage, and bundle branch block. In this case, the Pearson correlation coefficient between the model's predicted value and the actual pericardial thickness is 0.

52. The model formula is: Pericardial thickness = -4.819 × absolute value of Ptfv1 + 0.167 × pericardial thickness parameters measured by CT - 0.299 × female gender + 0.228 × ST segment changes + 0.602 × precordial lead low voltage - 0.755 × bundle branch block.

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