In one example, a
cardiac monitoring system comprises a processor to receive a segment of an electrocardiogram (ECG)
signal of a patient, and a memory to store the segment of the ECG. The processor is configured to identify QRS complexes in the segment of the
ECG signal, generate a supraventricular (SV) template for SV complexes in the QRS complexes, identify SV complexes in the QRS complexes using the template, identify
normal sinus rhythm (NSR) complexes in the segment of the
ECG signal, obtain an atrial template for atrial waveforms in the NSR complexes, measure a range of a P-wave of the atrial waveforms from the NSR complexes, save the measured P-
waves, and classify the identified SV complexes as either
atrial fibrillation (AF) or
supraventricular tachycardia (SVT) using the atrial template. Other examples and related methods are also disclosed herein.