1. A method comprising: sensing a signal indicative of cardiac electrical activity; comparing an amplitude of the signal to a first threshold; detecting at least one of a asystole or a bradycardia based on the comparison of the amplitude of the signal to the first threshold; comparing an amplitude of at least one R-wave detected in the signal to at least a second threshold; and determining whether the detection of the asystole or the bradycardia is false based on the comparison of the amplitude of the detected R-wave to the at least second threshold.