- Holter monitoring shows one or more of the following: Any symptomatic arrhythmia (except isolated extra systoles); Sustained cardiac arrhythmias (such as atrial fibrillation or flutter, SVT (>10 consecutive beats)); Sustained tachycardia >150 beats per minute; Non-sustained or sustained ventricular tachycardia (defined as >3 consecutive ventricular ectopic beats); Any conduction abnormality (including but not specific to left or right complete bundle branch block, AV block [2nd degree or higher in an awake subject], WPW syndrome, other pre-excitation syndromes); Symptomatic sinus pause or sinus pause >3 seconds - unless patient is straining, vomiting, or having some other type of hypervagal response; 300 or more supraventricular ectopic beats in 24 hours; 250 or more ventricular ectopic beats in 24 hours; Ischemia, diagnosed by a sequence of ECG changes that include flat or downsloping ST-segment depression >0.1 mV, with a gradual onset and offset that lasts for a minimum period of 1 minute. Each episode of ischemia must be separated by a minimum duration of at least 1 minute, during which the ST segment returns back to baseline (1x1x1 rule).