INADEQUACY OF QUALITATIVE IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR ELECTROGRAM ANALYSIS TO DISTINGUISH SUPRAVENTRICULAR FROM VENTRICULAR-TACHYCARDIA DUE TO ELECTROGRAM CHANGES DURING NORMALLY CONDUCTED COMPLEXES

Stored electrograms (EGMs) recorded from ICD leads are used to evaluat e the appropriateness of ICD therapies. Stored EGMs different from sin us have been interpreted as ventricular in origin. We present a patien t with an ICD for VT who received multiple shocks for a tachycardia wi th a stored EGM different than sin us, suggesting VT. An electrophysio logical study demonstrated EGMs different than sinus during atrial pac ing and induced supraventricular arrhythmias. This case points out the limitations of stored EGMs and suggests complete electrophysiological study with analysis of EGMs during induced arrhythmias should be perf ormed prior to discharge.