The 'compensatory pause' of atrial fibrillation

Abstract

A long pause after an abnormal beat during atrial fibrillation has been called a 'compensatory pause' and has been used to identify premature ventricular complexes (PVCs) and to differentiate them from supraventricular beats with aberration. The diagnostic value of the compensatory pause is controversial and has not been tested systematically with programmed stimulation and intracardiac recordings. In this study we used these methods to determine if PVCs induced during atrial fibrillation were followed by compensatory pauses. Five patients were studied who had ECGs with a normal PR interval and a normal QRS duration and morphology during sinus rhythm. Atrial fibrillation was induced by rapid atrial pacing. PVCs were induced by coupling a ventricular extrastimulus to every eighth or tenth QRS complex during atrial fibrillation. The coupling interval of the PVC was changed in 10- or 20-msec increments until the entire cardiac cycle was scanned. The mean duration of recorded atrial fibrillation was 15.7 minutes. Fifty-seven to 163 PVCs were induced in each patient. The mean cycle after the induced PVC was calculated and compared with the mean control cycle. The mean cycle after the PVC was 107-136 msec longer than the mean control cycle (p < 0.001 in every patient). This study confirms the presence of a compensatory pause after stimulated PVCs in atrial fibrillation.