Identification of ventricular late potentials in the surface electrocardiogram during atrial, atrioventricular sequential, or single-chamber ventricular pacing

Sudden cardiac death occurs in up to 30% of patients with cardiac pacemaker s, caused by ventricular arrhythmias, but in these patients noninvasive ris k stratification with Holter, exercise, or standard signal-averaged electro cardiogram is limited. This study investigated whether late potential analy sis during cardiac pacing is applicable. In 50 postinfarction patients with documented sustained ventricular tachycardia (VT) and in 50 patients witho ut VT, late potential analysis during sinus rhythm was compared with the co rresponding patient's analysis during temporary pacing. During sinus rhythm late potentials were seen in 48 of 50 patients with VT and in 2 of 50 pati ents without VT. No significant changes were observed during atrial pacing. Modified QRS alignment for signal averaging, QRS endpoint definition, and adjusted cutoff values for abnormality in time and frequency domain analysi s allowed retrieval of all late potentials observed during sinus rhythm eve n in ventricular-paced beats and retrograde conduction. By application of a n adjusted analysis to 100 selected patients with permanent pacemakers (50 patients with a history of VT, 50 patients without VT) late potentials were detectable in 44 of 50 patients with VT and in 4 of 50 without VT (sensiti vity 88%, specificity 92%). Thus, considering that varying pacing modes, ve ntricular-paced beats, and retrograde conduction do require modifications o f standard late potential analysis, this is an applicable mode for noninvas ive risk stratification even in patients with cardiac pacemakers.