Ventricular vulnerability assessed by programmed ventricular stimulation in patients with and without late potentials.

Abstract

Late potentials can be recorded noninvasively with the averaging technique in about 1/3 of patients with coronary heart disease in whom ventricular tachyarrhythmias have not been previously documented. The prognostic significance of these findings has not yet been established. Therefore, the presence or absence of late potentials was correlated to the results of programmed ventricular stimulation (single and double premature stimuli during sinus rhythm, and a paced ventricular rhythm, cycle lengths 500, 430, 370 and 330 ms) in 110 male patients (age 52 .+-. 5.9 yr, mean .+-. SD). The end of the stimulation protocol was reached as soon as 4 or more ventricular echo beats (defined as an abnormal response) were induced. Late potentials were recorded in 40 patients (36.4%). The duration of late potentials was < 20 ms in 12 patients, between 20 and 39 ms in 16 patients, and 40 ms or more in another 12 patients. In those patients with late potentials, 4 or more consecutive ventricular echo beats (repetitive ventricular response) were recorded more frequently (63%) than in those without (33%). The incidence of abnormal responses increased from 42% in those with late potentials of < 20 ms to 56% in those with late potentials of between 20-39 ms and to 92% in those with late potentials of 40 ms or more. There was a significant correlation between left ventricular function, and presence and duration of late potentials (.chi.2 = 12.96; P < 0.0115), and between left ventricular function and the results of programmed ventricular stimulation (.chi.2 = 16.24; P < 0.0003). In contrast, late potentials and the results of programmed ventricular stimulation were less closely associated (.chi.2 = 5.49; P < 0.0643). Late potentials proved to be a noninvasive indicator of abnormal left ventricular function, indicating an increase in ventricular vulnerability in patients that were free of symptomatic ventricular tachyarrhythmias. The predictive value of both late potentials and repetitive ventricular responses alone or in combination with regard to the occurrence of ventricular tachycardia or sudden death is still to be established.