Identifying patients at risk of sudden death after myocardial infarction: Value of the response to programmed stimulation, degree of ventricular ectopic activity and severity of left ventricular dysfunction

Abstract

The ability of programmed ventricular stimulation to identify risk of sudden death after acute myocardial infarction (MI) was compared with 24-hour electrocardiographic assessment of ventricular ectopic activity and determination of left ventricular (LV) dysfunction. Forty-six patients underwent programmed stimulation 8 to 60 days (mean 22) after documented MI. Programmed stimulation consisted of single and double extrastimuli from the right ventricular apex at 2 times diastolic threshold during ventricular pacing and normal sinus rhythm. Of the 46 patients, 44 underwent electrocardiographic monitoring at least 6 days after MI. In 43 of the 46 patients, LV ejection fraction (EF) and the presence of LV aneurysm were determined. In response to programmed ventricular stimulation, 5 patients had sustained ventricular tachycardia (VT), 5 had nonsustained VT (≥4 beats), 13 had intraventricular reentrant repetitive responses, and 23 had either bundle branch reentrant repetitive responses or no extra responses to programmed ventricular stimulation (negative study). During a mean follow-up of 18 months, 10 patients died, 6 suddenly. One of the 10 patients with sustained or nonsustained VT died suddenly, compared with 3 of 13 patients with intraventricular reentrant responses and 2 of 23 patients with a negative study (difference not significant). Of 25 patients with Grade 0 to 2 ventricular ectopic activity, 3 died suddenly after MI, compared with 3 of 19 patients with Grade 3 or 4 activity (difference not significant). By comparison, the frequency of sudden death was greater in patients with an LVEF of <40% (5 of 16 versus 1 of 27 patients) or an LV aneurysm (5 of 13 versus 1 of 30 patients). Thus, using the described protocol, the response to programmed ventricular stimulation is not helpful in identifying patients at risk for sudden death after MI. The presence of an LV aneurysm or EF of <40% appears to provide the greatest prognostic information with respect to risk for sudden cardiac death.