Risk factors for sudden death after acute myocardial infarction: two-year follow-up.

The risk of sudden coronary death after myocardial infarction (MI) was assessed in 533 patients who survived 10 days after MI and were followed for up to 24 months (mean 18) in the Multicenter Investigation of the Limitation of Infarct Size. Analysis of multiple clinical and laboratory variables determined before hospital discharge revealed that frequent ventricular premature beats (VPBs) (greater than or equal to 10/hour) on ambulatory electrocardiographic monitoring and left ventricular (LV) dysfunction (radionuclide LV ejection fraction less than or equal to 0.40) were independently significant markers of risk for subsequent sudden death believed to be the result of a primary ventricular arrhythmia. The incidence of sudden death was 18% in patients with both LV dysfunction and frequent VPBs (11 times that of patients with neither of these findings). Seventy-nine percent of all sudden deaths occurred within 7 months after the index MI. In 280 survivors reclassified 6 months after MI with regard to the presence or absence of frequent VPBs and LV dysfunction, these risk factors could not be associated with sudden coronary death over a further follow-up period of up to 18 months; the overall incidence of sudden cardiac death was low (1.4%) after 6 months. Thus, the presence of frequent VPBs in association with LV dysfunction early after MI identifies patients at high risk for sudden death over the next 7 months.