How long should high-risk patients with acute anterior wall myocardial infarction be monitored?

In 143 patients with an acute anterior wall myocardial infarction, left ventricular ejection fraction was determined within 72 h of admission. Left ventricular ejection fraction was below 40% in 114 patients. In this group late ventricular tachycardia or ventricular fibrillation occurred in 30 patients (26%). A left ventricular ejection fraction below 40% identified all patients who developed any late ventricular tachycardia and a left ventricular ejection fraction below 30% identified all who developed late ventricular fibrillation. After discharge another 2 patients with late ventricular tachycardia were detected. Death between 48 h and 3 weeks only occurred in patients with a left ventricular ejection fraction below 30%. Thus in patients with an acute anterior wall myocardial infarction a left ventricular ejection fraction below 30% within the first 72 h after the acute event identifies a high risk for late ventricular tachycardia or ventricular fibrillation. The occurrence of late ventricular tachycardia showed a gradual increase during 3 weeks of monitoring and no cut-off point could be detected within this time-window.