The relation between supraventricular tachyarrhythmias and left ventricular dysfunction after acute myocardial infarction.

The clinical characteristics of supraventricular tachyarrhythmias (SVTA) and their relation to left ventricular dysfunction were assessed in 208 consecutive patients with recent myocardial infarction. Arrhythmias were quantified on hospital discharge by 24 hour electrocardiographic recording. All the variables were evaluated between the second and the fourth week after infarction. SVTA occurred in 113 (54%) patients: Supraventricular premature beats (SVPB) in 49 (24%), frequent or repetitive SVPB in 37 (18%), atrial or junctional tachycardia in 23 (11%), atrial flutter or fibrillation in 4 (2%). Most of these arrhythmias occurred in the absence of symptoms, and the most complex forms were always selflimiting. No relation was found among the presence of different forms of SVTA and sex, coronary risk factors, previous history of ischemic heart disease, type or site of acute myocardial infarction, NYHA functional class. Age, left atrial dimension (LAD), cardio-thoracic ratio (CTR) and left ventricular ejection fraction (LVEF) at rest differed significantly among three groups of patients: those without SVTA, those with SVPB less than 100 per hour and those with frequent-repetitive SVPB or atrial-junctional tachycardia. The more SVTA complexity, the worse LAD, CTR, LVEF and the higher the age. Multivariate discriminant analysis showed that CTR was directly and LVEF inversely related to the occurrence of SVPB less than 100 per hour, while the presence of frequent-repetitive SVPB or supraventricular tachycardia was closely related to increasing age, LAD, CTR and decreasing LVEF. Patients with atrial fibrillation always showed the worst values of LAD, CTR, LVEF and age. The results of the present study show that different types of SVTA occurring at discharge from hospital after myocardial infarction are clinically benign, but always suggestive of different degrees of left ventricular dysfunction.