[Incidence, clinical characteristics and prognostic significance of supraventricular tachyarrhythmias in acute myocardial infarction].

Objectives: The study of incidence and prognostic significance of supraventricular tachyarrhythmias in patients with acute myocardial infarction.
Patients and Methods: Prospective study on 1,239 patients consecutively admitted because of a diagnosis of acute myocardial infarction. Clinical characteristics, indexes of myocardial infarction and complications were analysed.
Results: Supraventricular tachyarrhythmias were observed in 116 (9.3%) cases: atrial fibrillation in 96 (7.7%); atrial tachycardia in 15 (1.2%); and atrial flutter in the remaining five cases (0.4%). Patients with supraventricular tachyarrhythmias were older, and presented higher heart rate, lower blood pressure, a higher number of affected leads in ECG, and higher Killip class. A higher creatine kinase peak and a lower left ventricular ejection fraction were associated with the presence of supraventricular tachyarrhythmias. Predictors of supraventricular tachyarrhythmias were: age, systolic blood pressure, number of affected leads in ECG, and congestive heart failure at admission. The following complications were found more frequently in patients with supraventricular tachyarrhythmias: bundle-branch block, complete A-V block, ventricular tachycardia, ventricular fibrillation; heart failure; stroke; and mortality, in-hospital 18.1% vs 11.1% (p < 0.05) and one-year, 38.7% vs 18.4% (p < 0.001). The logistic regression model showed that supraventricular tachyarrhythmias had no independent prognostic value on mortality.
Conclusions: The appearance of supraventricular tachyarrhythmias during the acute phase of myocardial infarction is a relatively frequent finding, often associated with older age and larger infarctions. Supraventricular tachyarrhythmias are accompanied by higher short and long-term mortalities, although there is no independent prognostic significance.