[Cardiac autonomic tone in risk stratification after myocardial infarct: results of a prospective long-term study of 411 consecutive patients].

Prognosis of patients surviving acute myocardial infarction has substantially improved over the last two decades. However, stratification of patients at risk for death due to arrhythmic events remains a clinical challenge. Due to the important role of the autonomic nervous system in the genesis of sudden death, autonomic markers such as heart rate variability and baroreflex sensitivity have recently gained attention as risk stratification parameters. The present study reports the results of noninvasive risk stratification in 411 consecutive postinfarction patients treated due to contemporary therapeutical guidelines with a high proportion of patients discharged with a patent infarct related artery. The diagnostic arsenal of risk parameters comprised heart rate variability, baroreflex sensitivity, and more traditional markers such as non-sustained ventricular tachycardia, left ventricular ejection fraction, and ventricular late potentials. Patients were followed for a mean of 33 +/- 21 months. Stepwise logistic regression analysis revealed that left ventricular function, both autonomic markers, and the patency of the infarct related artery were independent predictors of the prospectively defined primary study endpoint, i.e., all-cause mortality plus ventricular tachyarrhythmic events. With respect to the secondary endpoint (ventricular tachyarrhythmic events), left ventricular function, heart rate variability, and infarct vessel patency were independent predictors. Ventricular late potentials and nonsustained ventricular tachycardia had no predictive value with respect to ventricular tachyarrhythmic events. These findings from a large prospective long-term study demonstrate the value of markers of cardiac autonomic tone in identifying infarct survivors at risk for malignant ventricular tachyarrhythmias and sudden death.