RELATIONSHIP BETWEEN AUTONOMIC NERVOUS-SYSTEM LEST RESULTS, EJECTION FRACTION AND INDUCIBILITY OF SUSTAINED VENTRICULAR ARRHYTHMIAS BY MEANS OF ELECTROPHYSIOLOGICAL STUDIES

Autonomic nervous system dysfunction and low left ventricular ejection fraction have been associated with an increased incidence of cardiac arrhythmias and sudden death. This research was conducted to determine whether Valsalva ratio (longest to shortest R-R interval during Valsa lva manoeuvre), R-R variability (standard deviation of R-R intervals i n a 60-second electrocardiographic recording strip), and corrected QT interval permit the identification of those patients with an inducible sustained ventricular arrhythmia when submitted to electrophysiologic al studies. We also evaluated the ejection fraction as a predictive in dex of inducibility. We studied 42 patients (21 males), 38 +/- 19 year s old, who were submitted to an electrophysiological study in order to evaluate supraventricular (control group: n = 16) or ventricular arrh ythmias (n = 26). The patients studied for the evaluation of ventricul ar arthythmias presented structural and functional cardiac damage. The ir ejection fraction (0.41 +/- 0.17) was significantly reduced (p = 0. 01) when compared to that of the control group (0.61 +/- 0.08). The pa tients with cardiac damage had abnormal autonomic nervous system test results. None of the measurements was significantly related to the ind ucibility of sustained ventricular tachyarrhythmias in the group of pa tients who had structural and functional involvement. The finding of a bnormal cardiac autonomic nervous system indices and low ejection frac tion can be related to structural heart disease, but neither the abnor mal cardiac autonomic nervous system indices nor the low ejection frac tion allows us to identify the patients who will develop inducible sus tained ventricular tachyarrhythmias when submitted to electrophysiolog ical study.