EFFECT OF THROMBOLYSIS ON HEART-RATE-VARIABILITY AND LIFE-THREATENINGVENTRICULAR ARRHYTHMIAS IN SURVIVORS OF ACUTE MYOCARDIAL-INFARCTION

Objectives. The aim of the present study was to determine the influenc e of early thrombolysis on ventricular tachyarrhythmias (clinical and inducible) and heart rate variability in survivors of myocardial infar ction at high risk for life-threatening ventricular arrhythmias. Backg round. A greater electrical heart stability may be important in improv ing survival in patients treated with thrombolysis. Few data are avail able about the influence of fibrinolysis on postinfarction arrhythmic events and other prognostic variables, such as inducible ventricular t achycardia and heart rate variability. Methods. The study group compri sed 51 consecutive patients who underwent electrophysiologic study wit hin 30 days of infarction, owing to the presence of two or more of the following criteria: left ventricular ejection fraction <40%, late pot entials and repetitive ventricular ectopic beats. Thirty patients unde rwent thrombolysis within 6 h of the onset of symptoms (Group A), and 21 received conventional treatment (Group B). Inducibility of sustaine d monomorphic ventricular tachycardia was tested in both groups, and t he standard deviation of all normal RR intervals during 24-h Holter mo nitoring was calculated. All patients were prospectively evaluated for occurrence of arrhythmic events. Results. The two groups were similar with regard to left ventricular ejection fraction (mean +/- 1 SD 38 /- 6% [Group A] vs. 36 +/- 8% [Group B]). Ventricular tachycardia was induced in 6 (20%) of 30 Group A patients versus 14 (67%) of 21 Group B patients (p = 0.002). The standard deviation of normal RR intervals was higher in Group A than in Group B (113 +/- 36 vs. 90 +/- 39 ms, p = 0.05). In patients with anterior infarction, the standard deviation of normal RR intervals was higher in 19 patients with thrombolysis tha n in 16 patients with conventional treatment (118 +/- 41 vs. 74 +/- 24 ms, p = 0.0002). During a mean follow-up period of 23 +/- 11 months, 4 (13%) of 30 Group A patients had an arrhythmic event versus 9 (43%) of 21 Group B patients (p = 0.04). Conclusions. After myocardial infar ction, in high risk patients, thrombolysis significantly reduced the o ccurrence of arrhythmic events independently of left ventricular funct ion. This effect may be related to both an improvement in electrical h eart stability, as elucidated by electrophysiologic study, and a favor able action on the cardiac sympathovagal balance.