Rfe. Pedretti et al., EFFECT OF THROMBOLYSIS ON HEART-RATE-VARIABILITY AND LIFE-THREATENINGVENTRICULAR ARRHYTHMIAS IN SURVIVORS OF ACUTE MYOCARDIAL-INFARCTION, Journal of the American College of Cardiology, 23(1), 1994, pp. 19-26
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.