INFLUENCE OF THROMBOLYTIC THERAPY ON THE EVOLUTION OF BAROREFLEX SENSITIVITY AFTER MYOCARDIAL-INFARCTION

Depressed baroreceptor sensitivity (BRS) has been associated with an increased risk of ventricular arrhythmias and sudden cardiac death after myocardial infarction, but the influence of thrombolytic therapy on BRS has not been examined. To determine the effect of thrombolytic therapy on the evolution of BRS after myocardial infarction, BRS was assessed at 6 days, 6 weeks, and 3 months in 76 patients, 53 (70%) of whom had received thrombolytic therapy. The mean age (57 vs 57 years), sites of infarction, and the proportion of patients taking beta-blockers (68% vs 52%) did not differ between patients who did and those who did not receive thrombolytic therapy. There was no difference in predischarge mean left ventricular ejection fractions (42% vs 46%) between the two groups of patients, but mean baseline BRS was 9.2 (0.8) msec/mm Hg in patients who were treated with thrombolysis and 5.9 (1.3) msec/mm Hg in those who were not (p = 0.03). At 6 weeks the corresponding values were 9.7 (1.1) and 11.1 (2.8) msec/mm Hg (p = 0.6) and at 3 months 9.1 (1.0) and 6.5 (1.1) msec/mm Hg (p = 0.07). At baseline 13% of patients who were treated with thrombolysis and 13% of those who were not had BRS <3.0 msec/mm Hg, but at 3 months 9% of patients who were treated with thrombolytic agents compared with 17% of those who had BRS <3.0 msec/mm Hg. In conclusion, early after myocardial infarction mean BRS was higher in patients treated with thrombolysis compared with nontreated patients. Similar trends were noted 3 months later, and the proportion of patients with low BRS was smaller in those given thrombolytic therapy compared with those who were not. Thrombolytic therapy should reduce the incidence of early and late sudden cardiac death after myocardial infarction.