Effects of thrombolysis in the evolution of right bundle-branch block complicating an acute anterior myocardial infarction.

Introduction: There is scant information about the effects of thrombolysis in the evolution of right bundle-branch block (RBBB) in the setting of acute anterior myocardial infarction. The aim of this study has been to analyse these effects and its impact on prognosis.

Methods: We studied 54 patients who presented a RBBB related to an acute anterior myocardial infarction. We defined two groups: those who received thrombolytic treatment and those who did not. We analysed the evolution of RBBB (transience, moment of onset, moment of disappearance) and its relationship with in-hospital mortality.Twenty-one patients (39%) received thrombolytic treatment (groupT) and 33 patients (61%) (group NT) did not.

Results: The incidence of late appearance (> 6 h) of RBBB was less frequent in group T compared with group NT (10% vs. 33%, p = 0.04). The incidence of transient block was similar in the two groups (57% vs. 45%, p ns). However, early disappearance of RBBB (in < 6 hours) was more common in group T than in group NT (33% vs. 9%, p = 0.04). Mortality was higher in patients with RBBB present at 24 h after admission) than in those with RBBB resolved in less than 24 hours (in group NT, 55% vs. 8%, p = 0.02 and in group T 50% vs. 0%, p = 0.02, respectively).

Conclusions: Thrombolysis seems to influence the moment of onset and disappearance of RBBB by promoting its early disappearance and avoiding its late appearance. Disappearance of RBBB is associated with a better prognosis.