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 bund(e-branch block (RBBB) in the setting of acu te anterior myocardial infarction. The aim of this study has been to analys e these effects and its impact on prognosis. Methods - We studied 54 patients who presented a RBBB related to an acute a nterior myocardial infarction. We defined two groups: those who received th rombolytic treatment and those who did not. We analysed the evolution of RB BB (transience, moment of onset, moment of disappearance) and its relations hip with in-hospital mortality. Twenty-one patients (39%) received thrombol ytic treatment (group T) and 33 patients (61%) (group NT) did not. Results - The incidence of late appearance (> 6 h) of RBBB was less frequen t 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). Howe ver, 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 w ith 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 disap pearance of RBBB by promoting its early disappearance and avoiding its late appearance. Disappearance of RBBB is associated with a better prognosis.