Rapid Resolution of New Right Bundle Branch Block in Acute Anterior Myocardial Infarction Patients after Thromholytic Therapy

The objectives of this retrospective study are to describe the effect of thrombolytic treatment on the clinical course of patients with acute anterior myocardial infarction complicated by acute right bundle branch block. Patients admitted to the intensive cardiac care unit vvilhin < 4 hours from onset of symptoms, and demonstrating an acute right bundle branch blockwith, or without left axis deviation, on the qualifying ECG were included. AIJ were given intravenous thrombolytic treatment consisting of: streptokinase (1.500,000 IU/40 min) or recombinant tissue type plasminogen activator (120 mg/6 hoursj. Following admission, patients were continuously monitored and a 12‐lead ECG was recorded during each of the first 3 hours and then every 3 hours over the next 21 hours. Eight patients were included (8/211 = 3.8%). Their mean age was 62 ± 7 years and time eJapse from onset to treatment was 122 ± 26 minutes. Complete resolution of the right bundle branch block occurred within < 3 hours in alJ and left axis deviation normalized in two patients. Mean peak creatine kinase wos 1214 ± 604 IU and global left ventricular ejection fracfion, measured by isotope ventriculography within 24 hours from admission, was 39%± 15%. Only one patient was prophylactically paced. In the others, rapid normalization of the conduction block with reperfusion exceeded the logistics required for the transvenous pacemaker implantation procedure. Coronary angiography performed in six patients during 72 hours from admission revealed high grade stenoses in the proximal portion of the left anterior descending coronary artery in five patients and complete occlusion in one. Clinical course was generally uneventful and patients were discharged with a mean ejection fraction of 38%± 15%. Thus, patients presenting with anterior myocardial infarction accompanied by a new right bundle branch or bifascicular block are not necessarily candidates for transvenous temporary pacing and may benefit from revascularization.