Comparison of clinical value of right bundle block in ST elevation myocardial infarction and in non-ST elevation myocardial infarction

Abstract

Objective To evaluate the incidence and clinical impact of right bundle branch block (RBBB) in patients with non-ST elevation myocardial infarction(NSTEMI) and patients with ST elevation myocardial infarction(STEMI).Methods Nine hundred and thirty-one patients with AMI were divided into STEMI team and NSTEMI group,each group was sub divided into right bundle branch block (RBBB) group and none bundle branch block (NBBB) group furtherly according to the ECG appearance.Patients with left bundle branch block were excluded.The difference of baseline clinical characteristics,short-term inhospital treatment,in hospital and one-year mortality between RBBB group and NBBB groups were analyzed.Independent predictors of raised mortality was screened by Logistic regression stepwise method.Results A total of 16 patients(7.14％) with NSTEMI and 47 patients(6.65％) with STEMI presented with RBBB on admission.In general,RBBB patients were older,more often had comorbidities,and less often received short-term inhospital treatment according to guidelines.In STEMI,RBBB patients had higher peak enzyme levels and lower left ventricular ejection fraction (LVEF) than patients without BBB.Right bundle branch block in STEMI was associated with an increased inhospital and long-term mortality.However,peak enzyme levels and LVEF were similar in both groups with and without BBB in NSTEMI.Right bundle branch block in NSTEMI was not independently associated with a worse outcome.Conclusions Unlike RBBB in STEMI,RBBB in NSTEMI is not an independent predictor of inhospital and long-term mortality. Key words: Acute non-ST elevation myocardial infarction;  Right bundle branch block ;  Clinical outcome