Prognostic impact of bundle branch blocks in patients with ST-segment elevation myocardial infarction

Background: In this study we aim to determine and compare short term outcomes of all type bundle branch blocks (BBB) according to their onset time among those patients presented with ST-Segment elevation myocardial infarction (STEMI) and underwent primary percutaneous coronary intervention (pPCI). Method: Three thousand fifty-seven ST-segment elevation myocardial infarction patients who underwent pPCI were retrospectively evaluated. Those patients with BBB in their ECG on admission were re-evaluated for their prior ECG records. A composite of death, recurrent myocardial infarction (re-MI) and stroke in one moth follow up were defined as major adverse cardiovascular events (MACE). Results: Three thousand fifty-seven STEMI patients underwent pPCI were enrolled to the study. Among these patients 134 (4.4%) had LBBB, and 120 (3.9%) had RBBB. Bundle brunch block was classified according to the timing of their onset as follows; New or Presumably New BBB, Old BBB, Indeterminate Onset BBB. At one month, 4.8% of the patients died, 2.6% had re-MI/stent thrombosis, 0.5% had stroke. MACE occurred in 7.6% of patients. Left ventricle ejection fraction, BBB, estimated glomerular filtration rate (eGFR), shock and age were ranked as the strongest predictors of MACE. Compared to non-BBB, all BBBs except for old RBBB was found to be associated with increased MACE. New onset LBBB was the strongest predictor (OR:13.1, 95%CI:3.98–43.4, p <.001) at one month MACE. Conclusion: Compared to non-BBB, all BBBs except for old RBBB was found to be associated with increased MACE. New onset LBBB was the strongest predictor for MACE at one month.