BUNDLE BRANCH BLOCKS AND OUTCOMES IN STEMI PATIENTS TREATED WITH PRIMARY PCI

Abstract

Bundle branch blocks (BBB) are associated with increased mortality in ST-elevation myocardial infarction (STEMI) patients treated with fibrinolysis. We assessed the relationship between BBB in STEMI patients treated with primary percutaneous coronary intervention (PCI) and acute and long-term outcomes. A prospective cohort of 3829 patients undergoing primary PCI for treatment of STEMI from Jan 1, 2002 to Dec 31, 2012 was analyzed. Old ECG’s from 1996 until presentation were obtained for patients with BBB to determine if the BBB previously existed. For patients with left bundle branch block (LBBB), only those with inappropriately concordant ST changes were included. Mortality data was obtained through hospital and provincial mortality records. Using patients with a QRS interval of < 120ms as a reference, crude and multivariate adjusted odds ratios (ORs) for ventricular arrhythmias during primary PCI, intra-aortic balloon pump (IABP) use, and for 30-day and 1-year mortality were calculated for different BBB types. For patients with RBBB (n=259), the ORs for 30-day and 1-year mortality were 7.73 (95%CI 5.35, 11.16) and 5.78 (4.16-8.05), respectively; and 6.03 (4.09-8.90) and 4.44 (3.12-6.32) after adjustment. Presence of RBBB was associated with malignant arrhythmias during catheterization (adjusted OR 3.12, 95%CI 2.00-4.87) and IABP use (adjusted OR 4.15, 95%CI 3.02-5.72). New persistent RBBB and transient RBBB were both associated with increased 30-day and 1-year mortality, whereas pre-existing RBBB was not. For patients with LBBB and inappropriate ST-segment concordance (n=55), the OR for 30-day and 1-year mortality were 11.31 (95%CI 5.97-21.40) and 8.75 (95%CI 4.40-17.40), respectively; and 11.46 (95%CI 6.47-20.28) and 8.86 (95%CI 4.77-16.45) after adjustment. In patients treated directly with PCI, the presence of LBBB with inappropriate ST-segment concordance or development of a new RBBB in STEMI is predictive of increased mortality. The timing of RBBB is associated with risk.