Abstract 15090: Evaluation of Right Bundle Branch Block for Risk Prediction and Guiding Revascularization Strategy in Patients with Non-ST-Elevation Acute Coronary Syndrome in the TACTICS-TIMI 18 Trial
Background: Although a new left bundle branch block (BBB) is known to be a high-risk presentation of MI, less is known about right BBB. We hypothesized that the presence of RBBB would represent a high-risk marker for patients (pts) with non-ST elevation acute coronary syndrome (NSTEACS) and that these pts would benefit from early invasive (INV) strategy.
Methods: 2,220 pts with (w/) NSTEACS were randomized to early INV or conservative (CON) management strategy in TACTICS-TIMI 18 and followed 6 months for death, non-fatal MI, or ACS. Risk was stratified by BBB at presentation (none [referent], RBBB, LBBB, other intraventricular conduction delay [IVCD]) and adjusted for sex, race, TIMI risk score factors, prior MI, and creatinine. Outcomes were compared across EKG groups.
Results: Overall, 6% (n=122) of NSTEACS pts presented w/ RBBB, which was more frequently associated w/ elevated troponin but less often ST-deviation compared w/ pts w/out BBB. Among CON managed pts, RBBB at ACS identified pts w/ an increased risk of CV events compared to pts w/ no BBB (34.9% vs. 18.5%; OR adj. 2.38 [1.36-4.15]). An INV strategy significantly reduced the risk of the primary endpoint in pts w/ RBBB (34.9% → 18.6%, OR INV vs. CON 0.43 [0.19-0.99], p=0.046); in pts w/out BBB (18.5% → 15.3%, OR INV vs. CON 0.79 [0.63-1.00], p=0.055; figure).
Conclusion: Presence of RBBB is an uncommon but powerful marker of a high-risk NSTEACS that appears to identify pts that preferentially benefit from an early INV strategy. This observation warrants confirmation in other studies.
- © 2012 by American Heart Association, Inc.