Is Wider Worse? QRS Duration Predicts Cardiac Mortality in Patients with Right Bundle Branch Block

Abstract

Increasing QRS duration may be of prognostic significance in patients with right bundle branch block (RBBB) and may assist in predicting overall cardiovascular risk. To test this hypothesis, we examined the Computerized Patient Records of patients with complete and persistent RBBB. Primary and secondary end points were all-cause and cardiac mortality. The effects of QRS duration on death rates were analyzed using the Cox proportional hazards regression model (P < 0.05). We identified 52,852 patients with EKGs and selected all those with diagnosis of RBBB (QRS > or = 120 ms) between January 2000 and January 2004. Some patients had EKG records confirming RBBB since 1987. The QRS durations were categorized into four groups: 120-129, 130-139, 140-149, and > or = 150 ms. A total of 997 (1.9%) patients (mean age 68.9 +/- 10 years) with RBBB were followed for 1-226 (median 45) months. All-cause mortality occurred in 344 (34.5%), cardiac deaths in 59 (5.9%), noncardiac in 191 (19.2%), and unknown causes in 94 (9.4%) patients. Mean left ventricular EF for cardiac patients was 38 +/- 15%. In patients with cardiac deaths, QRS duration was associated with increased morality (P < 0.007). For every 10 ms increase in QRS duration, the risk of death rose by 26.6%. The effect of QRS duration on all cause mortality was not statistically significant (P < 0.43). Increasing QRS duration was an independent predictor of cardiac mortality in patients with RBBB, but had no influence on all-cause mortality. QRS duration has added prognostic information to the presence of right bundle branch block.