Prognostic implications of intraventricular conduction defects in patients undergoing stress echocardiography for suspected coronary artery disease

Abstract

Purpose: To investigate the prognostic implications of conduction defects in subjects without proven coronary artery disease who had been referred for stress echocardiography.

Methods: The study sample consisted of 1230 patients (574 men and 656 women; mean [+/- SD] age, 63 +/- 10 years) who underwent stress echocardiography with dipyridamole (n = 780) or dobutamine (n = 450) to evaluate suspected coronary artery disease. A summary wall motion score (on a 1 to 4 scale) was calculated. Patients were followed for a mean of 41 +/- 27 months; mortality was the only endpoint.

Results: Four hundred and twenty patients (34%) had intraventricular conduction defects on a resting electrocardiogram (173 with complete left bundle branch block, 98 with isolated right bundle branch block, 43 with right bundle branch block with left anterior hemiblock, and 106 with left anterior hemiblock). Ischemia at stress echo (new or worsening of preexisting wall motion abnormality) was found in 250 patients (20%). There were 56 deaths during follow-up; 138 patients underwent revascularization and were censored. Multivariate predictors of mortality were resting wall motion score index (hazard ratio [HR] = 6.0 per unit increase; 95% confidence interval [CI]: 2.3 to 16; P <0.0001), ischemia at stress echo (HR = 3.9; 95% CI: 2.2 to 6.7; P <0.0001), age >65 years (HR = 3.2; 95% CI: 1.7 to 5.9; P <0.0001), hypertension (HR = 1.8; 95% CI: 1.1 to 3.2; P = 0.03), and right bundle branch block with left anterior hemiblock (HR = 3.7; 95% CI: 1.8 to 7.5; P <0.0001). The other three forms of intraventricular conduction defects (left bundle branch block, isolated complete right bundle branch block, and left anterior hemiblock) were not associated with mortality in multivariate analyses, or among the 980 patients who did not have ischemia.

Conclusion: Right bundle branch block with left anterior hemiblock is an independent predictor of mortality in patients with suspected coronary artery disease undergoing stress echocardiography, whereas isolated right bundle branch block is associated with outcomes similar to those observed in patients with no conduction defects.