Prognostic Significance of Exercise-Induced Left Bundle-Branch Block

Abstract

Context.-Approximately 0.5% of all patients who undergo exercise testing develop a transient left bundle-branch block (LBBB) during exercise, but its prognostic significance is unclear.Objective.-To determine whether exercise-induced LBBB is an independent predictor of mortality and cardiac morbidity.Design.-Matched control cohort study. Between September 1990 and February 10, 1994, 17 277 exercise stress tests were performed on patients.Setting.-Tertiary care, academic medical center.Patients.-From the cohort, 70 cases of exercise-induced LBBB were identified. The controls comprised 70 individuals without LBBB at rest or during exercise that matched the 70 cases based on age, test date, sex, prior history of coronary artery disease, hypertension, diabetes, smoking, and ␤-blocker use.Main Outcome Measures.-All-cause mortality, percutaneous coronary intervention, open heart surgery, nonfatal myocardial infarction, documented symptomatic or sustained ventricular tachydysrhythmia, or implantation of a permanent pacemaker or an implantable cardiac defibrillator.Results.-A total of 37 events (28 events from the exercise-induced LBBB cases and 9 from the control cohort) occurred in 25 patients (17 exercise-induced LBBB patients and 8 control patients) during a mean follow-up period of 3.7 (0.9 years) (median, 3.8 years [range, 0.9-5.2 years]). There were 7 deaths, of which 5 occurred among patients with exercise-induced LBBB. Four-year Kaplan-Meier event rates were 19% among exercise-induced LBBB patients and 10% among controls (logrank 2 , 5.2; P=.02). After further adjusting for small differences in age, exerciseinduced LBBB remained associated with a higher risk of primary events (adjusted relative risk, 2.78; 95% confidence interval, 1.16-6.65; P=.02).Conclusion.-Exercise-induced LBBB independently predicts a higher risk of death and major cardiac events.

Exercise Standards for Testing and Training

“…Left bundle-branch block that develops during exercise might or might not be associated with CAD, 146,147 but it does predict higher risk of death and major cardiac events. 149 The disappearance during exercise of intraventricular blocks that are present at rest is rare. 150 Preexisting right bundle-branch block 148,[151][152][153][154] does not invalidate interpretation of the exercise ECG, except in the anterior precordial leads (V 1 , V 2 , and V 3 ), where ST depression is frequently present at baseline and increases with exercise even in the absence of coronary obstruction.…”

Exercise induced left bundle branch block in a patient with slow coronary flow: A case report

“…About 0.5% to 1.1% of all patients who underwent exercise testing develop a transient LBBB during exercise, which is predictive of a higher risk for death and major cardiac events (9). The coronary slow flow is an angiographic phenomenon characterized by normal coronary arteries with delayed opacification of the distal vessels.…”

Exercise-Induced Left Bundle Branch Block and Chest Pain in the Absence of Coronary Artery Disease: A Case Report and Review of the Literature

“…Exercise-induced left bundle branch block (LBBB) has been reported in approximately 0.5% of patients undergoing exercise stress testing, and it independently predicts a higher risk of death and major cardiac events [1]. Seventy percent of patients with exercise-induced LBBB were shown to have significant coronary artery disease [2].…”