Long-Term Cardiovascular Outcomes in Patients With Angina Pectoris Presenting With Bundle Branch Block
What is the short- and long-term prognostic significance of bundle branch block (BBB) in patients presenting to the emergency department with angina?
The Olmsted County Chest Pain Study is a community-based cohort of 2,271 consecutive patients presenting to three Olmsted County emergency departments with angina from 1985 through 1992. Patients were followed for major adverse cardiovascular events (MACE) including death, myocardial infarction, stroke, and revascularization at 30 days and over a median follow-up period of 7.3 years, and for mortality only through a median of 16.6 years. Cox models were used to estimate associations between BBB and cardiovascular outcomes.
Mean age of the cohort on presentation was 63 years, and 58% were men. MACE at 30 days occurred in 11% with right BBB (RBBB), 8.8% with left BBB (LBBB), and 6.4% in patients without BBB (p = 0.17). Over a median follow-up of 7.3 years, patients with BBB were at higher risk for MACE (RBBB, hazard ratio [HR] 1.85, 95% confidence interval [CI] 1.44-2.38, p < 0.001; LBBB, HR 2.04, 95% CI 1.62-2.56, p < 0.001) compared to those without BBB. Over a median of 16.6 years, the two BBB groups had lower survival rates than patients without BBB (RBBB, HR 2.19, 95% CI 1.73-2.78, p < 0.001; LBBB, HR 3.32, 95% CI 2.67-4.13, p ≤ 0.001), but after adjustment for multiple risk factors, an increased risk of mortality for LBBB remained significant.
The authors concluded that appearance of LBBB or RBBB in patients presenting with angina predicts adverse long-term cardiovascular outcomes compared to patients without BBB.
In this study of patients with angina, the pattern of RBBB on presenting electrocardiogram predicted poor cardiovascular outcomes over 7 years and greater mortality rate of 15 years compared to those without BBB, but these differences were largely attributable to a greater burden of associated risk factors. For those presenting with LBBB, the relations to MACE at 7 years and mortality at 16 years were incompletely explained by identifiable concurrent risk factors, although the incidence of heart failure and need for pacemaker implantation was no different from patients without BBB. This study reaffirms the importance of LBBB and underscores the significance of RBBB on initial electrocardiogram in the initial risk stratification of patients presenting with angina.
Keywords: Myocardial Infarction, Follow-Up Studies, Survival Rate, Heart Block, Heart Failure, Bundle-Branch Block, Electrocardiography
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