Clinical outcome as a function of the PR-interval--there is virtue inmoderation: data from the Duke Databank for cardiovascular disease.

Aims: Recently, a U-shaped association between PR-interval and the risk of developing atrial fibrillation was described, with higher risk in patients with long and short PR-intervals. Little is known regarding the association of PR-interval duration and mortality. The objective of the current study was to explore the relationship between PR-interval and major cardiovascular outcomes in patients with known coronary heart disease. Methods and results: Patients in sinus rhythm, undergoing coronary angiography at Duke University Medical Center between 1989 and 2010, who had significant stenosis in at least one native coronary artery, were included. Patients with arrhythmia, second- or third-degree AV-block, QRS > 120 ms were excluded. A total of 9,637 patients were included (median age 63, IQR 55-71 years, 67% men). After adjustment for relevant covariates, the risk of a CV event increased with a decreasing PR-interval (10 ms decrements) for PR-interval values <162 ms (all-cause mortality; HR 1.057, 95% CI 1.019-1.096, P = 0.0030, composite of death or stroke; HR 1.047, 95% CI 1.011-1.085, P = 0.0095 and composite of cardiovascular death or cardiovascular rehospitalization; HR 1.032, 95% CI 1.002-1.063, P = 0.0387). No statistically significant changes in the risk associated with PR-interval for values >162 ms were seen for any of the studied endpoints. Conclusion: In patients with coronary heart disease, a prolongation of the PR-interval was not independently associated with poor outcomes, but a PR-interval shorter than normal was associated with increased all-cause mortality and other major cardiovascular events. [ABSTRACT FROM AUTHOR]