P wave duration is associated with cardiovascular and all-cause mortality outcomes: the National Health and Nutrition Examination Survey

Background: P wave indices are an intermediate phenotype modulated by atrial conduction and electrophysiology. Their clinical correlates and association with all-cause mortality have received limited scrutiny.

Objective: To determine the relationship between P wave indices and cardiovascular and all-cause mortality in the National Health and Nutrition Examination Survey (NHANES), a highly representative United States sample.

Methods: NHANES III (1988-1994) quantified PR interval and P wave duration and amplitude. Mortality data through 2006 were obtained from National Death Index (NDI) records.

Results: Of 8,561 subjects with electrocardiograms (ECGs), 7,486 (mean age 60.0 ± 13.3 years., 51.9% women, 50.1% ethnic minorities) had ECGs in sinus rhythm, linked mortality data, and complete assessments. Over a median 8.6-year follow-up (range 0.1-12.2 years), there were 679 cardiovascular deaths and 1,559 all-cause mortality deaths. Older age, male sex, and higher body mass index were significantly associated with greater PR interval and P wave duration and with lower P wave amplitude. African Americans had higher mean values of all three P wave indices. In a multivariable model adjusting for cardiovascular risk factors, P wave duration was the only P wave index significantly associated with cardiovascular mortality (hazard ratio [HR] 1.13, per 1 standard deviation [SD], 95% confidence interval [CI] 1.04-1.23; P = .004) and all-cause mortality (HR 1.06 per 1 SD; 95% CI 1.00-1.13; P = .050).

Conclusions: In a highly representative U.S. sample, P wave duration was significantly associated with increased cardiovascular and all-cause mortality. P wave duration may reflect subclinical disease and merits elucidation as a marker of risk for adverse outcomes.