Association of blood pressure and aortic distensibility with P wave indices and PR interval: the multi-ethnic study of atherosclerosis (MESA)

Abstract

Introduction: Hypertension is an established risk factor for atrial fibrillation. Understanding the association of blood pressure (BP) levels and aortic distensibility with P wave indices (PWIs) and PR interval, intermediate phenotypes of atrial fibrillation, could provide insights into underlying mechanisms.

Methods: This analysis included 3180 men and women aged 45-84years participating in the Multi-Ethnic Study of Atherosclerosis, a community-based cohort in the United States. Aortic distensibility was evaluated in 2243 of these individuals using cardiac magnetic resonance imaging. PWIs and PR interval were automatically measured in standard 12-lead ECGs. Sitting BP and other cardiovascular risk factors were assessed using standardized protocols. Left ventricular mass was measured by magnetic resonance imaging.

Results: Higher systolic BP, and diastolic BPs and greater pulse pressure were associated with a significantly greater P wave terminal force. These associations, however, were markedly attenuated or disappeared after adjustment for left ventricular mass. Systolic BP, diastolic BP, and pulse pressure were not strongly associated with PR interval or maximum P wave duration. Reduced aortic distensibility was associated with a longer PR interval but not with PWIs: compared with individuals in the top quartile of aortic distensibility, participants in the lowest quartile had on average a 3.7-ms longer PR interval (95% CI: 0.7, 6.7, p=0.02), after multivariable adjustment.

Conclusion: In this large community-based sample, associations of BP and aortic distensibility with PWIs and PR interval differed. These results suggest that processes linking hypertension with the electrical substrate of atrial fibrillation, as characterized by these intermediate phenotypes, are diverse.

Figure 1

Adjusted average maximum P wave duration by quartiles of aortic distensibility and pulse pressure, in men (light blue) and women (dark blue), Multi-Ethnic Study of Atherosclerosis, 2000-2002. Bars represent 95% confidence intervals. Results from general linear model including age, sex, race/ethnicity, study site, income, education, heart rate, height, body mass index, total cholesterol, HDL-c, creatinine, physical activity, smoking status, pack-years of smoking, alcohol intake, diabetes, use of lipid lowering medications, left ventricular mass, aortic distensibility or pulse pressure quartile, and an interaction term for sex and aortic distensibility or pulse pressure quartiles.