Associations of Left Atrial Function and Structure With Supraventricular Ectopy: The Multi-Ethnic Study of Atherosclerosis

Abstract

Background High levels of supraventricular ectopy are associated with greater risk of atrial fibrillation, stroke, and death. Little information is available about differences by race/ethnicity in the extent of supraventricular ectopy, or about whether high levels of supraventricular ectopy are associated with impaired left atrial (LA) function and LA enlargement. Methods and Results In the MESA (Multi-Ethnic Study of Atherosclerosis), 1148 participants (47% men; mean age, 67 years) had cardiovascular magnetic resonance imaging in 2010 to 2012, followed by 14-day ambulatory electrocardiographic monitoring in 2016 to 2018. We analyzed participant characteristics and cardiovascular magnetic resonance measures of LA function and structure in relation to average count of premature atrial contractions (PACs) per hour and average number of runs per day of supraventricular tachycardia. In adjusted regression analyses, older age, male sex, White race, elevated NT-proBNP (N-terminal pro-B-type natriuretic peptide), and a history of clinically detected atrial fibrillation were associated with more PACs/hour. Chinese and Hispanic participants had on average fewer PACs/hour than White participants (Chinese participants, 31% less [95% CI, 8%-49%]; Hispanic participants, 38% less [95% CI, 19%-52%]). Greater LA total emptying fraction was associated with fewer PACs/hour (per SD, 16% fewer PACs/hour [95% CI, 7%-25% fewer PACs/hour]). Larger LA minimum volume was associated with more PACs/hour (per SD, 7% more PACs/hour [95% CI, 2%-13% more PACs/hour]). Associations of LA volumes with runs of supraventricular tachycardia/day were similar in direction but were weaker. Conclusions Impaired LA function and LA enlargement were associated with more PACs/hour on extended ambulatory electrocardiographic monitoring. Measurement of supraventricular ectopy may provide information about the extent of atrial myopathy.

Keywords: emptying fraction; left atrium; strain; supraventricular ectopy; volume.

Figure 1. Study participation and inclusion in analysis.

AF indicates atrial fibrillation; CMR, cardiovascular magnetic resonance.

Figure 2. Adjusted percentage difference in average premature atrial contractions (PACs)/hour associated with left atrial (LA) function and volume from multivariable linear regression.

*Adjusted for weight, height, sex, age, race/ethnicity, diabetes mellitus, current smoking, antihypertensive medication use, systolic blood pressure, estimated glomerular filtration rate, NT‐proBNP (N‐terminal pro‐B‐type natriuretic peptide), history of clinically detected atrial fibrillation, left ventricular mass and end‐diastolic volume, and monitoring duration. ^†The SDs of strain and each of the emptying fractions were ≈10%. ^‡LA volume was indexed for height and weight by sex. A difference in indexed LA volume of 25% indicates a measured LA volume that is 25% larger than predicted for height, weight, and sex. The SD of both maximum and minimum indexed LA volumes was ≈25%.