Relationship Between Left Atrial Functional Measures and Incident Atrial Fibrillation in the General Population: The Copenhagen City Heart Study

Abstract

Objectives: This study sought to investigate whether left atrial (LA) functional measures predict atrial fibrillation (AF) in the general population.

Background: Increasing evidence suggests LA functional measures are predictors of AF in several patient groups.

Methods: In a community-based cohort study, approximately 2,000 individuals underwent a transthoracic echocardiogram. Conventional echocardiographic measures and extended LA measures, including the minimal and maximal LA volumes (LAV_min and LAV_max, respectively) and left atrial emptying fraction (LAEF), were performed. The endpoint was incident AF, and participants with known AF were excluded, which left 1,951 for inclusion.

Results: Over 11.0 years of follow-up, 184 (9.4%) developed AF. Those who developed AF had significantly larger LA volumes and lower LAEF than participants free of AF. These LA measures were univariable predictors of AF (LAV_max hazard ratio [HR]: 1.10 [95% confidence interval (CI): 1.08 to 1.12] per 1-ml increase, p < 0.001; LAV_min HR: 1.14 [95% CI: 1.12 to 1.16] per 1-ml increase, p < 0.001; LAEF HR: 1.03 [95% CI: 1.02 to 1.04] per percent decrease, p < 0.001). All LA measures remained predictors independent of clinical risk scores, with LAV_min providing the highest C-statistics when added to these risk scores (C-statistic for CHADS₂ 0.728 vs. CHADS₂ + LAV_min 0.778; C-statistic for CHARGE-AF 0.815 vs. CHARGE-AF + LAV_min 0.830). However, hypertension modified the relationship between the measures of LA function (both LAV_min and LAEF) and risk of AF (p for interaction < 0.001), which was not the case for LAV_max (p = 0.22). The measures of LA function mainly provided prognostic information regarding risk of AF in participants without hypertension. Even when we restricted our analysis to individuals without hypertension and nondilated LA (LAV_max<34 ml/m²), the LAV_min and LAEF remained significantly independent predictors of AF after multivariable adjustments (LAV_min HR: 1.12 [95% CI: 1.01 to 1.24], p = 0.028, and LAEF HR: 1.03 [95% CI: 1.00 to 1.06], p = 0.021, respectively).

Conclusions: LA functional measures predict AF in the general population and provide prognostic information incremental to clinical risk scores. In individuals without hypertension and nondilated LA, these measures indicate an increased risk of AF.

Keywords: atrial fibrillation; echocardiography; left atrium.