AHA Scientific Sessions 2026 Abstract · Nov 2, 2026
Association of the Left Atrioventricular Coupling Index (LACI) with Supraventricular Ectopy: The Multi-Ethnic Study of Atherosclerosis (MESA)
By Salameh E, Ebrahimihoor E, Ostovaneh A et al.
Background: Supraventricular ectopy (SVE), including premature atrial contractions (PACs) and supraventricular tachycardia (SVT), reflects early atrial electrical remodeling and is a precursor of atrial fibrillation (AF). The left atrioventricular coupling index (LACI), a cardiac magnetic resonance (CMR)-derived marker of atrial-ventricular interaction, predicts AF. However, whether relative alterations between left atrial (LA) and left ventricular (LV) volumes even within normal chamber volume ranges, are associated with SVE burden, is still unknown. Objectives: To evaluate the association of LACI with PAC and SVT burden in a multi-ethnic population. Methods: We studied 940 participants from the Multi-Ethnic Study of Atherosclerosis with serial CMR (Exams 1 and 5, 2000-02 and 2010-12) and ambulatory electrocardiographic monitoring (2016-18). LACI ₅ (%) was defined as the ratio of LA to LV end-diastolic volumes at Exam 5, and ΔLACI (%/year) as its annualized change. LACI variables were analyzed continuously (per 1-standard deviation, SD) and categorically using thresholds from classification and regression tree analysis. Outcomes were log-transformed PACs/hour and SVT runs/day. Associations were assessed using multivariable linear regression adjusting for demographics, cardiovascular risk factors, medications, and CMR parameters. Estimates were back-transformed and expressed as percent differences in SVE burden. Normal chamber volumes were defined as the 5th-95th percentiles. Results: LACI ₅ had a mean of 24.4±10.8%. Each 1-SD (10.8%) increase in LACI ₅ was independently associated with a 28.4% (95% CI: 11.1-48.4%) higher PAC burden and a 24.0% (10.3-39.5%) higher SVT burden. Participants with LACI ₅ ≥34% had 76.1% (26.8-144.6%) more PACs/hour and 57.3% (20.5-105.4%) more SVT runs/day than participants with LACI ₅ <34%. The annualized change in LACI showed a similar but less consistent pattern: ΔLACI≥2.5%/year and ΔLACI≥3%/year were respectively associated with 77.2% higher PAC (14.1-175.3%) and 97.6% higher SVT burden (17.3-232.9%), whereas continuous ΔLACI did not show significant associations. Associations of LACI ₅ with SVE burden persisted among participants with normal atrial and ventricular volumes. Conclusions: Greater atrioventricular uncoupling, as reflected by higher LACI, is independently associated with increased SVE burden, even within normal individual chamber volume ranges, highlighting the importance of atrioventricular interaction in early atrial electrical remodeling.