Left Atrioventricular Coupling Index (LACI) incrementally predicts future mortality and outcomes in older adults independent of left ventricular function

Background While left atrial (LA) dysfunction is often considered a reflection of diastolic dysfunction, typifying changes in the ageing heart, it may also serve as an indicator of early left ventricular (LV) systolic deterioration that remains undetectable through conventional LV evaluation in cardiovascular imaging. Despite the lack of gross LV dysfunction in population studies, the development of subsequent cardiovascular disease (CVD) over time among settings of LA dysfunction may suggest early perturbations in the LV. Left atrioventricular coupling (LACI), a marker of LA-to-LV physiological interactions, is believed to be a marker for characterizing early perturbations in the LV. We investigated the prognostic value of LACI and LA measures obtained by advanced cardiac magnetic resonance (CMR) imaging and incident outcomes in older adults. Methods This prospective, population-based cohort study included 255 adults (70.8±9.1years, 55% male) without CVD at baseline. LA and LV volumes were derived from CMR. LACI was calculated as the ratio of LA-to-LV end-diastolic volume indexed (LAEDVi/LVEDVi). Feature tracking on CMR assessed LA emptying fractions (LAEF), LA and LV strains. Clinical outcomes were defined as a composite of all-cause mortality or hospitalization. Results CMR measurements for the cohort showed a mean±SD of LACI (30.1±14.3%), with 60% having LACI>25%. Total LAEF was 52.0±9.5%, while LV parameters included an ejection fraction of 65.1±7.5%, LVEDVi of 64.3%±13.8 ml/m2 and LV mass-indexed (LVMi) of 46.3±11.6 g/m2. Over a follow-up of 5.21±1.60 years, 61 participants developed incident clinical outcomes. LACI>25% was most strongly associated with the risk of incident outcomes on univariable analysis (hazard ratio (HR) = 1.88, 95% confidence interval (CI) (1.07-3.29), p = 0.027) and multivariable analysis (HR = 2.18 95%CI (1.05-4.52), p = 0.035) adjusting for cardiovascular risk factors, LVMi and LV global longitudinal strain (Table 1). The log-rank test further supported this association (x2 = 5.27, p = 0.022) (Figure 1). LACI, when included in this model, demonstrated incremental discrimination and calibration in the prediction of incident outcomes (C-statistic = 0.656, 95%CI (0.564-0.747)); likelihood-ratio-test x2 = 4.26, p = 0.039; Gronnesby-Borgan’s score test (G-B) x2 = 14.07 p = 0.120). LACI>25% had the highest discriminatory value (C-statistic = 0.678, 95%CI (0.590-0.765)) and Total LAEF had the best model calibration (G-B x2 = 8.89 p = 0.448) in the prediction of incident outcomes, after adjusting for the multivariable model (Table 1). Conclusion Among a prospective cohort of older adults free of baseline CVD, an increased LACI and decreased LAEF was independently associated with and incrementally predictive of future clinical outcomes. Determination of LACI in asymptomatic older adults may reflect heightened risks of CVD development in ageing.