Noninvasive Diagnosis of Heart Failure With Preserved Ejection Fraction Using the Left Atrioventricular Coupling Index

Background Right heart catheterization is the gold standard for diagnosing heart failure with preserved ejection fraction but is invasive and not readily accessible. The left atrioventricular coupling index (LACI), defined as the ratio of left atrial minimal volume to left ventricular end‐diastolic volume, has been proposed as a surrogate of left ventricular diastolic dysfunction. This study compares 3 imaging modalities for LACI assessment and evaluates diagnostic performance for heart failure with preserved ejection fraction. Methods We retrospectively included 1680 patients from 2 academic hospitals (Amsterdam UMC, The Netherlands, and ASPIRE registry). All underwent diagnostic right heart catheterization and cardiac magnetic resonance imaging (CMR); a subset additionally underwent cardiac computed tomography, and/or echocardiography. Patients were divided into derivation and validation cohorts. left atrial and left ventricular volumes were measured at end‐diastole. Agreement between imaging modalities was evaluated with Bland–Altman plots. The predictive performance of LACI for heart failure with preserved ejection fraction was evaluated using receiver operating characteristic analysis, with cut‐off values derived in the derivation cohort and tested unchanged in the validation cohort. Results Assessment of LACI measurement accuracy across imaging modalities showed strong agreement between CMR and echocardiography. CMR LACI outperformed echocardiography (area‐under‐the‐curve=0.84 versus 0.65), while cardiac computed tomography tended to overestimate LACI. The derivation cohort identified LACI ≥36% on CMR as the optimal threshold (sensitivity: 64%, specificity: 83%), which was tested in the validation cohort (sensitivity: 58%, specificity: 82%). Conclusions LACI ≥ 36%, particularly measured via CMR, shows strong diagnostic potential for heart failure with preserved ejection fraction as a noninvasive adjunct to current diagnostic strategies.