Cardiovascular magnetic resonance rest and exercise-stress left atrioventricular coupling index to detect diastolic dysfunction

Left atrial and ventricular (LA/LV) dysfunction are interlinked in heart failure with preserved ejection fraction (HFpEF); however, little is known about their interplay and relation to cardiac decompensation. We hypothesized that cardiovascular magnetic resonance (CMR) left atrioventricular coupling index (LACI) would identify pathophysiological alterations in HFpEF and be amenable to rest and ergometer-stress CMR. Patients with exertional dyspnoea, signs of diastolic dysfunction (E/e' ≥ 8), and preserved ejection fraction (EF; ≥50%) on echocardiography were prospectively recruited and classified as HFpEF (n = 34) or noncardiac dyspnoea (NCD, n = 34) according to pulmonary capillary wedge pressure (PCWP) on right-heart catheterization (rest/stress ≥ 15/25 mmHg). LA and LV volumes were assessed on short-axis real-time cine sequences at rest and during exercise stress. LACI was defined as the ratio of the LA-to-LV end-diastolic volume. Cardiovascular hospitalization (CVH) was assessed after 24 mo. Volume-derived LA (P ≥ 0.008) but not LV (P ≥ 0.347) morphology and function at rest and during exercise stress detected significant differences comparing HFpEF and NCD. There was impaired atrioventricular coupling in HFpEF at rest (LACI, 45.7% vs. 31.6%, P < 0.001) and during exercise stress (45.7% vs. 27.9%, P < 0.001). LACI correlated with PCWP at rest (r = 0.48, P < 0.001) and during exercise stress (r = 0.55, P < 0.001). At rest, LACI was the only volumetry-derived parameter to differentiate patients with NCD from patients with HFpEF, which were identified using exercise-stress thresholds (P = 0.001). Resting and exercise-stress LACI dichotomized at their medians were associated with CVH (P ≤ 0.005). Assessment of LACI is a simple approach for LA/LV coupling quantification and allows easy and fast identification of heart failure with preserved ejection fraction (HFpEF).NEW & NOTEWORTHY Evaluation of the left atrioventricular coupling index (LACI) in a rest and exercise-stress cardiovascular magnetic resonance imaging protocol allows identification of patients with heart failure and preserved ejection fraction with high diagnostic accuracy. LACI holds similar diagnostic accuracy at rest compared with left atrial ejection fraction during exercise stress. This highlights the value of LACI as a widely available and cost-effective test for diastolic dysfunction, which may help to guide patient selection for referral to specialized testing/treatment.