Atrioventricular area difference assessed by exercise cardiovascular magnetic resonance shows impaired diastolic filling in patients with heart failure

Heart failure (HF) is a complex clinical syndrome characterized by exercise intolerance. However, most diagnostic assessments are performed at rest, when many patients are asymptomatic. To better understand the underlying pathophysiology, examination during exercise is needed. Hydraulic force, a newly identified mechanism of diastolic filling, is proportional to the difference in short-axis areas between the left ventricle and atrium, known as the atrioventricular area difference (AVAD). Although hydraulic force has been shown to augment diastolic filling during exercise in healthy individuals, its role in HF during exercise remains unexplored. This study aimed to investigate whether hydraulic forces impair or augment diastolic filling in patients with HF during exercise, using AVAD measurements from exercise cardiovascular magnetic resonance (CMR) imaging. We examined 13 healthy volunteers and 22 patients with HF at rest and during exercise using a CMR-compatible ergometer. AVAD was measured at end-systole (ES) and end-diastole (ED). In patients with HF, AVAD at ED decreased during exercise (from 17 ± 5 cm² to 15 ± 6 cm², P = 0.006), whereas it increased in healthy volunteers (from 16 ± 3 cm² to 17 ± 3 cm², P = 0.014). AVAD at ES decreased in both HF (from -2 ± 5 cm² to -8 ± 5 cm², P < 0.001) and healthy volunteers (from -3 ± 2 cm² to -5 ± 3 cm², P = 0.011). In conclusion, the results suggest impaired diastolic function during exercise in HF through reduced hydraulic force compared with rest. These findings provide new mechanistic insights and may partly explain the hallmark symptom of exercise intolerance in heart failure.NEW & NOTEWORTHY Hydraulic force is a newly identified mechanism of diastolic function. This study is the first to assess hydraulic forces in patients with heart failure during exercise using cardiovascular magnetic resonance. In contrast to healthy individuals, hydraulic force decreased from rest to exercise in patients with heart failure, suggesting impaired diastolic filling. These findings offer new mechanistic insights into diastolic dysfunction during exercise and may help explain the hallmark symptom of exercise intolerance in heart failure.