To aim of the EXPOSURE study is to investigate the effects of epicardial fat on cardiac function, pericardial constraint and pulmonary artery vasodilatation using cardiac magnetic resonance (CMR) imaging at rest and during exercise stress testing in patients with HFpEF.

The EXPOSURE study investigates the effects of epicardial fat on ventricular interdependence at peak exercise. Epicardial fat, the visceral fat situated directly adjacent to the heart, seems involved in the pathophysiology of heart failure with preserved ejection fraction (HFpEF). It has been suggested that an abundance of epicardial fat surrounding the heart within a closed pericardial sac may constrain the heart leading to ventricular interdependence. The study is an investigator initiatied, cross-sectional, observational study, including 50 patients with HFpEF. Patients will be stratified according to high and low epicardial fat volume measured with CMR. The primary outcome parameter is the difference in LV eccentricity index at peak exercise between the two groups. Pre-specified secondary outcome parameters between the subgroups are: 1) VO2-max, 2) LV and right ventricular (RV) diastolic strain rate, 3) slope of early LV/RV filling, 3) left and right atrial reservoir strain and emptying fraction, 4) pulmonary artery distensibility and pulsatility and 5) cardiac output, all at peak exercise. The amount of epicardial fat will be correlated with change in LV eccentricity index from rest to peak exercise, change in LV/RV diastolic strain rate, change in slope of LV/RV filling, change in atrial reservoir strain and emptying fraction, change in pulmonary artery distensibility and pulsatility, and change in cardiac output. All results will be also compared between men and women.

Inclusion Criteria:

1. Signs and symptoms of HF according to the Europeans Society of Cardiology guideline.
2. LV ejection fraction ≥40%.
3. HFA-PEFF score ≥5 or HFA-PEFF score 2-4 in combination with positive stress test (Figure 1).
4. >18 years of age
5. In sinus rhythm
6. Able to perform a bicycle exercise test
7. Willing to sign informed consent

Exclusion Criteria:

1. Body weight >140 kg
2. Atrial fibrillation or other significant arrhythmia during the assessment
3. Contraindications for CMR (e.g. claustrophobia, implanted cardiac devices)
4. Myocardial infarction, percutaneous coronary intervention or coronary artery bypass graft <3 months or untreated severe obstructive coronary artery stenosis
5. More than moderate left-sided valve disease.
6. Complex congenital heart disease.

A cohort of 50 patients with HFpEF, in which the effects of epicardial fat on cardiac function, pericardial constraint and pulmonary artery vasodilatation will be tested using cardiac magnetic resonance (CMR) imaging at rest and during exercise stress testing.