Exercise Cardiac Magnetic Resonance Imaging in Heart Failure with Preserved Ejection Fraction

Background Exercise intolerance is the primary manifestation in heart failure with preserved ejection fraction (HFpEF); yet the pathophysiologic mechanism(s) remains incompletely understood. Exercise cardiac magnetic resonance imaging offers a unique opportunity to examine the cardiac response to simulated activities of daily living, with high spatial resolution, independent of body habitus. Purpose To compare the cardiac response to exercise in HFpEF and age-matched healthy controls. Methods Twenty-seven individuals with HFpEF (10 Males, BMI: 36 ± 7 kg/m2, age: 71 ± 7 years) and 21 age-matched healthy controls (10 Males, BMI: 27 ± 5 kg/m2, age: 68 ± 5 years) participated. Left ventricular (LV) volumes were assessed by the method of disks, using high-resolution short-axis cine imaging. Brachial artery blood pressure was measured using a brachial oscillometric cuff. Imaging was performed at rest and during supine cycle exercise at 30 Watts using an MRI-compatible ergometer. Control participants also completed a second bout of exercise at 40% of their upright maximum to mimic the average relative intensity that 30 Watts represented in the HFpEF group. Results The left ventricular response to exercise in HFpEF patients and age matched controls is summarized in Table 1. At the same absolute workload (i.e., 30 Watts), both groups demonstrated a similar rise in stroke volume and ejection fraction, which was primarily driven by an increase in end-diastolic volume. In contrast, when the control group exercised at a similar relative intensity (i.e., 40% maximum), the increase in stroke volume and ejection fraction was driven almost entirely by a reduction in end-systolic volume. Conclusions Taken together, these data provide novel insight into the cardiac response to supine exercise in HFpEF. That left ventricular end-systolic volume was reduced in control participants— but not HFpEF patients— when exercising at a similar relative intensity, highlights a potential cardiac limitation in HFpEF that warrants further investigation.