Coronary Microvascular Dysfunction and Diffuse Myocardial Fibrosis Measured by Cardiovascular Magnetic Resonance are Characteristic of HFpEF

Heart failure with preserved ejection fraction (HFpEF) is frequently accompanied by comorbidities and a systemic proinflammatory state, resulting in coronary microvascular dysfunction (CMD), as well as myocardial fibrosis. Recent studies have shown a high prevalence of CMD in HFpEF. The purpose of this study is to examine the relationship between myocardial perfusion reserve (MPR) and diffuse myocardial fibrosis in patients with HFpEF using CMR. A single center study was performed in 19 patients with clinical HFpEF and 15 healthy control subjects who underwent quantitative first-pass perfusion imaging to calculate global MPR. T1 mapping was used to assess fibrosis and to calculate extracellular volume (ECV). Spiral cine displacement encoded stimulated echo (DENSE) was used to calculate myocardial strain. Comprehensive 2D echocardiograms with speckle tracking, cardiopulmonary exercise testing, and BNP levels were also obtained. In patients with HFpEF, mean left ventricular (LV) EF was 61 ± 9% and LV mass index 45 ± 12 g/m 2 . Compared to controls, HFpEF patients had reduced global MPR (2.29 ± 0.64 vs 3.38 ± 0.76, p = 0.002) and VO 2 max (16.5 ± 6.8 vs 30.9 ± 7.7 ml/kg*min, p < 0.001) while ECV (0.29 ± 0.04 vs 0.25 ± 0.04, p = 0.02), pulmonary artery systolic pressure (35.4 ± 13.7 vs 22.3 ± 5.4 mmHg, p = 0.004), and average E/e’ (15.0 ± 7.6 vs 8.6 ± 2.0, p = 0.005) were increased. DENSE peak systolic circumferential strain (p = 0.60) as well as echocardiographic derived global longitudinal strain (p = 0.07) were similar between both groups. The prevalence of CMD, defined as global MPR < 2.5, among the HFpEF group was 69%. In conclusion, HFpEF patients have a high prevalence of CMD and diffuse fibrosis. These parameters may be useful clinical endpoints for future therapeutic trials.