Frequency of Coronary Microvascular Dysfunction and Diffuse Myocardial Fibrosis (Measured by Cardiovascular Magnetic Resonance) in Patients With Heart Failure and Preserved Left Ventricular Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is frequently accompanied by co-morbidities and a systemic proinflammatory state, resulting in coronary microvascular dysfunction (CMD), as well as myocardial fibrosis. The purpose of this study is to examine the relation between myocardial perfusion reserve (MPR) and diffuse myocardial fibrosis in patients with HFpEF using cardiovascular magnetic resonance. 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. Spiral cine displacement encoded stimulated echo was used to calculate myocardial strain. Comprehensive 2D echocardiograms with speckle tracking, cardiopulmonary exercise testing, and brain natriuretic peptide levels were also obtained. In patients with HFpEF, mean left ventricular EF was 61% ± 9% and left ventricular mass index 45 ± 12 g/m2. Compared with controls, HFpEF patients had reduced global MPR (2.29 ± 0.64 vs 3.38 ± 0.76, p = 0.002) and VO2 max (16.5 ± 6.8 vs 30.9 ± 7.7 ml/kg min, p <0.001) whereas extracellular volume (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 mm Hg, p = 0.004), and average E/e' (15.0 ± 7.6 vs 8.6 ± 2.0, p = 0.005) were increased. Displacement encoded stimulated echo 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, in the HFpEF group was 69%. In conclusion, HFpEF patients have a high prevalence of CMD and diffuse fibrosis. These parameters may be useful clinical end points for future therapeutic trials.