Heart Failure With Preserved Ejection Fraction in Outpatients With Unexplained Dyspnea

The aim of the present study was to diagnose heart failure with preserved ejection fraction (HFPEF) in outpatients with unexplained chronic dyspnea and to elucidate its underlying mechanisms in this population using invasive pressure-volume loop analysis. The diagnosis of HFPEF in stable outpatients with unexplained dyspnea is difficult. Thirty patients (age 67 ± 8.6 years, 27% males) with preserved left ventricular (LV) ejection fraction (>50%) and unexplained chronic New York Heart Association functional class II to III dyspnea underwent heart catheterization. Patients with significant coronary artery stenosis (>50%) were excluded. Pressure-volume loops were assessed using a conductance catheter at rest, hand-grip exercise, leg lifting, and nitroprusside and dobutamine infusion. Twenty (66%) patients showed LV end-diastolic pressure >16 mm Hg (HFPEF), whereas the remaining 10 patients served as controls. Patients with HFPEF had significantly higher end-diastolic stiffness (0.205 ± 0.074 vs. 0.102 ± 0.017, p < 0.001) at rest, and their end-diastolic pressure-volume relationship showed a consistent upward and leftward shift during all hemodynamic interventions compared with controls. Regarding the underlying mechanism of HFPEF, 14 (70%) patients had markedly increased end-diastolic stiffness, which was considered a sufficient single pathology to induce increased LV end-diastolic pressure. Four (20%) patients showed a concomitant presence of moderately increased stiffness and severe LV dyssynchrony, and the remaining 2 (10%) patients, with normal stiffness, showed significant exercise-induced mitral regurgitation at hand-grip exercise. If the invasive pressure measurements were absent, only 5 (25%) of the outpatients with HFPEF fulfilled the European Society of Cardiology definition of HFPEF. A significant proportion of stable outpatients with unexplained chronic dyspnea may have HFPEF. In the patients whom we studied, increased LV stiffness, dyssynchrony, and dynamic mitral regurgitation were the major mechanisms underlying development of HFPEF.