Left Ventricular Diastolic Dysfunction and Exercise Intolerance in Obese Heart Failure with Preserved Ejection Fraction.

This study tested the hypothesis that early left ventricular (LV) relaxation is impaired in older obese heart failure with preserved ejection fraction (HFpEF) patients, and related to decreased peak exercise oxygen uptake (peak VO2 ). LV strain and strain rate were measured by feature tracking of magentic resonance cine images in 79 older obese HFpEF patients (mean age: 66 years; mean BMI: 38 kg/m2 ) and 54 healthy control participants. LV diastolic strain rates were indexed to cardiac preload as estimated by echocardiography derived diastolic filling pressures (E/e'), and correlated to peak VO2 . LV circumferential early diastolic strain rate was impaired in HFpEF compared to controls (0.93±0.05 s-1 vs 1.20±0.07 s-1 , p=0.014); however, we observed no group differences in early LV radial or longitudinal diastolic strain rates. Isolating myocardial relaxation by indexing all three early LV diastolic strain rates (i.e. circumferential, radial, and longitudinal) to E/e' amplified the group difference in early LV diastolic circumferential strain rate (0.08±0.03 vs 0.13±0.05, p<0.0001), and unmasked differences in early radial and longitudinal diastolic strain rate. Moreover, when indexing to E/e', early LV diastolic strain rates from all three principal strains, were modestly related with peak VO2 (R=0.36, -0.27, 0.35, respectively, all p<0.01); this response, however, was almost entirely driven by E/e' itself, (R=-0.52, P<0.001). Taken together, we found that while LV relaxation is impaired in older obese HFpEF patients, and modestly correlates with their severely reduced peak exercise VO2 , LV filling pressures appear to play a much more important role in determining exercise intolerance.