INTER-INDIVIDUAL RESPONSE DIFFERENCES ON CARDIORESPIRATORY FITNESS IN HEART FAILURE
Previous studies have shown an association between low cardiorespiratory fitness (CRF) and mortality in adults with heart failure with preserved ejection fraction (HFpEF). While exercise-based cardiac rehabilitation (EBCR) has been reported to increase CRF in adults with HFpEF, true inter-individual response differences (IIRD) to EBCR among those with HFpEF is not known nor has it ever been assessed. The purpose of this study was to address this gap. Using data from the recent American Heart Association and American College of Cardiology statement on supervised exercise training for chronic HFpEF, eight randomized controlled trials representing 503 adults (260 exercise, 243 control) were included and pooled for a standard deviation of individual response (SDIR) meta-analysis on changes in CRF, assessed as VO2peak in mL.kg-1min-1. The inverse heterogeneity (IVhet) model was used to pool results. The pooled 95% confidence interval (CI) for the SDIR included zero (mean, 0.5, 95% CI, -1.9 to 2.0 mL.kg-1min-1). With each study deleted from the model once, results continued to not reach statistical significance. The 95% prediction interval for the SDIR, indicative of what result one might expect is they conducted their own randomized controlled trial, was -3.3 to 3.3 mL.kg-1min-1. The probability of a clinically meaningful difference of at least 1.0 mL.kg-1.min-1 in VO2peak was 50.6% (only possibly clinically important). There is a lack of exercise-associated IIRD on VO2peak in adults with HFpEF once random and within-subject variation are properly accounted for. Thus, a search for potential moderators and mediators, including genetic interactions, on VO2peak in adults with HFpEF cannot be supported at this time.BACKGROUND
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