Abstract 15786: Effect of Inorganic Nitrate on Wave Reflections vs. Microvascular Dilatory Reserve: Role in Improving Aeobic Capacity in Heart Failure With Preserved Ejection Fraction
Background: We have previously shown that a single dose of Inorganic nitrate supplementation increases peak oxygen consumption in heart failure with preserved ejection fraction (HFpEF). Inorganic nitrate increased exercise microvascular dilatory reserve (resistive load during exercise) and reduced arterial wave reflections (which increase pulsatile load to the LV and induce diastolic dysfunction). However, the relative contribution of these arterial effects to the improvement in aerobic capacity in this population is unknown.
Methods: We analyzed data from a randomized, double-blind, crossover study comparing a single dose of nitrate-rich beetroot juice (BR, 12.9 mmol of inorganic nitrate) with an identical nitrate-depleted placebo (PB) juice. Subjects performed supine-cycle maximal-effort cardiopulmonary exercise tests, with measurements of peak VO2, and measurements of exercise vasodilatory reserve with Doppler echocardiography. We also measured augmentation index, a marker of arterial wave reflections, via radial arterial tonometry. The relative changes in arterial endpoints (% change relative to placebo) were assessed as predictors of the percent change in peak VO2.
Results: As previously reported, NO3- supplementation increased peak VO2 (12.6±3.7 versus 11.6±3.1 mL O2·min(-1)·kg(-1); P=0.005), exercise-induced microvascular dilatory reserve (-42.4±16.6% versus -31.8±20.3%; P=0.03) and reduced aortic augmentation index (132.2±16.7% versus 141.4±21.9%; P=0.03). The reduction in augmentation index was strongly and significantly associated with the increase in peak VO2 in response to BR (Standardized Beta=-0.63, P=0.016). The improvement in microvascular dilatory reserve with BR tended to be associated with the improvement in peak VO2 (standardized Beta=-0.49, P=0.054).
Conclusions: NO3- affected both microvascular dilation during exercise and pulsatile load (wave reflections) in HFpEF. The reduction in wave reflections more strongly correlated with the improvement in peak VO2. Our findings support the importance of late systolic pulsatile load from wave reflections in HFpEF.
Author Disclosures: J.A. Chirinos: Research Grant; Significant; NIH, American College of Radiology Network, Fukuda Denshi, Bristol Myers Squibb, Microsoft and CVRx Inc. Other Research Support; Modest; Fukuda Denshi, Withings, Atcor Medical. Consultant/Advisory Board; Modest; Fukuda Denshi, Microsoft Research, Merck and Vital Labs. Consultant/Advisory Board; Significant; Bristol Myers Squibb, OPKO Healthcare. M. Beraun: None. R.R. Townsend: None. S. Varakantam: None. P. Zamani: None.
- © 2016 by American Heart Association, Inc.