Abstract 13676: Sublingual Nitroglycerin Lowers Aortic Augmentation Pressure at Rest and During Exercise in Patients With HFpEF

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Infusion or inhalation of organic nitrates lower ascending aortic pressures, and reduce mid-late systolic afterload via a reduction in augmentation pressure (aAP, the difference between the first [aP1] and second [aP2] peaks of the aortic pressure waveform) at rest and during exercise in patients with heart failure and preserved ejection fraction (HFpEF). Sublingual nitroglycerin (NTG) is more accessible for patients as compared to the infusion or inhalation of nitrates. It is unknown whether NTG spray (400μg) elicits these same effects as organic nitrates on aortic hemodynamics at rest and during exercise. Therefore, in 15 patients with HFpEF (age, 71 ± 6 years; 10 women; BMI 39.2 ± 6.2 kg/m 2 ), as part of our ongoing clinical trial, we measured beat-by-beat radial artery blood pressure and estimated aortic pressure in real-time via a generalized inverse transfer function (SphygmoCor). Data were collected in the seated upright position at rest and throughout six-minutes of cycling at 20 Watts during either a placebo or NTG condition (randomized order). Stroke volume (SV) was calculated from cardiac output (Qc, acetylene rebreathe) and heart rate (ECG). NTG lowered stroke volume at rest, but not during exercise (Table); however, SV responses to exercise were similar (Placebo: Δ22 ± 19 vs NTG: Δ25 ± 18 ml, P = 0.1991). Aortic diastolic pressure was not different at rest with NTG compared to placebo (Table). aP1 and aP2 were lower at rest with NTG, with greater reductions in aP2 (Table). NTG lowered aAP during rest (Placebo: 11 ± 11 vs NTG: 0 ± 14 mmHg, P = 0.0002) and exercise (Placebo: 12 ± 11 vs NTG: 4 ± 12 mmHg, P < 0.0001). These results suggest patients with HFpEF do not augment SV responses to exercise despite a lower aAP contribution to (mid-late) systolic afterload with NTG. The inability to take advantage of a lower aAP during exercise may reflect impairments in contractile function and end-systolic reserve.