Abstract 13669: Ascending Aortic Augmentation Pressure Does Not Decrease During Exercise in HFpEF: Implications for SV Reserve Impairment

Abstract

Aortic augmentation pressure (aAP; difference between first [aP1] and second [aP2] peaks of the aortic pressure waveform) decreases during exercise in young healthy individuals, lowering mid-late systolic afterload, an important determinant of cardiac work and stroke volume (SV). In patients with heart failure and preserved ejection fraction (HFpEF), SV responses to exercise (i.e. SV reserve) are often abnormal (≤ 50%). A lack of fall in aAP during exercise in HFpEF could contribute to impairments in SV reserve. Therefore, we studied 15 HFpEF patients (age, 71 ± 6 years; 10 women; BMI 39.2 ± 6.2 kg/m 2 ) in the seated upright position. During rest and six-minutes of cycling at 20 Watts, we recorded beat-by-beat radial arterial blood pressure and estimated ascending aortic blood pressure waveforms in real-time via a generalized inverse transfer function (SphygmoCor). SV was calculated from cardiac output (Qc, acetylene rebreathe) and heart rate (ECG), with total peripheral resistance (TPR) calculated as the quotient of radial MAP and Qc. HR (Rest: 75 ± 14 vs 20W: 93 ± 12 bpm, P < 0.0001), SV (Rest: 61 ± 17 vs 20W: 84 ± 19 ml, P = 0.0003) and Qc (Rest: 4.5 ± 1.0 vs 20W: 7.7 ± 1.6 L/min, P < 0.0001) increased from rest to 20 Watts, whilst TPR decreased (Rest: 21.3 ± 4.4 vs 20W: 14.0 ± 3.8 mmHg/L/min, P < 0.0001); SV reserve was 43 ± 33 %. Aortic diastolic pressure did not change (Rest: 70 ± 12 vs 20W: 76 ± 15 mmHg, P = 0.0976), whereas aP1 (Rest: 112 ± 18 vs 20W: 130 ± 20 ml, P = 0.0002) and aP2 (Rest: 123 ± 26 vs 20W: 142 ± 25 ml, P = 0.0021) increased during exercise (Figure). Notably, aAP was not different between rest and exercise (Rest: 11 ± 11 vs 20W12 ± 11 mmHg, P = 0.4969). Therefore, the contribution of aAP to mid-late systolic afterload is unchanged during exercise in HFpEF, unlike in young healthy adults. Unchanged aAP may be a mechanism of high mid-late systolic afterload during exercise in HFpEF, which could contribute to impairments in SV reserve related to reduced ventricular contractile reserve.