Blood Pressure Responses to Exercise in Patients with Heart Failure with Preserved Ejection Fraction: the Importance of Normalizing Blood Pressure to Workload

Background: Exaggerated exercise blood pressure (EEBP) is assessed using systolic blood pressure (SBP) thresholds at peak exercise (>210 [men], >190 [women] mmHg), which is confounded by the presence of hypertension. However, SBP-workload slopes are independent of resting SBP and predict future cardiovascular events in those at high-risk for and those diagnosed with heart failure and preserved ejection fraction (HFpEF). Thus, we compared the two methods of EEBP assessment between normotensive high-risk individuals and hypertensive patients with HFpEF. Methods: We studied 71 individuals at high-risk for HFpEF (obesity and elevated cardiac biomarkers; 58% Female; age: 49±6 years, BMI: 39.0±5.7 kg/m 2 ) and 42 patients with HFpEF (67% Female; age: 71±6 years, BMI: 40.0±6.4 kg/m 2 ) during cycle ergometry. Blood pressure was measured via Brachial electrosphygmomanometry. SBP/Watts slopes were constructed using data from rest, 2 sub-maximal, and peak exercise workloads. To index central arterial stiffness we calculated the SBP/cardiac output (Q˙c; acetylene rebreathing) slope and systemic arterial compliance (SAC; stroke volume / pulse pressure). Results: Resting SBP was higher in HFpEF compared to high-risk (132±23 vs 120±19 mmHg, P =0.001). Peak workload ( P <0.001), oxygen uptake (1.284±0.420 vs 2.016±0.453 L/min; 11.7±3.3 vs 18.2±4.1 mL/min/kg, both, P <0.001), and Q˙c ( P <0.001) were lower in HFpEF. Peak exercise SBP was not different between HFpEF (189±28) and high-risk groups (180±33 mmHg, P =0.104), but the SBP/Watts slope was higher in HFpEF (0.9±0.7 vs 0.4±0.2 mmHg/Watt, P <0.001). In patients with HFpEF the SBP/Q˙c slope was higher (9.8±6.7 vs 5.6±2.8 mmHg/L/min, P <0.001) and SAC was lower (1.2±0.4 vs 1.7±0.5 mmHg/ml , P <0.001). Conclusion: Only reporting peak SBP masks the greater SBP response to exercise in HFpEF when compared to younger high-risk individuals; a difference likely mediated by higher arterial stiffness. Thus, the slope method may be more appropriate for quantifying BP responses to exercise as it more accurately reflects the physiology of EEBP in patients with HFpEF.