Ventilatory Efficiency Is Reduced in People With Hypertension During Exercise

Background An elevated ventilatory efficiency slope during exercise (minute ventilation/volume of expired CO₂; V_E/VCO₂ slope) is a strong prognostic indicator in heart failure. It is elevated in people with heart failure with preserved ejection, many of whom have hypertension. However, whether the V_E/VCO₂ slope is also elevated in people with primary hypertension versus normotensive individuals is unknown. We hypothesize that there is a spectrum of ventilatory inefficiency in cardiovascular disease, reflecting an increasingly abnormal physiological response to exercise. The aim of this study was to evaluate the V_E/VCO₂ slope in patients with hypertension compared with age-, peak oxygen consumption-, and sex-matched healthy subjects. Methods and Results Ramped cardiovascular pulmonary exercise tests to peak oxygen consumption were completed on a bike ergometer in 55 patients with primary hypertension and 24 normotensive controls. The V_E/VCO₂ slope was assessed from the onset of exercise to peak oxygen consumption. Data were compared using unpaired Student t test. Age (mean±SD, 66±6 versus 64±6 years; P=0.18), body mass index (25.4±3.5 versus 24±2.4 kg/m²; P=0.13), and peak oxygen consumption (23.2±6.6 versus 24±7.3 mL/min per kg; P=0.64) were similar between groups. The V_E/VCO₂ slope was elevated in the hypertensive group versus controls (31.8±4.5 versus 28.4±3.4; P=0.002). Only 27% of the hypertensive group were classified as having a normal V_E/VCO₂ slope (20-30) versus 71% in the control group. Conclusions Ventilatory efficiency is impaired people with hypertension without a diagnosis of heart failure versus normotensive individuals. Future research needs to establish whether those patients with hypertension with elevated V_E/VCO₂ slopes are at risk of developing future heart failure.