Hypertension tied to weakened ventilatory efficiency

Hypertensive individuals without a diagnosis of heart failure appear to have impaired ventilatory efficiency, which reflects an abnormal physiological response to exercise, according to a study.

The study assessed the ventilatory efficiency slope during exercise (minute ventilation/volume of expired CO₂; V_E/VCO₂ slope) in 55 patients with hypertension vs 24 normotensive individuals matched according to age, sex, and peak oxygen consumption. All participants completed ramped cardiovascular pulmonary exercise tests to peak oxygen consumption using a bike ergometer in 55 patients with primary hypertension and 24 normotensive controls.

The hypertensive and control groups were similar in terms of age (mean, 66 vs 64 years; p=0.18), body mass index (mean, 25.4 vs 24.0 kg/m²; p=0.13), and peak oxygen consumption (mean, 23.2 vs 24.0 mL/min per kg; p=0.64).

Peak exercise systolic and diastolic blood pressure (BP) levels were higher in hypertensive vs control groups (207 vs 178 mm Hg [p<0.0001] and 103 vs 88 mm Hg [p<0.0001], respectively), whereas peak heart rate was comparable (143 vs 142 beats/min; p=0.9).

The V_E/VCO₂ slope was significantly higher in the hypertensive than in the control group (31.8 vs 28.4; p=0.002), as was peak breathing frequency (34 vs 31 breaths/min; p=0.048).

Of note, only 27 percent of individuals in the hypertensive group had a normal V_E/VCO₂ slope (20–30) as opposed to 71 percent in the control group.

More studies are needed to establish whether those patients with hypertension with elevated V_E/VCO₂ slopes are at risk of subsequent heart failure.