Parasympathetic activity in pulmonary arterial hypertension: could a simple measure do the trick?

Abstract

Rationale: A reduction in heart rate recovery (HRR) has been considered a marker of parasympathetic dysfunction, and it has been shown to be predictive of mortality in different clinical settings. It is unclear whether HRR is impaired in patients with pulmonary arterial hypertension (PAH) and whether it correlates with exercise impairment. Aim of this study was to evaluate the parasympathetic nervous activity by means of HRR after cardiopulmonary exercise testing (CPET) in patients with PAH and to explore its possible correlation with parameters of exercise capacity. Methods: 24 consecutive patients with Group 1 PAH (24 women, mean age 51.0 ± 6.6 years, 15 with idiopathic PAH, 7 with connective tissue-associated PAH, 2 PAH due to congenital heart disease) underwent maximal symptom-limited incremental CPET. HRR was calculated as the difference in heart rate between maximum tolerated exercise and 1 minute later. The results were compared with those of 15 healthy controls, and 15 patients with heart failure due to reduced left ventricular ejection fraction (HFrEF). Results: HRR was significantly lower in PAH compared to controls (11.83 ± 8.0 versus 25.67 ± 13.1, p Conclusions: A significant impairment in parasympathetic nervous activity was observed in our cohort of PAH patients, similar to that of HFrEF, and it was correlated with indices of exercise performance. Parasympathetic function imbalance may be a contributing factor to the reduced exercise tolerance in PAH patients.