Abstract
BACKGROUND: Heart rate turbulence (HRT) impairment is a validated and an independent indicator of cardiovascular death. There are limited data on HRT in pulmonary hypertension (PH), so we assessed potential HRT alterations in PH, especially in relation to its severity. METHODS: Thirty-three out of 41 patients were enrolled in the study aged 49.7 ± 15.9 years (22 with arterial, 11 with chronic thromboembolic PH). Routine evaluations, right heart catheterization, and 24-hour Holter monitoring with heart rate variability and HRT assessment were performed. RESULTS: HRT was significantly impaired in PH patients, as compared to 25 healthy controls: mean turbulence onset (TO) was -0.27% versus -2.60% (P < 0.0001), and median turbulence slope (TS) was 3.13 versus 13.5 msRR (P < 0.0001). Abnormal HRT (TO ≥ 0.0% and/or TS ≤ 2.5 ms/RR) was found in 63.3% of PH patients. Patients with PH and abnormal HRT presented more compromised functional, biochemical, and hemodynamic status than PH patients with normal TO and TS values. Multivariate stepwise regression analysis showed that TO value was related to oxygen desaturation <90% in 6-minute walking test (6-MWT; OR 0.41, P < 0.001) and was related to N-Terminal pro-B type Natriuretic Peptide concentration (OR 0.40, P < 0.001); TS was related to 6-MWT distance (OR 0.53, P < 0.0001). CONCLUSIONS: Patients with arterial or chronic thromboembolic PH are characterized by significant impairment of HRT which is related to the disease severity. We hypothesize that patients with abnormal HRT could be considered as subjects with an increased risk of cardiovascular death, however, it needs further investigation.