Functional class and type of pulmonary hypertension determinate severity

OBJECTIVE: Heart rate variability (HRV) and turbulence (HRT) are validated methods of evaluation of cardiac autonomic nervous system (cANS) dysfunction which is associated with sudden cardiac death. There is limited data on cANS imbalance and its significance,in patients with pulmonary hypertension (PH), so we assessed HRV and especially HRT alterations in PH. METHODS AND RESULTS: Thirty-three out of 41 PH patients were enrolled in the study: 22 (66.7%) with pulmonary arterial hypertension (PAH) and 11 (33.3%) with chronic thromboembolic PH (CTEPH), 11 patients were in World Health Organization Functional Class (WHO-FC) I-II, and 22 others in WHO-FC III-IV. The control group consisted of 25 healthy persons. Routine evaluations, echocardiography, right heart catheterization and 24-hour Holter monitoring with time-domain HRV and HRT evaluation were performed. Most of HRV indices and both of HRT parameters were significantly impaired in PH patients, as compared to control subjects. Abnormal HRT (turbulence onset 0.0% and/or turbulence slope 2.5 ms/RR) was found in 36.4% WHO-FC I-II and in 77.3% WHO-FC III-IV patients (P=0.05). Patients in WHO-FC III-IV or with CTEPH presented compromised HRV and HRT values when compared to patients in WHO-FC I-II or with PAH, respectively. Multivariate analysis showed that abnormal HRT occurrence in PH was influenced by higher WHO-FC only (odds ratio 5.3, 95% CI 1.4-19.9, P= 0.01). CONCLUSION: Higher WHO-FC and probably type of pulmonary hypertension (CTEPH more than PAH) determinate the severity of cANS dysfunction assessed by heart rate variability and turbulence. Potential clinical consequences of our findings need further investigations.