Heart Rate Variability in Severe Right or Left Heart Failure: The Role of Pulmonary Hypertension and Resistances

BACKGROUND: The decrease in heart rate variability (HRV) might be related to the hemodynamic status in heart failure. However, HRV in patients with severe isolated right heart failure has not been extensively studied. AIMS: This study compared HRV in patients with congestive heart failure (CHF) and in patients with isolated right heart failure. METHODS: Time and frequency domain analysis of HRV on 24-h ECG recording was assessed in 15 healthy subjects and in two groups of patients with severe heart failure awaiting heart or heart/lung transplantation. These were 15 patients with CHF due to idiopathic dilated cardiomyopathy (IDC) and 10 patients with isolated right heart failure due to primary pulmonary hypertension (PPH). RESULTS: Measurement of HRV were significantly decreased in both groups of patients compared with the control group. Patients with IDC had higher pulmonary capillary wedge pressure than patients with PPH (P=0.04) but lower pulmonary artery pressure and lower pulmonary vascular resistance (PVR) (P<0.0001). However, all the measurements of HRV were significantly lower in patients with IDC than in patients with PPH (range 22-77%, P<0.05 to P<0.01). None of the HRV measurements correlated with filling pressure measurements. CONCLUSIONS: The increase in pulmonary vascular resistance in heart failure is not the main causal factor behind a decrease in HRV.