Alleviation of pulmonary hypertension by cardiac resynchronization therapy is associated with improvement in central sleep apnea

Abstract

Background: Recent studies have demonstrated that cardiac resynchronization therapy (CRT) reduces sleep apnea in heart failure (HF); however, the mechanism of benefit remains unclear. Methods: Overnight polysomnography (PSG) was performed in consecutive HF patients who were scheduled for CRT implant. Patients with sleep apnea defined by an apnea-hypopnea index (AHI) of >10/hour were recruited and underwent echocardiogram examination at baseline and 3 months after CRT. Results: Among 37 HF patients screened, 20 patients (54%) had sleep apnea and 15 of them consented for the study. After 3 months of CRT, there was a significant improvement in New York Heart Association functional class (3.1 ± 0.1 vs 2.1 ± 0.1, P < 0.01), quality-of-life (QoL) score (62.9 ± 3.3 vs 56.1 ± 4.5, P = 0.02), left ventricular ejection fraction (LVEF, 28.8 ± 2.5% vs 38.1 ± 2.3%, P < 0.01), and reduction in pulmonary artery systolic pressure (PASP, 41.0 ± 2.7 vs 28.6 ± 2.2 mmHg; P < 0.01) compared with baseline. Repeated PSG after CRT demonstrated a reduction in the duration of arterial oxygen desaturation ≤95% (251.2 ± 36.7 vs 141.0 ± 37.1 minutes), AHI (27.5 ± 4.7 vs 18.1 ± 3.0, P = 0.05), and number of central sleep apnea (CSA) (7.8 ± 2.6 vs 3.0 ± 1.3/hour, P = 0.03), but not number of obstructive sleep apnea (OSA, 8.6 ± 3.3 vs 7.2 ± 2.3/hour, P = 0.65) compared to baseline. Percentage change in PASP was significantly correlated with percentage changes in LVEF (r = -0.57, P = 0.04), AHI (r = 0.5, P = 0.05), and number of CSA episodes (r = 0.55, P = 0.02). Conclusions: The results demonstrated that CRT significantly reduces CSA in patients with HF. Importantly, we have noted a decrement of PASP correlated to drop in CSA which maybe one of the mechanisms explaining this observation. Future studies are required to confirm our finding and elucidate other possible mechanisms in this regard. © 2008, The Authors.