Echocardiographic changes with non-invasive ventilation and CPAP in obesity hypoventilation syndrome

Abstract

Rationale: Despite a significant association between obesity hypoventilation syndrome (OHS) and cardiac dysfunction, no randomised trials have assessed the impact of non-invasive ventilation (NIV) or CPAP on cardiac structure and function assessed by echocardiography.

Objectives: We performed a secondary analysis of the data from the largest multicentre randomised controlled trial of OHS (Pickwick project, n=221) to determine the comparative efficacy of 2 months of NIV (n=71), CPAP (n=80) and lifestyle modification (control group, n=70) on structural and functional echocardiographic changes.

Methods: Conventional transthoracic two-dimensional and Doppler echocardiograms were obtained at baseline and after 2 months. Echocardiographers at each site were blinded to the treatment arms. Statistical analysis was performed using intention-to-treat analysis.

Results: At baseline, 55% of patients had pulmonary hypertension and 51% had evidence of left ventricular hypertrophy. Treatment with NIV, but not CPAP, lowered systolic pulmonary artery pressure (-3.4 mm Hg, 95% CI -5.3 to -1.5; adjusted P=0.025 vs control and P=0.033 vs CPAP). The degree of improvement in systolic pulmonary artery pressure was greater in patients treated with NIV who had pulmonary hypertension at baseline (-6.4 mm Hg, 95% CI -9 to -3.8). Only NIV therapy decreased left ventricular hypertrophy with a significant reduction in left ventricular mass index (-5.7 g/m²; 95% CI -11.0 to -4.4). After adjusted analysis, NIV was superior to control group in improving left ventricular mass index (P=0.015). Only treatment with NIV led to a significant improvement in 6 min walk distance (32 m; 95% CI 19 to 46).

Conclusion: In patients with OHS, medium-term treatment with NIV is more effective than CPAP and lifestyle modification in improving pulmonary hypertension, left ventricular hypertrophy and functional outcomes. Long-term studies are needed to confirm these results.

Trial registration number: Pre-results, NCT01405976 (https://clinicaltrials.gov/).

Keywords: non invasive ventilation; sleep apnoea.