Right Ventricular Hemodynamics Using Cardiac MRI in Patients COPD and OSA

The coexistence of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA) in the same patient has been termed overlap syndrome, affecting 1% of the U.S. population.The investigators propose to conduct this study that aims: (1) to compare right and left ventricular hemodynamic parameters using cardiac magnetic resonance imaging (MRI) in overlap syndrome vs. COPD only and OSA only; (2) to compare the effects of bi-level positive airway pressure (BPAP) vs. nocturnal oxygen therapy (NOT) on right ventricular (RV) hemodynamics in overlap syndrome. This study will allow us to test the hypothesis: (1) Patients with overlap syndrome have more RV dysfunction than those with COPD only or OSA only; (2) treatment of both hypoxemia and hypercapnia during sleep will improve RV hemodynamics compared with treatment of hypoxemia alone in patients with overlap syndrome.

Despite the high prevalence of overlap syndrome, few data are available on its pathophysiology and clinical consequences of these patients. Overlap syndrome has recently been reported to have excess cardiovascular mortality compared with COPD alone. However, no study has evaluated the mechanisms of excess cardiovascular mortality in untreated overlap syndrome. In addition, no prospective, randomized, controlled data are currently available on treatment of overlap syndrome. This study is divided into two parts. The first part (Part 1) is a cross-sectional cohort study comparing subjects with overlap syndrome to those with COPD alone and those with OSA alone. Patients with COPD and OSA overlap syndrome will be evaluated by an overnight sleep study, cardiac MRI, serum inflammatory biomarker, urine catecholamine level, pulmonary function test, and questionnaires of sleep and health related quality of life. These measurement will be compared between overlap syndrome and control groups with either COPD or OSA alone. The second part (Part 2) of the study is a prospective, parallel-group, randomized, controlled pilot study examining the effect of BPAP (and nocturnal oxygen if needed) vs. nocturnal oxygen therapy alone in patients with overlap syndrome (20 subjects in each treatment arm). The same measurement done during Part 1 will be repeated to evaluate the treatment effects.