The Impact of Underlying Obstructive Sleep Apnea Treatment on Exercise Capacity in Patients With Pulmonary Hypertension Undergoing a Cardiac Rehabilitation Program

Purpose:Obstructive sleep apnea (OSA)-related pulmonary hypertension (PH) can often be reversed with treatment of OSA via continuous positive airway pressure. We hypothesized that treatment of OSA would be associated with a greater improvement in exercise capacity (EC) with cardiac rehabilitation (CR), especially in patients with PH as compared with those who are untreated. Methods:We reviewed medical records of 315 consecutive patients who participated in CR. Pulmonary hypertension status was assessed on the basis of peak tricuspid regurgitant velocity (>2.8 m/sec) on pre-CR echocardiograms. The OSA status (no, untreated, or treated OSA) was determined on the basis of results from sleep studies, continuous positive airway pressure device data, and physician notes. Exercise capacity was assessed by measuring metabolic equivalents (METs) using a treadmill stress test before and after CR. Results:We included 290 patients who participated in CR with available echocardiographic data: 44 (15%) had PH, and 102 (35%) had known OSA (30 treated and 72 untreated). Patients with OSA versus those with no OSA were more likely to have PH (P = .06). Patients with PH versus no-PH were associated with significantly lower baseline METs in crude and adjusted analyses (P <=. 004). The PH and OSA status in isolation were not associated with changes in METs (P > .2) with CR. There was a significant interaction between OSA treatment and PH in crude and adjusted analyses (P <=.01): treatment vs no treatment of OSA was associated with a clinically and statistically greater improvement in METs in patients who participated in CR with but not without PH. Conclusion:Baseline PH was associated with decreased baseline EC but did not attenuate CR-related improvements in METs. However, in the subset of OSA patients with PH, OSA therapy was associated with improved EC after CR.