Heart Biomarker Evaluation in Apnea Treatment - HeartBEAT
Obstructive sleep apnea (OSA) is highly prevalent, and is a risk factor for adverse cardiovascular events. The current trial sought to study the efficacy of continuous positive airway pressure (CPAP) and supplemental oxygen in reducing markers of cardiovascular risk in patients with OSA.
Treatment of patients with moderate to severe OSA with CPAP and supplemental oxygen would be superior to healthy lifestyle and sleep education in reducing 24-hour mean arterial blood pressure (MAP) at 12 weeks.
- Age 45-75 years
- OSA with AHI 15-50/hour
- Established CAD or multiple risk factors
Number of screened applicants: 5,747
Number of enrollees: 281
Duration of follow-up: 12 weeks
Mean patient age: 63 years
Percentage female: 26%
- AHI >50
- Oxygen saturation of <85% for >10% of the recording
- Central apnea index >5
- 24-hour MAP at 12 weeks
Patients were screened using the Berlin questionnaire and Epworth Sleepiness Scale for OSA. Patients at high risk for OSA and with established coronary artery disease (CAD) or with multiple risk factors underwent home sleep testing with a nasal cannula pressure transducer and an oronasal thermal sensor.
Patients with apnea-hypopnea index (AHI) between 15 and 50/hour and with an oxygen saturation ≥85% for at least 90% of the recordings were randomized in a 1:1:1 fashion to either healthy lifestyle and sleep education (conservative management), CPAP with conservative management, or supplemental oxygen with conservative management.
Participants in the CPAP group received a CPAP device with automatic adjustment (REMstar Auto CPAP, Philips Respironics), set at a pressure range of 4-20 cm of water for 7 days, and then reset to the best fixed pressure for each patient during those 7 days.
For the group receiving supplemental oxygen, a stationary oxygen concentrator (EverFlo, Philips Respironics) was used to provide nightly treatment with oxygen at a rate of 2 L/min through a nasal cannula.
Lipid-lowering medications (89%), beta-blockers (68%)
A total of 281 patients were enrolled at four medical centers, 90 to CPAP, 94 to supplemental oxygen, and 97 to conservative management. Baseline characteristics were similar between the two arms. Median body mass index was 33.5 kg/m2, with diabetes mellitus in 45% of patients and hypertension in 88%. Pre-existing CAD was noted in 53% of patients. Median AHI index was 25 episodes/hour and an SpO2 <90% was observed approximately 5% of the time. Baseline mean 24-hour systolic blood pressure (SBP)/diastolic blood pressure (DBP)/MAP values were approximately 124/71/89 mm Hg in the three arms. Mean number of antihypertensive medications was 2.4. Mean duration of CPAP use was 3.5 hours, whereas mean duration of supplemental oxygen use was 4.8 hours.
Patients receiving CPAP and supplemental oxygen had similar reductions in nocturnal hypoxemia (>64% reduction in frequency of 3% desaturation events). The adjusted 24-hour MAP at 12 weeks was significantly lower in the CPAP arm compared with the conservative management arm (-2.4 mm Hg, p = 0.02) and the supplemental oxygen arm (-2.8 mm Hg, p = 0.02). Similar results were observed for 24-hour mean SBP and DBP for CPAP compared with conservative management and supplemental oxygen arms. No differences were observed between the supplemental oxygen and conservative management arms. CPAP also significantly reduced C-reactive protein (CRP) levels at 12 weeks compared with conservative management (geometric mean ratio 0.80, p = 0.03).
The results of this trial indicate that treatment of moderate to severe OSA with CPAP is superior to supplemental oxygen or conservative management in reducing 24-hour MAP at 12 weeks in patients with established CAD or at high risk for it. Although the magnitude of benefit was small, it was observed on the background of existing BP treatment.
Future studies will need to assess the impact of this strategy on clinical outcomes. Efficacy in patients with severe OSA (excluded from this study) will also need to be assessed, although the effect is likely to be larger. A major issue with long-term CPAP use is compliance.
Gottlieb DJ, Punjabi NM, Mehra R, et al. CPAP versus oxygen in obstructive sleep apnea. N Engl J Med 2014;370:2276-85.
Basner RC. Cardiovascular morbidity and obstructive sleep apnea. N Engl J Med 2014;370:2339-41.
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