Some nonsleepy patients with coronary artery disease and obstructive sleep apnea (OSA) may receive cardiovascular benefit from continuous positive airway pressure (CPAP) therapy, according to a post hoc analysis of the RICCADSA clinical trial. That study found no benefit among patients overall, but the new analysis found that patients whose heart rate increases (delta heart rate, or dHR) more than average during apnea or hypopnea experienced fewer cardiovascular or cerebrovascular events during apnea or hypopnea when treated with CPAP.
Although RICCADSA showed no benefit, an analysis of the Multi-Ethnic Study of Atherosclerosis (MESA) and the Sleep Heart Health Study (SHHS) cohorts found that elevated pulse rate response to respiratory events was associated with greater risk of cardiovascular disease (CVD) morbidity and mortality. But the effect was seen only in nonsleepy patients. “We hypothesized that pulse rate response to apneas would predict which patients with OSA may most benefit from CPAP treatment. Now, our study suggests that there is, in fact, a subgroup of nonsleepy patients with OSA for whom CPAP could provide a reduction in risk, specifically those with a higher pulse rate response to their respiratory events,” Ali Azarbarzin, PhD, said in an interview.
Dr. Azarbarzin presented the study at the American Thoracic Society’s virtual international conference (Abstract A1103). He is in the division of sleep and circadian disorders at Brigham and Women’s Hospital, and is assistant professor of medicine at Harvard Medical School, both in Boston.
The study is in line with recent efforts to subgroup OSA patients to determine which are at higher risk of cardiovascular events and other complications, and which are most likely to respond to treatment, according to Esra Tasali, MD, of the University of Chicago, who moderated the session where the study was presented. “The field is really urgently in need of coming up with new methods, and I think this study is getting a handle on that,” said Dr. Tasali in an interview.
Dr. Esra Tasali
“I think that this is really pointing toward a new area that the whole (sleep field) is moving toward, which is better phenotyping of sleep apnea so that we can come up with more personalized treatments,” said Dr. Tasali.
The patients who appeared to gain a cardiovascular benefit from CPAP represented about 16% of trial participants. Dr. Azarbarzin refrained from making clinical recommendations, citing the need for more data. The team next plans to reproduce the findings in additional, larger trials such as the SAVE and ISAACC trials. “Ultimately, our goal is to confirm our findings in a future randomized controlled trial of CPAP by enrolling participants based on their pulse rate response,” said Dr. Azarbarzin.
The RICCADSA study was a single center randomized, controlled trial with 226 patients with coronary artery disease and OSA who were randomized to CPAP or no CPAP treatment. In the overall population, CPAP treatment was not associated with a statistically significant change in repeat revascularization, myocardial infarction, stroke, or cardiovascular mortality (hazard ratio [HR], 0.79; P = .435). That study assumed that the effect of OSA on CVD is similar across all subgroups of dHR.
The mean increase in heart rate was 7.1 beats per minute (BPM; standard deviation, 3.7). Each standard deviation increase in dHR was linked to greater CVD risk (HR, 1.45; P = .029). For each standard deviation decrease in dHR, treatment with CPAP decreased the CVD risk (HR, 0.54; P = .043).
For patients with a low dHR of 4 BPM, the hazard ratio for CVD was 0.8 with no CPAP treatment and 1.2 for CPAP treatment. For those at the mean value of 7 BPM, the HRs were 1.1 and 0.9 respectively. For those with a high dHR, (10 BPM), the hazard ratio was 1.6 without treatment and 0.7 with CPAP.
“We modeled delta heart rate interaction with CPAP, which was significant. What this means is that for someone with a mean delta heart rate of 7 beats per minute, the risk reduction (with CPAP) is similar to what RICCADSA reported. But if you look at those with high delta heart rate, the risk reduction was significantly larger. It was actually a more than 50% reduction of risk with CPAP treatment,” said Dr. Azarbarzin.
Dr. Azarbarzin has consulted for Somnifix and Apnimed and has received grants from Somnifix. Dr. Tasali has no relevant financial disclosures.