Background: Obstructive sleep apnea (OSA) is highly prevalent in patients with coronary artery disease (CAD) and is associated with recurrent cardiovascular risk. However, whether treatment with continuous positive airway pressure (CPAP) reduces this risk remains unclear. We performed a systematic review and meta-analysis to assess the effect of CPAP on long-term cardiovascular outcomes in patients with concomitant CAD and OSA. Methods: We searched the PubMed, EMBASE, and Cochrane library from their inceptions to October 7, 2017. We included observational studies and randomized controlled trials (RCTs) that described the association of CPAP treatment with cardiovascular events in patients with CAD and OSA. The primary outcome of interest was major adverse cardiovascular event (MACE), including all-cause or cardiovascular death, myocardial infarction, stroke, repeat revascularization, or hospitalization for heart failure. Outcomes data were pooled using random effects models and heterogeneity assessed with the I-2 statistic. Results: We identified 9 studies (2 RCTs and 7 observational studies) with 1430 participants. The median follow-up duration was from 36 to 86.5 months. Treatment with CPAP was associated with a significantly lower risk of MACE in 6 observational studies (RR 0.61, 95% CI: 0.39-0.94, P = 0.02), but this was not reproduced in 2 RCTs (RR 0.57, 95% CI: 0.32-1.02, P = 0.06). Similarly, CPAP significantly reduced the risk of all-cause death (4 observational studies) and cardiovascular death (3 observational studies), which were also not confirmed in RCTs. Conclusions: The use of CPAP in patients with CAD and OSA might prevent subsequent cardiovascular events, which was only demonstrated in observational studies, but not in RCTs. The value of CPAP therapy as second prevention for CAD needs further investigation.