Obstructive Sleep Apnea and Outcomes in Cardiac Surgery: A Systematic Review with Meta-Analytic Synthesis (PROSPERO CRD420251049574)

Abstract

Background: Obstructive sleep apnea (OSA) is a prevalent but frequently underdiagnosed comorbidity in patients undergoing cardiac surgery, including coronary artery bypass grafting (CABG), aortic valve replacement (AVR), and mitral valve repair or replacement (MVR). This systematic review and meta-analytic synthesis investigates the relationship between OSA and postoperative morbidity and mortality, with particular attention to the predictive utility of established screening instruments. Methods: A systematic search of the PubMed database was conducted (April 2025), identifying 724 articles published in the last ten years. Seventeen primary studies met the inclusion criteria for qualitative synthesis, and four additional studies were included in the meta-analyses. Outcomes assessed included atrial fibrillation, major adverse cardiac and cerebrovascular events (MACCE), acute kidney injury (AKI), respiratory complications, pneumonia, hospital length of stay (LOS), and mortality. Risk of bias was assessed qualitatively based on study design and reporting limitations. This review was registered in the PROSPERO database under registration number CRD420251049574. Results: Meta-analyses demonstrated significantly elevated odds of atrial fibrillation (OR = 2.44, 95% CI: 1.46-4.07), major adverse cardiac and cerebrovascular events (OR = 2.06, 95% CI: 1.61-2.63), acute kidney injury (OR = 2.24, 95% CI: 1.67-3.01), and respiratory complications (OR = 1.15, 95% CI: 1.05-1.25) among patients with OSA. Additionally, OSA was associated with a significantly prolonged hospital length of stay (standardized mean difference [SMD] = 0.62, 95% CI: 0.46-0.78) and a marginal increase in pneumonia risk (OR = 1.07, 95% CI: 1.00-1.15). Evidence regarding stroke, intensive care unit (ICU) stay, and mortality was inconsistent or underpowered. Conclusions: Across core outcomes, findings were consistent across multiple studies involving a large patient population. Obstructive sleep apnea is a clinically consequential risk factor in cardiac surgery, associated with increased perioperative complications and prolonged hospitalization. These findings support the integration of routine OSA screening into preoperative risk assessment protocols. Further prospective, multicenter trials are warranted to assess the efficacy of perioperative management strategies, including continuous positive airway pressure (CPAP) therapy, in improving surgical outcomes.

Keywords: CPAP; MACCE; atrial fibrillation; cardiac surgery; meta-analysis; obstructive sleep apnea; postoperative complications; risk stratification.

Figure 1

Visual summary of the strengths and limitations inherent to prospective and retrospective designs in this context.

Figure 2

Bar chart depicting the frequency of use of each tool across studies, illustrating the dominance of STOP-BAG2, STOP-Bang, and ESS.

Figure 3

Distribution of AUC values across studies, highlighting the heterogeneity and reinforcing the need for standardized reporting and prospective validation [51,55].

Figure 4

Presents a forest plot summarizing individual and pooled odds ratios for POAF in OSA versus non-OSA patients, visually reinforcing the strength and consistency of the association [49,50,68]. The solid horizontal lines represent the 95% confidence intervals for each individual study’s OR, while the light blue bars denote the actual odds ratio values. The vertical red dashed line marks the pooled OR of 2.44, emphasizing the overall estimated effect across studies [48,49,65].

Figure 5

Forest plot summarizing the odds ratios from individual studies and the aggregated meta-analytic estimate, visually emphasizing the consistency and strength of this association. Each black horizontal line represents the 95% confidence interval for an individual study’s odds ratio, while the black dots indicate the point estimates. The red horizontal line and red dot represent the pooled odds ratio and its confidence interval (random-effects model), and the vertical dashed grey line marks the null effect line (OR = 1), aiding in visual interpretation of significance and direction of association [47,48,52].

Figure 6

Summary of cardiac ischemic outcomes in patients with obstructive sleep apnea (OSA) following cardiac surgery. OR—Odds Ratio; OSA—Obstructive sleep apnea; P MI—Postoperative myocardial infarction [47,52,64].

Figure 7

Comparison of postoperative acute kidney injury incidence in patients with and without obstructive sleep apnea, based on Gali et al. (2020) [58], with pooled risk from the Wang et al. (2020) [47] meta-analysis.

Figure 8

Reported stroke outcomes across studies, highlighting the overall paucity and inconsistency of the existing evidence base [47,52,61].

Figure 9

Postoperative mortality rates in patients with and without obstructive sleep apnea following cardiac surgery [49,53,58,60].

Figure 10

Forest plot summarizing the odds ratios for postoperative respiratory complications in OSA versus non-OSA patients, based on data from three cohort studies. Each blue square represents the point estimate of the odds ratio (OR) for an individual study, and the accompanying black horizontal lines show the 95% confidence intervals (CI). The red square and dashed red line denote the pooled OR from the meta-analysis (OR = 1.15; 95% CI: 1.05–1.25), indicating a statistically significant increase in risk. The vertical dashed grey line at OR = 1.0 represents the line of no effect, helping to visualize whether individual and pooled estimates suggest elevated risk in the OSA group [54,61,64].

Figure 11

Ribbon plot showing standardized mean differences in hospital length of stay between OSA and non-OSA patients across three studies. Shaded bands indicate 95% confidence intervals. The red dashed line marks the pooled SMD (0.62), suggesting consistently longer LOS in OSA patients [12,58,66].

Figure 12

Lollipop plot of odds ratios (ORs) for postoperative pneumonia in OSA versus non-OSA patients, visually illustrating the narrow but consistent increase in risk observed across studies. Each blue dot represents the point estimate of the OR for an individual study. The horizontal black lines extending from the blue dots indicate the 95% confidence intervals. The red dot and horizontal red line at the bottom represent the pooled odds ratio (OR = 1.07; 95% CI: 1.00–1.15) from the meta-analysis. The vertical dashed black line at OR = 1.0 denotes the line of no effect, aiding interpretation of statistical significance [12,50,54,61].

Figure 13

Suggested protocol for the grouping and reporting of patients with obstructive sleep apnea in cardiac surgery studies.