Chest
Volume 147, Issue 5, May 2015, Pages 1352-1360
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Original Research: Sleep Disorders
Impact of OSA on Cardiovascular Events After Coronary Artery Bypass Surgery

https://doi.org/10.1378/chest.14-2152Get rights and content

BACKGROUND

The impact of OSA on new cardiovascular events in patients undergoing coronary artery bypass graft (CABG) surgery is poorly explored.

METHODS

Consecutive patients referred for CABG underwent clinical evaluation and standard polysomnography in the preoperative period. CABG surgery data, including percentage of off-pump and on-pump CABG, number of grafts, and intraoperative complications, were collected. The primary end point was major adverse cardiac or cerebrovascular events (MACCEs) (combined events of all-cause death, myocardial infarction, repeated revascularization, and cerebrovascular events). Secondary end points included individual MACCEs, typical angina, and arrhythmias. Patients were evaluated at 30 days (short-term) and up to 6.1 years (long term) after CABG.

RESULTS

We studied 67 patients (50 men; mean age, 58 ± 8 years; mean BMI, 28.5 ± 4.1 kg/m2). OSA (apnea-hypopnea index ≥ 15 events/h) was present in 56% of the population. The patients were followed for a mean of 4.5 years (range, 3.2-6.1 years). No differences were observed in the short-term follow-up. In contrast, MACCE (35% vs 16%, P = .02), new revascularization (19% vs 0%, P = .01), episodes of typical angina (30% vs 7%, P = .02), and atrial fibrillation (22% vs 0%, P = .0068) were more common in patients with than without OSA in the long-term follow-up. OSA was an independent factor associated with the occurrence of MACCE, repeated revascularization, typical angina, and atrial fibrillation in the multivariate analysis.

CONCLUSIONS

OSA is independently associated with a higher rate of long-term cardiovascular events after CABG and may have prognostic and economic significance in CABG surgery.

Section snippets

Participants

We studied consecutive patients with severe coronary artery disease (CAD) over 40 years of age referred for CABG at the Heart Institute (InCor), University of São Paulo Medical School, São Paulo, Brazil.3 This is a follow-up study from a previous investigation devoted to validating the diagnosis of OSA with portable sleep monitors among consecutive patients referred for elective CABG.3 Details on patient recruitment were previously reported.3 Patients were excluded if they had a previous

Preoperative Clinical Evaluation

All participants underwent a detailed history and physical examination, including anthropometric and BP measurements. All subjects underwent an overnight standard polysomnography performed at the sleep laboratory as previously described.3 Hypopnea was defined as a 50% airflow lasting ≥ 10 s associated with oxygen desaturation of > 3% or with an arousal. Apnea was defined when cessation of airflow lasted ≥ 10 s and was further classified based on the presence or absence of respiratory effort as

Follow-up

Percentage of off-pump and on-pump CABG, on-pump time (minutes), number of grafts, and intraoperative complications (see standard definitions in e-Appendix 1) were recorded. In the postoperative setting, all patients were initially monitored in the ICU. As previously described,13 blood samples for serum creatinine kinase MB and troponin determination were collected prior to surgery and every 6 h after surgery, until the peak elevation was determined. We followed up all participants during the

Statistical Analysis

Data were analyzed with SPSS 18.0 (IBM Corporation). After checking normality with the Kolmogorov-Smirnov test, the results were expressed as mean ± SD, median (interquartile range), or percentage, when appropriate. Wilcoxon signed-rank test and paired Student t or Mann-Whitney U tests were used for independent samples, and the χ2 test was used to compare the variables of frequency between patients with and without OSA. The time to the first occurrence of any one of the components of the

Results

We prospectively evaluated 100 patients who underwent elective CABG. None had a previous history of arrhythmias. Sixty-seven patients (50 men) composed the final sample (Fig 1). The baseline characteristics of the entire population are presented in Table 1. The study population was predominantly middle-aged, overweight, and white. The frequency of patients with OSA was 56% (mean AHI, 23.3 ± 20.3 events/h of sleep).

Compared with patients without OSA, patients with OSA had significantly higher

Discussion

To our knowledge, this is the first study to evaluate the impact of OSA on short- and long-term cardiovascular events after CABG. We extend our previous findings that OSA is extremely common in patient candidates for CABG.3 Contrary to our initial hypothesis, we found no short-term differences in cardiovascular events in patients with and without OSA. However, in the long-term follow-up, the rate of MACCE (primary outcome) was higher in patients with than without OSA. This combined end point is

Acknowledgments

Author contributions: L. F. D. and C. H. G. U. had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. N. d. J. D.-S., F. S. N., F. B. N., and R. P. P. contributed substantially to the study design, data collection, data interpretation, and the writing of the manuscript; and C. H. G. U., A. A. L. d. S., L. A. M. C., G. L.-F., and L. F. D. contributed substantially to the study design, data analysis and

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FUNDING/SUPPORT: This study was supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) and Fundação Zerbini, Brazil. Dr Uchôa is funded by CAPES/CNPq. Dr Drager is funded by a Young Investigator Award from FAPESP [Grant 2012/02953-2].

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