Postoperative Atrial Fibrillation in Adults with Obstructive Sleep Apnea Undergoing Coronary Artery Bypass Grafting in the RICCADSA Cohort

Round 1

Reviewer 1 Report

In the current study, authors analyzed the prevalence of POAF in a
subgroup of patients from the RICCADSA cohort, who had undergone CABG, and addressed the association between POAF and OSA, and its possible impact on reoccurrence of AF and long-term adverse cardiovascular outcomes.

The authors of this study included 147 patients with CABG, who underwent a home sleep apnea testing, in average 73 ± 30 days after the surgical intervention. POAF was observed among 50 (34.0%), and the distribution of the apnea-hypopnea-index (AHI) categories <5.0 events / h (no-OSA); 5.0-14.9 events / h (mild OSA); 15.0-29.9 events / h (moderate OSA); and ≥30 events / h (severe OSA), OSA was 4.0%, 14.0%, 36.0%, and 46.0%, in the POAF group, and 16.5%, 17.5%, 39.2%, and 26.8%, respectively, in the no -POAF group (p = 0.042). In a multivariate logistic regression model, there was a significant risk increase for POAF across the AHI categories with the highest odds ratio (OR) for severe OSA (OR 6.57,% 95 confidence interval 1.26-34.19; p = 0.025) vs no-OSA , independent of age, sex and body-mass-index. In the entire cohort, 90% were on β-blockers according to the clinical routines, they all had sinus rhythm on the electrocardiogram at baseline before the study start, and 28 out of 40 patients with moderate to severe OSA (70%) were allocated is CPAP. During a median follow-up period of 67 months, two patients (none with POAF) were hospitalized due to AF. To conclude, severe OSA was significantly associated with POAF in patients with CAD undergoing CABG. However, none of those individuals had an AF-reoccurrence at long term, and whether CPAP should be considered as an add-on treatment to β-blockers in secondary prevention models for OSA patients presenting POAF after CABG requires further studies in larger cohorts.

The study is well written and brings new knowledge to atrial fibrillation, which in my opinion is a strong point of this study.

Nevertheless, a small group of patients is a limitation.

I only propose to mention in the introduction that risk factors for atrial fibrillation are also risk factors for ischemic stroke (1PA Wolf; 2Wańkowicz P.).

Author Response

Please see the attachment

Reviewer 2 Report

Dear Authors, thank you for your submission. The paper is well written and results are clearly presented. I have some minor points:

1. While the timeframe for postoperative atrial fibrillation (POAF) is not strictly defined, it has been usually considered within a week after surgery or AF occurring before discharge. The Authors choose a period of 30 days after surgery for the definition of POAF. Please briefly comment on why did you choose this time-frame. And if you have the data, it would be interesting to provide the percentage of POAF occurring within first week post-operatively vs. the rest (7-30 days).
2. The multivariate regression analysis is well done. It would be also interesting to look for the time of desaturation to less than 90% (T90%). If you have these information, was T90% also predictive for POAF occurrence? thank you! 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Currently, the manuscript is ready for publication.

Reviewer 2 Report

Dear Authors,

Thank you very much for your Revised Manuscript. The Authors have sufficiently responded to all comments and i endorse the publication of the corrected manuscript.

Kind regards.