Dear Editor,
We have read with great interest the article entitled “Systemic immune-inflammation index as a novel predictor of atrial fibrillation after off-pump coronary artery bypass grafting” by Topal et al. 1 . First of all, we congratulate the authors for their valuable contribution and their successful high-volume off-pump coronary surgeries performed within approximately 5 years in a tertiary referral center. However, we would like to discuss some points about postoperative atrial fibrillation (PoAF), systemic immune-inflammation index (SII), and study design.
The study was performed on patients who underwent an off-pump coronary artery bypass grafting (CABG) operation 1 . Did the authors include all consecutive patients in the study during the years they specified? Also, how many operations did they perform in this process? In the exclusion criteria, they have made a definition as “concomitant cardiac operation such as mitral valve surgery were excluded from the study.” How many operations did they exclude that they performed off-pump CABG operation at their clinic and performed additional cardiac surgical procedures? In addition, how did they diagnose PoAF in the postoperative period? How long was the atrial fibrillation attack considered as PoAF in their study? Since various durations (60 s, 5 min?) are given in the literature, we believed that it is important to clarify these issues 2,3 .
Platelet and neutrophil-to-lymphocyte ratio have been the subjects of valuable studies in many fields of medicine 4,5 . SII, which is obtained by multiplying these parameters, is an important marker that has been recently investigated in various cardiovascular studies 6,7 . It is also important to note that it is cheap and easily available. Studies have also shown a relationship between SII and the prevalence of atherosclerosis. Peripheral artery disease (PAD) was used as a categorical variable in this study. As an indicator of the extent of coronary artery disease, the number of distal bypasses was given. In the literature, the relationship between SII and SYNTAX score I was shown 8 . Did the authors calculate the SYNTAX score I for the patients in their study? Also, what did they accept the presence of PAD as? The TransAtlantic Inter-Society Consensus II (TASC II) classification is an important indicator of the prevalence of PAD 9 . If the authors have accepted the presence of PAD as having stenosis greater than 50%, the SII value may be higher in patients with a higher TASC II class, which may lead to misleading results 10 .
Therefore, PoAF is an important problem. We believe that clarification of the issues that we have mentioned will increase the value of this precious work.
Footnotes
Funding: none.
REFERENCES
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