IL6 and atrial fibrillation: Another limitation of the study is that the rate of positive AF cultures in the exploratory phase, by chance, was significantly higher in the non-iSPTD controls than in the iSPTD cases, which may have led us to overlook many other inflammatory proteins (e.g., IL-6 and IL-8) as candidate markers, and thus a small number of markers of interest were identified in the current study.