Authors’ reply

We thank Kornej et al for their comments. Chronic coronary syndromes (CCS) represent the major cause of death worldwide, and atrial fibrillation (AF) deteriorates the quality of life and prognosis in patients with CCS. Kornej et al contrasted 2 large studies that contradict previous hypotheses that the incidence of AF is higher in patients with CCS.1,2

Indeed, Kornej et al1 studied a large sample size of patients with invasively confirmed coronary status and advanced phenotyping of the study cohort using clinical, echocardiographic, and laboratory data. In the Bialystok Coronary Project, our main conclusion was consistent with the results of Kornej et al,1 but we respectfully suggest that our detailed results have been misinterpreted. In our analysis, the absence of diseases such as chronic heart failure (odds ratio [OR], 0.68; 95% CI, 0.56–0.83; P <0.001) and other classic risk factors for CCS such as hypertension (OR, 0.68; 95% CI, 0.56–0.82; P <0.001), chronic kidney disease (OR, 0.79; 95% CI, 0.66–0.94; P <0.001), and diabetes (OR, 0.69; 95% CI, 0.59–0.81; P <0.001) increased the probability of developing nonsignificant atherosclerotic lesions in epicardial coronary arteries. Consequently, patients with these comorbidities were at higher risk of CCS.

The study protocols used in both cohorts differed, but, in our opinion, it is worth noting that, similar to the LIFE Heart Study, the severity of coronary artery disease was correlated with the presence of AF. Comparing the groups of patients with and without AF, the percentage of patients with 2-vessel and 3-vessel coronary artery disease was higher in the group without CCS. Interestingly, our cohorts did not differ in terms of age, and a similar proportion of CCS was reported in both groups (40.4% versus 40.1%), although marked differences between the incidence of AF were evident (6.9% versus 20.2%).1,2 We also found no significant differences with regard to the prevalence of classic risk factors for AF. This fact seems to be even more alarming when considering sex distribution in the study cohorts (female sex, 45% vs 34%).

Pathophysiological mechanisms such as inflammation and oxidative stress represent the underlying causes of both AF and CCS. Our hypothesis on the difference in the prevalence of AF in both study cohorts may be due to the burden of nonclassic risk factors such as air pollution or socioeconomic factors. In our previous studies, we demonstrated the impact of air pollution on both the incidence of acute coronary syndromes (ACS)3 and deaths from any cardiac causes.4

Decision making on patient selection for coronary angiography in the setting of AF is more difficult than in patients without AF.5 Hence, further prospective evaluation of this population is also necessary. Our study cohort was followed up for a relatively long period of time, a median (interquartile range) of 2616 (1849–3649) days. In the followed-up group of patients with AF, as many as 557 deaths (37.4%) were recorded, 26% of which were coded as ACS. In the group of patients without AF, the death rate was 19.4%, only 14.5% of which was due to ACS. Hence, the progression of coronary artery disease was observed during long-term follow-up, which may have serious health implications for patients with AF.