Competitive interaction between chronic obstructive pulmonary disease and CHA2DS2-VASc score in predicting incident atrial fibrillation

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality, and an emerging risk factor for atrial fibrillation (AF). CHADS2 and CHA2DS2-VASc scores are significantly associated with incident AF independently of other risk factors. The aim of this study was to demonstrate a possible interaction between COPD and CHA2DS2-VASc in predicting incident AF. METHODS: This observational prospective cohort study included 4322 Caucasians with cardiovascular risk factors, stratified by CHA2DS2-VASc score (>2 vs <2) and presence/absence of COPD. To detect AF appearance, patients underwent, every 6months, physical examination, standard 12‑lead electrocardiogram and routine laboratory tests. RESULTS: COPD prevalence was significantly higher in patients with CHA2DS2-VASc≥2 vs CHA2DS2-VASc<2 category (13.3% vs 10.5%, P=0.009). During the follow-up, 589 cases of AF were documented (3.8 events/100 patients-year). COPD+ showed a significantly higher incidence of AF vs COPD- patients (17.4 vs 8.4 events/100 patients-year, P<0.0001). In Cox regression models both CHA2DS2-VASc score (HR=4.70, 95% CI=3.63-6.08) and COPD (HR=2.04, 95% CI=1.69-2.48) significantly predicted the incidence rate of AF; this was also confirmed introducing the two variables into the same Cox model. A significant competitive interaction between CHA2DS2-VASc and COPD was found in a Cox model in patients with CHA2DS2-VASc<2 (HR=8.45, 95% CI=5.20-13.74) than in those with CHA2DS2-VASc≥2. CONCLUSIONS: COPD is an independent and strong predictor of incident AF. The presence of COPD increases the HR for incident AF about five times in patients with CHA2DS2VASc score<2, while the coexistence of a CHA2DS2Vasc score≥2 minimizes the prognostic significance of COPD.