Atrial fibrillation in patients with dilated cardiomyopathy: prevalence, risk factors and prognostic significance

Aim. To study the epidemiological profile and long-term prognostic significance of atrial fibrillation (AF) as a risk factor for adverse clinical outcomes in patients with dilated cardiomyopathy (DCM).Material and methods. The study included 270 patients with DCM (206/76,3% men, age 47 [37; 56] years, left ventricular (LV) ejection fraction 29 [21; 35]%). The observation period was 6 years (Me 76 [57; 119] months). To assess the effect of AF on DCM prognosis, Kaplan-Meier curves and Cox regression of clinical outcomes, including cardiovascular death, heart transplantation, and ventricular assist device implantation, were analyzed.Results. Of 270 patients with DCM, paroxysmal AF was detected in 10 (3,7%) patients (initial, 5/1,85%; during the first follow-up year, 5/1,85%). After 5 years, another 65 (24,1%) individuals had AF (paroxysmal, persistent or permanent). Ventricular tachyarrhythmias were registered in 163 (60,4%) patients. Compared with patients maintaining sinus rhythm, patients with AF were older (51,4±10 vs  43,6±13 years, p=0,001) and had lower exercise tolerance (6-minute walk test: 379±45 vs 445±43 meters; p=0,0002) and a higher heart failure functional class (NYHA class III-IV: 38/50,7% vs 52/26,7%; χ2=13,6; p=0 ,0003). In patients with AF, initially more pronounced manifestations of right ventricular contractile dysfunction (TAPSE: 13,1±3,4 vs 15,5±4,6 mm; p=0,0001) and LV diastolic dysfunction (E/A: 2,9±1,5 vs 2,1±1,3; p=0,006; E/e' 15,6±6,9 vs 11,8±7,2; p=0,019), more dilated left atrium (left atrial volume index: 63,3±19 vs 50±18,7 ml/m2; p=0,006). During the 6-year median follow-up, AF was observed in 75 patients (0,46 new cases/100 patients/year). As a result of Cox regression analysis, AF as a time-dependent factor was identified as an independent predictor of cardiovascular death (hazard ratio 3,99; 95% confidence interval, 1,67-8,59; p=0,0001).Conclusion. AF, as one of the most common sustained atrial tachyarrhythmias in the population, demonstrated a lower prevalence (27,8%) in the DCM cohort compared to ventricular tachyarrhythmias (60,4%), but a high prognostic significance of the negative impact on the risk of fatal outcomes. The development of AF in patients with DCM is associated with a 4-fold increase in cardiovascular death risk over a 6-year period.