['Symptoms and symptom burden have a central place in diagnosis and management of atrial fibrillation (AF). The aim of the present study is to investigate whether severity of AF symptoms impacts prognosis in permanent AF.', 'We studied the relation between AF symptom severity [quantified with the Toronto AF Severity Scale (AFSS)] and cardiovascular outcome in patients included in the RACE II study. The primary endpoint was a composite of cardiovascular morbidity and mortality. Secondary outcome was cardiovascular hospitalizations. Of 614 permanent AF patients in RACE II, AFSS questionnaires were available in 558 patients (91%). Mean age was 68 ± 8 years. One hundred and seventy-four patients (31%) reported a low score (score 0-3; lowest tertile), 190 patients (34%) reported a moderate score (score 4-9; middle tertile), and 194 (35%) reported a high score (score 10-35; highest tertile). Patients with the most severe symptoms were more often women, had higher N-terminal prohormone of brain natriuretic peptide concentrations, and had more previous heart failure hospitalizations. Median follow-up was 3.0 (interquartile range 2.3-3.0) years. The primary endpoint occurred most frequently in the highest tertile of the AFSS [16 (9%), 19 (10%), 36 (19%), respectively, P = 0.01], being mainly driven by heart failure hospitalizations [4 (2%), 1 (1%), 16 (8%), respectively, P < 0.001]. After multivariable adjustment, higher AFSS scores were associated with the primary endpoint [hazard ratio 1.38 (1.15-1.66), P = 0.001], as well as with cardiovascular hospitalizations [hazard ratio 1.33 (1.14-1.54), P < 0.001].'] Is symptom severity associated with cardiovascular outcome in patients with permanent atrial fibrillation in the RACE II study?