Progression to Heart Failure in Patients withAtrial Fibrillation: Time to event analysis from a A Nationwide Cohort-TRAF ( TuRkish Atrial Fibrillation Data Base) Banu Evranos, Private Akay Hospital, Ankara, Turkey; Emre Oto, MITS, Ankara, Turkey; Naim Ata, Social Security Inst, Ankara, Turkey; Bünyamin Yavuz, Keçiören Training and Res Hosp, Ankara, Turkey; Deniz Katırcıoglu Öztürk, MITS, Ankara, Turkey; Uğur Canpolat, Yuksek Ihtısas Training and Res Hosp, Ankara, Turkey; Kudret Aytemir, Hacettepe University of Medical School, Ankara, Turkey; Altay Güvenir,Bılkent University Computer Engineering Department, Ankara, Turkey; Ergun Karaagaoglu,Hacettepe Univ of Medical School, Ankara, Turkey; Emre Ertugay, Rasim Koselerli, Abdülkadir Bürkan, Mustafa Kuruca, Yadigar Gokalp Ilhan, Social Security Inst, Ankara, Turkey; John Camm, St. George's University of London, London, United Kingdom; Ali Oto, Hacettepe Univ of Medical School, Ankara, Turkey Objective: Atrial fibrillation (AF) and heart failure frequently present in same patients. AF may contribute to LV dysfunction as a consequence of rapid ventricular rates, irregularity in ventricular rhythm or due to loss of atrial systole. Tachycardia-mediated cardiomyopathy secondary to uncontrolled AF has been well described as a reversible cause of LV dysfunction. Heart failure worsens the prognosis in atrial fibrillation. We aimed to investigate the time to clinical heart failure after the diagnosis of AF as well as mortality and hospitalizations. Methods: We analyzed the records of 402674 patients over the age 18 who had the diagnosis of non-valvular atrial fibrillation (AF) according to ICD-10 code I48 from a nation-wide claims and utilization management system which processes claims for all health insurance funds in Turkey since 2007. In this study we have used completely anonymized data. Time-to-event analysis were used to measure the time to heart failure after being diagnosed with AF. Results: A total of 61789 AF patients(15,3%) progressed to heart failure in 54,28±0,04 months(% 95 CI, 54,19-54,37, p<0.001) from the diagnosis of AF. Heart failure was observed most frequently in the age group >75 and followed by the age group of 65-74 (43.9 % and 33.7 % respectively). Forthy percent of patients with AF were hospitalized for heart failure. Mortality was much higher in those who develop heart failure as compared to those without heart failure development (24 .0 % and 20.7 % respectively p=0.000) Conclusions: A significant number of patients with AF progressively develop heart failure. Heart failure is one of the most important adverse events in AF patients and contributes to hospitalizations and mortality. The elderly patients are more prone to develop heart failure as compared to the young age groups of patients with atrial fibrillation.