Objective: Atrial fibrillation (AF) is the most formidable supraventricular tachyarrhythmia, which worsens the natural course of mitral valve disease. In this study, we evaluated early and long-term results and quality of life (QOL) after simultaneous surgical radiofrequency ablation (RFA) of AF, left atrial reduction and mitral valve repair or replacement. Methods: Overall, 147 patients with mitral valve diseases who underwent mitral valve surgery were included in this prospective cohort study. Patients were divided into two groups according to the type of operation: the study group-patients after mitral valve surgery with concomitant radiofrequency surgical ablation and left atrial reduction procedure (54 patients), and the control group-patients undergoing only mitral valve surgery (93 cases). We assessed AF recurrence and sinus rhythm restoration rates and mortality rates, QOL measures, postoperative complications rates, and left atrial size during follow-up. Results: In the study group, sinus rhythm restoration rate in the early postoperative period was 63%, but at the time of discharge it reduced to 29%; after 6 months, it significantly increased to 72% and after 3 years, to 81% (p=0.02). In the control group, the sinus rhythm restored only in 14% after 1 year, and at 3 years, it was 22%, although in the early postoperative period it, was 43%. Analysis of left atrial size before and after surgery showed that dimension significantly reduced in both groups (study group, p=0.013; control group, p=0.024). In addition, in patients undergoing surgical RFA procedure, there was a significant association between shorter heart disease history (p=0.02) and shorter AF history (p=0.074) with maintenance of sinus rhythm. The mortality rate in the study group was 4% (two patients) and in the control group 5% (five patients). Comparison of QOL measures between study and control groups after 1 year showed that patients undergoing concomitant atrial reduction surgery and RFA had significant improvement of QOL physical (p=0.03) and role (p=0.03) functioning, heartbeat (p=0.01), general (p=0.03) and mental health (p=0.01), vitality (p=0.007), and social role (p=0.02) functioning measures as compared to preoperative state, being higher than in patients who underwent only mitral valve surgery. Conclusion: Application of surgical RFA using irrigated cooling electrode and atrial reduction during mitral valve surgery is associated with higher restoration and maintenance of SR as compared to patients undergoing only mitral valve surgery. We did not observe complications related to AF surgery that required permanent pacemaker implantation. Performing concomitant surgery as surgical RFA, atrial reduction along with mitral valve surgery, improves QOL in the short- and long-term and reduces the feeling of heartbeat and discomfort. [ABSTRACT FROM AUTHOR]