Non-valvular atrial fibrillation: potential clinical implications of the heterogeneous definitions used in trials on new oral anticoagulants

Aims To evaluate the potential impact of the different definitions of non-valvular atrial fibrillation reported in the literature and to analyse the possible implications for eligibility for novel oral anticoagulants (NOACs) in clinical practice. Methods We derived the definitions of 'non-valvular atrial fibrillation' from the exclusion criteria of the trials on NOACs, and then assessed the number and percentage of patients fulfilling the various definitions in a cohort of 500 consecutive atrial fibrillation patients, undergoing clinical and echocardiographic evaluation in our cardiology department, as either in-patients or out-patients. Results Among the 500 atrial fibrillation patients (mean age 71.2 +/- 12.6 years), with permanent atrial fibrillation in 45.2% of the cases, hypertension was very common, either as the main diagnosis or as an associated disease. Valvular heart disease as the main diagnosis (including valvular prosthesis) accounted for 22.8% of the cases. At the echocardiographic evaluation, valvular alterations were very common, especially mitral regurgitation (present, with a variable degree of severity in 63.6% of the cases). Application of the RE-LY exclusion criteria with regard to valvular disease resulted in 116 (23.2%) patients of our cohort classified as valvular atrial fibrillation. This percentage was reduced to 12.2 and 8.8% if ROCKET-AF and ARISTOTLE/ENGAGE-AF criteria, respectively, were applied. Conclusions Non-valvular atrial fibrillation is a common clinical entity, but without a unified definition in the literature. The impact in daily practice of the different definitions adopted in trials is noteworthy, since in one patient out of seven, the eligibility for NOACs can be questioned, simply as a consequence of adopting a more or less restrictive definition.