Functional Regurgitation of Atrioventricular Valves and Atrial Fibrillation: An Elusive Pathophysiological Link Deserving Further Attention

In patients with structurally normal atrioventricular valvular apparatus, functional regurgitation of the mitral or tricuspid valves has been attributed mainly to ventricular dilation and/or dysfunction, through a combination of annulus dilation and tethering of the valve leaflets. The occurrence of functional regurgitation of atrioventricular valves in patients with long-standing persistent atrial fibrillation and atrial dilation but normal ventricular size and function has received much less attention, and its peculiar mechanisms still remain to be understood. This distinct form of functional regurgitation (i.e., "atrial functional regurgitation") may require different treatment and interventional repair approaches than the classical functional regurgitation due to ventricular dilatation and dysfunction ("ventricular functional regurgitation"), and current guideline recommendations do not yet address this distinction. Clarifying the differences in the pathophysiology of atrial functional regurgitation and its management implications is of paramount importance. This review describes briefly the comparative anatomy of mitral and tricuspid apparatus and the pathophysiology and typical echocardiographic features of atrial functional regurgitation compared with ventricular functional regurgitation, as well as the added value of three-dimensional echocardiography as an essential imaging tool to clarify the mechanisms involved in its development.