Functional tricuspid regurgitation: an underestimated issue.

This review article focuses on functional tricuspid regurgitation (FTR) that has long been a neglected and underestimated entity. FTR is defined as leakage of the tricuspid valve during systole in the presence of structurally normal leaflets and chordae. FTR may be secondary to several heart diseases, more commonly mitral valve disease, pulmonary hypertension, atrial fibrillation, cardiomyopathies, right ventricular dysplasia, and idiopathic annular dilatation. The reported prevalence of moderate or greater FTR is roughly 16%, but it rises up to 89% when considering FTR of any grade. According to the recommendations of the European Association of Echocardiography, two-dimensional transthoracic echocardiography (TTE) is the first-line imaging modality for the assessment of valvular regurgitation, whereas three-dimensional TTE may provide additional information in patients with complex valve lesions. Transesophageal echocardiography may be used when TTE results are inconclusive. The natural history of FTR is unfavorable, even in less than severe tricuspid regurgitation. Data from the literature suggest that moderate or greater FTR is a risk factor for worse survival. In addition, FTR of any grade may worsen over time, which makes it reasonable to consider the correction of FTR at an early stage, preferably at the time of mitral valve surgery. Tricuspid valve annuloplasty is the gold standard surgical treatment for FTR and is associated with a recurrence rate, defined as postoperative moderate or severe FTR, ranging from 2.5 to 5.5% at 1-year follow-up.