Isolated functional tricuspid regurgitation: When should we go to surgical treatment?

The tricuspid valve has been called a "forgotten" valve; however, it is receiving increasing attention, since tricuspid regurgitation (TR) may be the next target of transcatheter intervention. Atrial fibrillation-related TR and TR that develops late after left-sided valve surgery are the main etiologies of isolated functional TR, in both of which annular dilatation is the main mechanism of TR. Isolated functional TR has been undertreated because of the high mortality rate of isolated tricuspid valve surgery. Furthermore, a recent study showed that surgery does not improve survival as long as it is performed at the late timing as is common in the current clinical settings. Right ventricular function is a key factor in determining the indication for isolated tricuspid valve surgery and in predicting early and late outcomes. However, none of them have been validated as predictors of prognosis for patients with severe functional TR. Liver function and renal function are also important predictors, but the cut-off values of these parameters for improved outcomes of isolated tricuspid valve surgery should be determined by large-scale data analysis. Now is a good time to reconsider the indications and the optimal timing of isolated tricuspid valve surgery in light of the upcoming transcatheter interventions.