By Michael H. Crawford, MD, Editor

SYNOPSIS: A retrospective study of moderate to severe secondary tricuspid valve regurgitation showed that right ventricular systolic dysfunction (but not dilatation alone) is predictive of all-cause mortality.

SOURCE: Dietz MF, et al. Prognostic implications of right ventricular remodeling and function in patients with significant secondary tricuspid regurgitation. Circulation 2019;140:836-845.

The prognosis of patients with significant tricuspid regurgitation (TR) is closely related to right ventricular (RV) performance. However, the precise measures of RV performance that are indicative of a poor prognosis in significant TR and are possible indications for tricuspid valve (TV) repair or replacement are unknown.

Dietz et al selected patients with moderate to severe secondary TR from their echocardiographic database between 1995 and 2016. Patients with primary TR (prolapse, endocarditis, congenital deformity) were excluded. Key measurements included tricuspid annular (TA) diameter, RV end-diastolic and systolic areas from a focused RV apical view and tricuspid annular plane systolic excursion (TAPSE) from an M-mode recording of the lateral TA from the apical RV view. TR grade was assessed using an integrative approach. Pulmonary artery systolic pressure was estimated from the TR gradient plus the right atrial pressure, which was estimated from imaging the inferior vena cava. Patients were followed for the primary endpoint of all-cause mortality and the secondary endpoint of TV surgery. In the 1,292 patients identified (median age, 71 years; 50% men), four patterns of RV remodeling were defined: 1) no RV dilation or dysfunction (14%), 2) RV dilation but no dysfunction (20%), 3) no RV dilation but RV dysfunction (24%), and 4) RV dilation and dysfunction (43%). Whether the patient had moderate or severe TR was not predictive of the remodeling category. During the median follow-up of 34 months, 40% of the patients died, and only 8% of patients underwent TV surgery (annuloplasty in all). The five-year survival rate was worse in patients with RV dysfunction. (52% in pattern 3, 49% in pattern 4 vs. 70% in pattern 1; P = 0.002 and P < 0.001, respectively). A multivariate analysis showed that both patterns 3 and 4 (hazard ratio, 1.4 for both) were independent predictors of mortality. The authors concluded that patients with secondary moderate or severe TR and RV systolic dysfunction (but not dilatation alone) experience poor clinical outcomes.

COMMENTARY

Data on the natural history of TR is especially welcome now that we have a more viable percutaneous option with the new MitraClip XTR, which includes longer gripping arms. Currently, use in TR is off-label but looks promising. The data presented in this paper suggest that TV repair for severe TR could be entertained for those without RV dysfunction. Interestingly, both American and European guidelines endorse TV repair for symptomatic severe secondary TR if there is no LV or RV systolic dysfunction (class IIa-c). However, this may be a limited number of patients if this series reflects current practice, because two-thirds of their patients with secondary TR showed RV dysfunction and about one-third showed LV systolic dysfunction (ejection fraction < 40%).

Prior studies have shown worse prognosis when TR was associated with RV dilatation and dysfunction, left heart disease, and pulmonary hypertension. The Dietz et al study confirms these findings and adds information on the type of RV remodeling. Also, Dietz et al showed that one can have moderate to severe TR without left heart disease or pulmonary hypertension. Such patients often experienced atrial fibrillation with atrial and tricuspid annular dilatation. Perhaps such patients should be considered for TV repair if RV function is normal. Exact RV functional cutpoints for this decision were not defined in the study and may require more research.

One limitation to this study was the fact it was conducted at one center with a largely homogeneous population and was retrospective. Although the authors could accurately determine the mortality rate, the causes of death were unknown. Also, the study spanned 21 years. Certainly, there were changes in the approach to significant TR during this period. Finally, the authors noted that echo determination of RV size and function is challenging. Cardiac MRI probably would provide more accurate data on RV size and function. However, their data inform future directions in the care of patients with significant secondary TR as well as the type of research needed to flesh out possible future revisions to clinical guidelines.