To assess functional tricuspid regurgitation (FTR) determinants, consequences and independent impact on outcome in degenerative mitral regurgitation (DMR).

All patients diagnosed with isolated DMR 2003–2011, structurally normal tricuspid leaflets, prospective FTR grading, pulmonary artery pressure (sPAP) estimation by Doppler-echocardiography at diagnosis were identified and long-term outcome analysed.

The 5083 DMR eligible patients (63±16years, 47%female, ejection-fraction (EF) 63±7% and sPAP 35±13mmHg) presented with FTR graded trivial in 45%, mild in 37%, moderate in 15%, and severe in 3%. While pulmonary hypertension (PHTN) was the most powerful FTR severity determinant, other FTR determinants were older age, female sex, DMR, and Atrial Fibrillation (P≤0.002). FTR moderate/severe independently linked to worse clinical presentation. Survival throughout follow-up (70% at 10-year) was strongly associated with FTR-severity (82% for trivial, 69% for mild, 51% for moderate and 26% for severe, P<0.0001). Excess-mortality persisted after comprehensive adjustment [HR 1.40(1.18–1.67) for moderate-FTR, 2.10(1.63–2.70) for severe-FTR, P≤0.01], adjusting for sPAP/RV-function (P<0.0001), by matching [2.08(1.50–2.89), P<0.0001] and vs. expected survival [1.79(1.48–2.16), P<0.0001]. Within 5-year of diagnosis surgery was performed in 73%/15% of mod/severe DMR and in only 26%/6% of mod/severe FTR. Surgery improved outcome without alleviating completely higher mortality associated with FTR (P<0.0001) (Fig. 1).

In this large DMR cohort, FTR was frequent, not only linked to PHTN and associated with worse clinical presentation. Long term, FTR is independently of all confounders, associated with considerably worse mortality. FTR moderate and severe is profoundly undertreated. Thus careful assessment, consideration for TR surgery and testing of new transcatheter therapy is warranted.