Overall impact of tethering and of its symmetric and asymmetric subtypes on early and long-term outcome of transcatheter edge-to-edge repair of significant mitral valve regurgitation

Background: Tethering is a common condition of the mitral valve apparatus in the presence of significant regurgitation. Its impact on outcomes of transcatheter edge-to-edge repair (TEER) remains poorly characterized. Methods: We appraised the prevalence, features, procedural details, and outcomes of patients with or without mitral valve tethering in a prospective multicenter observational study. The primary endpoint was the risk of cardiac death or rehospitalization for heart failure at mid-term follow-up. Results: We included 2238 patients, 1467 (65.5 %) without tethering and 771 (34.5 %) with tethering (487 [21.8 %] with symmetric and 284 [12.7 %] with asymmetric tethering). Several differences in baseline features were evident among groups, yet procedural results were similar. After a median of 14 months, rates of cardiac death or rehospitalization for heart failure was significantly higher at unadjusted analysis in patients with tethering (191 [24.8 %] vs. 272 [18.5 %] in those without tethering, p = 0.001), but weres similar between tethering subtypes (p = 0.666). At adjusted analysis, the presence of any tethering was no longer a significant predictor of cardiac death or rehospitalization for heart failure, and the same results were obtained focusing on tethering subtypes (all p > 0.05). Conclusions: Tethering is common among patients with an indication to TEER, and is associated with adverse baseline and procedural features. In spite of this, device and procedural success rates are not significantly impacted by the presence of tethering that does not even have a negative prognostic effect at follow-up. Accordingly, tethering should not be considered a contraindication to TEER in suitable patients.