This section describes efficacy outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the interventional procedure overview.
4.1 In a case series of 23 patients treated by transapical transcatheter mitral valve‑in‑valve implantation for degenerated mitral bioprosthetic valves, the procedure was successful in 100% of patients. Procedural success was definedaccording to the Valve Academic Research Consortum‑2 definition (device success and no occurrence of in‑hospital or 30‑day death). In 1 procedure, implantation through the left atrium via a right thoracotomy was unsuccessful (because the delivery system failed to align properly) but was successfully done via a left thoracotomy and transapical approach.
4.2 In the case series of 23 patients, survival at 30 day follow‑up was 100%. At a median follow‑up of 753 days (range 376 days to 1119 days), survival rate calculated using Kaplan–Meier analysis was 90%. In a case series of 6 patients, 5 patients were alive and had not had any valve‑related events at a median follow‑up of 70 days (range 25 days to 358 days).
4.3 In the case series of 23 patients, there was improvement in New York Heart Association (NYHA) functional class after the procedure. Before treatment, 96% (22/23) of the patients were in NYHA class III/IV and 1 patient was in class II. At last follow‑up (range 376 days to 1119 days), 96% (22/23) of the patients had clinically improved to NYHA class I/II. One patient with hypertrophic obstructive cardiomyopathy continued to be in NYHA class III despite satisfactory valve function and septal ablation.
4.4 In the case series of 23 patients, there was a significant decrease in the mean mitral transvalvular pressure gradient after implantation (from 11.1±4.6 mmHg to 6.9±2.2 mmHg; p=0.014).
4.5 In the case series of 23 patients, mitral regurgitation reduced from severe or moderate regurgitation (in 61% [14/23] and 17% [4/23] of patients respectively) at baseline to mild or no regurgitation (in 52% [12/23] and 48% [10/23] of patients respectively) at discharge.
4.6 The specialist advisers listed key efficacy outcomes as: correct and stable positioning of a new valve; valve function (that is, no valvular or paravalvular regurgitation, no significant pressure gradient across the valve, and no left ventricular outflow tract obstruction); symptom improvement; survival; and long‑term durability of the valve.