This section describes safety 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.
5.1 In a case series of 349 patients treated by transcatheter mitral valve‑in‑valve implantation for degenerated mitral bioprosthetic valves, 30‑day all‑cause mortality was reported as 9% (32/349) and 30‑day cardiovascular death was reported as 6% (21/349). One patient died in a case series of 7 patients (mortality rate 14%); this patient had an unsuccessful transseptal approach for transcatheter mitral valve‑in‑valve implantation, which resulted in embolisation and the need for conversion to a prolonged open operation. The patient developed multisystem failure and died on the second postoperative day.
5.2 An all‑cause mortality rate of 10% (2/23) at a median follow‑up of 753 days was reported in a case series of 23 patients. Death was from respiratory failure in 1 patient (at 45 days) in whom the transatrial approach was converted to transapical implantation, and was from an unknown cause (defined as cardiovascular according to Valve Academic Research Consortum‑2) in 1 patient (on day 135).
5.3 In‑hospital fatal pneumonia (on day 34, due to respiratory failure) was reported in 1 patient with chronic obstructive pulmonary disease in the case series of 7 patients. The patient needed reintubation, but later died. Prolonged assisted ventilation (not defined) was reported in 25% (3/13) of patients who had transapical mitral valve‑in‑valve implantation in a retrospective case series of 20 patients (13 with degenerated valve in the mitral position and 7 with degenerated ring in mitral position).
5.4 Major stroke was reported in 3% (11/349) of patients in the case series of 349 patients at a median follow‑up of 408 days. Major periprocedural stroke (complicated by nosocomial pneumonia and acute renal injury needing temporary renal replacement therapy) was reported in 1 patient in the case series of 23 patients. This patient had a prolonged intensive care stay and died on day 45 with respiratory failure, despite renal and neurological recovery.
5.5 Transient ischaemic attack was reported in 1 patient (who had transapical mitral valve‑in‑valve implantation) in the retrospective case series of 20 patients.
5.6 Major bleeding was reported in 26% (6/23) of patients in the case series of 23 patients (further details were not reported).
5.7 Late bleeding at the apical site was reported in 33% (2/6) of patients in a case series of 6 patients. One patient needed a further thoracotomy on day 4 because of haemothorax and had an uneventful recovery. One patient became haemodynamically compromised on day 6 and needed cardiopulmonary resuscitation, but died of haemorrhagic shock because of acute bleeding from the apical wound.
5.8 Gastrointestinal bleeding (caused by anticoagulation and sepsis 2 months after the procedure) was reported in 1 patient in the case series of 6 patients. The patient was admitted to hospital but no signs of endocarditis were found.
5.9 Bioprosthesis thrombosis (3 months after transcatheter mitral valve‑in‑valve implantation) was reported in a case report of 1 patient. The patient had increasing shortness of breath and transoesophageal echocardiography revealed symptomatic and severe mitral valve stenosis with unusual leaflet thickening. After antithrombotic treatment, there was a significant decrease in transvalvular gradient and significant regression of the leaflet thickening.
5.10 Acute kidney injury (Acute Kidney Injury Network staging 2 and 3) was reported in 11% (39/349) of patients in the case series of 349 patients with a median follow‑up of 408 days. Further details were not reported. Continuous venovenous haemodialysis was needed in 18% (2/13) of patients who had transapical mitral valve‑in‑valve implantation in the retrospective case series of 20 patients.
5.11 Permanent pacemaker implantation (on day 3 for pre‑existing atrioventricular conduction disturbance) was needed in 1 patient in the case series of 23 patients.
5.12 An incisional haematoma was reported in 1 patient in the case series of 23 patients (further details were not reported).
5.13 Wound infection was reported in 25% (3/13) of patients who had transapical mitral valve‑in‑valve implantation in the retrospective case series of 20 patients.
5.14 Atrial clot (detected at 6‑month follow‑up echocardiogram) was reported in 1 patient in the case series of 23 patients. The patient was asymptomatic with no embolic events but treated with systemic anticoagulation.
5.15 Haemothorax (drained with a thoracostomy tube) was reported in 1 patient in the case series of 23 patients.
5.16 Implantation of a second transapical transcatheter mitral valve‑in‑valve was needed (at 2 months; because of acute heart failure) in 1 patient in the case series of 23 patients. Echocardiography showed 4–5 mm atrial migration of the valve, which caused severe valvular regurgitation. A second transapical transcatheter mitral valve‑in‑valve implantation was done with no complications or valvular regurgitation.
5.17 In addition to safety outcomes reported in the literature, specialist advisers are asked about anecdotal adverse events (events which they have heard about) and about theoretical adverse events (events which they think might possibly occur, even if they have never done so). For this procedure, specialist advisers described left ventricular outflow tract obstruction as an anecdotal adverse event. They considered that the following were theoretical adverse events: incorrect positioning of the transcatheter valve, paravalvular regurgitation, mitral stenosis and surgical wound infection.