One-year outcome data for transcatheter mitral valve implantation (TMVI), in inoperable patients, indicate most patients who survive the first 30 days after the procedure will be alive at one year. However, they also show that mortality is high at both 30 days and at one year—with left ventricular outflow tract (LVOT) obstruction as the most important and independent predictor of mortality.
Mayra Guerrero (Division of Cardiology, Evanston Hospital, Evanston, USA) and others write in the Journal of the American College of Cardiology that TMVI, with balloon-expandable valves, in inoperable patients (on compassionate grounds) has been shown to be feasible. However, they note that only short-term outcome data are available meaning that “long-term outcomes are unknown”. “The present study evaluated the clinical results and function of mitral prosthesis at one-year follow-up. Our hypothesis was that patients who survive the 30-day procedural period remain stable at one year,” Guerrero et al comment.
Using data from the TMVR in Mitral Annular Calcification (MAC) registry, the authors identified 116 patients with severe mitral annular calcification who underwent TMVI with an aortic balloon-expandable transcatheter heart valve. Of these, 106 were eligible for the one-year follow-up (had the procedure before a data lock was imposed). Seventy-seven patients were alive after 30 days and eligible for one-year follow-up, and 49 of them were alive at the one-year follow-up point. This meant that 30-day mortality was 25% and one-year mortality was 53.7%.
Of those alive at one year, there was no significant difference in left ventricular ejection fraction at one year compared with baseline. However, mean mitral valve gradient and mitral valve area significantly improved between baseline and one year.
The authors state that the one-year mortality rate of 53.7% is “concerning” and that “efforts should be made to improve patient selection to achieve better outcomes”. However, they note that most of the deaths that occurred after 30 days were non-cardiovascular and, therefore, suggest that “these late events are most likely related to the multiple comorbidities, non-cardiac frailty, and advanced age of these extremely ill patients who had a baseline Society of Thoracic Surgeons score of 15.3%”. Furthermore, Guerrero report: “landmark analysis after 30 days showed that most patients who survived the 30-day post procedure period remained alive at one year.”
In terms of the predictors of mortality after the TMVI procedure, LVOT obstruction was an independent predictor both at 30 days and at one year. The authors comment: “Efforts should be made to avoid this complication to improve short- and long-term outcomes”. They add that strategies to prevent and treat this complication include pre-emptive alcohol septal ablation performed several weeks before TMVI, percutaneous anterior leaflet laceration, and alcohol septal ablation as bailout treatment. “Another strategy could be the use of self-expanding aortic retrievable devices, which may have the advantage of allowing device retrieval if severe LVOT obstruction occurs after TMVI,” Guerrero et al observe.
They comment that TMVI “might be an alternative for carefully selected high-risk or inoperable patients with limited treatment options” but add that “efforts are required to improve outcomes”. “The role of TMVI and predictors of outcomes in mitral annular calcification patients treated with TMVI requires further evaluation in clinical trials,” the authors conclude.
Guerrero told Cardiovascular News: “Although we found in this initial experience that TMVI with balloon-expandable aortic transcatheter heart valves in high surgical risk patients with severe mitral annular calcification is associated with high 30-day and one-year mortality, the outcomes improved with experience. There were fewer complications and no need for conversion to surgery in the second half of the experience and a trend towards lower 30-day mortality. We also identified the most important predictor of mortality, LVOT obstruction. Avoiding this lethal complication will help improve mortality. I am cautiously optimistic that with improved patient selection and procedural techniques, we can further improve overall outcomes. Further evaluation under clinical trials is needed.”