The largest study to date of prosthesis-patient mismatch following transcatheter aortic valve implantation (TAVI) shows that severe mismatch is associated with a significantly higher risk of death at one year. Furthermore, the study indicates that the predictors of prosthesis-patient mismatch include small valve prosthesis (<23mm), valve-in-valve procedure, larger body surface area and non-White/Hispanic race.
Writing in Journal of American College of Cardiology, Howard C Herrmann (University of Pennsylvania, Philadelphia, USA) and others report that prosthesis-patient mismatch after TAVI as only been studied “in small studies with limited follow-up”. “In this report, from the Society of Thoracic Surgeons (STS)/American College of Cardiology (ACC) Transcatheter Valve Therapy (TVT) Registry, we report the incidence, predictors, and one-year outcome of patient prosthesis mismatch in 62,125 patients undergoing TAVI in the USA between 2014 and 2017,” they add.
Of 62,125 patients enrolled in the registry between January 2014 and March 2017, 12.1% and 24.6% of patients were found to have severe and moderate prosthesis-patient mismatch, respectively. The authors state these figures did not significantly change between 2014 and 2017, commenting: “Important predictors included valve prosthesis ≤23mm diameter, valve-in-valve procedure, larger body surface area, lower left ventricular ejection fraction, non-white Hispanic, female, younger age, atrial fibrillation, and large body mass index, higher aortic valve mean gradient, prior coronary artery bypass grafting, and severe mitral or tricuspid regurgitation”.
At 30 days, severe prosthesis-patient mismatch was associated with higher rates of heart failure hospitalisation, stroke, and death. Furthermore, after multivariate adjustment, severe (but not moderate) prosthesis-patient mismatch was associated with adverse outcomes of death, heart failure hospitalisation, and combined death or heart failure hospitalisation at one year.
According to Herrmann et al, their study findings have “important implications for further improving outcomes in patients undergoing TAVI” and that their results suggest “efforts should be made to identify and limit the risk patient prosthesis-patient mismatch after TAVI”. They comment that awareness of the baseline risk factors for prosthesis-patient mismatch among patients undergoing surgical aortic valve replacement has led—along with techniques to minimise its occurrence—to a 55% decrease in its incidence after surgical valve replacement. “The TAVI community should follow this lead by identifying patients at risk for severe prosthesis-patient mismatch and consider techniques to reduce this risk,” the authors write.
Concluding, Herrman et al state: “A future study that compares devices and techniques to limit prosthesis-patient mismatch in patients at risk for severe mismatch would be of interest to guide decision making in this population.”
Herrmann told Cardiovascular News: “Awareness of this issue is the first step to avoiding it. For patients at risk of severe prosthesis-patient mismatch, options may include fracture of a prior surgical prosthesis during valve-in-valve procedures, use of TAVI prostheses with a larger effective orifice area if anatomically feasible, and even consideration of surgery with root enlargement in lower risk patients.”
Coinciding with its publication in the Journal of American College of Cardiology, the study was presented at the 2018 Transcatheter Cardiovascular Therapeutics (TCT) meeting (21–25 September, San Diego, USA).