Daniel J Blackman (Department of Cardiology, Leeds Teaching Hospital NHS Trust, Leeds, UK) and others report in the Journal of the American College of Cardiology (JACC) that in their study, 91% of patients remained free of severe structural valve degeneration between five and 10 years after receiving a transcatheter aortic valve implantation (TAVI) device. They note that they have described the largest cohort of patients with echocardiographic assessment of valve function between five to 10 years.
Blackman et al write that studies “have consistently shown preserved valve function up to five years after TAVI”. But, they add structural valve degeneration is usually not seen with surgical valves until five to 10 years post procedure “and data in this timeframe following TAVI are very sparse”. Thus, reviewing data from the UK TAVI registry, the authors sought to “evaluate long-term valve function and to determine the incidence of haemodynamic structural valve degeneration between five and 10 years after TAVI”.
Data were available from 15 UK centres that performed TAVI between 2007 and 2011, with paired echocardiographic data both at baseline and ≥4.5 years post TAVI available for 241 patients. Overall, the median follow-up was 5.8 years but this extended to six years in 168 patients, seven in 68, eight in 30, and nine in four, and 10 in two.
At five years, four months, one patient who received a 26mm self-expanding valve developed severe structural valve degeneration and was not considered fit for further treatment. No other cases of severe degeneration were reported and only 21 cases of moderate structural valve degeneration were reported. In the moderate cases, degeneration was observed at a median duration of six years and one month (range four years, 11 months to eight years, seven months). Blackman et al comment: “Thirteen (62%) of these patients were treated with the self-expandable valve, and eight (38%) with a balloon-expandable valve”. However, according to the authors, the “substantial majority of patients (220; 91%)” did not experience structural valve degeneration.
Furthermore, at follow-up, peak gradient was significantly lower (17.1mmHg vs. 19.1mmHg; p=0.002), the rate of none/trivial aortic regurgitation was increased (47.8% vs. 32.9%; p=0.055), and the rate of mild aortic regurgitation was lower (42.5% vs. 57%; p=0.02) compared with baseline levels. However, there was no change in the rate of moderate regurgitation and one patient developed severe aortic regurgitation at follow-up.
In terms of different types of TAVI valves, 149 patients received CoreValve (Medtronic) and 80 received Sapien/Sapien XT (Edwards Lifesciences). “The self-expanding bioprothesis was associated with a fall in peak gradient from baseline to follow-up, and a change in the degree of aortic regurgitation from mild to none/trivial,” Blackman et al comment. No such differences were observed with the balloon-expandable valve.
They conclude: “Long-term TAVI valve function after TAVI was excellent with no increase in gradient of regurgitation at a median follow-up of 5.8 years, up to a maximum of 10 years, and severe structural valve degeneration occurred in <0.5% of patients.”
Blackman told Cardiovascular News: “As new data demonstrate the efficacy and safety of TAVI in low-risk patients, the key remaining question is whether TAVI will also match surgery for valve durability. Our findings provide early encouragement that TAVI will provide a long-term solution for all patients with severe aortic stenosis.”