Intermediate-risk patients with severe symptomatic aortic stenosis do not necessarily have to go for a surgery. According to a recent trial published in the New England Journal of Medicine (NEJM) on 28th April, 2016, an alternative therapy – Transcatheter Aortic Valve Replacement (TAVR) – is equally effective in preventing risk of stroke and death in such patients.
TAVR is a novel therapy for high-risk patients with severe aortic stenosis – narrowing of the heart’s aortic valve – who are not candidates for surgery or at high risk of complications associated with the surgery.
Recently, however, the trend of using enhanced TAVR in low- or intermediate risk patients is on the rise. But whether this trend would substantiate into a medically effective and clinically feasible alternative is still a question.
Results of one such randomized trial were recently published in one of the renowned journals.
The trial was titled “Placement of Aortic Transcatheter Valves (Partner) 2” and included 2,032 patients with severe aortic stenosis. The patients were enrolled in 57 different centers in the United States and Canada. All the patients were categorized “intermediate-risk” based on the risk model developed by the Society of Thoracic Surgeons (STS). For the trial, the risk score was at least 4%. Depending upon their eligibility, the patients receiving TAVR therapy were assigned to either transfemoral (76.3%) or transthoracic (23.7%) cohorts – access routes for the placement of valve. Patients in the transthoracic cohort further underwent either transapical or transaortic access i.e., 174 and 62 respectively.
Patients in both cohorts were then randomly assigned to undergo either transcatheter (n = 1011) or surgical aortic valve replacement (n = 1021). All patients were monitored by a team of competent cardiothoracic surgeons and interventional cardiologists. The primary end point of the trial was death or stroke (modified Rankin scale: score ≤2) at two years. All the patients were followed for at least two years.
6.7% of the patients had an STS score <4%, 81% had the score between 4-8%, and 12% had a score >8%. Eight patients died during or within three days of the procedure.
The prime finding of the trial was a lack of a substantial difference in the primary endpoint i.e., death or stroke at two years, between the two treatment modalities i.e., TAVR VS surgery. Compared to the surgery cohort, the risk ratio for the primary endpoint in the TAVR group was 0.92.
In the transfemoral cohort, TAVR resulted in a lower death rate than surgery. There was no significant difference in the primary outcome between the two cohorts i.e., transfemoral VS transthoracic.
There was no specific difference in the rate of death and stroke between the TAVR group and the surgery group i.e., 16.7% VS 18%, and 6.2% VS 6.4% respectively.
Furthermore, both TAVR and surgical cohorts showed a significant reduction in the symptoms of New York Heart Association (NYHA) class I or II at 30 days. But interestingly, patients in the TAVR arm showed a reduction in the cardiac symptoms at 30 days than did those in the surgery group.
The chief finding of the trial is that TAVR is noninferior to surgery in patients with intermediate risk aortic stenosis. It was also noted that TAVR therapy lowered the risk of secondary endpoints in the patients i.e., hemorrhage, kidney injury and irregular heart beat (atrial fibrillation).
However, the incidence of paravalvular aortic regurgitation – leaking of the aortic valve of the heart – was higher in the TAVR group.
The trial vouches for the noninferiority of TAVR to surgery with respect to death and stroke at two years.
The superiority of transfemoral-access TAVR over surgery was the new finding of the trial which needs further authentication and confirmation through prospective studies and trials.
Transthoracic-access TAVR was found to be similar or worse than surgery in terms of outcomes.
It was concluded that further studies are needed to authenticate the findings of the current trials in intermediate-risk patients with aortic stenosis.
Limitations Of The Trial
Like all other studies and trials, the current trial had its limitations. For starters, there was a high withdrawal of the patients who were scheduled to undergo surgery.
The trial used SAPIEN XT valve whereas the newer version i.e., SAPIEN 3, is already available indicating that technological advances can influence the outcomes of TAVR therapies in future.
About Aortic Valve Stenosis
Aortic valve stenosis is a medical condition in which the heart’s aortic valve does not open fully, obstructing normal blood flow in the heart. Your heart has four chambers – two atria and two ventricles.
Aortic valve stenosis needs a surgical repair i.e., aortic valve replacement, otherwise it can lead to serious cardiac complication. Patients who are not candidates for surgery can undergo valvuloplasty – a procedure to widen a heart valve.