Lively Debate on Use of TAVR for Lower-Risk Patients

Based on encouraging data from nonrandomized trials on intermediate-risk patients and the usage patterns in lower-risk patients in Europe, Nicolo Piazza, MD, PhD, of McGill University Health Center, Montreal, Canada, argued that clinical indications for transcatheter aortic valve replacement (TAVR) in the United States should be expanded to lower-risk cohorts. But during a debate at TCT 2014, Michael J. Mack, MD, of Baylor Health Care System, Dallas, Texas, advised caution since the noninferiority of TAVR vs. conventional surgical aortic valve replacement (SAVR) has yet to be proven in randomized trials.

Low-risk patients receiving TAVR 

Piazza stated that a lack of universally accepted criteria for surgical risk that clearly distinguishes between risk categories is one of the main obstacles in establishing a TAVR trial for low-risk patients.

Among the data supporting use of TAVR in lower surgical risk patients is a study that he and colleagues conducted in 3,666 consecutive patients with symptomatic severe aortic stenosis who underwent TAVR (n=782) or surgery (n=2,884) at three European centers. The study, published last year in the JACC: Cardiovascular Interventions found similar cumulative all-cause mortality at 30 days and 1 year among propensity-score matched TAVR and SAVR patients at intermediate surgical risk.

Furthermore, Piazza noted that compared with patients at calculated high risk, well-selected patients at intermediate or low risk, as defined by STS score, experience favorable clinical outcomes following TAVR.

Piazza added that there is a systematic fall in surgical risk scores in Europe, where more lower-risk patients are currently being treated than in the United States. “Appropriate surgical and TAVR risk scores are currently lacking, which may provide physicians with better guidance in the treatment of patients,” he said. “And, needless to say, we are awaiting the results of the SURTAVI and PARTNER IIA intermediate-risk trials.”

Into the unknown

In his rebuttal, Mack highlighted data from Messé and colleagues recently published in Circulation showing that clinical stroke after SAVR was more common than reported previously, more than double for this same cohort in the STS database (17% vs. 7%). In addition, this study found that silent cerebral infarctions were detected in more than half of stroke-free patients.

Mack said that despite recent studies demonstrating TAVR’s superiority to medical therapy in inoperable patients and its noninferiority to SAVR in high-risk patients, without supporting evidence from randomized trials there are too many areas of uncertainty to fully embrace TAVR implementation in this cohort.

In addition to awaiting outcomes of PARTNER IIA and SURTAVI, “we also don’t know the long-term durability or the consequences of paravavular leak,” he added.

Mack cited data from a study he and colleagues conducted, which showed that among patients undergoing TAVR at U.S. centers in the STS/ACC TVT Registry, device implantation success was 92%, the overall in-hospital mortality rate was 5.5% and the stroke rate was 2%. However, he further emphasized that long-term follow-up is essential to assess continued efficacy and safety.

Mack concluded that TAVR will inevitably “creep” into treatment considerations for intermediate-risk patients, and the outcomes of TAVR will continue to improve with the advent of new devices and ongoing operator experience.

 Disclosures: 

• Piazza reports serving as a proctor and consultant for Medtronic.

• Mack reports off-label use of MitraClip (Abbott Vascular) and transcatheter aortic valves and serving on the executive committee of the PARTNER trial.