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Long-Term Clinical Outcomes After TAVR With Balloon-Expandable Versus Self-Expanding Valves
Can you tell us about your analysis comparing balloon-expandable and self-expanding transcatheter valves?
This study came from the Massachusetts Cardiovascular Consortium (MassCar), which is a collaborative effort led by the Smith Center for Outcomes Research at Beth Israel Deaconess Medical Center (BIDMC). Clinical data was aggregated from multiple tertiary care centers in Massachusetts including Brigham and Women’s, Massachusetts General Hospital, Beth Israel Deaconess Medical Center, and Lahey Medical Center. The goal of the Consortium is to maintain a robust multicenter registry where cardiovascular surgical and procedural data are aggregated with Medicare files and state claims data to help us understand longitudinal outcomes for different clinical questions. The registry offers a rich source of data from which we can evaluate multiple clinical questions. In our study, senior mentors from the Consortium, including Dr. Robert W. Yeh, Dr. Dhaval Kolte, Dr. Sammy Elmariah, and Dr. Pinak Shah, my co-fellow, Dr. Zaid Almarzooq, and I examined longitudinal clinical outcomes across different valve platforms. We compared longitudinal clinical outcomes in patients undergoing TAVR with balloon-expandable versus self-expanding valves in patients who received either therapy from 2014 to 2020. Our goal was to evaluate any significant difference in major adverse events such as mortality or an increased need for aortic valve re-intervention between the two platforms. By using inverse probability weighting, we attempted to account for the random assignment of treatment, either with balloon expandable or with self-expanding valves, and for unmeasured cofounders. The study included longitudinal data in patients who received therapy early after FDA approval of both platforms. Therefore, these patients represented a higher risk cohort as patients who were deemed high risk for surgical intervention were the ones who initially received TAVR. As we move through those years, two main patient and procedural factors changed in the registry. First, patients that were of less magnitude of risk were accepted to receive such therapies. Second, there have been iterative improvements in these valve platforms, defined by different generations in the valves. We adjusted for unmeasured confounders to the best of our ability, knowing that ultimately there will be a limitation where the definitive answer regarding differences in clinical outcomes will be settled in a head-to-head, randomized clinical trial. We concluded that in our observational, multicenter registry linked to claims data, we saw no significant difference in a composite primary endpoint of all-cause mortality plus aortic valve reintervention over a median follow-up period of 2.1 years. 
In addition, over the same period, we didn't see any difference in key secondary outcomes, including all-cause mortality alone, aortic valve, intervention alone, readmissions from any cause, and heart failure readmissions.
What are you hoping that physicians will take away from your study?
At the end of the day, individualized decision making and patient selection will be the key factors that are going to push physicians and patients to one platform versus the other. In my opinion, the question about whether there is a significant difference in one platform versus the other over time still largely remains unanswered. There has been a lot of excitement about comparison of TAVR platforms to surgical AVR in different modalities, but it is challenging to extrapolate that without such a head-to-head comparison between valve platforms. The current data set for head-to-head comparisons in a randomized clinical trial for balloon-expandable versus self-expanding platforms is quite limited. There have been some registry-based data published in the past few years. However, these often had a smaller period of follow-up. There has been a randomized controlled trial, the CHOICE trial, that involved earlier iterations of devices. The SMART trial, comparing clinical outcomes across the two platforms in patients with small aortic valve annuli, is currently enrolling. As newer iterations of devices are developed, as the patient population expands to different risk categories, it would be interesting to see more randomized trial data in this space.
Any final thoughts?
There is discussion around differences between the balloon-expandable and self-expanding platforms in terms of hemodynamics and in terms of technical ease of use. These hypothesis-generating questions are certainly interesting from a scientific perspective. When comparing the two platforms, we tend to want things to be binary, which is a tougher question to answer without the gold standard of a randomized clinical trial. Looking at the current data, understanding the strengths and limitations is fundamental to interpretation. At the end of the day, what really matters is how these platforms perform in terms of longitudinal clinical outcomes. As a patient, this is what I would want answered — how am I going to do with one platform versus the other? As a physician, strong data with respect to long-term clinical outcomes in TAVR is what I want to be able to share with our patients.
Lastly, our research efforts are led by multiple investigators in Massachusetts-area hospitals. I am grateful for the unwavering support and mentorship from physicians and clinical investigators at the Smith Center for Clinical Outcomes Research, Beth Israel Deaconess Medical Center, Brigham Women's Hospital, Massachusetts General Hospital, and Lahey Medical Center.
Dr. Jay Khambhati presented “TCT 416: Long-Term Clinical Outcomes After Transcatheter Aortic Valve Replacement With Balloon-Expandable Versus Self-Expanding Valves” at TCT 2023 on Tuesday, October 24, in an Emerging Clinical Science & Research session.
You can view his slides here.
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