Houston Methodist Video Examines Risk of Valve Underexpansion in TAVR Procedures for Aortic Stenosis

As transcatheter aortic valve replacement (TAVR) continues to expand into younger, lower-risk populations, the long-term performance of the implanted valves is under increasing scrutiny. A new whiteboard video from Houston Methodist Hospital addresses one key variable: valve underexpansion, a frequent but underappreciated challenge in the treatment of aortic stenosis.

In the video, Dr. Neal Kleiman, chief of Interventional Cardiology at Houston Methodist, walks viewers through the science and clinical implications of suboptimal valve deployment, particularly among low-risk patients who may outlive their initial bioprosthetic valve.

"We're seeing more patients in their 60s and 70s undergoing TAVR, and this shift raises important questions about durability," Dr. Kleiman says. "Valve underexpansion has emerged as a likely contributor to leaflet thickening, altered flow dynamics and potentially early failure."

The video highlights recent data showing that over half of TAVR valves have more than 10% underexpansion — the threshold identified in flow chamber studies as marking suboptimal performance. Valve-in-valve procedures present an even greater concern, with underexpansion rates reaching 70%.

Dr. Kleiman explains how underexpanded or deformed valves may impair leaflet coaptation, lead to hypoattenuated leaflet thickening (HALT), and elevate the long-term risk of dysfunction. Observational data suggest a 6- to 8-fold increase in HALT among patients with significant underexpansion.

In a case study, Kleiman illustrates how post-implant CT imaging revealed a still-elliptical valve frame despite high-pressure balloon inflation.

"The valve looked fine angiographically, but CT told a different story," Dr. Kleiman notes. "This highlights the importance of cross-sectional imaging when evaluating deployment success."

To address the gap in intraoperative assessment, Houston Methodist is launching a new clinical protocol using intravascular ultrasound (IVUS) — a tool traditionally used in coronary stent optimization — to evaluate TAVR expansion and symmetry in real time.

The goal is to correlate IVUS findings with CT imaging and determine whether the technology can guide intraprocedural decisions, such as the need for further balloon dilation.

"Our hope is that this research will help define best practices for optimizing valve deployment, ultimately improving valve durability and lifetime management for the growing population of patients with aortic stenosis who undergo TAVR," Dr. Kleiman concludes.