The use of bioprosthetic valves has surpassed the use of mechanical valves in most age groups, said Dr. Santiago Garcia, The Christ Hospital, Cincinnati, Ohio, at the TVT 2023 meeting in Phoenix, Arizona. The price of this transition, which occurred due to a desire to avoid anticoagulation, is an increased incidence in bioprosthetic valve degeneration. While redo surgery is possible, transcatheter aortic valve-in-valve procedures are gaining in popularity, with an increase of 500 to 600 additional valve-in-valve procedures performed every year. High residual gradients are the “Achilles’ heel” of valve-in-valve procedures, Dr. Garcia said. His presentation focused on not only why high residual gradients matter, but how to prevent and handle them.

The mechanism of valve failure, whether resulting from stenosis, aortic regurgitation, or a combination of both, impacts survival. Registry data have shown that patients that are treated for stenosis have a high risk of one-year mortality relative to those who present with regurgitation. The PARTNER 2 trial’s ViV Registry showed that patients with gradients >20 mmHg are linked to more than double the risk of mortality at 12 months versus patients with gradients <20 mmHg. A smaller valve (labeled) size of ≤21 mm versus a larger valve size of >25 mm is also linked to a higher risk of mortality at one year. “The first message is that if the mode of failure is stenosis in a small surgical valve, the prognosis tends to be worse than if the valve is larger and the mode of failure is AR [aortic regurgitation],” noted Dr. Garcia.

Nearly 50% of patients undergoing transcatheter aortic valve replacement (TAVR) procedures receive a 26 mm valve and as clinical trials have progressed from the PARTNER trial, PARTNER 2, and PARTNER 3, there has not been much of a change in terms of TAVR valve sizing. In all of these trials, almost 50% of TAVR patients got a 26 mm valve, approximately 20% received a 23 mm valve, and the rest received a 29 mm valve. Conversely, on the surgical side there has been an evolution from the PARTNER 2 to the PARTNER 3 trials, noted Dr. Garcia. Almost 40% of patients in PARTNER 2 received 21 mm and 19 mm valves, but in PARTNER 3, it decreased to <20%, with an increased percentage of patients getting 23 mm and 25 mm valves. This change in surgical practice may result from an increase in computed tomography (CT) sizing and a better understanding of the consequences of prosthesis-patient mismatch.

From an intraprocedural standpoint, Dr. Garcia discussed optimal valve-in-valve implantation techniques for both balloon-expandable and self-expanding valves. For a balloon-expandable Sapien 3 (Edwards Lifesciences), an optimal implantation technique places the central marker position 3 to 6 mm above the swing ring of the surgical valve. A non-optimal implantation technique places the central marker at the level of the swing ring, leading to a much deeper implant. Dr. Garcia showed two cases where in the first, the final gradient was  8 mmHg after an optimal implantation technique and contrasted it with a final gradient of 32 mmHg with a non-optimal technique in the second case. The risk of pacemaker implantation, while low overall, is also significantly higher when a balloon-expandable valve is implanted low during a valve-in-valve procedure. Dr. Garcia also shared a valve-in-valve case using a self-expanding valve and noted the effective orifice area (EOA) is higher when the valve is implanted high.

Visibility of surgical valves is an issue, and an understanding of the types of surgical valves and their fluoroscopic markers is important. Stentless valves are tougher to treat, in part because fluoroscopic markers are lacking, and have greater malapposition, more paravalvular leakage and an increased risk of coronary obstruction. There are several stented valves with fluoroscopic markers, and operators should be familiar with them and know what the markers represent, said Dr. Garcia.

The use of a transcatheter heart valve (THV) for a valve-in-valve procedure to treat a degenerated surgical valve was studied in the VIVID registry, and showed no difference between a self-expanding or a balloon-expandable THV in mortality at one year. At 8 years, there was a higher risk of reintervention with balloon-expandable valves (6% versus 2% with self-expandable valves) along with those patients who had preexisting severe prosthesis-patient mismatch, determined by the size of the surgical valve.

To mitigate the problem of prosthesis-patient mismatch and avoid the “Russian doll effect” (smaller and smaller valves being placed inside each other), Dr. Garcia discussed the technique of bioprosthetic valve fracture, pioneered in Kansas City, Missouri. “The goal here is to intentionally disrupt the stent frame of the surgical valve to hopefully aid in the expansion of the THV, improve gradients, and increase the effective orifice area,” said Dr. Garcia. The Kansas City group has shared data on which valves can be fractured, thresholds required to fracture, and the optimal technique for fracture. The TVT Registry has collected data on bioprosthetic valve fracture for a few years, and has shown that it is performed more frequently in small valves, with 30% of small valves (≤21 mm) and 10-15% of >21 mm valves in the United States undergoing at least an attempt at valve fracture. A review of in-hospital safety outcomes did not favor bioprosthetic valve fracture, with higher all-cause mortality, cardiac death, and stroke in the fracture versus non-fracture group. The safety signal occurred when the surgical valves were fractured prior to transcatheter heart valve (THV) implantation and was likely related to the hemodynamic instability associated with this strategy, said Dr. Garcia. A review of echocardiographic data showed “a rather modest benefit, in terms of hemodynamics,” he said. “Importantly, almost 20% of these procedures failed to achieve the goal…the operator did not feel they were able to successfully fracture” the surgical valve. Dr. Garcia concluded by noting that valve fracture needs further investigation and emphasizing that knowledge of each surgical valve is an important prerequisite for a successful valve-in-valve TAVR procedure with or without fracture.

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Find Dr. Garcia's slides here.