Recently released research indicates that a particular medical device could be advantageous for individuals who have experienced a stroke and are scheduled for a transcatheter aortic valve replacement (TAVR), a surgical procedure aimed at addressing heart valve issues.
Recently released research indicates that a specific medical device could be beneficial for individuals who have previously suffered a stroke and are preparing to undergo a transcatheter aortic valve replacement (TAVR), a surgical procedure that addresses heart valve conditions.
Dr. Neel Butala, an assistant professor in the Division of Cardiology at the University of Colorado’s Department of Medicine, is the lead author of this study. The research was unveiled as a late-breaking clinical trial at the New York Valves 2024 conference and published simultaneously in Circulation: Cardiovascular Interventions, a journal associated with the American Heart Association.
The objective of the study was to gather insights on the effectiveness of a cerebral embolic protection device in reducing the stroke risk during TAVR procedures.
“Although this device received approval, its usefulness was uncertain,” Butala states. “Utilizing a large dataset, we sought answers and ultimately discovered that patients with a history of stroke could gain the most from this device.”
What is TAVR?
A transcatheter aortic valve replacement, commonly known as TAVR, is a less invasive therapy intended for patients suffering from severe aortic stenosis.
“Aortic stenosis occurs when the aortic valve narrows, obstructing blood flow from the heart to the body, forcing the heart to work harder,” Butala explains. “While this narrowing progresses with age, certain individuals face severe restrictions. Once symptoms arise, it is critical to intervene and replace the valve.”
Traditionally, open heart surgery was the standard treatment for severe aortic stenosis. However, many patients in their 70s and 80s are often not considered suitable for such surgical procedures.
“TAVR was introduced as a minimally invasive alternative. We access the heart via an artery in the leg and insert a slender tube across the aortic valve. Through this tube, we place a compressed aortic valve,” he explains. “We can inflate a balloon inside the existing aortic valve to facilitate the new transcatheter valve expanding to its designated size, or we can deploy a self-expanding valve.”
“This process effectively places a new valve inside the existing aortic valve, ensuring unobstructed blood flow from the heart,” he adds.
Reducing the risk of stroke
Currently, TAVR has become more refined, and the likelihood of complications is generally low, according to Butala.
“Despite this, the risk of stroke remains a notable complication. When the new valve is inflated within the old valve, fragments of calcium may dislodge and travel to the brain, potentially blocking blood vessels and causing a stroke,” he mentions. “Approximately 1.5% to 2% of patients experience a stroke as a result of this procedure. This ongoing complication remains unresolved, and predictors for stroke occurrence are still uncertain.”
To combat this issue, an embolic protection device was engineered to avert strokes by employing filters in the vessels supplying blood to the brain.
“Currently, there’s only one embolic protection device available in the U.S.,” Butala states. “It features small baskets designed to capture debris from three out of four vessels leading to the brain. The theory is that these baskets will retain any calcium fragments, thereby helping to prevent strokes.”
Even though the logic behind these devices is clear, there has been insufficient data to support their effectiveness. Various studies assessing whether these devices can lower the stroke risk during TAVR procedures have produced mixed findings.
“In our prior extensive observational study encompassing all TAVR procedures in the U.S., we could not identify any difference in stroke occurrence based on device usage,” he explains.
In a randomized trial known as the PROTECTED-TAVR trial, findings revealed the device did not lower the stroke rates within 72 hours post-procedure. Nonetheless, it suggested a 62% reduction in “disabling strokes,” representing more severe strokes that cause significant symptoms.
“With these inconsistent outcomes, there remained debate regarding the device’s value. The medical community was still uncertain about its use,” Butala notes.
Examining the device’s impact on disabling strokes
In light of the mixed results from the PROTECTED-TAVR trial, Butala’s research focused on the device’s effectiveness in minimizing disabling stroke occurrence.
Researchers used data on patients’ discharge locations as indicators of stroke severity.
“The reasoning was that if a patient leaves the hospital for a care facility, such as a rehab center, their stroke was likely more serious than if they returned home,” he says. “Consequently, we devised an innovative approach to identify disabling strokes.”
The study analyzed data from 414,649 patients, with 53,398 having received the embolic protection device. This represents the largest study to date involving TAVR patients.
Overall, the findings indicated a slight, nearly significant decrease in disabling strokes associated with device use, a much smaller effect than shown in the PROTECTED-TAVR trial, according to Butala. Notably, the device did not correlate with a reduction in non-disabling strokes.
“One possible explanation for the lack of reduction in non-disabling strokes is that minute calcium fragments might bypass the baskets, or that the baskets themselves might cause minor damage to blood vessels, leading to small strokes,” he explains.
The researchers also discovered that patients with previous strokes experienced a more substantial benefit from the device compared to those without a history of strokes.
“Our data indicates that this subgroup of patients with prior strokes experiences a significant benefit of meaningful magnitude. This is the first time a subgroup deriving benefit from this device has been identified,” he notes. “It may be advisable to use this device more routinely for patients with a prior stroke. For others, the benefits remain ambiguous.”
“While I don’t believe it poses any harm, there is an associated cost in terms of both time and money,” he adds.
Looking ahead, Butala is eager to see innovators develop devices with improved protective capabilities for patients.
“There is a clear need for advancements in this area to establish more effective protection against strokes for individuals undergoing TAVR procedures, as this technique is growing increasingly common, even among younger demographics,” he comments.
“The device’s overall effectiveness remains a complex challenge,” he adds. “Our findings contribute additional insight by demonstrating that the device can reduce the likelihood of disabling strokes in certain patients, albeit to a minor extent. However, as its application extends to younger patients, it is vital to deepen our understanding of how we can avert strokes.”
