A study conducted by Michigan Medicine (Ann Arbor, USA) researchers suggests that hospitals without the highest stroke care designation may be missing strokes that occur after transcatheter aortic valve implantation (TAVI)—a common, minimally invasive procedure whereby a patient’s thickened aortic valve is replaced with a manmade device.
The researchers analysed outcomes of more than 6,200 TAVIs performed across 22 Michigan-based hospitals between 2016 and mid-2019 using data from the Michigan Structural Heart Consortium. The study zeroed in on identification of stroke after TAVI at health systems with and without certification by the US Joint Commission as a comprehensive stroke centre (CSC), the highest certification for acute stroke care.
Published recently in JACC: Cardiovascular Interventions, these findings reveal that CSCs reported significantly greater rates of stroke up to 30 days after TAVI—2.21 times higher than hospitals without the designation.
A press release from Michigan Medicine posits that this raises two key questions:
- Are hospitals with stroke centre accreditation finding more strokes because they take care of sicker, more complex patients?
- Or, are they not performing TAVI at the level/rate of those without such status?
But, after adjusting for patient characteristics, such as heart function and lung disease—and comparing other meaningful clinical outcomes after TAVI like mortality and renal failure—investigators found no significant differences in other clinically important outcomes outside of stroke detection.
A possible explanation for this finding is that patients receiving TAVI at high-level stroke centres are not having more strokes but, instead, hospitals with CSC status are better at detecting them—particularly smaller strokes. That is according to senior author Michael Grossman (University of Michigan Health Frankel Cardiovascular Center, Ann Arbor, USA).
“This becomes an issue because stroke has been suggested as a nationally and publicly reported outcome measure for TAVI,” Grossman said. “Based on these data, stroke is not indicative of a universal quality issue. A death is a death. A transfusion is a transfusion. Stroke detection is inconsistent, and that variability will potentially put high-level stroke centres at a disadvantage in those quality measures.”
CSC status signifies an organisation’s capabilities and resources for integrated acute stroke management and care. Such centres have staff specifically trained in recognising signs of stroke, diagnosing it and activating systems of care to treat those patients, according to the Michigan Medicine release.
These high-level centres were also more likely to participate in clinical trials for TAVI, which have reported higher rates of stroke up to 30 days after TAVI—between 3.4% and 6.1%—than the national average of 2.3% reported in the Society of Thoracic Surgeons (STS)/American College of Cardiology (ACC) Transcatheter Valve Therapy (TVT) Registry.
This is an “extremely important” study, because it shows that TAVI sites with high-level stroke designation have a higher incidence of recognising, diagnosing and accurately reporting stroke to the TVT Registry, said co-author G Michael Deeb (University of Michigan Health Frankel Cardiovascular Center, Ann Arbor, USA).
“The national TVT Registry uses a composite score, which includes the incidence of stroke to rank the quality of care at all US TAVI sites,” Deeb said. “Those sites with high-level stroke designation are penalised by the composite endpoint, since sites with lower-level stroke designation may be underreporting the incidence of stroke and, thus, have a better composite score and higher TAVI site quality rating.”
Hospitals that participate in TAVI clinical trials are adhering to more rigorous protocols used to assess neurologic outcomes, Grossman noted, which would explain the higher rates of stroke detection.
“While these stroke rates are low overall, we need to be careful about how we are measuring quality for TAVI outcomes,” he added. “It could both punish sites that strive to mitigate stroke consequences and incentivise sites that are underreporting stroke rates after this procedure.”
TAVI is an alternative for patients with aortic stenosis who likely could not withstand surgical aortic valve replacement—an open-heart procedure that was the standard treatment for several years. As of 2019, TAVI is now the dominant form of aortic valve replacement. That year, there were 72,991 TAVI cases, topping 57,626 cases of all forms of surgical replacement, according to data from the STS/ACC TVT Registry.
