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Two measures may predict aortic regurgitation, mortality after TAVR
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Two factors were predictive of aortic regurgitation and mortality after transcatheter aortic valve replacement in patients with aortic stenosis, according to findings published in The New England Journal of Medicine.
The two measures were defects in high-molecular-weight von Willebrand’s factor multimers and a high value for the closure time with adenosine diphosphate, a way to measure hemostasis at the point of care.
According to the study background, 10% to 20% of patients undergoing TAVR experience postprocedural aortic regurgitation.
Eric Van Belle
Von Willebrand’s factor is a blood glycoprotein involved in hemostasis that is deficient or defective in von Willebrand’s disease, the most common hereditary blood-clotting disorder.
Eric Van Belle, MD, PhD, from the department of cardiology, Centre Hospitalier Régional Universitaire Lille in France, and colleagues analyzed data from two cohorts.
The first included 183 patients undergoing TAVR. After the initial implantation, those with aortic regurgitation received additional corrective balloon dilation. High-molecular-weight multimers and closure time with adenosine diphosphate (CT-ADP) were measured at baseline, as well as 5 minutes after every procedural step, and mortality was assessed 1 year later.
The second cohort included 201 patients evaluated for the efficacy of using CT-ADP to assess aortic regurgitation.
Predictive value
In the first cohort, high-molecular-weight multimers normalized after initial implantation for the 137 patients who did not have aortic regurgitation, according to the researchers.
Of the 46 patients who experienced aortic regurgitation, normalization occurred in 20 after additional balloon dilation, but not in 26.
A CT-ADP value higher than 180 seconds displayed predictive value for aortic regurgitation regarding sensitivity (92.3%), specificity (92.4%) and negative predictive value (98.6%) in the first cohort, and similar results in the second cohort, the researchers wrote.
At 1 year, 18% of patients died. In the first cohort, persistent aortic regurgitation was associated with increased risk for death (34.6% vs. 15.3% in those without it; log-rank P = .02).
According to the researchers, patients with a high-molecular-weight multimer ratio of less than 0.8 were three times more likely to die at 1 year than those who did not (40.6% vs. 13.2%; log-rank P < .001), and a similar rate of death was seen those with final CT-ADP of more than 180 seconds vs. those who did not (41.7% vs. 12.2%; log-rank P < .001).
Relevance at lower risk
In a related editorial, Firas E. Zahr, MD, and Steven R. Lentz, MD, PhD, both from the department of internal medicine at University of Iowa Carver College of Medicine, Iowa City, said the results may not be able to be extrapolated beyond the study population, most of whom had severe aortic stenosis, a high transaortic gradient and normal ejection fraction.
“As indications for TAVR expand, more data will be needed to define the value for CT-ADP and other point-of-care tests of von Willebrand’s factor function in lower-risk patients who are more likely to undergo TAVR without transesophageal echocardiographic guidance,” they wrote. – by James Clark
Disclosure: Van Belle reports no relevant financial disclosures. Please see the full study for a list of the other researchers’ relevant financial disclosures. Lentz reports receiving grant support and personal fees from Novo Nordisk and holding equity in Celgene. Zahr reports being a site investigator for a trial sponsored by Edwards Lifesciences.
Perspective
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Danny Dvir, MD
The study surprisingly shows that there is a potential to use a point-of-care blood test during TAVR to assist us in decision making. This will help us recognize significant aortic regurgitation and worse patient outcomes after valve implantation. This is a very novel finding that has many clinical implications.TAVR is associated with perivalvular leakage much more commonly than surgical valve replacement. This aortic regurgitation is related to worse clinical outcomes when significant. However, when a patient is on the table it is not easy to quickly decide whether regurgitation is mild or more than that.
We look at patient hemodynamics. We use echocardiograms and inject contrast above the implanted valve. But, in some cases we are still not completely sure if the leakage is significant or only mild. This is especially a concern with the growing approach of performing TAVR using a minimalist approach, in which the patient is only mildly sedated and the echo exam is transthoracic and less accurate in its evaluation of valvular dysfunction.
The authors were able to show that their unique blood exams were associated with regurgitation and patient mortality within one year. What I liked the most was their ability to show a dynamic relationship between correction of aortic regurgitation using post-dilatation and blood-test results. These point-of-care lab tests have the potential to assist us during TAVR cases in the decision of whether the implant result is satisfactory or we need to post-dilate the valve in order to reduce regurgitation degree.
The current study is still of a relatively small number of cases, and a larger evaluation that will include numerous centers and different transcatheter heart valve devices than the one utilized here is clearly required.
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