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Large transcatheter heart valve size may increase risk for thrombosis
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Among patients undergoing transcatheter aortic valve replacement, larger transcatheter heart valve size may be a predictor of thrombosis, but warfarin treatment appears to lower the risk, according to recent findings.
In the study, researchers evaluated 460 consecutive patients (median age, 83 years; 54% women) who underwent TAVR with the Sapien XT or Sapien 3 (Edwards Lifesciences) valve at Aarhus University Hospital, Denmark, between January 2011 and January 2016.
Patients were placed on a standard post-TAVR antithrombotic regimen, which included dual antiplatelet therapy with aspirin (75 mg per day) and clopidogrel (75 mg per day) for 12 months, followed by aspirin (75 mg per day) for life.
Of the 460 patients who underwent TAVR, 405 (88%) also underwent post-TAVR multidetector CT along with transthoracic and transesophageal echocardiography at 1 to 3 months.
The researchers assessed the multidetector CT scans for hypoattenuated leaflet thickening suggestive of transcatheter heart valve thrombosis. They defined leaflet thrombus as diffuse thickening of one or more transcatheter heart valve leaflets or a more focal hypoattenuating abnormality attached to the transcatheter heart valve leaflet.
The researchers calculated the RR with 95% CIs and the chi-square to compare transcatheter heart valve thrombosis risks.
Thrombosis verified
They found that, in 28 of 405 patients (7%), transcatheter heart valve thrombosis could be verified on multidetector CT. In 23 patients, transcatheter heart valve thrombosis was subclinical, whereas five patients (18%) demonstrated clinically evident obstructive transcatheter heart valve thrombosis. The two different generations of transcatheter heart valves did not show any difference in thrombosis risk (8% vs. 6%; P = .42), the researchers wrote.
Patients who were not treated with warfarin had a higher risk for transcatheter heart valve thrombosis vs. those who received warfarin (10.7% vs. 1.8%; RR = 6.09; 95% CI, 1.86-19.84). Patients who were treated with antiplatelet therapy alone had an 18.8% risk for transcatheter heart valve thrombosis. The risk for transcatheter heart valve thrombosis also was higher in patients who received a larger transcatheter heart valve (P = .03). Multivariable analysis revealed a 29-mm transcatheter heart valve (RR = 2.89; 95% CI, 1.44-5.8) and a lack of post-TAVR warfarin treatment (RR = 5.46; 95% CI, 1.68-17.7) as independent predictors of transcatheter heart valve thrombosis, but not left ventricular ejection fraction of 35% or less at hospital discharge.
Four patients (14%) were prescribed warfarin alone, and 17 patients (61%) were prescribed warfarin in addition to antiplatelet therapy. In the three patients (11%) already being treated with warfarin, there was an increase in the target INR, from 2.5 to 3, according to the researchers. Four patients (14%) were kept on routine antithrombotic therapy without warfarin, and further follow-up transesophageal echocardiography and multidetector CT imaging were scheduled. Of these patients, two showed spontaneous regression of transcatheter heart valve thrombus, whereas two had transcatheter heart valve thrombus progression and were started on warfarin. After 3 months of treatment, 85% of cases demonstrated complete thrombus resolution.
Medication important
Arie Pieter Kappetein, MD , and Stuart J. Head, MD, of the department of thoracic surgery, Erasmus Medical Centre, Rotterdam, Netherlands, wrote that although the optimal peri- and post-TAVR antithrombotic regimens are not yet known, these findings support the value of such regimens in preventing transcatheter heart valve thrombosis.
“The study ... manifests a high incidence of valve thrombosis and shows that anticoagulation is effective in restoring leaflet function,” the authors wrote. “As always in medicine, it is better to prevent than to cure and points to the fact that antithrombotic therapy in the setting of TAVR has only been empirically determined.” – by Jennifer Byrne
Disclosure: Some of the researchers report financial relationships with AstraZeneca, Baxter, Bayer, Boehringer Ingelheim, Bracco Imaging, Bristol-Myers Squibb, Circle Imaging, Edwards Lifesciences, HeartFlow, Medtronic, Neovasc, Pfizer, Siemens and Tendyne. Kappetein reports serving on the steering committee for the SURTAVI trial, sponsored by Medtronic, and the UNLOAD study, sponsored by Edwards Lifesciences. Head reports no relevant financial disclosures.
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