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Clinical transcatheter heart valve thrombosis may be common enough to merit routine imaging after transcatheter aortic valve replacement (TAVR), a German study suggested.

A retrospective analysis of a single-center registry found a 2.8% incidence of clinical valve thrombosis, according to Mohamed Abdel-Wahab, MD, of Germany's Segeberger Kliniken, and colleagues. No one on oral anticoagulation got bioprosthetic valve thrombosis, however, and no patients died from it.

Thrombosis was more likely with balloon-expandable valves (OR 3.45, 95% CI 1.22-9.81) and with valve-in-valve procedures (OR 5.93, 95% CI 2.01-17.51), the authors reported in the April 10 issue of JACC: Cardiovascular Interventions.

At the time of bioprosthetic valve thrombosis diagnosis with transesophageal echo (done for all patients with worsening symptoms or elevated gradients, most with the addition of CT), the average transvalvular gradient and valve area were 34 mm Hg and 1.0 cm², respectively. The median N-terminal pro-brain natriuretic peptide level was 1,318 pg/mL.

Initiating oral anticoagulation effectively reduced transvalvular gradient and was associated with clinical improvement.

"Patients with progressive dyspnea and rising gradients should be referred early to experienced centers with CT [capabilities] to rule out valve thrombosis," the investigators suggested.

The findings follow on the heels of yet more data adding to concern about device thrombosis with another newer cardiac technology -- bioresorbable vascular scaffolds.

Abdel-Wahab's analysis included 642 consecutive patients who underwent TAVR from 2007 to 2015. Long-term anticoagulation was indicated in 261 patients; 377 got dual antiplatelet therapy (DAPT) after TAVR. It took a median of 181 days to get diagnosed with TAVR valve thrombosis.

"Because [clinical valve thrombosis] was not present in patients on anticoagulation and 40% of the patients were on oral anticoagulation, the true prevalence of transcatheter heart valve thrombosis was 4.8% in the absence of anticoagulation," argued an accompanying editorial. "This number falls between the reported prevalence of 10% to 14% for subclinical leaflet thrombosis on high-resolution CT imaging to 0.6% to 2% of hemodynamically or clinically overt transcatheter heart valve thrombosis."

Raj R. Makkar, MD, and Tarun Chakravarty, MD, both of Cedars-Sinai Heart Institute in Los Angeles, concluded that "the prevalence of transcatheter heart valve thrombosis appears significant enough to warrant routine followup transthoracic echocardiographic imaging after TAVR. The treating physicians should be vigilant for new elevations in transvalvular gradients or changes in symptoms concerning for transcatheter heart valve thrombosis. Confirmatory diagnosis with transesophageal echocardiography or CT, preferably the latter, should precede trial therapy with anticoagulation."

The duo co-authored a separate JACC: Cardiovascular Imaging report that detailed their systematic methodology for detecting subclinical leaflet thrombosis on CT and called for its standardized reporting.

Their Portico trial was the first to describe thrombosis of bioprosthetic heart valve leaflets, visible on CT as hypoattenuated leaflet thickening associated with reduced leaflet motion.