Study Published on Possible Subclinical Leaflet Thrombosis in Bioprosthetic Aortic Valves

October 9, 2015—Online in The New England Journal of Medicine (NEJM), Raj R. Makkar, MD, et al published a finding of reduced aortic valve leaflet motion seen on computed tomography (CT) in a patient who had a stroke after transcatheter aortic valve replacement (TAVR) during an ongoing clinical trial. This finding raised a concern about possible subclinical leaflet thrombosis and prompted further evaluation. The investigators advised that the condition resolved with therapeutic anticoagulation, but noted that the effect of this finding on clinical outcomes including stroke needs further investigation.

As summarized in NEJM, data were analyzed from 55 patients in a clinical trial of TAVR and from two single-center registries that included 132 patients who were undergoing either TAVR or surgical aortic valve bioprosthesis implantation. The investigators obtained four-dimensional, volume-rendered CT scans along with data on anticoagulation and clinical outcomes (including strokes and transient ischemic attacks).

The investigators noted reduced leaflet motion on CT in 22 of 55 patients (40%) in the clinical trial and in 17 of 132 patients (13%) in the two registries. Reduced leaflet motion was detected among patients with multiple bioprosthesis types, including transcatheter and surgical bioprostheses. Therapeutic anticoagulation with warfarin, as compared with dual antiplatelet therapy, was associated with a decreased incidence of reduced leaflet motion (0% and 55%, respectively, P = .01 in the clinical trial; and 0% and 29%, respectively, P = .04 in the pooled registries). 

In patients who were reevaluated with follow-up CT, restoration of leaflet motion was noted in all 11 patients who were receiving anticoagulation and in 1 of 10 patients who were not receiving anticoagulation (P < .001). There was no significant difference in the incidence of stroke or transient ischemia attack between patients with reduced leaflet motion and those with normal leaflet motion in the clinical trial (2 of 22 patients and 0 of 33 patients, respectively; P = .016), although in the pooled registries, a significant difference was detected (3 of 17 patients and 1 of 115 patients, respectively; P = .007), reported the investigators in NEJM.

Also online in NEJM, a commentary from the US Food and Drug Administration (FDA) provides perspective and additional insights on the issue. “Reduced Leaflet Motion in Bioprosthetic Aortic Valves—The FDA Perspective” by John C. Laschinger, MD, et al is available here.

On October 5, 2015, the FDA issued a related notification advising that advanced imaging studies have detected reduced leaflet motion in some bioprosthetic aortic valves, including both surgical and transcatheter devices. The cause and occurrence rate of reduced leaflet motion and whether or not this finding has clinical implications for patients and patient care is not known, noted the FDA.