Subclinical Valve Thrombosis in Sutureless Bioprosthetic Valves

I n the current issue of JAHA, Dal en et al 1 report the results of a single-center prospective observational study of 47 patients with implantation of the Perceval sutureless bioprosthesis (LivaNova, Milan, Italy). Cardiac computed tomography (CT) performed at a median of 491 days (range 36– 1247 days) found hypo-attenuated leaflet thickening (HALT) in 18 (38%) and reduced leaflet motion (RLM) in 13 (28%) patients. HALT affected a single leaflet in 10 (56%), 2 leaflets in 6 (33%), and all leaflets in 2 patients (11%). The mean HALT leaflet thickening was 3 mm. For RLM, 1 leaflet was affected in 11 and 2 leaflets in 2 patients. Surprisingly, 5 of 18 patients with HALT (28%) and 3 of 13 patients with RLM (23%) were receiving anticoagulants at the time of CT. In fact, there was no significant difference in warfarin use between HALT and no HALT groups (22% versus 14%, P=0.45), but there was a trend towards reduced novel oral anticoagulant use in patients with HALT (6% versus 28%, P=0.06). Clinically, there were 3 strokes and 1 transient ischemic attack but no association with presence of HALT and RLM. Makkar et al first alerted the cardiovascular community to the existence of a significant and previously unrecognized risk of prosthetic leaflet motion reduction following transcatheter aortic valve replacement (TAVR) and bioprosthetic surgical aortic valve replacement (SAVR) in the absence of formal anticoagulation. It was hypothesized that this reduced leaflet motion was caused by subclinical leaflet thrombosis, which may trigger premature structural valve deterioration and constitute a nidus for cerebral thromboembolic events. The measures of valve thrombosis are HALT and RLM. The clinical consequences of such phenomena, and the role of anticoagulation for prevention and treatment are uncertain. This report by Dal en et al adds important data to the overall literature of HALT and RLM and is the first report of protocol-driven CT focusing on sutureless SAVR. Subclinical valve thrombosis is a newly recognized clinical entity that has been described in a variety of surgical and transcatheter bioprostheses. These patients may present with early significant increases in transvalvular gradients and even overt thrombosis. Del Trigo et al reviewed 1521 patients who underwent TAVI to find that 4.5% experienced clinical premature valve hemodynamic deterioration and an independent risk factor was no anticoagulation, suggesting that the mechanism was thrombosis related. Egbe et al examined explanted bioprostheses at the Mayo Clinic (mean 24 months) and found that overt thrombosis (11% in the aortic position) was associated with HALT and RLM. The importance of this issue of subclinical valve thrombosis is underscored by the fact that the seminal study prompted the Food and Drug Administration to state that, “if reduced leaflet motion is detected by imaging, treatment options should be discussed with the team of physicians responsible for the patient’s care.” Full anticoagulation with warfarin is currently the only treatment shown to reverse leaflet motion reduction in observational studies, although high-quality data in this regard are lacking. Sutureless valves are bioprosthetic valves that are implanted in an open surgical procedure but require few or no sutures, thus allowing for significantly shortened cardiopulmonary bypass and cross-clamp times. Sutureless valves are particularly useful for redo aortic procedures with calcified annuli that do not allow for conventional annular suturing, multiple valve procedures to reduce surgical times, and to facilitate minimally invasive procedures. There has previously been a single case report of early valve thrombosis with a size S sutureless SAVR. Given that HALT and RLM have been reported with conventional SAVR and TAVR, it is not surprising that they also occur with sutureless SAVR. What is surprising from this study is that the incidence of HALT and RLM was higher than that in the published literature for SAVR and even for TAVR. In a recent report from the Assessment of TRanscathetEr and Surgical Aortic The opinions expressed in this article are not necessarily those of the editors or of the American Heart Association. From the Division of Cardiac Surgery (B.Y., S.V.) and Department of Anesthesia (C.D.M.), Li Ka Shing Knowledge Institute of St Michael’s Hospital, University of Toronto, Ontario, Canada. Correspondence to: C. David Mazer, MD, FRCPC, Department of Anesthesia, St. Michael’s Hospital, University of Toronto, 30 Bond St, Toronto, Ontario, Canada M5B 1W8. E-mail: [email protected] J Am Heart Assoc. 2017;6:e006862. DOI: 10.1161/JAHA.117.006862. a 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.