Subclinical Leaflet Thrombosis After SAVR and TAVR

Study Questions:

What is the prevalence of subclinical leaflet thrombosis after surgical (SAVR) and transcatheter aortic valve replacement (TAVR); and what is the effect of novel oral anticoagulants (NOACs) on subclinical leaflet thrombosis, valve hemodynamics, and clinical outcomes?

Methods:

The RESOLVE and SAVORY registries both are single-center prospective registries including patients who underwent TAVR or bioprosthetic SAVR. Patients enrolled in the RESOLVE registry between 12/22/ 2014 and 1/18/ 2017, and in the SAVORY registry between 6/2/2014 and 9/28/2016, had computed tomography (CT) imaging done with a dedicated four-dimensional volume-rendered imaging protocol at varying intervals after TAVR and SAVR. Subclinical leaflet thrombosis was identified as the presence of reduced leaflet motion, along with corresponding hypo-attenuating lesions on CT. Data collected included baseline demographics, antithrombotic therapy, and clinical outcomes. All CT scans, echocardiograms, and neurological events were analyzed in a masked fashion.

Results:

Of 931 patients who had CT imaging done (657 [71%] in the RESOLVE registry and 274 [29%] in the SAVORY registry), 890 [96%] had interpretable CT scans (626 [70%] in the RESOLVE registry and 264 [30%] in the SAVORY registry). 106 (12%) of 890 patients had subclinical leaflet thrombosis, including 5 (4%) of 138 with thrombosis of surgical valves versus 101 (13%) of 752 with thrombosis of transcatheter valves (p = 0.001). The median time from AVR to CT for the entire cohort was 83 days (interquartile range, 33-281). Subclinical leaflet thrombosis was less frequent among patients receiving anticoagulants (8 [4%] of 224) than among those receiving dual antiplatelet therapy (31 [15%] of 208; p < 0.0001); NOACs were equally as effective as warfarin (3 [3%] of 107 vs. 5 [4%] of 117; p = 0.72). Subclinical leaflet thrombosis resolved in 36 (100%) of 36 patients (warfarin 24 [67%]; NOACs 12 [33%]) receiving anticoagulants, whereas it persisted in 20 (91%) of 22 patients not receiving anticoagulants (p < 0.0001). A greater proportion of patients with subclinical leaflet thrombosis had aortic valve gradients of >20 mm Hg and increases in aortic valve gradients of >10 mm Hg (12 [14%] of 88) than did those with normal leaflet motion (7 [1%] of 632; p < 0.0001). Although stroke rates were not significantly different between those with (4.12 strokes per 100 person-years) or without (1.92 strokes per 100 person-years) reduced leaflet motion (p = 0.10), subclinical leaflet thrombosis was associated with increased rates of transient ischemic attacks (TIAs; 4.18 TIAs per 100 person-years vs. 0.60 TIAs per 100 person-years; p = 0.0005) and all strokes or TIAs (7.85 vs. 2.36 per 100 person-years; p = 0.001).

Conclusions:

Subclinical leaflet thrombosis occurred frequently in association with bioprosthetic aortic valves, and more commonly after TAVR than bioprosthetic SAVR. Anticoagulation (both NOACs and warfarin), but not dual antiplatelet therapy, was effective in prevention or treatment of subclinical leaflet thrombosis. Subclinical leaflet thrombosis was associated with increased rates of TIAs and strokes or TIAs. Despite excellent outcomes after TAVR with new-generation valves, the authors concluded that prevention and treatment of subclinical leaflet thrombosis might offer an opportunity for further improvement in valve hemodynamics and clinical outcomes.

Perspective:

Post-intervention CT imaging has revealed subclinical leaflet thrombosis of bioprosthetic aortic valves after both TAVR and SAVR. This study, which combines data from two large single-center registries of patients undergoing TAVR or bioprosthetic SAVR, suggests that subclinical leaflet thrombosis is not uncommon, and occurs more often after TAVR than after SAVR; is associated with higher gradients and with a higher incidence of TIA or combined TIA and stroke (without statistically significant differences in rates of stroke as an isolated endpoint); and occurs less often and can be effectively treated with either warfarin or a direct oral anticoagulant, but not with dual antiplatelet therapy. This study comes close on the heels of a newly released (2017) AHA/ACC focused update of the 2014 guidelines for the management of patients with heart valve disease. Those revised guidelines include: 1) an expanded recommendation for the use of a vitamin K antagonist for 3-6 months after bioprosthetic mitral or aortic valve replacement among patients at low risk for bleeding (Class IIa, Level of Evidence B-NR), and 2) a recommendation for a vitamin K antagonist (international normalized ratio target 2.5) for at least 3 months after TAVR among patients at low risk for bleeding (Class IIa, Level of Evidence B-NR).

Clinical Topics: Anticoagulation Management, Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Valvular Heart Disease, Aortic Surgery, Cardiac Surgery and VHD, Interventions and Imaging, Interventions and Structural Heart Disease, Computed Tomography, Nuclear Imaging

Keywords: ACC17, ACC Annual Scientific Session, Anticoagulants, Aortic Valve, Cardiac Imaging Techniques, Cardiac Surgical Procedures, Fibrinolytic Agents, Heart Valve Diseases, Heart Valve Prosthesis, Hemodynamics, Ischemic Attack, Transient, Platelet Aggregation Inhibitors, Registries, Stroke, Thrombosis, Tomography, Tomography, X-Ray Computed, Transcatheter Aortic Valve Replacement, Vitamin K, Warfarin


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