Detection and Prediction of Bioprosthetic Aortic Valve Degeneration

Background

Bioprosthetic aortic valve degeneration is increasingly common, often unheralded, and can have catastrophic consequences.

18F-GP1 Positron Emission Tomography and Bioprosthetic Aortic Valve Thrombus

BackgroundBioprosthetic valve thrombosis may have implications for valve function and durability.ObjectivesUsing a novel glycoprotein IIb/IIIa receptor radiotracer 18F-GP1, we investigated whether positron emission tomography (PET)-computed tomography (CT) could detect thrombus formation on bioprosthetic aortic valves.MethodsEx vivo experiments were performed on human platelets and explanted bioprosthetic aortic valves. In a prospective cross-sectional study, patients with either bioprosthetic or normal native aortic valves underwent echocardiography, CT angiography, and 18F-GP1 PET-CT.ResultsFlow cytometric analysis, histology, immunohistochemistry, and autoradiography demonstrated selective binding of 18F-GP1 to activated platelet glycoprotein IIb/IIIa receptors and thrombus adherent to prosthetic valves. In total, 75 participants were recruited: 53 with bioprosthetic valves (median time from implantation 37 months [IQR: 12-80 months]) and 22 with normal native aortic valves. Three participants had obstructive valve thrombosis, and a further 3 participants had asymptomatic hypoattenuated leaflet thickening on CT angiography. All bioprosthetic valves, but none of the native aortic valves, demonstrated focal 18F-GP1 uptake on the valve leaflets: median maximum target-to-background ratio 2.81 (IQR: 2.29-3.48) vs 1.43 (IQR: 1.28-1.53) (P < 0.001). Higher 18F-GP1 uptake was independently associated with duration of valve implantation and hypoattenuated leaflet thickening. All 3 participants with obstructive valve thrombosis were anticoagulated for 3 months, leading to resolution of their symptoms, improvement in mean valve gradients, and a reduction in 18F-GP1 uptake.ConclusionsAdherence of activated platelets is a common and sustained finding on bioprosthetic aortic valves. 18F-GP1 uptake is higher in the presence of thrombus, regresses with anticoagulation, and has potential use as an adjunctive clinical tool. (18F-GP1 PET-CT to Detect Bioprosthetic Aortic Valve Thrombosis; NCT04073875)     

Long-Term Outcomes of Anticoagulation for Bioprosthetic Valve Thrombosis

BackgroundEarly in the prevention and treatment of bioprosthetic valve thrombosis (BPVT), anticoagulation is effective, but the long-term outcome after BPVT is unknown.ObjectivesThe goal of this study was to assess the long-term outcomes of patients with BPVT treated with anticoagulation.MethodsThis analysis was a matched cohort study of patients treated with warfarin for suspected BPVT at the Mayo Clinic between 1999 and 2017.ResultsA total of 83 patients treated with warfarin for suspected BPVT (age 57 ± 18 years; 45 men [54%]) were matched to 166 control subjects; matching was performed according to age, sex, year of implantation, and prosthesis type and position. Echocardiography normalized in 62 patients (75%) within 3 months (interquartile range [IQR]: 1.5 to 6 months) of anticoagulation; 21 patients (25%) did not respond to warfarin. Median follow-up after diagnosis was 34 months (IQR: 17 to 54 months). There was no difference in the primary composite endpoint between the patients with BPVT and the matched control subjects (log-rank test, p = 0.79), but the former did have a significantly higher rate of major bleeding (12% vs. 2%; p < 0.0001). BPVT recurred (re-BPVT) in 14 (23%) responders after a median of 23 months (IQR: 11 to 39 months); all but one re-BPVT patient responded to anticoagulant therapy. Patients with BPVT had a higher probability of valve re-replacement (68% vs. 24% at 10 years’ post-BPVT; log-rank test, p < 0.001).ConclusionsBPVT was associated with re-BPVT and early prosthetic degeneration in a significant number of patients. Indefinite warfarin anticoagulation should be considered after a confirmed BPVT episode, but this strategy must be balanced against an increased risk of bleeding.     

3D Transesophageal Echocardiography for Guiding Transcatheter Aortic Valve Replacement Without Prior Cardiac Computed Tomography in Patients With Renal Dysfunction

BackgroundPre-procedural chronic kidney disease (CKD) and in-hospital acute kidney injury (AKI) are associated with worse outcomes following transcatheter aortic valve replacement (TAVR). We tested the feasibility of reducing overall AKI by avoiding pre-procedural cardiac CT angiography (CCTA) by using direct 3D-TEE guidance in TAVR patients with known CKD.MethodsAn institutional TAVR database was examined from January 2016 to June 2020 to identify 396 patients in whom CCTA sizing was performed and 54 patients with creatinine (Cr) of >1.6 mg/dL in whom direct 3D-TEE, without prior CCTA, was used for TAVR guidance. Baseline demographics, procedural, echocardiographic, and clinical endpoints were compared as defined by the Valve Academic Research Consortium-2 criteria.ResultsBaseline demographics and risk factors were similar in both groups other than the creatinine level in CCTA vs. TEE groups (1.33 ± 1.1 vs 1.76 ± 0.7 mg/dL, p = 0.005). Procedural contrast volume was significantly lower in the TEE group compared to the CCTA group. No differences were noted in echocardiographic and clinical endpoints for both groups. Despite higher baseline Cr, patents in the TEE group experienced a similar pattern of changes in Cr compared to the CCTA group, with an overall renal improvement noted at the time of discharge for both groups.ConclusionsIn patients with baseline CKD, careful avoidance of large contrast loads associated with CCTA and intra-procedural aortography by using TEE guidance may help reduce AKI following TAVR.     

Rapid Deployment Versus Conventional Bioprosthetic Valve Replacement for Aortic Stenosis

Background

Surgical aortic valve replacement using conventional biological valves (CBVs) is the standard of care for treatment of old patients with aortic valve disease. Recently, rapid deployment valves (RDVs) have been introduced.

Serial Doppler Gradients Are Predictive of Future Bioprosthetic Valve Degeneration

Doppler echocardiography and color flow imaging are helpful techniques in evaluating the functional status of a bioprosthetic valve. The aim of this study was to determine whether serial Doppler gradients are predictive of future bioprosthetic valve degeneration. We performed serial echo-Doppler studies over a 6-year period (1988–1994) on 228 patients who had undergone mitral (n = 112) or aortic (n = 116) bioprosthetic valve implantation between 1973 and 1994. Thirtynine mitral prostheses and 30 aortic prostheses became dysfunctional and required reoperation. A serial rise in mean gradient of 5 mmHg or more across the mitral valve and 25 mmHg or more across the aortic valve was significantly associated with increased valve degeneration (odds ratio 3.40 and 16.11 and 95% confidence intervals 1.31 and 8.80 and 13.6 and 72.13 for the mitral and aortic valve, respectively). Both aortic and mitral valves began to degenerate after 8 years. Serial echo-Doppler studies showed a rise in transvalvular gradients around the same time. Closer evaluation for prosthetic valve dysfunction should be considered in patients 8 or more years status post surgery, especially those with high transvalvular gradients.     

Risk Assessment of Coronary Obstruction During Transcatheter Aortic Valve Replacement: Insights From Post-BASILICA Computed Tomography

ObjectivesThe aim of this study was to examine the predictive value of preprocedural computed tomography (CT)–based risk stratification of coronary obstruction during transcatheter aortic valve replacement (TAVR) on the basis of geometric measurements on postprocedural CT.BackgroundProper patient selection for additional procedures to prevent coronary obstruction during TAVR has not been adequately evaluated.MethodsPre- and postprocedural computed tomographic scans of 28 patients treated using bioprosthetic or native aortic scallop intentional laceration to prevent iatrogenic coronary artery obstruction (BASILICA) and TAVR were analyzed. Using the postprocedural computed tomographic images, threatened coronary obstruction (TCO) was defined as: 1) ostial obstruction (adherence of the transcatheter heart valve [THV] to the coronary ostium with leaflet extension above the ostium); and/or 2) sinus sequestration (THV adherence to the sinotubular junction [STJ] with leaflet extension above the STJ) and was substratified into complete and incomplete types.ResultsA total of 51 leaflets were evaluated (88% surgical tissue valves) after excluding leaflets not visible on CT (n = 5). On postprocedural CT, complete TCO was observed in 25.4% (13 of 51 leaflets). On preprocedural CT, leaflets were at high risk for complete TCO (incidence 53%) if the virtual THV–to–coronary distance (VTC) was <3.0 mm, or if the virtual THV–to–STJ distance (VTSTJ) was <1.0 mm with STJ height ? leaflet length <0 mm (leaflet-STJ mismatch). Leaflets were at low risk (incidence 0%) if the VTC was ≥3 mm and VTSTJ was ≥3.0 mm or STJ height ? leaflet length was ≥+2.0 mm. Of 28 leaflets treated using BASILICA, complete TCO was seen in 35.7% (n = 10), due to sinus sequestration (100%) with coexisting ostial obstruction (30%). Actual coronary events occurred in 7.1% (n = 2) because of leaflet prolapse, corresponding to an absolute risk reduction by BASILICA of 29% (P = 0.021).ConclusionsRisk assessment of coronary obstruction after TAVR may improve with a multiparametric approach incorporating VTC, VTSTJ, and leaflet-STJ mismatch. BASILICA appeared to reduce actual coronary events even in leaflets with anticipated coronary obstruction.