Hypo-Attenuated Leaflet Thickening After Balloon-Expandable TAVR
What is the frequency of early hypo-attenuated leaflet thickening (HALT) after SAPIEN 3 transcatheter aortic valve replacement (TAVR)?
Of 249 patients who underwent SAPIEN 3 implantation, 156 patients (85 women, median age 82.2 ± 5.5 years) underwent electrocardiogram (ECG)-triggered dual-source computed tomography angiography (CTA) after a median of 5 days post-TAVR. The prosthesis was assessed for hypo-attenuated leaflet thickening. Apart from heparin, peri-interventional antithrombotic therapy consisted of single- (aspirin 29%) or dual- (aspirin plus clopidogrel 71%) antiplatelet therapy.
Hypo-attenuated leaflet thickening was found in 16 patients (10.3%; 95% confidence interval [CI], 5.5–15.0%). None of the baseline and procedural variables were significantly associated with hypo-attenuated leaflet thickening, and there was no statistically significant association with the antithrombotic regimen either peri-interventionally or at the time of CTA. Hypo-attenuated leaflet thickening was found in 6 of 45 patients with peri-interventional single antiplatelet therapy and in 10 of 111 patients with dual antiplatelet therapy at the time of intervention (13.3% [95% CI, 3.4–23.3%] vs. 9% [95% CI, 3.7–14.3%], p = 0.42). Hypo-attenuated leaflet thickening was not associated with clinical symptoms, but was associated with a small but significant difference in mean pressure gradient at the time of CTA (11.6 ± 3.4 vs. 14.9 ± 5.3 mm Hg, p = 0.03). Anticoagulation with a vitamin K antagonist led to almost complete resolution of hypo-attenuated leaflet thickening in 13 patients with follow-up CTA.
Early hypo-attenuated leaflet thickening occurred in 10% of patients undergoing TAVR with the SAPIEN 3 valve, apparently independent of the antiplatelet regimen. Early hypo-attenuated leaflet thickening after TAVR was clinically inapparent, and reversible by anticoagulation with a vitamin K antagonist.
Hypo-attenuated leaflet thickening on CTA associated with decreased leaflet motion has been reported early after TAVR and after bioprosthetic surgical AVR. Frequent resolution after treatment with a vitamin K antagonist suggests that this might represent subclinical thrombus formation. A recent report found even higher rates (13-40%) of reduced leaflet motion on CTA following TAVR or surgical bioprosthetic AVR (Makkar RR, et al., N Engl J Med 2015;Oct 5:[Epub ahead of print]). In small patient cohorts, the finding does not appear to be associated with adverse clinical events. Whether reduced leaflet motion/hypo-attenuated leaflet thickening on CTA is associated with a possibly small increased risk of adverse events including stroke probably requires investigation in larger patient cohorts.
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