Transcatheter Aortic Heart Valve Thrombosis
What are the incidence, potential predictors, and clinical implications of transcatheter aortic valve replacement (TAVR) thrombosis determined by contrast-enhanced multidetector computed tomography (MDCT)?
Among 460 consecutive patients undergoing TAVR with the Edwards Sapien XT or Sapien 3 (Edwards Lifesciences; Irvine, CA) valves, 405 (88%) underwent MDCT in addition to transthoracic and transesophageal echocardiography 1-3 months post-TAVR. MDCT scans were evaluated for hypo-attenuated leaflet thickening indicative of transcatheter heart valve thrombosis.
MDCT found evidence of TAVR thrombosis in 28 of 405 (7%) patients. A total of 23 patients had subclinical thrombosis, while 5 (18%) patients experienced clinically overt obstructive thrombosis. TAVR thrombosis risk did not differ between the Edwards Sapien XT and the Sapien 3 valves (8% [14 of 173] vs. 6% [14 of 232], p = 0.42). The risk of thrombosis in patients not receiving warfarin was higher compared to patients receiving warfarin (10.7% vs. 1.8%; relative risk [RR], 6.09; 95% confidence interval [CI], 1.86-19.84). A larger valve was associated with an increased thrombosis risk (p = 0.03). In multivariable analysis, 29 mm TAVR (RR, 2.89; 95% CI, 1.44-5.80) and no post-TAVR warfarin treatment (RR, 5.46; 95% CI, 1.68-17.7) independently predicted TAVR thrombosis. Treatment with warfarin effectively reverted thrombosis and normalized valve function in 85% of patients, as documented by follow-up transesophageal echocardiography and MDCT.
The incidence of transcatheter heart valve thrombosis in this large study was 7%. Larger TAVR size may predispose to valve thrombosis, whereas treatment with warfarin appears to have a protective effect. Although often subclinical, TAVR thrombosis may have important clinical implications.
There appears to be a risk of thrombosis early after bioprosthetic surgical and transcatheter valve implantation (also see Makkar RR, et al., N Engl J Med 2015;373:2015-24), potentially associated with high transvalvular gradients. This large multicenter study found a 7% prevalence after Sapien XT or Sapien 3 TAVR, with increased risk associated with larger devices and absent therapy with warfarin. Although the current (2014) American Heart Association/American College of Cardiology guideline includes a Class IIb recommendation for therapy with warfarin for 3 months after bioprosthetic AVR, and recommends only dual antiplatelet therapy after TAVR, this and other recently published studies suggest that reconsideration might be warranted, potentially strengthening a recommendation for early postoperative anticoagulation after bioprosthetic (surgical or transcatheter) AVR.
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