Characteristics of Transcatheter Heart Valve Thrombosis After TAVR

Transcatheter heart valve (THV) thrombosis is often non-obstructive and is more likely to develop with larger THV size and lack of post-treatment warfarin use, study results indicate.  

Nicolaj C. Hansson, MD of Aarhus University Hospital in Denmark and colleagues presented their findings at the 2016 European Society of Cardiology Congress in Rome. Their accompanying paper was simultaneously published by the Journal of the American College of Cardiology.

THV thrombosis after transcatheter aortic valve replacement (TAVR) for severe aortic stenosis can lead to complications such as stroke, heart failure, or decreased long-term THV durability. Recent data have shown that enhanced multidetector computed tomography (MDCT) is superior to transthoracic echocardiography (TTE) for detecting THV thrombosis.

However, THV thrombosis post-TAVR is poorly characterized since current available data are derived from case series and small studies. Researchers evaluated the incidence, risk factors, and clinical implications of THV thrombosis after TAVR.

A total of 405 consecutive patients underwent TAVR and were followed with MDCT and echocardiography within 3 months post-procedure and with TTE at 12 months. Patients received either the Sapien XT or Sapien 3 THV (both Edwards Lifesceinces).

The incidence of THV thrombosis confirmed by MDCT was 7%. Although most patients with THV thrombosis did not have signs of THV obstruction on initial TTE, 18% developed heart failure symptoms by 12 months.

Independent predictors for THV thrombosis were 29 mm THV (relative risk [RR]: 2.89; 95% confidence interval [CI]: 1.44-5.80) and no warfarin use post-TAVR (RR: 5.46; 95% CI: 1.68-17.7). Thrombosis risk was similar for each THV type.

Warfarin treatment completely resolved THV thrombosis and normalized THV function in 85% of patients treated.

“There is limited evidence on the optimal antithrombotic therapy following TAVR,” the authors noted. “The protective effect of anticoagulant therapy may explain the lower incidence of THV thrombosis among patients with atrial fibrillation in this study. Several ongoing randomized trials, such as the GALILEO trial (NCT02556203) and the POPular-TAVI trial (NCT02247128), will provide data on the use of non-vitamin K antagonist oral anticoagulants (NOAC) and antiplatelets after TAVR.”

“Larger THV size may predispose to THV thrombosis, whereas treatment with warfarin appears to have a protective effect. Although often subclinical, THV thrombosis may have important clinical implications,” the authors concluded. “Studies including a larger number of THV thrombosis cases are needed in order to further elucidate specific risk factors for THV thrombosis.”

References

1. Hansson NC, Grove EL, Andersen HR, et al. Transcatheter aortic heart valve thrombosis: incidence, predisposing factors, and clinical implications. J Am Coll Cardiol. doi: 10.1016/j.jacc.2016.08.010.
2. Hansson NC, Grove EL, Leipsic J, et al. Abstract 1890. Transcatheter aortic valve thrombosis: incidence and predisposing factors. Presented at European Society of Cardiology Congress. August 27-31, 2016; Rome, Italy.