CT Scans Show Reduced Leaflet Motion After TAVR in RESOLVE and SAVORY Registries
March 19, 2017—The American College of Cardiology (ACC) announced that an observational study found that approximately 12% of patients undergoing aortic valve replacement developed subclinical leaflet thrombosis that reduced the motion of the valves. Raj Makkar, MD, delivered the findings in a Late-Breaking Trials presentation at the ACC's 66th annual scientific session in Washington, DC. Tarun Chakravarty, MD, et al simultaneously published the findings online in The Lancet.
According to the ACC, the study is the largest to date investigating thrombosis as a potential cause of reduced valve motion after aortic valve replacement. It confirms a previous, smaller study that suggested blood clots that are detectable with CT scans, but not with more commonly used echocardiography, can develop around the valve and constrain the valve’s motion.
In the new study, the CT-detected valve-associated clots were found to increase the risk of transient ischemic attacks, but were not associated with an increased risk of death, heart attack, or stroke. Anticoagulant therapy—but not antiplatelet therapy—was associated with a significantly lower risk of developing valve-associated clots.
In the ACC press release, Dr. Makkar commented, “This phenomenon of subclinical leaflet thrombosis can be missed if you just use transthoracic echocardiogram. Based on our study, CT is clearly a more sensitive and appropriate technique to actually make a diagnosis of subclinical leaflet thrombosis. This suggests clinicians might want to have a lower threshold to do a CT scan if there is suspicion of reduced motion in the valve, such as from slightly elevated mean gradients on echocardiogram.” Dr. Makkar is Associate Director of Cedars-Sinai Heart Institute in Los Angeles, California.
As summarized in the ACC announcement, the investigators analyzed CT scans and other health records from 850 patients enrolled in two single-center medical registries: RESOLVE, which includes patients treated at Cedars-Sinai Heart Institute, and SAVORY, which includes patients treated at Rigshospitalet Hospital in Copenhagen, Denmark. The patients had undergone CT scans an average of 3 months after transcatheter aortic valve replacement (TAVR; n = 720) or surgical aortic valve replacement (SAVR; n = 130).
Analysis of CT scans revealed subclinical leaflet thrombosis in 13.6% of TAVR patients and 3.8% of SAVR patients, for an overall rate of 12.1% among the combined patient groups.
Dr. Makkar observed that although thrombosis was observed in a significantly greater proportion of TAVR patients than SAVR patients, this difference may be attributable to the younger average age and better overall health of patients undergoing SAVR.
The results also showed that subclinical leaflet thrombosis was significantly more common in patients on antiplatelet therapy (typically aspirin plus a P2Y12 inhibitor) compared to those taking anticoagulants. A total of 14.8% of patients on antiplatelet therapy had thromboses compared to 4% among patients taking warfarin and 3% among patients taking non-vitamin K antagonist anticoagulants. There was no significant difference in risk observed among those taking warfarin versus non-vitamin K antagonist anticoagulants.
Dr. Makkar advised, “We need to further study whether routine anticoagulation may be useful for this patient population. Dual antiplatelet therapy was not effective in preventing and treating subclinical leaflet thrombosis, and it does have a small risk of bleeding, particularly in older patients. There is an impetus to study the risks and benefits of dual antiplatelet therapy further in randomized clinical trials.”
An analysis of a small group of patients (n = 58) who underwent a second CT scan showed subclinical leaflet thrombosis resolved over time in the vast majority of patients who were started on oral anticoagulant therapy after the first CT scan and that thromboses resolved in only a small portion of patients who were not started on anticoagulants.
The study also showed that subclinical leaflet thromboses detected with CT scans were reflected in significantly higher mean gradients. However, Dr. Makkar said this difference was not large enough to enable clinicians to diagnose subclinical leaflet thrombosis using echocardiography alone.
As an observational study, the results do not directly assess cause and effect, and Dr. Makkar noted that ongoing randomized clinical trials that include CT scans as part of the protocol should help to further elucidate the factors that contribute to subclinical leaflet thrombosis after aortic valve replacement.
“Our study findings can help optimize the use of different blood thinning medications in patients undergoing aortic valve replacement, which might potentially result in further improvements in valve hemodynamics and clinical outcomes,” concluded Dr. Makkar in the ACC announcement.