CT scans reveal reduced leaflet motion after aortic valve replacement

March 20, 2017

About 12 percent of patients undergoing aortic valve replacement developed non-symptomatic blood clots around the valve leaflets (known as subclinical leaflet thrombosis) that reduced the motion of the valves, according to an observational study presented at the American College of Cardiology's 66th Annual Scientific Session.

The study is the largest to date investigating as a potential cause of reduced valve motion after . It confirms a previous, smaller study that suggested that are detectable with computed tomography (CT) scans but not with more commonly-used echocardiogram (ultrasound) scans 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, also called "mini-strokes," but were not associated with an increased risk of death, heart attack or stroke. Anticoagulant therapy, but not anti-platelet therapy, was associated with a significantly lower risk of developing valve-associated clots.

"This phenomenon of subclinical leaflet thrombosis can be missed if you just use transthoracic echocardiogram," said Raj Makkar, MD, associate director of Cedars-Sinai Heart Institute in Los Angeles, and the study's lead author. "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."

CT scans expose to more radiation than echocardiogram alone.

The researchers analyzed CT scans and other health records from 850 patients enrolled in two single-center medical registries, known as 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 three months after transcatheter aortic valve replacement (TAVR) or surgical aortic valve replacement (SAVR), two procedures used to replace a patient's faulty aortic valve with an artificial valve. In TAVR, clinicians thread the new valve to the heart through a catheter in the groin or chest; this procedure is generally used for patients at intermediate to high cardiovascular risk, which typically includes older patients and those who have multiple health problems. SAVR is an open-heart procedure used in lower-risk patients.

A total of 720 patients in the two registries had undergone TAVR and 130 had undergone SAVR. Analysis of CT scans revealed subclinical leaflet thrombosis in 13.6 percent of TAVR patients and 3.8 percent of SAVR patients, for an overall rate of 12.1 percent among all patients combined. 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, Makkar said.

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 percent of patients on antiplatelet therapy had thromboses compared to 4 percent among patients taking warfarin and 3 percent among patients taking non-vitamin K antagonist anticoagulants, or NOACs. There was no significant difference in risk observed among those taking warfarin versus NOACs.

"We need to further study whether routine anticoagulation may be useful for this patient population," Makkar said. "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 further in randomized clinical trials."

An analysis of a small group of patients (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, a measure used to assess functioning of the aortic valve using echocardiogram. However, Makkar said this difference was not large enough to enable clinicians to diagnose subclinical leaflet thrombosis using echocardiogram alone.

As an observational study, the results do not directly assess cause and effect. Makkar said 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 hemodynamics and clinical outcomes," Makkar said.

This study was simultaneously published online in The Lancet at the time of presentation.

Explore further: Heart procedure linked with bleeding in the brain, neurological impairment

More information: Tarun Chakravarty et al. Subclinical leaflet thrombosis in surgical and transcatheter bioprosthetic aortic valves: an observational study, The Lancet (2017). DOI: 10.1016/S0140-6736(17)30757-2

Related Stories

Heart procedure linked with bleeding in the brain, neurological impairment

March 20, 2017
Small leakages from blood vessels in the brain, known as microbleeds, increase with age and are associated with cognitive decline. Of 84 older patients undergoing transcatheter aortic valve replacement (TAVR), nearly a quarter ...

STS: SAVR still excellent option for intermediate-risk seniors

January 25, 2017
(HealthDay)—For intermediate-risk elderly patients, surgical aortic valve replacement (SAVR) remains a safe and effective way to treat aortic stenosis, according to a study presented at the annual meeting of the Society ...

Blood clots may complicate aortic valve replacements

October 5, 2015
Heart valve replacements made from tissue (bioprosthetic valves) have long been thought to be spared the complication of blood clot formation. Researchers have now found that about 15 percent of all bioprosthetic aortic heart ...

Results of PARTNER II QUALITY OF LIFE study presented

November 1, 2016
Patients with severe aortic stenosis (AS) at intermediate surgical risk, and who are treated with transcatheter aortic valve replacement (TAVR) had improved health status at one month compared with surgical aortic valve replacement ...

Self-expanding TAVR as good as surgery in intermediate-risk patients

March 17, 2017
Two-year data reveal no difference in the combined rate of stroke and death from any cause when comparing the use of self-expanding transcatheter aortic valve replacement (TAVR) with standard open-heart surgery in intermediate ...

One-year clinical outcomes with SAPIEN 3 transcatheter aortic valve replacement

July 12, 2016
Overall one-year survival was over 85 percent for high-risk or inoperable patients who underwent aortic valve replacement with the SAPIEN 3 trans-catheter aortic valve replacement system, according to a study published in ...

Recommended for you

How genes and environment interact to raise risk of congenital heart defects

October 19, 2017
Infants of mothers with diabetes have a three- to five-fold increased risk of congenital heart defects. Such developmental defects are likely caused by a combination of genetic and environmental factors. However, the molecular ...

Mouse studies shed light on how protein controls heart failure

October 18, 2017
A new study on two specially bred strains of mice has illuminated how abnormal addition of the chemical phosphate to a specific heart muscle protein may sabotage the way the protein behaves in a cell, and may damage the way ...

Newborns with trisomy 13 or 18 benefit from heart surgery, study finds

October 18, 2017
Heart surgery significantly decreases in-hospital mortality among infants with either of two genetic disorders that cause severe physical and intellectual disabilities, according to a new study by a researcher at the Stanford ...

Saving hearts after heart attacks: Overexpression of a gene enhances repair of dead muscle

October 17, 2017
University of Alabama at Birmingham biomedical engineers report a significant advance in efforts to repair a damaged heart after a heart attack, using grafted heart-muscle cells to create a repair patch. The key was overexpressing ...

High blood pressure linked to common heart valve disorder

October 17, 2017
For the first time, a strong link has been established between high blood pressure and the most common heart valve disorder in high-income countries, by new research from The George Institute for Global Health at the University ...

Blood cancer gene could be key to preventing heart failure

October 16, 2017
A new study, published today in Circulation, shows that the gene Runx1 increases in damaged heart muscle after a heart attack. An international collaboration led by researchers from the University of Glasgow, found that mice ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.