Insights into Stent Thrombosis Risk
This past March, CRF partnered for the first time with the American College of Cardiology (ACC) in organizing the i2 Summit, the interventional component of the annual ACC Scientific Session. A highlight of this year’s meeting in Orlando, Florida, was the presentation of a CRF-authored study focusing on factors that predict the risk of stent thrombosis. This life-threatening event occurs when a blood clot forms within a stent that has been placed in an artery to keep it propped open after angioplasty.
The new analysis was based on data from the HORIZONS AMI trial, which tested different regimens of anticoagulant medications given to people undergoing angioplasty after a heart attack.
The new study, which followed patients for one year, featured several CRF faculty members as authors: George D. Dangas, MD, PhD; Alexandra J. Lansky, MD; Roxana Mehran, MD; and Gregg W. Stone, MD. The results were presented at a late breaking trial session by Dr. Dangas.
Reassuringly, the study found that over the course of one year, the odds of suffering stent thrombosis were not affected by whether patients received a drugeluting stent (the kind of stent that releases a drug to prevent artery renarrowing) or a bare-metal stent (one that does not release any drug). Nor does it matter which regimen of anticoagulant medication is prescribed to minimize the chances of stent thrombosis.
The Highest Risk Comes Early
But some important differences in risk over various time periods did emerge. One of the most important lessons is that in heart attack patients who receive the new anticlotting drug bivalirudin before undergoing angioplasty, adding extra blood-thinning medications early on and in optimal doses significantly reduces the increased risk of near-term stent thrombosis.
For example, heart attack patients would be less likely to experience stent thrombosis in the first 24 hours after stent implantation if they received heparin either in the ambulance or as soon as they arrived in the emergency department, instead of waiting until they got to the catheterization lab.
Another finding was that loading bivalirudin patients with twice the standard dose of the antiplatelet drug clopidogrel before angioplasty reduces the risk of stent thrombosis over the next month.
Over the longer term, the strongest risk factor for stent thrombosis—and one patients can modify—is smoking. Other predictors of so-called late stent thrombosis, which covers the period between 30 days and one year after stent implantation, include having diabetes or having suffered a prior heart attack.
Dr. Dangas summed up the findings: "We can do a few simple things to bring stent thrombosis rates down. Get heparin and a potent antiplatelet agent into patients as fast as possible, and reinforce the importance of stopping smoking."
