Percutaneous coronary intervention (PCI) is often performed after a heart attack, or to alleviate symptoms of chest pressure, but a new study published in Nature questions the efficacy of the current guidelines.
Current American Heart Association guidelines recommend that patients who undergo PCI, a minimally invasive procedure to open clogged arteries, be prescribed dual antiplatelet therapy (DAPT) to prevent blood clots, and that they continue using the combination of aspirin and a second antiplatelet medication for at least one year after the procedure with continuation of DAPT beyond one year for patients with acceptable bleeding risk.
The current guidelines are based on previous research, including the DAPT Study, a large clinical trial 10 years ago of patients undergoing PCI with a stent, that found using DAPT beyond one year after PCI decreased ischaemic events but posed a higher risk of bleeding. Since then, questions have arisen as to whether the evidence is representative of real-world populations and changing practice patterns.
To better understand whether the results of prior trials of DAPT duration are applicable today, researchers at Beth Israel Deaconess Medical Center (BIDMC) developed new analytic methods to update a previously conducted trial to better reflect contemporary practice. The findings, published in Circulation, suggest that because of improvements in stent technology and changes in the types of patients receiving stents, the risks of DAPT may now outweigh the benefits for the average patient.
“Clinical research can become outdated as practices and technologies evolve,” said corresponding author Robert W. Yeh, MD, MSc, an interventional cardiologist at BIDMC. “By extrapolating what an older trial might have shown had it been conducted today, we found that many patients who’ve received stents and are currently on combination antiplatelet therapy may actually benefit from stopping one of those antiplatelet drugs – adding to growing evidence that aspirin and drugs like it may be less useful than previously thought.”
Yeh and colleagues extrapolated the results of 5743 DAPT Study participants to national data from 568 540 patients undergoing PCI with a stent. Using new analytic methods, the team estimated a contemporary “real-world” treatment effect of 30 months versus 12 months of DAPT after coronary stent procedures. Compared to the previous trial population, contemporary registry patients had more comorbidities and were more likely to present with heart attack and receive second generation drug-eluting stents. After adjustment to represent the registry population, the researchers no longer saw a significant effect of prolonged DAPT on reducing stent thrombosis or heart attack, but increased risk of bleeding persisted.
Additionally, the team used their previously developed risk tool called the DAPT Score to stratify subgroups of patients who may or may not benefit from prolonged DAPT. They found that the projected ischemic benefits of prolonged DAPT in the subgroup of patients with DAPT score less than two disappeared, while the bleeding risk persisted. In contrast, in the subgroup of patients with DAPT score of two or greater, ischemic benefits of prolonged DAPT persisted, though were slightly attenuated, with negligible increase in bleeding.
“While patients at highest risk of ischaemic event, [a] small group of patients should likely remain on these medications, longer duration DAPT may have more limited benefits and greater harms for most,” said lead author Neel M. Butala, MD, MBA, a research fellow in the Smith Center. “These results illustrate the importance of a nuanced interpretation of clinical trials to guide clinical decision-making. The methods may be applicable across various cardiovascular conditions to help ensure that evidence is up-to-date and appropriate for real world populations.”
