The greatest risk of major adverse cardiac events (MACE) from stopping dual antiplatelet therapy (DAPT) after PCI occurred in patients who became noncompliant with their medications or who stopped because of bleeding. These findings from an international cohort study were presented Sept. 1 at the European Society of Cardiology Congress 2013 in Amsterdam and published online in The Lancet.
The Patterns of Non-Adherence to Antiplatelet Regimens in Stented Patients (PARIS) registry was a prospective observational study of patients who underwent stent placement between July 2009 and December 2010 at 15 sites in the U.S. and Europe. Bristol-Myers Squibb and Sanofi-Aventis provided the funding for the research.
“The primary objectives of the PARIS study were to examine the different modes of DAPT cessation in patients with coronary artery disease undergoing PCI with stenting and to assess the associations between these modes and subsequent clinical events,” wrote the authors, led by Roxana Mehran, MD, of the Icahn School of Medicine at Mount Sinai in New York.
The researchers enrolled more than 5,000 adult patients who underwent successful stent implantation and were discharged on DAPT. They classified DAPT cessation as either discontinuation, interruption or disruption. Discontinuation was cessation recommended by a physician because patients no longer needed the therapy. Interruption was defined as temporary cessation because of surgical necessity. DAPT was started again within 14 days. Disruption was considered a cessation because of noncompliance or bleeding.
The adverse events they assessed were the composite of cardiac death, definite or probable stent thrombosis, heart attack or revascularization of target lesions.
Over the two-year period, the overall cessation rate was 57.3 percent. The rate of discontinuation was 40.8 percent, interruption was 10.5 percent and disruption was 14.4 percent.
The MACE rate overall was 11.5 percent, and most incidences occurred in patients who were taking DAPT. Most of the events that occurred were revascularizations, which were the main driver of the MACE risk.
In comparison to patients taking DAPT, the adjusted hazard ratio (HR) for MACE caused by interruption was 1.41. The HR for disruption was 1.5. However, patients who discontinued their DAPT had a lower risk for MACE (HR 0.63).
They also found that the MACE risk was highest within 30 days after cessation, but diminished over time.
Because physician-ordered discontinuation led to the lowest MACE risk of the three groups and because most adverse events happened during DAPT, “the overall contribution of DAPT cessation on cardiac risk was small, thereby challenging existing paradigms for extension of antiplatelet treatment in otherwise stable patients after PCI,” the authors argued.
In an accompanying editorial, Andreas E. May, MD, of University Hospital Tubingen in Germany noted that current guidelines recommend DAPT for four weeks after elective stenting and up to 12 months in patients with drug-eluting stents or patients getting stent placements for acute coronary syndrome.
The PARIS trial, however, seems to call that timing into question.
“The optimum duration of DAPT after coronary stenting is unknown and depends on individual patient and procedural criteria,” he wrote. “The PARIS registry shows a pronounced heterogeneity of treatment patterns and risk in patients who discontinue DAPT.”
Temporarily stopping DAPT is safe, he said, but “unanticipated disruptions of antiplatelet therapy put the patient at increased risk and necessitate the best care and alertness by treating physicians.”