MIAMI—Dual-antiplatelet therapy (DAPT) cessation after stent implantation within one year was associated with an increased risk for all adverse events, an association that was strongest in the first seven days and attenuated after 30 days, according to the one-year results of the PARIS registry, presented Oct. 22 at the annual Transcatheter Cardiovascular Therapeutics (TCT) conference.

Current guidelines from the American College of Cardiology/American Heart Association (ACC/AHA) recommend 30 days DAPT following placement of a bare-metal stent (BMS) and one year following placement of a drug-eluting stent (DES). In patients with acute coronary syndrome (ACS), 12 months of DAPT is recommended regardless of stent type.

Premature discontinuation of DAPT within the first six months after DES has been associated with an increased risk of stent thrombosis, explained principal investigator Roxana Mehran, MD, director of interventional cardiovascular research and clinical trials at the Zena and Michael A. Wiener Cardiovascular Institute at Mount Sinai School of Medicine in New York City. However, the optimal duration of DAPT has not been precisely determined, nor has the mode of and circumstances around nonadherence to DAPT previously been studied.

The multicenter, multinational, observational PARIS Registry (Patterns of Non-Adherence to Anti-Platelet Regimens In Stented patients: An observational single arm study) followed 5,033 patients from 15 centers in five countries for approximately 24 months post-stent implantation (both DES and BMS).

The researchers determined three modes of DAPT cessation:

• Discontinuation:  Patients discontinued use of DAPT based on the recommendation of their physician who felt the patient no longer needed therapy.
• Interruption:  Patients interrupted DAPT use on a voluntary basis and under guidance and recommendation of their physician due to need for surgery. DAPT was to be reinstituted within 14 days.
• Disruption:  Patients disrupted DAPT due to bleeding or nonadherence, which included use of DAPT at lower dose levels than prescribed.

In this analysis, the researchers included any participants with DAPT cessation due to interruption or disruption. Adherent subjects were those who remained on DAPT at one year or those who stopped DAPT due to physician-guided recommendations.

The 30-day findings from PARIS were presented at last year’s TCT conference in San Francisco.

At six months, 11.8 percent of patients were off DAPT, 7.6 percent were classified with disruption or interruption and 4.2 percent had a physician recommend discontinuation. At one year, 19.9 percent of patients were off DAPT, 12.3 percent were classified with disruption or interruption and 7.8 percent had a physician recommend discontinuation.

Among patients stopping DAPT at one year in PARIS, approximately 62 percent were classified as nonadherent by the prespecified PARIS criteria, reported Mehran.  

The major adverse events at one year, comparing on DAPT vs. off DAPT use, were death (2.1 vs. 3 percent), target lesion revascularization (4.2 vs. 6.6 percent), spontaneous MI (1.4 vs. 4.8 percent), stent thrombosis (1.9 vs. 2.7 percent), definite/probable stent thrombosis (1 vs. 1.6 percent), major bleeds (1 vs. 9 percent) and major adverse coronary event (6.5 vs. 11 percent).  

For the DES patients, the overall event rate at one year, comparing on DAPT vs. off DAPT use, were death (1.6 vs. 2 percent), target lesion revascularization (3.7 vs. 6.3 percent), spontaneous MI (1.2 vs. 4.8 percent), stent thrombosis (1.7 vs. 1.8 percent), definite/probable stent thrombosis (0.8 vs. 1.5 percent), major bleeds (1 vs. 10 percent) and major adverse coronary event (5.5 vs. 9.9 percent).  

For the BMS patients, the overall event rate at one year, comparing on DAPT vs. off DAPT use, were death (5.6 vs. 4.7 percent), target lesion revascularization (7.7 vs. 7.1 percent), spontaneous MI (2.9 vs. 4.7 percent), stent thrombosis (4 vs. 3.8 percent), definite/probable stent thrombosis (2.3 vs. 1.5 percent), major bleeds (1 vs. 7.4 percent) and major adverse coronary event (13.6 vs. 12.9 percent).  

Risk associated with DAPT cessation following PCI is not uniform but rather varies by underlying mode, according to Roxana, who concluded that this is a “novel finding that might influence practice patterns and risk assessment in post-PCI patients stopping DAPT.”