Predicting Risk of Ischemic or Bleeding Events After PCI
What are the predictors that identify patients expected to derive benefit versus harm from continuing thienopyridine beyond 1 year after percutaneous coronary intervention (PCI)?
Among 11,648 randomized DAPT Study (Dual Antiplatelet Therapy) patients from 11 countries (August 2009-May 2014), a prediction rule was derived stratifying patients into groups to distinguish ischemic and bleeding risk 12-30 months after PCI. Validation was internal via bootstrap resampling and external among 8,136 patients from 36 countries randomized in the PROTECT trial (June 2007-July 2014). Patients received 12 months of open-label thienopyridine plus aspirin, then randomized to 18 months of continued thienopyridine plus aspirin versus placebo plus aspirin. The main outcome measures were ischemia (myocardial infarction or stent thrombosis) and bleeding (moderate or severe) 12-30 months after PCI.
Among DAPT Study patients (derivation cohort; mean age, 61.3 years; women, 25.1%), ischemia occurred in 348 patients (3.0%) and bleeding in 215 (1.8%). Derivation cohort models predicting ischemia and bleeding had c-statistics of 0.70 and 0.68, respectively. The prediction rule assigned 1 point each for myocardial infarction at presentation, prior myocardial infarction or PCI, diabetes, stent diameter <3 mm, smoking, and paclitaxel-eluting stent; 2 points each for history of congestive heart failure/low ejection fraction and vein graft intervention; −1 point for age 65 to <75 years; and −2 points for age ≥75 years. Among the high score group (score ≥2, n = 5,917), continued thienopyridine versus placebo was associated with reduced ischemic events (2.7% vs. 5.7%; risk difference [RD], −3.0%; 95% confidence interval [CI], −4.1% to −2.0%; p < 0.001) compared with the low score group (score <2, n = 5,731; 1.7% vs. 2.3%; RD, −0.7%; 95% CI, −1.4% to 0.09%; p = 0.07; interaction p < 0.001). Conversely, continued thienopyridine was associated with smaller increases in bleeding among the high score group (1.8% vs. 1.4%; RD, 0.4%; 95% CI, −0.3% to 1.0%; p = 0.26) compared with the low score group (3.0% vs. 1.4%; RD, 1.5%; 95% CI, 0.8% to 2.3%; p < 0.001; interaction p = 0.02). Among PROTECT patients (validation cohort; mean age, 62 years; women, 23.7%), ischemia occurred in 79 patients (1.0%) and bleeding in 37 (0.5%), with a c-statistic of 0.64 for ischemia and 0.64 for bleeding. In this cohort, the high-score patients (n = 2,848) had increased ischemic events compared with the low-score patients, and no significant difference in bleeding.
The authors concluded that among patients not sustaining major bleeding or ischemic events 1 year after PCI, a prediction rule assessing late ischemic and bleeding risks to inform DAPT duration showed modest accuracy in derivation and validation cohorts.
This analysis reports that among patients not sustaining major bleeding or ischemic events 1 year after PCI, the DAPT score assessing late ischemic and bleeding risks to decide on DAPT duration showed modest accuracy in derivation and validation cohorts. Despite its limitations, the DAPT score provides an important tool to inform an important clinical decision, but requires further prospective evaluation to assess potential effects on patient care, as well as validation in other cohorts. For now, this score will provide clinicians with a framework, but the clinician’s evaluation of the patient remains critical in the decision-making process taking into account ischemic risk, bleeding risk, and patient preference for deciding duration of DAPT.
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