June 12, 2017
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DAPT score can identify patients who may benefit from shorter DAPT

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In patients undergoing PCI, prolonged dual antiplatelet therapy may reduce ischemic events in patients with high DAPT scores but may be harmful for those with low scores, according to published findings.

To assess the safety and efficacy of DAPT duration according to DAPT score, the researchers applied the DAPT score to patients who underwent PCI in the PRODIGY trial. Patients randomly received one of four stent types and were randomly assigned to 6 or 24 months of DAPT at 30 days. Treatment included a maintenance dose of clopidogrel of 75 mg daily for up to 6 or 24 months as well as a low dose of aspirin, which was prescribed indefinitely in all patients.

The primary efficacy endpoint was a composite of death, MI or cerebrovascular accident, and the primary safety endpoint was a composite of type 3 or 5 bleeding according to the Bleeding Academic Research Consortium (BARC) definitions.

Efficacy affected

Of the 1,970 patients included in the study, 44.9% had a DAPT score of 2 or higher and 55.1% had a score less than 2. The reduction in the primary efficacy endpoint with prolonged vs. shorter DAPT was greater among patients with DAPT scores of at least 2 (risk difference, –2.05 percentage points; 95% CI, –5.04 to 0.95), compared with those with DAPT scores less than 2 (risk difference, 2.91 percentage points; 95% CI, –0.43 to 6.25), according to the data.

The researchers noted, however, that the reduction in the primary efficacy endpoint with prolonged DAPT among patients with high DAPT scores varied by stent type (P for interaction = .005), with patients who received paclitaxel-eluting stents having a lower risk for events with prolonged vs. shorter DAPT. After excluding patients who received PES, the risk difference with prolonged vs. shorter DAPT was similar for those with high (risk difference, 1.23 percentage points; 95% CI, –2.41 to 4.86) and low DAPT scores (risk difference, 2.38 percentage points; 95% CI, –1.12 to 5.87; P for interaction = .65).

Results also indicated an increase in BARC type 3 or 5 bleeding with prolonged DAPT among patients with DAPT scores less than 2 (risk difference, 2.58 percentage points; 95% CI, 0.71-4.46), compared with those with DAPT scores of 2 or greater (risk difference, 0.2 percentage points; 95% CI, –1.2 to 1.6; P = .046).

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Clinical judgment essential

“[The] study suggests that the DAPT score can be used to identify patients who should be treated with short-term DAPT, but it is not useful for determining which patients treated with current-generation drug-eluting stents derive a net benefit from extending therapy beyond 1 year,” J. Dawn Abbott, MD, from the Warren Alpert School of Medicine at Brown University in Providence, Rhode Island, wrote in an accompanying editorial.

Abbott noted other DAPT duration scores also have shortcomings.

“Although risk scores can assist with decision-making, clinical judgment remains essential. There may be PCI patients with current-generation [DES] for whom DAPT duration as short as 1 month or as long as a lifetime is reasonable,” she wrote.

Additionally, Abbott noted genetic determinants of responsiveness to antiplatelet therapy are not yet accounted for in the current DAPT scores.

“The future may bring point-of-care genetic tests or imaging methods that better identify patients who are vulnerable to recurrent ischemic events. Patient preferences also matter. We should strive to practice shared decision-making that factors in evidence and patient values,” she wrote. – by Melissa Foster

Disclosure: Please the full study for a list of the researchers’ relevant financial disclosures. Abbott reports receiving grants from Abbott Cardiovascular Systems, AstraZeneca, Bristol-Myers Squibb and Medinol, and having financial ties with Pfizer and Recor.