Mar 29, 2016 | Debabrata Mukherjee, MD, FACC

A 76-year-old- male with past history of smoking and a prior myocardial infarction (MI) two years ago for which he was treated medically presents for evaluation. He now has stable angina despite optimal guideline-directed medical management, which interferes with his ability to play golf. Stress test reveals moderate to large size anterolateral ischemia and coronary angiography reveals an 80% mid-LAD stenosis. He undergoes PCI with a 3.0 X 15 mm Xience stent. Based on current guidelines and the recently developed DAPT score, optimal duration of DAPT for this gentleman would be

• At least 6 months of DAPT with clopidogrel
• At least 6 months of DAPT with clopidogrel, prasugrel or ticagrelor
• At least 12 months of DAPT with clopidogrel
• Prolonged DAPT therapy beyond 12 months

The correct answer is (a), at least 6 months of DAPT with clopidogrel based on the 2016 ACC/AHA guideline focused update on duration of dual antiplatelet therapy in patients with coronary artery disease.¹ Clopidogrel is the only P2Y12 inhibitor approved for SIHD so answer (b) is incorrect. The 2016 guideline has shortened the duration of DAPT from 12 months to 6 months so answer (c) is incorrect. Finally the gentleman has a low DAPT score (<2) and his bleeding risks outweigh potential ischemic benefits and prolonged DAPT would not be recommended. DAPT longer than 12 months is recommended for those with a DAPT score ≥ 2. A score of ≥2 is associated with a favorable benefit/risk ratio for prolonged DAPT while a score of <2 is associated with an unfavorable benefit/risk ratio.

Clinical and Procedural Factors Associated With Increased Ischemic Risk (Including Stent Thrombosis) or Increased Bleeding Risk
Increased Ischemic Risk/Risk of Stent Thrombosis (may favor longer-duration DAPT)	Increased Bleeding Risk (may favor shorter-duration DAPT)
Increased ischemic risk Advanced age ACS presentation Multiple prior MIs Extensive CAD Diabetes mellitus CKD Increased risk of stent thrombosis ACS presentation Diabetes mellitus Left ventricular ejection fraction <40% First-generation drug-eluting stent Stent undersizing Stent underdeployment Small stent diameter Greater stent length Bifurcation stents In-stent restenosis	History of prior bleeding Oral anticoagulant therapy Female sex Advanced age Low body weight CKD Diabetes mellitus Anemia Chronic steroid or NSAID therapy

ACS indicates acute coronary syndrome; CAD, coronary artery disease; CKD, chronic kidney disease; DAPT, dual antiplatelet therapy; MI, myocardial infarction; and NSAID, nonsteroidal anti-inflammatory drug.

Factors Used to Calculate a “DAPT Score”
Variable	Points
Age ≥75 y	-2
Age 65 to <75 y	-1
Age <65 y	0
Current cigarette smoker	1
Diabetes mellitus	1
MI at presentation	1
Prior PCI or prior MI	1
Stent diameter <3 mm	1
Paclitaxel-eluting stent	1
CHF or LVEF <30%	2
Saphenous vein graft PCI	2

A score of ≥2 is associated with a favorable benefit/risk ratio for prolonged DAPT while a score of <2 is associated with an unfavorable benefit/risk ratio. CHF indicates congestive heart failure; DAPT, dual antiplatelet therapy; LVEF, left ventricular ejection fraction; MI, myocardial infarction; and PCI, percutaneous coronary intervention.

Adapted with permission from Yeh RW, Secemsky E, Kereiakes DJ, et al. Development and validation of a prediction rule for benefit and harm of dual antiplatelet therapy beyond one year after percutaneous coronary intervention: an analysis from the randomized Dual Antiplatelet Therapy Study. JAMA. March 2016. In Press1).

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Reference

1. Levine GN, Bittl JA, Brindis RG, et al. 2016 ACC/AHA Guideline Focused Update on Duration of Dual Antiplatelet Therapy in Patients With Coronary Artery Disease. J Am Coll Cardiol 2016; doi=10.1016/j.jacc.2016.03.513.