DAPT Calculator

Q: What is the DAPT score and what does it determine?

The DAPT (Dual Antiplatelet Therapy) score is a clinical decision-support tool developed to help determine the optimal duration of dual antiplatelet therapy after coronary stent implantation. The score was derived from the landmark DAPT Study, which randomized over 11,000 patients who had tolerated 12 months of DAPT without events to either continued thienopyridine therapy or placebo for an additi

Q: How is the DAPT score calculated and what are its components?

The DAPT score assigns points based on nine clinical and procedural factors assessed at the time of the decision about extending DAPT beyond 12 months. Age provides negative points: age 75 or older gets -2, age 65-74 gets -1, and age under 65 gets 0 points. Positive points are assigned for current cigarette smoking (+1), diabetes mellitus (+1), MI at presentation (+1), prior PCI or prior MI (+1),

Q: When should the DAPT score be applied in clinical practice?

The DAPT score should be applied at or around the 12-month mark after coronary stent implantation to guide the decision about whether to continue or discontinue the P2Y12 inhibitor component of dual antiplatelet therapy. Critically, the score is only valid for patients who have completed 12 months of DAPT without experiencing a major bleeding event, myocardial infarction, or stroke during that per

Q: What are the risks of stent thrombosis if DAPT is stopped too early?

Stent thrombosis is among the most feared complications after coronary intervention, occurring when a blood clot forms within the stent and abruptly occludes the coronary artery. It presents as acute myocardial infarction with mortality rates of 20 to 45 percent per event. Stent thrombosis is classified by timing: acute (within 24 hours), subacute (1-30 days), late (30 days to 1 year), and very la

Q: How do newer P2Y12 inhibitors affect the DAPT duration decision?

Prasugrel and ticagrelor are more potent P2Y12 inhibitors than clopidogrel, providing faster onset, greater platelet inhibition, and more consistent pharmacological effect. The TRITON-TIMI 38 trial showed prasugrel reduced ischemic events by 19 percent compared to clopidogrel but increased major bleeding by 32 percent, with particular harm in patients over 75, those with prior stroke, and those we

Q: What bleeding complications can occur with prolonged DAPT?

Prolonged dual antiplatelet therapy increases the risk of various bleeding complications through sustained inhibition of platelet aggregation. Gastrointestinal bleeding is the most common major bleeding site, occurring in approximately 1 to 2 percent of patients per year on DAPT, often from peptic ulcers, erosive gastritis, or lower GI sources. Intracranial hemorrhage, though rare at 0.1 to 0.3 pe

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Formula

DAPT Score = Age points + Smoking + Diabetes + MI + Prior PCI + Stent size + Stent type + CHF + Vein graft

Age provides -2 (75+), -1 (65-74), or 0 (<65) points. Other factors add +1 or +2 points each. Total ranges from -2 to 10. Score of 2 or higher favors extended 30-month DAPT; below 2 favors standard 12-month duration.

Worked Examples

Example 1: Score Favoring Prolonged DAPT

Problem: A 58-year-old male smoker with diabetes who presented with MI, received a 2.5mm DES. No prior PCI, no CHF, no vein graft. Calculate DAPT score at 12 months.

Solution: Age <65: 0 points\nCigarette smoking: +1\nDiabetes: +1\nMI at presentation: +1\nPrior PCI/MI: 0\nStent diameter <3mm: +1\nPaclitaxel stent: 0\nCHF/LVEF <30%: 0\nVein graft: 0\nTotal DAPT Score = 4

Result: DAPT Score: 4 (>=2, prolonged DAPT for 30 months is favored)

Example 2: Score Favoring Standard Duration

Problem: A 76-year-old non-smoking, non-diabetic patient who had elective PCI with a 3.5mm DES for stable angina. No prior PCI, no CHF, no vein graft.

Solution: Age >=75: -2 points\nCigarette smoking: 0\nDiabetes: 0\nMI at presentation: 0 (stable angina)\nPrior PCI/MI: 0\nStent diameter <3mm: 0 (3.5mm stent)\nPaclitaxel stent: 0\nCHF/LVEF <30%: 0\nVein graft: 0\nTotal DAPT Score = -2

Result: DAPT Score: -2 (<2, standard 12-month DAPT duration is favored)

Frequently Asked Questions

What is the DAPT score and what does it determine?

The DAPT (Dual Antiplatelet Therapy) score is a clinical decision-support tool developed to help determine the optimal duration of dual antiplatelet therapy after coronary stent implantation. The score was derived from the landmark DAPT Study, which randomized over 11,000 patients who had tolerated 12 months of DAPT without events to either continued thienopyridine therapy or placebo for an additional 18 months. The score integrates nine clinical and procedural variables to produce a value ranging from -2 to 10. A score of 2 or higher identifies patients who derive greater ischemic benefit from prolonged DAPT (30 months) relative to the increased bleeding risk, while a score below 2 suggests the bleeding risk of extended therapy outweighs the ischemic benefit. The tool helps personalize treatment duration rather than applying a one-size-fits-all approach.

How is the DAPT score calculated and what are its components?

The DAPT score assigns points based on nine clinical and procedural factors assessed at the time of the decision about extending DAPT beyond 12 months. Age provides negative points: age 75 or older gets -2, age 65-74 gets -1, and age under 65 gets 0 points. Positive points are assigned for current cigarette smoking (+1), diabetes mellitus (+1), MI at presentation (+1), prior PCI or prior MI (+1), stent diameter less than 3 mm (+1), paclitaxel-eluting stent (+1), CHF or LVEF less than 30 percent (+2), and saphenous vein graft PCI (+2). The total score ranges from -2 to 10. The scoring reflects the balance between ischemic risk factors (which favor prolonged therapy) and bleeding risk factors (primarily age, which favors shorter therapy).

When should the DAPT score be applied in clinical practice?

The DAPT score should be applied at or around the 12-month mark after coronary stent implantation to guide the decision about whether to continue or discontinue the P2Y12 inhibitor component of dual antiplatelet therapy. Critically, the score is only valid for patients who have completed 12 months of DAPT without experiencing a major bleeding event, myocardial infarction, or stroke during that period. Patients who have complications during the initial 12 months require individualized assessment rather than score-based guidance. The score is most applicable to patients who received drug-eluting stents, as bare-metal stents typically require only 1 month of DAPT. Additionally, the score was developed primarily for patients on clopidogrel and may not directly apply to those on prasugrel or ticagrelor, though the risk factor principles remain relevant.

What are the risks of stent thrombosis if DAPT is stopped too early?

Stent thrombosis is among the most feared complications after coronary intervention, occurring when a blood clot forms within the stent and abruptly occludes the coronary artery. It presents as acute myocardial infarction with mortality rates of 20 to 45 percent per event. Stent thrombosis is classified by timing: acute (within 24 hours), subacute (1-30 days), late (30 days to 1 year), and very late (beyond 1 year). Premature discontinuation of DAPT is the strongest predictor of stent thrombosis, with risk increasing 90-fold in the first 30 days and remaining elevated for months. First-generation drug-eluting stents had higher rates of very late stent thrombosis (0.4-0.6 percent per year) compared to newer-generation stents (0.1-0.2 percent per year), which have thinner struts and more biocompatible polymers. The improved safety profile of contemporary stents has enabled consideration of shorter DAPT durations in selected low-risk patients.

How do newer P2Y12 inhibitors affect the DAPT duration decision?

Prasugrel and ticagrelor are more potent P2Y12 inhibitors than clopidogrel, providing faster onset, greater platelet inhibition, and more consistent pharmacological effect. The TRITON-TIMI 38 trial showed prasugrel reduced ischemic events by 19 percent compared to clopidogrel but increased major bleeding by 32 percent, with particular harm in patients over 75, those with prior stroke, and those weighing less than 60 kg. The PLATO trial demonstrated ticagrelor reduced cardiovascular death by 21 percent compared to clopidogrel with modestly increased non-CABG bleeding. When considering DAPT duration with these agents, their greater antiplatelet potency means both the ischemic protection and bleeding risk per unit time are amplified compared to clopidogrel. Some clinicians use the DAPT score as a framework but apply lower thresholds for extended duration or consider de-escalation strategies switching from potent agents to clopidogrel after an initial high-risk period.

What bleeding complications can occur with prolonged DAPT?

Prolonged dual antiplatelet therapy increases the risk of various bleeding complications through sustained inhibition of platelet aggregation. Gastrointestinal bleeding is the most common major bleeding site, occurring in approximately 1 to 2 percent of patients per year on DAPT, often from peptic ulcers, erosive gastritis, or lower GI sources. Intracranial hemorrhage, though rare at 0.1 to 0.3 percent annually, is the most devastating complication with high mortality and morbidity. Other bleeding manifestations include epistaxis, hematuria, bruising, and prolonged bleeding from minor wounds. The DAPT trial showed that extending therapy from 12 to 30 months increased GUSTO moderate or severe bleeding from 1.6 to 2.5 percent. Proton pump inhibitor co-prescription reduces GI bleeding risk significantly and is recommended for all patients on DAPT with risk factors including age over 65, concurrent anticoagulation, corticosteroid use, or prior GI bleeding.