This document summarizes recent studies on the duration of dual antiplatelet therapy (DAPT) following percutaneous coronary intervention (PCI) with drug-eluting stents (DES). The 2016 ACC/AHA guidelines recommend 6-12 months of DAPT depending on patient risk factors. Newer studies show shorter DAPT durations of 1-3 months followed by antiplatelet monotherapy may be noninferior or superior to 12 months of DAPT in reducing bleeding risks, especially for patients at high bleeding risk. Emerging data suggests a P2Y12 inhibitor alone may be preferable to aspirin monotherapy after DAPT. While shorter DAPT durations show promise, the 2016 guidelines should still be

1. When to Switch to
Antiplatelet
Monotherapy
By: Michael A. Kutcher, MD, FSCAI, and Faisal Latif, MD,
FACC, FSCAI

2. Introduction
• Dual antiplatelet therapy (DAPT) with aspirin
(ASA) and a P2Y12 inhibitor (clopidogrel,
ticagrelor, or prasugrel) is a standard therapeutic
regimen to prevent stent thrombosis after
percutaneous coronary intervention (PCI) with
drug-eluting stents (DESs). The duration of DAPT
has significant risk/benefit consequences and
implications on quality improvement and patient
safety. Since the last American College of
Cardiology (ACC) and American Heart Association
(AHA) PCI DAPT Guidelines were published in
2016,1 there has been an explosion of data
regarding strategies to shorten the duration of
DAPT. This Tip of the Month (TOTM) will place
perspective on the most recent studies in
comparison with the older guidelines—but with
advice to address the current demands of
contemporary decision processes.

3. Review of Published
ACC/AHA 2016
DAPT Duration
Guidelines in DES
patients
• Stable ischemic heart disease (SIHD): Six months followed by
monotherapy with ASA. Patients with a high bleeding risk
(HBR) may be shortened to three months.
• Acute coronary syndromes (ACS): ACS without ST-segment
elevation (NSTE-ACS) or ST-elevation myocardial infarction
(STEMI): 12 months followed by monotherapy with ASA.
Patients with an HBR may be shortened to six months.
• Patients requiring noncardiac surgery: Interruption of DAPT
before three months after a DES is harmful. It may be
considered between three to six months if the risk of delaying
surgery outweighs the risk of stent thrombosis. Interruption or
discontinuation of DAPT six months after a DES is appropriate,
regardless of original clinical presentation. If at all possible,
low-dose ASA should be continued if the P2Y12 agent is
interrupted or discontinued.

4. Risk Scores:
DAPT Score: > 2, favorable
benefit/risk ratio for prolonged
DAPT; < 2, unfavorable benefit/risk
ratio for prolonged DAPT
PRECISE-DAPT Score: <25, non-HBR;
> 25 HBR

5. Most Recent
Studies on
DAPT Duration

6. PRECISE-DAPT Study
• A meta-analysis of 14,963 patients
from eight randomized trials where the
PRECISE-DAPT score was applied in
complex versus noncomplex and long-
DAPT versus short-DAPT DES patients.
Long-term DAPT in non-HBR patients (<
25 score) reduced ischemic events in
both complex and noncomplex PCI.
Short-term-DAPT in both groups
reduced bleeding and ischemia risk
only in the HBR (> 25 score) patients.

7. SENIOR Study
• A multicenter trial of 12,604 patients >
75 years old were randomized to PCI
with a bare-metal stent (BMS) or a
platinum-chromium bioabsorbable
polymer everolimus-eluting stent (PtCr-
BP-EES) with one month of DAPT for
SIHD and six months of DAPT for ACS. A
strategy of PtCr-BP-EES and a short
duration of DAPT were better than a
BMS and a similar duration of DAPT
with respect to the occurrence of all-
cause mortality, myocardial infarction,
stroke, and ischemia-driven target
lesion revascularization.

8. STOPDAPT-2 Trial
• A multicenter Japanese trial of 3,045 patients who underwent PCI with implantation of a
cobalt-chromium durable polymer (CoCr-DP-EES) were randomized to one month of DAPT
followed by clopidogrel monotherapy or 12 months of DAPT with ASA and clopidogrel. The
one-month strategy compared with the 12-month strategy resulted in a significantly lower
rate of a composite of cardiovascular and bleeding events, meeting criteria for both
noninferiority and superiority.
•

9. SMART-CHOICE Trial
• A multicenter Korean open-label trial of 2,993 patients who underwent PCI with a
variety of durable polymer (DP) or bioabsorbable polymer (BP) DESs were
randomized to receive ASA and a P2Y12 inhibitor for three months followed by
P2Y12 inhibitor monotherapy alone or DAPT for 12 months. The three-month
DAPT strategy followed by monotherapy with a P2Y12 inhibitor was noninferior
to rates of major adverse events compared to the 12-month DAPT strategy.

10. TWILIGHT Trial
• A multicenter international trial of 9,006 HBR patients who underwent PCI with a variety of
DESs were followed by three months of DAPT with ASA and ticagrelor. If at three months
there were no bleeding or ischemic events, they were continued on ticagrelor and double-
blind randomized to either ASA or a placebo. At one year, ticagrelor monotherapy was
associated with a lower incidence of clinically relevant bleeding compared to ticagrelor
plus ASA with no higher risk of death, myocardial infarction, or stroke.

11. Summary
• Patient risk for stent thrombosis versus the increased bleeding risk and the duration of
DAPT will vary with patient clinical characteristics, acute versus stable presentation,
complexity of coronary anatomy, type of DES, and bleeding/thrombotic scores.
• Ongoing data for a shorter duration of DAPT and a switch to monotherapy at three
months—and even one month after implantation of a newer-generation, thinner strut
DP DES and BP DES—are intriguing and may very well justify a change in clinical practice.
• There is emerging data that a P2Y12 agent may be a better choice than ASA for
antiplatelet monotherapy after DAPT in a DES. If so, the type of P2Y12—clopidogrel,
ticagrelor, or prasugrel—will be another issue.
• From a medical-legal standpoint, the strategy for duration of DAPT after a DES should still
follow the current 2016 ACC/AHA guidelines.