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Clopidogrel vs aspirin monotherapy in chronic maintenance period after percutaneous coronary intervention: Findings from Host-Exam trial

Key Takeaway

The findings from Host-Exam, the first large scale randomized trial comparing clopidogrel and aspirin monotherapy in patients who received PCI with DES, and successfully completed 6–18 months of DAPT without events showed that, during the 24-month follow-up period:

  • Clopidogrel monotherapy significantly (P = 0.003) reduced the risk of the composite of all-cause death, non-fatal MI, stroke, readmission due to ACS, and BARC type bleeding ≥3.
  • The beneficial effect of clopidogrel monotherapy was found to be consistent in various subgroups without any significant interaction.
  • Clopidogrel monotherapy was superior to aspirin monotherapy in preventing future adverse clinical events, including thrombotic composite as well as any bleeding.

Why this Matters

  • Result from registry-based studies showed promising activity of clopidogrel as anantiplatele agent in the chronic maintenance period after PCI.
  • No randomized trial in the contemporary DES era has particularly suggested the optimal choice of antiplatelet agent during the period of indefinate antiplatelet monotherapy in the PCI population. monotherapy in the PCI population.

Host-Exam trial compared head-to-head efficacy and safety of aspirin and clopidogrel monotherapy in patients who received PCI with DES for CAD and required chronic maintenance antiplatelet therapy.

Study Design

Study The Host-Exam (NCT02044250) was an investigator-inited, prospective, randomized, open-label, multicenter trial carried out at 37 study sites South Korea.

​​​​​​Eligibility Criteria

  • Age, >20 years, who underwent PCI with DES and maintained DAPT without any clinical events within 6-18 months after PCI.

Key Exclusion Criteria

  •  Patients with any ischemic and major bleeding complications*

  •  Patients with known hypersensitivity or contraindications for clopidogrel, or those who could not cease their current antiplatelet agents for medical/financial/personal reasons.


  • Patients were randomly assigned (1:1) in consecutive order to either clopidogrel group (75 mg OD) or aspirin group (100 mg OD)

Endpoints Assessed

  • Primary endpoint: Composite of all-cause death, non-fatal MI, stroke, readmission due to ACS, and major bleeding complications during the 24-month follow-up period.

  • Secondary endpoints: Individual components of the primary endpoint, revascularization, and minor GI complications at 24 months.

  • Post-hoc secondary composite endpoints: Thrombotic composite endpoint† and any bleeding (BARC ≥2 bleeding).

Key Result

Overall, 5,530 patients were enrolled. Of these, 98.3% of patients were randomly assigned to aspirin monotherapy (50.2%) or clopidogrel monotherapy (49.8%).

Baseline Characteristics

  • Mean age (SD): 63.5 (10.7) years

  • Males: 74.5%

  • Median time from PCI to randomization (days): 382 (IQR = 357–422)

  • DAPT regimen before randomization: Aspirin plus clopidogrel = 81.5%

Incidence of Primary Endpoint at 24-months

Primary endpoint was determined in 98.2% of patients.

  • Absolute risk reduction: 2.0% (95% CI: 0.6 - 3.3)

  • Number needed to treat: 51 patients

Incidences of Secondary Endpoints

Incidences of Post-hoc Secondary Composite Endpoints

  • The beneficial effect of clopidogrel monotherapy vs aspirin monotherpy was found to be consistent accross all prespecified subgroups

  • Post-hoc analyses showed no statistically significant interaction between the treatment effect and various subgroups§

Key Limitations

  • The open-label design of study had a potential for bias in outcome reporting and ascertainment; a possibility of selection bias or under-reporting of events and a false-negative result.

  • The follow-up duration of 24 months might have been too short to provide a concrete conclusion.

  • No phenotypic and genetic testing for clopidogrel was carried out, and the study population was east Asian patients, which might have limited the generalizability of the study.

For additional details, please refer source publication Koo BK, et al.

*Non-fatal MI, any repeat revascularization, readmission due to a cardiovascular cause, and major bleeding
Cardiac death, non-fatal MI, ischemic stroke, readmission due to ACS, and definite/probable stent thrombosis .
Prespecified subgroups were defined according to age, sex, clinical presentation (acute MI or not and ACS or not), renal function, diabetes, and complex PCI.
§Post-hoc analysis subgroups were defined according to angiographic severity, DES generation, duration from index PCI to randomization, potent P2Y12 inhibitor usage before randomization, and usage of proton pump inhibitor.


ACS; acute coronary syndrome; BARC, Bleeding Academic Research Consortium; CAD, coronary artery disease; CI, confidence interval; DAPT, dual antiplatelet therapy; DES, drug eluting stents; HR, hazard ratio; IQR, interquartile range; MI, myocardial infarction; OD, once daily; PCI, percutaneous coronary intervention; SD, standard deviation.


  1. Koo BK, Kang J, Park KW, Rhee TM, Yang HM, Won KB, et al. Aspirin versus clopidogrel for chronic maintenance monotherapy after percutaneous coronary intervention (HOST-EXAM): An investigator-initiated, prospective, randomised, open-label, multicentre trial. Lancet. 2021;397(10293):2487–2496. doi: 10.1016/S0140-6736(21)01063-1. PMID: 34010616.