Introduction and methods

Aspirin vs. Clopidogrel for Chronic Maintenance Monotherapy after Percutaneous Coronary Intervention – The HOST-EXAM trial

Presented at ACC.21 by Hyo-Soo Kim (Seoul, South Korea)

Guidelines recommend chronic maintenance of single antiplatelet therapy after the initial 6- to 12-months of dual antiplatelet therapy (DAPT) in patients after percutaneous coronary intervention (PCI). Aspirin is mostly widely used as antiplatelet therapy, and clopidogrel can be used as an alternative strategy. But there have been no trials that examined which antiplatelet therapy is the optimal option for patients after PCI with DES as chronic maintenance.

The HOST-EXAM trial enrolled patients who were event-fee when using DAPT for 6-18 months after index PCI with DES. 5438 Patients were randomized to aspirin or clopidogrel for 24 months. Primary outcome was all-cause death, nonfatal MI, stroke, readmission due to ACS, or major bleeding (BARC type ≥3).

Main results

• Event rate for the primary outcome was 7.7% in the aspirin group vs. 5.7% in the clopidogrel group, resulting in reduction of the primary outcome by clopidogrel compared to aspirin (HR 0.73, 95%CI: 0.59-0.90, P=0.0030). NNT to prevent 1 primary outcome event was 50.6.
• The thrombotic outcome (cardiac death, non-fatal MI, ischemic stroke, readmission due to ACS, and definite or probable stent thrombosis) was reduced in the clopidogrel group compared to the aspirin group (3.7% vs. 5.5%, respectively, HR 0.68, 95%CI: 0.52-0.87, P=0.003).
• The outcome of any bleeding (BARC type ≥2 bleeding) was lower in the clopidogrel group than in the aspirin group (2.3% vs. 3.3.%, respectively, HR 0.68, 95%IC: 0.52-0.87, P=0.003).

Conclusion

Clopidogrel monotherapy compared to aspirin monotherapy reduced the primary outcome of all-cause death, nonfatal MI, stroke, readmission due to ACS and BARC type ≥3 bleeding in patients who were event-free using DAPT for 6-18 months after PCI with DES. Endpoints of a thrombotic composite endpoint and any bleeding endpoint were also reduced by clopidogrel compared to aspirin in this group of patients.

Discussion

The discussant Claire Duvernoy, MD (Ann Arbor, MI, USA) called this trial provocative and potentially practice changing. Aspirin has been the corner stone in the treatment of CAD. Yet, aspirin comes with the cost of gastrointestinal side effects, bleeding risk (intracranial and intraocular). There has been a search for an alternative drug, and this trial contributes to the question for an alternative. This trial demonstrates that you can now safely and efficaciously transition to clopidogrel monotherapy in stable patients after stent placing and who have used DAPT for 1 year. This give confidence to use this in clinical practice, said Duvernoy. We have to see though how widely applied these results are. An important issue raised by Duvernoy is whether patients on clopidogrel maintenance therapy can safely go the OR for non-cardiac or non-vascular surgery without stopping their clopidogrel therapy. This study suggest though that bleeding risk was not higher in patient on clopidogrel, it was even lower, but it is not known whether this applies to peri-operative bleeding. Finally she noted that the CYP2C19 LOF gene is more common in Korea and yet high efficacy of clopidogrel was observed.

- Our coverage of ACC.21 is based on the information provided during the congress –

The findings of this study were simultaneously published in The Lancet Watch a video by prof. Verheugt on this trial