Monotherapy with clopidogrel was associated with a reduced risk of recurrent ischaemic events compared with aspirin in patients with drug eluting stents (DES), in an observational study. All patients had previously undergone 12 months of dual antiplatelet therapy following stent insertion.

A total of 3,243 consecutive patients receiving DES between January 2003 and December 2010 at a medical centre in Korea were studied.

Of these, 2,472, mean age 62, had received aspirin and 771, mean age 64, clopidogrel alone after 12 months’ treatment with dual antiplatelet therapy.

Patients in the clopidogrel group had more comorbidities and more complex lesions than those in the aspirin group and were also more likely to be smokers.

At 36 months after initiation of antiplatelet monotherapy:

• Clopidogrel was associated with a reduction in risk for a composite of cardiac death, myocardial infarction,

or stroke: aspirin (3.8%) versus clopidogrel (2.6%); hazard ratio (HR) 0.54 (95% CI: 0.32-0.92; P = 0.02)

• Risk of cardiac death was lower with clopidogrel (0.5%) than with aspirin (1.4%); HR 0.31 (95% CI: 0.11-0.93;P = 0.04).

Dual antiplatelet therapy for 12 months is recommended following DES insertion to reduce the risk of early in-stent restenosis and further cardiac events. Such therapy can increase the risk, particularly of upper gastrointestinal, bleeding but that increase in bleeding risk becomes more important as the risk of recurrent cardiac events declines and the transition to an unacceptable bleeding risk is felt to be 12 months. However, up until now there have been no studies to determine which antiplatelet gives the best long-term outcome when the switch from dual therapy to monotherapy occurs.

The authors concluded that in patients with DES, after 12 months of dual antiplatelet therapy, clopidogrel when compared with aspirin monotherapy, appeared to be associated with a reduced risk of recurrent ischaemic events.

This finding warrants further research with randomised controlled trials as the current practice of stopping clopidogrel after 12 months and continuing with aspirin long term may not necessarily be the optimal strategy.

Dr Peter Savill