Compared with clopidogrel, prasugrel and, in particular ticagrelor, led to a significant reduction in risk of recurrent fatal and non-fatal myocardial infarction (MI) in patients with acute coronary syndrome (ACS), in a study from France.

The authors used data from the PGRx acute coronary syndrome registry. The registry recruited patients from 275 cardiology centres and 26 general practices. Overall, 1,047 cases with recurrent MI and 2,234 matched referents, who had not suffered a recurrent event, were included in the study. The cases were predominantly male (71%) and had a mean age of 70.6 years. The referents were matched to cases by index ACS type and date, age and sex in a ratio of 2:1.

Compared with clopidogrel, the newer antiplatelets were associated with an odds ratio (OR) for recurrent MI of 0.65 (95% CI: 0.52-0.81) for ticagrelor and 0.71 (95% CI: 0.53-0.96) for prasugrel.

In patients aged 70 years and over, the respective figures were: OR 0.63 (95% CI: 0.45-0.87) for ticagrelor and 0.77 (95% CI: 0.41-1.45) for prasugrel.

A generally similar pattern was seen across several different presentations in the index cases:

• First MI, OR 0.50 (95% CI: 0.38-0.67) for ticagrelor and 0.66 (95% CI: 0.45-0.95) for prasugrel

• First ST-elevation MI (STEMI), OR 0.39 (95% CI: 0.24-0.62) for ticagrelor and 0.44 (95% CI: 0.26-0.75) for prasugrel

• First non-STEMI, OR 0.63 (95% CI: 0.43-0.92) for ticagrelor and 1.20 (95% CI: 0.69-2.07) for prasugrel

Risk reduction for patients with a first episode of unstable angina as their index ACS taking ticagrelor was less than that of those taking prasugrel, but neither was significant OR 0.80 (95% CI: 0.41-1.59) vs OR 0.51 (95% CI: 0.15-1.74).

The study authors concluded:

‘In this real world case referent study using clinical data, ticagrelor and prasugrel were associated with a significant relative risk reduction of recurrent MI compared with clopidogrel, ticagrelor being associated with a greater decrease of risk than prasugrel notably for first MI, regardless of being STEMI or non-STEMI.’

‘This finding is consistent with clinical trials. The larger magnitude of the observed effect compared with clinical trials, may be attributed to potential residual confounding and/or higher effectiveness compared with reported trial efficacy,’ they add.

Dr Peter Savill