Poor long-term adherence to aspirin after a heart attack increases the risk of death, recurrent myocardial infarction (MI) or ischaemic stroke, according to research presented during the recent European Society of Cardiology Congress. 

Researchers used a registry to identify 40,114 patients aged 40 years and older who underwent percutaneous coronary intervention and who were alive, not receiving anticoagulants and who had not experienced a recurrent coronary event a year after their first MI. 

Patients were also adherent to aspirin a year after their MI. The researchers defined poor adherence as 80 per cent or fewer days covered. Two to four years after the MI, poorly adherent patients were 29 per cent more likely to have died or experienced a recurrent MI or ischaemic stroke than those who were adherent.

Four to six and six to eight years after their MI, participants who were poorly adherent to aspirin were 40 and 31 per cent more likely to have died or experienced a recurrent MI or ischaemic stroke than those who were adherent. 

After eight to 10 years, poorly adherent patients were 20 per cent more likely to have died or experienced a recurrent MI or ischaemic stroke than those who were adherent.

“Our results should be interpreted with caution because they show an association but do not establish causality,” says Dr Anna Meta Kristensen of Bispebjerg and Frederiksberg Hospital, Denmark. “We do not have information about the specific reasons as to why patients did not take their aspirin. 

“Our findings cannot be generalised to all patients who experience a heart attack, as our study specifically focused on those who received treatment with a coronary stent and were not taking other medications to prevent blood clot formation. 

“With that in mind, the results support current guidelines recommending long-term aspirin after a heart attack,” she says.