WASHINGTON — Long-term clopidogrel use appears to improve outcomes—including all-cause mortality and recurrent myocardial infarction—after either bare-metal or drug-eluting stent placement for acute coronary syndrome, Dr. Michael Ho reported at a conference sponsored by the American Heart Association.
His retrospective study found a 60% reduced risk of death in stent patients who continued taking the drug for up to 2 years, compared with those who did not. There were also significantly reduced risks of hospitalization for acute myocardial infarction and the combined end point of death and acute MI, Dr. Ho said in an interview.
“These findings are hypothesis generating because of the observational nature of the study, and they suggest the urgent need for a randomized clinical trial to assess the efficacy of extended clopidogrel use among ACS patients receiving stents,” said Dr. Ho, a cardiologist at the Denver Veterans Affairs Medical Center.
The findings are particularly intriguing “given the broader concerns of late events in drug-eluting stent patients,” he said.
Data were extracted from a national sample of 1,455 acute coronary syndrome patients admitted to 127 VA medical centers during 2003–2004. The patients' mean age was 64 years. Twenty-one percent had previously experienced an MI; 19% had diabetes. Cerebrovascular disease was present in 5%, and 24% had reduced left ejection fraction.
All presented with acute MI or unstable angina and underwent percutaneous coronary intervention with the placement of a bare-metal or drug-eluting stent.
All of the patients were prescribed clopidogrel at discharge. Dr. Ho compared mortality and MI hospitalization rates between those who were still taking the drug and those who were not, using pharmacy records with a median follow-up of 18 months.
Overall, there was a 60% reduced risk of all-cause mortality in those who continued to take the drug, with both stent groups reaping a similar benefit (bare-metal stent, hazard ratio 0.36; drug-eluting stent, HR 0.48).
There was also a significantly reduced overall risk of another acute MI (HR 0.55) and the combined end point of all-cause mortality and acute MI (HR 0.51).
The magnitude of association between clopidogrel use and reduced mortality was consistent throughout the entire 18 months, Dr. Ho said. In the first 6 months, the reduced risk was 0.36; at 7–12 months, it was 0.43; and at 13–18 months, it was 0.37.
“This theory should be tested immediately in a randomized clinical trial,” he said.
“Observational studies like this really raise the question of whether we should be giving these patients clopidogrel for longer periods than current guidelines recommend.”