NEW YORK (Reuters Health) – Results of a large observational study reinforce current European and American guidelines that clopidogrel be given as early as possible after ST-segment elevation myocardial infarction (STEMI), researchers say.
They found that upstream clopidogrel treatment prior to arrival at the catheterization lab is associated with a reduction in the combined risk of death or MI as well as death alone in STEMI patients undergoing primary percutaneous coronary intervention (PCI).
Dr. David Erlinge, head of the department of cardiology at Lund University Hospital and president-elect of the Swedish Society of Cardiology, and colleagues report their observations in a paper in the European Heart Journal, available online now.
Clopidogrel, which has a slow onset of effect, is commonly used early after STEMI (prior to primary PCI), despite a lack of definitive evidence for this practice, they note in their paper.
The current study provides a “strong indication that upstream clopidogrel is beneficial for STEMI patients,” Dr. Erlinge wrote in an email to Reuters Health.
Dr. Erlinge and colleagues used the national Swedish Coronary Angiography and Angioplasty Registry to evaluate long-term clinical outcomes of upstream clopidogrel treatment in 13,847 patients undergoing primary PCI for STEMI between 2003 and 2008.
Of the total, 9,813 (71%) received upstream clopidogrel prior to arrival at the catheter lab and 4,034 (29%) did not. To minimize confounding factors, all patients were required to have received aspirin upstream and no concomitant warfarin therapy was permitted.
“In this large register study upstream clopidogrel was associated with a clear reduction in death,” Dr. Erlinge said.
During 1-year follow-up, the combined primary endpoint of death or MI occurred in 1,325 patients with upstream clopidogrel treatment (14.3%) and in 712 (17.9%) without upstream treatment.
After propensity score adjustment, upstream clopidogrel was associated with a significant reduction in relative risk of death or MI at 30 days (hazard ratio [HR] 0.83) and 1-year (HR 0.82), the investigators report. Both results remained significant after additional multivariate adjustment.
At 1-year, there were 665 deaths (7.2%) in the upstream clopidogrel arm and 376 (9.4%) in the non-upstream clopidogrel arm. Again, using propensity score methods, the adjusted mortality risk reduction was significant at 30 days and 1-year (HR 0.70 and 0.76, respectively). These results also held up after multivariate adjustment.
During follow-up, a total of 719 MIs occurred in the upstream clopidogrel arm (8.2%) and 369 (9.9%) in the non-clopidogrel arm. After adjustment by propensity score, the groups did not differ at 30 days (HR 1.00), but there was a tendency for benefit at 1-year (HR 0.90).
Dr. Erlinge and colleagues say to their knowledge this is the largest study published to date regarding upstream clopidogrel treatment in STEMI patients undergoing primary PCI.
It supports the practice by showing a clear reduction in cardiovascular clinical endpoints, including total mortality, they conclude.
Euro Heart J 2011.
