Outcomes of Clopidogrel Reloading for MI Patients on Pre-Admissions Clopidogrel Therapy

Clopidogrel reloading occurs most frequently in patients with acute myocardial infarction (MI) who are already taking clopidogrel, particularly for STEMI. Results from a recent study published in the European Heart Journal has now found that clopidogrol reloading does not cause an increased risk of in-hospital major bleeding or mortality.

Using data from ACC's ACTION Registry, Jacob A. Doll, MD, et al., analyzed 51,524 patients who were admitted to 735 PCI-capable hospitals between July 2009 and Dec. 2014. Approximately 39 percent of the study population presented with STEMI, while 61 percent presented with NSTEMI. Only 9 percent of STEMI patients used pre-admission P2Y12 inhibitors, whereas 19 percent of NSTEMI patients did.

The authors note that "clopidogrel was the most common agent (91.9 percent), though rates of clopidogrel use declined slightly in later years in concert with increasing use of prasugrel and ticagrelor." In fact, they excluded 4,803 patients for switching to one of these two P2Y12 inhibitors during the study period.

Of those taking clopidogrel, 38 percent were reloaded with a dose ≥300 mg upon presentation. Majority of STEMI patients (76 percent) received a loading dose, while only a quarter of NSTEMI patients were reloaded. Across both subgroup populations, reloaded patients "were more likely to be younger, male and had lower rates of prior cardiovascular disease, diabetes, renal disease, and other comorbidities compared with patients not receiving a loading dose." Researchers also found no association between clopidogrel reloading and an increased risk of major bleeding.

However, there were a few minor differences among the two subgroups. For example, reloaded STEMI patients were more likely to be treated with PCI, whereas NSTEMI patients had an early angiography (<24 hours) and PCI. Additionally, reloaded STEMI patients had lower rates of in-hospital death (odds ratio [OR], 0.80; 95 percent confidence interval [CI], 0.66-0.96); however, researchers observed no significant difference in mortality in reloaded NSTEMI patients (OR, 1.13; 95 percent CI, 0.93-1.37).

"Clinicians may be selectively reloading patients with more acute disease but also greater likelihood of survival and recovery," state the study authors. "Patients already taking clopidogrel at the time of MI are a large and understudied population." As such, they suggest further investigation with a prospective randomized study to "determine if this should be the preferred treatment strategy for this common clinical scenario."

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: Prospective Studies, Comorbidity, Confidence Intervals, Acute Disease, Ticlopidine, Adenosine, Myocardial Infarction, Hemorrhage, Registries, Diabetes Mellitus, Angiography

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