Beta-Blocker Use in ST-Segment Elevation Myocardial Infarction in the Reperfusion Era (GRACE)
What are patterns of beta-blocker use during hospitalization, particularly early use within the first 24 hours, in patients with ST-elevation myocardial infarction (STEMI), and what is the comparative impact of intravenous versus oral beta-blockade?
This was a retrospective analysis of the Global Registry of Acute Coronary Events (GRACE) registry. Data from patients enrolled between 2000 and 2007 for STEMI were categorized based on beta-blocker use: early (first 24 hours) intravenous (IV) (± oral), only early oral, or delayed (after first 24 hours in some form). The composite study outcome was death, cardiogenic shock, ventricular fibrillation/tachycardia, and acute heart failure.
Ninety percent of eligible patients received some form of beta-blocker therapy. From an analytic sample of 13,110 patients with STEMI, 21% received any early IV beta-blocker, 65% received only early oral beta-blocker, and 14% received delayed beta-blocker. Chronic beta-blocker treatment was the strongest factor associated with the likelihood of receiving early beta-blocker therapy. In-hospital mortality was increased with IV beta-blocker use (adjusted odds ratio [aOR], 1.41; 95% confidence interval [CI], 1.03-1.92), but significantly reduced with delayed beta-blocker use (aOR, 0.44; 95% CI, 0.26-0.74). Early IV beta-blocker administration was associated with increased odds of developing cardiogenic shock (aOR, 1.70; 95% CI, 1.21-2.39). Delayed beta-blocker administration was associated with an even higher odds of developing cardiogenic shock (aOR, 1.97; 95% CI, 1.43-2.72), despite the decreased mortality observed with a delayed pattern of administration.
In this analysis of GRACE, the early administration of any form of beta-blocker was associated with an increase in death, cardiogenic shock, ventricular fibrillation/tachycardia, and acute heart failure.
This is an important analysis that should serve as a reminder about the possible deleterious consequences of early beta-blockade in patients presenting with STEMI. The limitations of this observational study aside, the authors provide cogent evidence that early IV beta-blocker administration is associated with adverse outcomes and may be best avoided or reserved for appropriately selected patients. Such a finding corroborates, in part, observations from the COMMIT (ClOpidogrel and Metoprolol in Myocardial Infarction Trial) study, in which early IV metoprolol increased the risk of cardiogenic shock. As the authors opine, the increased odds of developing cardiogenic shock in those given delayed beta-blocker therapy may reflect severity of illness in these patients. The paradoxical finding of increased mortality in those receiving early oral beta-blocker therapy, counterbalanced by favorable changes in other outcomes, warrants further investigation.
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