We’ve done many columns on the controversy over use of beta blockers in patients undergoing surgery. On the other hand, beta blockers have been a mainstay of treatment in patients who have had an MI. Studies have clearly demonstrated the long-term benefit of chronic beta blockers in patients with a history of MI. But recently questions have been raised about the acute short-term benefits of beta blockers, noting that prior studies demonstrating an acute benefit were largely done in the era before coronary reperfusion strategies became widespread.
A new analysis of data (Park 2014) from the large Global Registry of Acute Coronary Events (GRACE) has raised issues regarding the timing and route of administration of beta blockers in patients with ST-segment elevation MI (STEMI). It must be kept in mind that this is a retrospective analysis of data from a registry, not a randomized controlled trial. In such analyses it is always impossible to determine whether there were confounding factors (eg. the patient may have had clinical factors that led to certain decisions about the use, route, and timing of beta blockers) that may have impacted outcomes.
Nevertheless, the new analysis raises interesting questions. They classified patients as receiving early (within the first 24 hours) or delayed (after 24 hours) beta blocker therapy and further differentiated IV from oral early beta blocker therapy. Early IV beta blockers and delayed beta blockers were associated with higher rates of some adverse outcomes (cardiogenic shock, ventricular arrhythmias, acute heart failure). But in-hospital mortality was significantly increased with IV beta blockers but reduced with delayed beta blockers. On the other hand, early oral beta blocker therapy was associated with reduced rates of cardiogenic shock, ventricular arrhythmias, acute heart failure but was associated with higher in-hospital mortality rates.
Again, it is difficult to use data from registries to conclusively change practice recommendations. What the analysis really tells us is that we need further randomized trials to answer the question about optimal timing of beta blocker therapy in patients with acute MI.
Park KL, Goldberg RJ, Anderson FA, et al. Beta-blocker Use in ST-segment Elevation Myocardial Infarction in the Reperfusion Era (GRACE). The American Journal of Medicine 2014; 127(6): 503–511
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