How to Dose Beta-Blockers After Myocardial Infarction?
In patients after myocardial infarction (MI), there is a frequent administration of too low doses of beta-blockers (BB) and rare upward titration of their dose after discharge from the hospital. The SWEDEHEART study investigated to what extent the BB dose actually affects 5-year cardiovascular (CV) outcomes, and data from the American registry allowed a focus on mortality after MI depending on BB dosing.
Recommended Prescription of Beta-Blockers After STEMI
The European Society of Cardiology (ESC) recommends the administration of BBs in patients after ST-segment elevation myocardial infarction (STEMI). A high level of recommendation applies especially to patients with a left ventricular ejection fraction (LVEF) < 40%. BBs should be titrated to target doses, if the patient tolerates them.
Are BBs Administered in Sufficient Doses After STEMI?
A recent work by Swiss authors (Bruggmann et al., 2020) attempted to evaluate the prescription of BBs and the titration of their doses in patients after STEMI during 1 year after discharge from the hospital in routine clinical practice. This observational study included 266 patients without contraindication to BB use after STEMI in the years 2014–2016.
The primary parameters observed were the prescription of BBs upon discharge from the hospital and after 1 year of percutaneous coronary intervention, as well as the evolution of BB doses during this year. The dose was considered low if it was < 50% of the target dose, and high if it was ≥ 50% of the target dose.
At the time of discharge from the hospital, 90.8% of patients with LVEF ≥ 40% were taking BBs, 6.0% of them in a high dose. During 1 year, the dose was titrated to high in 4.9% of patients initially on a low dose. Of the 49 patients with LVEF < 40%, 93.3% were prescribed BBs upon discharge from the hospital, 6.1% of them in a high dose. During 1 year after STEMI, the dose was titrated to high in 4.7% of patients initially on a low dose.
Does a High Dose of BB Mean Better CV Outcomes After STEMI?
A national Swedish observational study (Mars et al., 2021) evaluated the risk of recurrent MI and overall mortality during 1 year after MI depending on the prescribed dose of BB in 33,126 patients. Of these, 66.1% were prescribed a high dose and 33.9% a low dose.
The results showed a comparable incidence of the primary observed parameter when administering high and low doses of BB. Patients on a high dose even showed a slightly higher risk of the composite observed parameter, which included recurrence of MI, overall mortality, as well as cerebrovascular accidents, atrial fibrillation, and hospitalizations for heart failure (hazard ratio [HR] 1.08; 95% confidence interval [CI] 1.04–1.12). Similar results persisted after 5 years and in all subgroups, including patients with heart failure.
Is There an Optimal Dose of BB to Reduce Overall Mortality After STEMI?
Data analysis from an American registry (Goldberger et al., 2021) evaluated mortality in 3004 patients after acute MI according to the dose of BB divided into 5 categories: no BB, > 0 to 12.5%, > 12.5 to 25%, > 25 to 50%, and > 50% of the target dose.
The lowest mortality was observed in the group of patients with > 12.5 to 25% of the target dose of BB. Patients who took a high dose (> 50%) did not have a significantly higher mortality (HR 1.196; 95% CI 0.687–2.083). However, significantly higher mortality was observed in patients without BB (HR 1.997; 95% CI 1.118–3.568; p < 0.02), with > 0 to 12.5% of the target dose of BB (HR 1.817; 95% CI 1.094–3.016; p < 0.02), and with > 25 to 50% of the target dose of BB (HR 1.764; 95% CI 1.105–2.815; p < 0.02) compared to the group with > 12.5 to 25% of the target dose.
Conclusion
As real-world data shows, the prescription of BB after STEMI is high. However, most patients use < 50% of the target dose, and during the year following hospitalization, they do not undergo titration. This can be serious, especially for patients with LVEF < 40%. The observational studies conducted, however, do not clearly show that a high dose of BB after STEMI is associated with significantly greater CV benefits than a lower dose. The SWEDEHEART study showed that 5-year cardiovascular (CV) outcomes are not better in patients after MI treated with ≥ 50% dose of BB compared to those receiving < 50% dose of BB. Moreover, a recently published American study found the lowest mortality after MI with BB dosing either in the range of 12.5–25% or > 50% of the recommended dose.
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Sources:
- Bruggmann C., Fournier S., Panchaud A. et al. Beta-blocker use and up-titration after acute ST-segment elevation myocardial infarction: a cohort study. Swiss Med Wkly 2020; 150: w20321, doi: 10.4414/smw.2020.20321.
- Mars K., Wallert J., Held C. et al. Association between β-blocker dose and cardiovascular outcomes after myocardial infarction: insights from the SWEDEHEART registry. Eur Heart J Acute Cardiovasc Care 2021 May 25; 10 (4): 372−379, doi: 10.1093/ehjacc/zuaa002.
- Goldberger J. J., Subačius H., Marroquin O. C. et al.; OBTAIN (Outcomes of Beta‐Blocker Therapy After Myocardial Infarction) Investigators. One-year landmark analysis of the effect of beta-blocker dose on survival after acute myocardial infarction. J Am Heart Assoc 2021 Jul 20; 10 (14): e019017, doi: 10.1161/JAHA.120.019017.
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