β-blocker dosage and outcomes after acute coronary syndrome
Jason E Allen1, Stacey Knight1, Raymond O McCubrey2
1Intermountain Healthcare, Heart Institute, Murray, UT; University of Utah, Division of Internal Medicine, Salt Lake City, UT.
Insights
In acute coronary syndrome (ACS) patients, high-dose and low-dose beta-blocker (β-blocker) therapy show similar rates of major adverse cardiac events (MACE). This suggests that achieving high beta-blocker doses may not be crucial for ACS outcomes.
Area of Science:
- Cardiology
- Pharmacology
Background:
- Beta-blockers improve survival in acute coronary syndrome (ACS) patients.
- Clinical trial doses often exceed current practice, with recent data questioning higher dose benefits.
Purpose of the Study:
- To compare major adverse cardiac events (MACE) rates between low-dose and high-dose beta-blocker therapy in ACS patients.
- To determine if high-dose beta-blockers offer superior outcomes compared to low-dose regimens.
Main Methods:
- Retrospective study of 7,834 ACS patients with ≥70% coronary stenosis (1994-2013).
- Low dose defined as ≤25% and high dose as ≥50% of 200 mg metoprolol equivalent.
- Multivariate analyses assessed MACE at 0-6 and 6-24 months.
Main Results:
- Of 5,287 patients on beta-blockers, 87% received low dose and 12% high dose.
- MACE rates at 6 months were not equivalent (P=.18), with low-dose showing decreased myocardial infarction risk (HR=0.53).
- MACE event rates at 6-24 months were equivalent between low-dose and high-dose beta-blocker groups (P=.009).
Conclusions:
- Beta-blocker dosage (low vs. high) showed similar MACE rates in ACS patients.
- Findings challenge the necessity of high-dose beta-blockers in ACS care.
- Further research is needed to clarify optimal beta-blocker dosing strategies.
Background:
Although β-blockers increase survival in acute coronary syndrome (ACS) patients, the doses used in trials were higher than doses used in practice, and recent data do not support an advantage of higher doses. We hypothesized that rates of major adverse cardiac events (MACE), all-cause death, myocardial infarction, and stroke are equivalent for patients on low-dose and high-dose β-blocker.
Methods:
Patients admitted to Intermountain Healthcare with ACS and diagnosed with ≥70% coronary stenosis between 1994 and 2013 were studied (N = 7,834). We classified low dose as ≤25% and high dose as ≥50% of an equivalent daily dose of 200 mg of metoprolol. Multivariate analyses were used to test association between low-dose versus high-dose β-blocker dosage and MACE at 0-6 months and 6-24 months.
Results:
A total of 5,287 ACS subjects were discharged on β-blockers (87% low dose, 12% high dose, and 1% intermediate dose). The 6-month MACE outcomes rates for the β-blocker dosage (low versus high) were not equivalent (P = .18) (hazard ratio [HR] = 0.76; 95% CI, 0.52-1.10). However, subjects on low-dose β-blocker therapy did have a significantly decreased risk of myocardial infarction for 0-6 months (HR = 0.53; 95% CI, 0.33-0.86). The rates of MACE events during the 6-24 months after presentation with ACS were equivalent for the 2 doses (P = .009; HR = 1.03 [95% CI, 0.70-1.50]).
Conclusions:
In ACS patients, rates of MACE for high-dose and low-dose β-blocker doses are similar. These findings question the importance of achieving a high dose of β-blocker in ACS patients and highlight the need for further investigation of this clinical question.
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