The following is a summary of “Impact of Diabetes Mellitus on Benefit of β-Blocker Therapy After Myocardial Infarction,” published in the July 2023 issue of the Cardiovascular Disease by Zaatari et al.

Beta-blockers are universally indicated for all patients following myocardial infarction (MI), including individuals with diabetes mellitus (DM). This study evaluates the influence of β-blocker type and dosage on survival rates among patients with diabetes mellitus following myocardial infarction. A cohort of 6,682 patients in the Outcomes of Beta-blocker Therapy After Myocardial Infarction registry were discharged following a myocardial infarction. In this cohort, 2,137 patients presented with diabetes mellitus (32%). The beta-blocker dose was adjusted based on the target daily dose utilized in randomized clinical trials and expressed as a percentage. The dosage groups were categorized as follows: absence of β blocker, greater than 0% to 12.5%, greater than 12.5% to 25%, greater than 25% to 50%, and greater than 50% of the target dose. The average discharge β-blocker dose in patients with diabetes mellitus (DM) was 42.7 ± 34.1%, compared to 35.9 ± 27.4% in patients without DM (P<0.0001). 

Patients diagnosed with diabetes mellitus were prescribed carvedilol, a medication commonly used to manage cardiovascular conditions, at a comparatively higher rate than individuals without DM (27.8% vs 19.6%). The estimated mortality rates at 3 years were 24.4% and 12.8% for patients diagnosed with diabetes mellitus compared to those without DM (P <0.0001). The unadjusted hazard ratio was calculated as 1.820 (CI 1.587 to 2.086, P <0.0001). Patients diagnosed with diabetes mellitus who were prescribed β blockers and received a dose ranging from greater than 12.5% to 25% exhibited the most favorable survival rates. Conversely, patients discharged on β blockers and received a quantity greater than 50% had the lowest survival rate. This difference in survival rates among the different dose categories was statistically significant (P<0.0001). In the multivariable analysis conducted on patients with diabetes mellitus following myocardial infarction (MI), it was observed that all categories of β-blocker doses exhibited a lower mortality rate compared to no therapy. However, only the dose range of >12.5% to 25% showed a statistically significant hazard ratio of 0.450 (95% CI 0.224 to 0.907, P = 0.025).

In individuals diagnosed with diabetes mellitus, no statistically significant disparity was observed in the three-year mortality rates between patients who received metoprolol and those who were administered carvedilol. Researcher’s analysis of patients diagnosed with diabetes mellitus following myocardial infarction indicated a potential survival advantage associated with β-blocker therapy. Notably, there was no observable benefit in using high-dose β-blocker therapy compared to low-dose β-blocker therapy. However, it is worth mentioning that physicians tended to prescribe higher doses of β-blockers to patients with DM. There was no observed survival benefit for carvedilol compared to metoprolol in patients with diabetes mellitus.

Source: sciencedirect.com/science/article/abs/pii/S0002914923002321