Diabetes as a Predictor of Myocardial Infarction Occurrence and Outcomes

An analysis of over three million patients assessed the impact of diabetes on in-hospital mortality after myocardial infarction.   

Diabetes mellitus has been known to increase cardiovascular disease risk, including coronary artery disease (CAD). In patients with diabetes, CAD is worsened due to increased multivessel disease, higher rates of total occlusion, and increased coronary artery calcification. Diabetes is associated with higher myocardial infarction rates (MI), and patients with diabetes have increased mortality compared to patients without diabetes. Although significant advances have been made to improve clinical outcomes in patients with CAD and MI, substantial decreases in mortality have not been seen in patients with diabetes. Therefore, it is critical to identify possible causes of mortality in patients with diabetes to recognize potential interventions and improve outcomes. Researchers in Germany conducted an analysis to investigate the effect of diabetes on MI, trends in outcomes, and the possible causes of MI in patients with diabetes. 

This study included 3,307,703 patients hospitalized for MI between 2005 – 2016 in Germany. Patients with diabetes were compared to those without diabetes for in-hospital adverse events and mortality post-MI. The study’s primary outcome was all-cause death during the hospital stay and adverse effects such as pneumonia, venous thromboembolism, acute renal failure, stroke, and gastrointestinal bleeding. Statistical analysis was conducted using Mann-Whitney U tests, Fisher’s exact tests, and chi-squared tests. The population assessed was 37.6% female, with 56.8% of patients at least 70 years old. At baseline, more patients with diabetes had peripheral artery disease, atrial fibrillation, sleep apnea, and acute and chronic kidney disease.  

During the study period, 12.4% (n = 410,737) of patients died in-patient. Furthermore, 30.6% (n = 1,007,326) of patients with a MI had a prior history of diabetes. Over the eleven years, the rate of MI in patients increased in patients with diabetes from 29.5% to 30.7%. In contrast, in-hospital mortality associated with MI in patients with diabetes significantly decreased from 15.2% to 11.5% (p < 0.001). Moreover, the rate of recurrent MI significantly decreased from 1.7% to 0.4% (p < 0.001). When compared to patients without diabetes, those with diabetes were older (75 years vs. 72 years), more likely to be female (41.2% vs. 36%), and obese (14.1% vs. 7.2%). Regarding revascularization treatments, patients with diabetes had fewer cardiovascular procedures than those without diabetes, except for CABG surgery which was completed higher in patients with diabetes.  Rates of pneumonia, acute kidney injury, stroke, and the need for blood constituent transfusions were all higher in MI patients with diabetes than those without diabetes. Furthermore, throughout the study duration, trends for rates of pneumonia, pulmonary embolism, acute kidney injury, and gastrointestinal bleeding increased.  

Altogether, this study showed that patients with diabetes had higher rates of in-hospital mortality and recurrent MI than patients without diabetes. However, both these endpoints decreased significantly over the study period. This decline may result from increased awareness of diabetes and cardiovascular risk factors and improved healthcare interventions and lifestyle changes. Furthermore, patients were less likely to undergo revascularization procedures, highlighting a possible improvement area for clinicians. The study’s limitations include the reliance on coding by healthcare providers to determine outcomes and a lack of follow-up data. 

Furthermore, the study did not involve glycemic control trends over the study duration, which may affect the rate of MI and in-hospital mortality. The population focused primarily on German patients, limiting generalizability. In contrast, this study’s strengths include the long duration and the large number of patients analyzed. Overall, when compared to patients without diabetes, patients with diabetes still had higher rates of in-hospital mortality over the study duration. Although trends have improved significantly in patients without diabetes, more attention is needed on patients with diabetes to reduce the risk of CAD and MI.  

Practice Pearls 

• Patients with diabetes are at an increased risk for first-time and recurrent myocardial infarction. 
• Clinicians should focus on patient education and management strategies to reduce cardiovascular risk factors and improve morbidity and mortality outcomes. 
• Healthcare providers can make future improvements to increase the rate of revascularization procedures performed on patients with diabetes.    

Schmitt, Volker H et al. “Impact of diabetes mellitus on mortality rates and outcomes in myocardial infarction.“ Diabetes & metabolism, vol. 47,4 101211.  

Morgan KP, Kapur A, Beatt KJ. Anatomy of coronary disease in diabetic patients explains poorer outcomes after percutaneous coronary intervention and a potential target for intervention. Heart 2004;90:732–8.  

Macrina Ghali, PharmD Candidate 2021, Florida A&M University, College of Pharmacy and Pharmaceutical Sciences