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Prevalence of Unrecognized Myocardial Infarction in Asymptomatic Patients With Diabetes

Nov 9, 2019
 
Editor: David L. Joffe, BSPharm, CDE, FACA

Author: Maya Rudolph, Florida A&M University, College of Pharmacy & Pharmaceutical Sciences, PharmD Candidate

Can using DE-MRI image scans determine the prevalence of unrecognized myocardial infarction in asymptomatic patients with diabetes?

Having diabetes is a contributing risk factor to developing cardiovascular events such as myocardial infarction (MI), but not all patients with diabetes will have this life-threatening outcome. Some clinicians argue that to identify asymptomatic patients with diabetes, cardiac imaging should be used to assess cardiovascular risks. However, according to the American Heart Association (AHA) cardiac testing is not recommended for routine use for assessment of cardiovascular risk in asymptomatic patients with diabetes. Delayed-enhancement MRI (DE-MRI) is a resolution technique that can recognize MI, used in symptomatic patients with diabetes. Unrecognized MI identified by DE-MRI is linked with an increased risk of cardiovascular events in symptomatic patients with diabetes. The significance of an unrecognized MI by DE_MRI in asymptomatic patients with diabetes is unclear. Therefore, a study was designed to assess the usage of DE-MRI to identify unrecognized MIs in asymptomatic patients with diabetes.

The aim of this study was to detect if the DE-MRI scans would find unrecognized MIs in patients with diabetes without a history of cardiovascular disease. The study also wanted to detect if these patients would have an MI or increased risk of death. Within the study, the high-risk group consisted of 50 patients with type 1 diabetes and advanced nephropathy. These patients were screened from kidney and pancreas transplantation at Northwestern Memorial Hospital. 70 patients with type 2 diabetes without known renal insufficiency were classified in the average risk group. These patients were enrolled from an internal clinic at Duke University Medical Center. All patients involved in the study received a complete medical examination. The primary endpoint of the study was to detect all-cause mortality and clinical MI.

The borders of the scar size from the DE-MRI images were examined by the MRI core laboratory. The mean age of the patient was 52, 46% women. Of the total patients, the prevalence of unrecognized MI by the DE-MRI was 19% (n=23; 95% CI 17-21%). The high-risk patients showed an increase in the prevalence versus the average-risk patients (28% vs. 13%, P= 0.038). The infarct small size averaged around 5.1% (range 0.8-15.3%) in the patients with an unrecognized MI. Follow-up of the patients was conducted via telephone interview with the patient or family members, communication with patient’s physician, and review of hospital records over 46 months.  A total of 17 patients experienced 19 events (12 deaths and 7 MIs) with an event rate of 5.3% per year and 2.9% per year for high-risk and average-risk patients, respectively. Of the 23 patients with unrecognized MI, 10 patients encountered an event. Sudden death occurred in 3 patients, heart failure occurred in one patient, and noncardiac events occurred in 2 patients, which all caused death in these 6 patients. Four nonfatal MIs and cardiac events represented a total event rate of 16.0% per and 12.8% per year, respectively. Within the 97 patients with unrecognized MI, 7 had a cardiac event, including six deaths (noncardiac) and one nonfatal MI. In these patients there was total event rate of 1.8% per year and a cardiac event rate of 0.3 % per year. An eightfold increase in risk of death/MI (95% CI 3.0-21.1, P< 0.0001) was associated with the adjusted Framingham risk score, left ventricular ejection fraction, and diabetes type, and the presence of unrecognized MI by DE-MR. 

In summary, during the follow up period 43% of high-risk patients with unrecognized MI experienced a cardiac event and 6% without unrecognized MI experienced an event. In the average-risk patients, 44% of the patients with unrecognized MI experienced a cardiac event, while 8% without unrecognized MI experienced an event. Concluding, asymptomatic patients with diabetes without a history of cardiovascular disease are prevalent to unrecognized MIs.

Practice Pearls:

  • This study evaluated the occurrence of unrecognized MI in patients with type 2 diabetes without known cardiac history, using delayed-enhancement MRI (DE-MRI).
  • DE-MRI scans showed the prevalence of unrecognized MI in patients was 28% in the high-risk group of cardiac events and 13% in the low-risk group of cardiac events.
  • The researchers from this study concluded that unrecognized MI is associated with an increased risk of mortality and clinical recognized MI in patients with type 2 diabetes.

 

References for “Prevalence of Unrecognized Myocardial Infarction in Asymptomatic Patients With Diabetes”:

Elliott, Michael D., et al. “Prevalence and Prognosis of Unrecognized Myocardial Infarction in Asymptomatic Patients With Diabetes: A Two-Center Study With Up to 5 Years of Follow-Up.” Diabetes Care, American Diabetes Association, 19 Apr. 2019, care.diabetesjournals.org/content/early/2019/04/11/dc18-2266.

“Prevalence and Prognosis of Unrecognized MI in Asymptomatic Patients With Diabetes.” Practice Update, www.practiceupdate.com/c/82881/3/2/?elsca1=emc_enews_top-10&elsca2=email&elsca3=practiceupdate_cardio&elsca4=cardiology&elsca5=newsletter&rid=OTE0MTIxOTE4NTkS1&lid=10332481.

Maya Rudolph, Florida A&M University, College of Pharmacy & Pharmaceutical Sciences, PharmD Candidate