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It’s estimated that about 25% to 50% of patients admitted to hospitals with acute coronary syndrome (ACS) may be affected by hyperglycemia. This condition often remains untreated or undetected due to clinicians’ focus on the recanalization of coronary arteries and less attention being paid toward other prognostic indicators. However, there has been much evidence showing that the presence of hyperglycemia is associated with poorer prognoses in ACS patients, both in the short term (30 days) and long term (up to 1 year and beyond). In the March 2008 issue of Circulation, a collaboration of experts from the American Heart Association (AHA) published a scientific statement in an effort to prompt national organizations to pursue appropriate trials that examine the pathophysiology of hyperglycemia in ACS and the most effective and safe therapies.

Hyperglycemia: A Marker or Mediator?

The exact prevalence of hyperglycemia in ACS patients is largely undefined. A key question is whether elevated blood glucose in ACS is a marker or mediator of more severe myocardial damage. Efforts should be made to determine if the stress of a major myocardial infarct, for example, produces hypoglycemia—secondary to the larger infarct, which in itself is a poor prognosticator. On the other hand, if hyperglycemia is a mediator, elevated glucose levels will exacerbate conditions such as ACS, myocardial infarction, or unstable angina, and further increase injury to the heart. Despite remaining gaps in knowledge and the inability to issue definitive recommendations, the AHA statement offers some guidance to physicians.

Identifying Hyperglycemia in ACS Patients

The AHA statement recommends that all patients with suspected or confirmed ACS undergo glucose measurement upon arrival to the hospital. Those patients identified as being hyperglycemic should receive treatment with insulin, maintaining plasma glucose levels between 120 mg/dL and 140 mg/dL (patients with ACS who are hospitalized but not in the ICU should maintain glucose levels of 180 mg/dL).

Insulin administered as an intravenous infusion is currently the most effective method of intensive glucose control in the ICU. Although research has yet to confirm insulin administration as the best course of action, it is advised to use insulin infusion with careful monitoring until optimal treatment methods are established. Proper staffing and monitoring are crucial during insulin infusion to ensure that treatment normalizes glucose levels while avoiding the dangers of hypoglycemia.

Additionally, ACS patients with detected hyperglycemia and no prior history of diabetes should undergo further evaluation to determine the severity of their metabolic derangements. This evaluation may include fasting glucose, oral glucose tolerance test, and A1C assessment. Diabetes is typically diagnosed when fasting blood glucose levels are 126 mg/dL or higher. Patients diagnosed with diabetes should be treated accordingly following diabetic treatment measures (eg, controlling glucose, cholesterol, and blood pressure).

A Call to Action

Physicians treating patients with ACS must be aware that hyperglycemia is a common occurrence. Efforts should be made to identify these patients and take measures to control the condition. Ignoring elevated glucose levels will likely have a negative impact on the outcomes we’re trying to achieve. Our hope is that larger institutions will conduct the trials necessary to address knowledge gaps and improve outcomes in patients with ACS. This is a significant problem that can no longer be ignored, and we as physicians, researchers, and clinicians have much more work to do.

Dr. Deedwania has indicated to Physician’s Weekly that he has or has had the following financial interest: AstraZeneca, GlaxoSmithKline, and Novartis Pharmaceuticals Corporation.