RIVIERA MAYA, MEXICO — To avoid missing an acute myocardial infarction, look beyond the elephant in the emergency department.
“The old 'elephant on my chest' story of the classic … is the one that we love,” Dr. John Marx said at a meeting on medical negligence and risk management.
But up to 40% of patients with acute myocardial infarction come to the ED with atypical presentations, including a normal or nondiagnostic electrocardiogram or with a complete absence of chest pain.
In fact, many patients complain only of anginal equivalents—nonspecific symptoms that may go unrecognized as red flags for a heart attack, said Dr. Marx, chair of emergency medicine at the Carolinas Medical Center and professor of emergency medicine at the University of North Carolina at Chapel Hill.
“Perhaps they may just be short of breath, weak, nauseated, and sweaty, which is very typical [of MI] in those with long-standing diabetes. These are extraordinarily general symptoms and very problematic for us,” he said.
Atypical presentations, along with ECG misses, make heady opportunities for plaintiffs' lawyers, Dr. Marx said at the meeting, which was sponsored by Boston University. “Three to five percent of acute MIs are sent home from the emergency department, and these account for 26% of malpractice losses in emergency medicine. The average award in these cases is about $981,000.”
Anginal equivalents are most common in elderly patients (up to 70% of those over age 85); those with long-standing insulin-dependent diabetes (40% vs. 25% of those without diabetes); women (up to 60% in some series); nonwhite patients; and those with no risk factors for heart attack.
These patients require risk stratification, multiple sets of enzyme studies performed at least 6 hours apart, and continuous ST-T monitoring, Dr. Marx said.
“Never rely on a single set of enzyme studies,” he warned. “If you do, you are harming yourself two ways: First, you have established on the chart that you're worried [about an MI], and second, you've failed to exclude that possibility by ordering only one set of tests.”
If both sets of enzymes are normal and the continuous ST-T monitoring is negative, you can safely submit that patient to provocative testing, either immediately or, if the patient is very low risk, within 5 days.
Don't overrely on the ECG, Dr. Marx stressed. “A normal or unchanged [ECG] does not rule out a diagnosis of MI or unstable angina. It may be helpful if you can get a look at some previous [ECGs] for comparison.”