Myocardial Infarction Differential Diagnoses

Updated: Sep 15, 2015
  • Author: A Maziar Zafari, MD, PhD, FACC, FAHA; Chief Editor: Eric H Yang, MD  more...
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Diagnostic Considerations

Epigastric or chest symptoms from myocardial ischemia may incorrectly be attributed to a GI source. Often, this occurs despite the presence of dyspnea or diaphoresis, symptoms that are difficult to attribute to the GI system. Additionally, patients with myocardial ischemia may report relief or improvement with GI remedies (eg, antacids). Remember that even myocardial ischemia can worsen with recumbency (eg, angina decubitus) because of an increase in venous return and a temporary greater workload.

The discomfort of myocardial ischemia may erroneously be attributed to a musculoskeletal etiology. Tenderness of the chest wall is reported in as many as 5% of patients who prove to have an MI. If no injury or event is defined that could have led to a soft tissue injury, the clinician should be reluctant to render a diagnosis of musculoskeletal chest pain.

Younger patients are overly represented in cases of missed MI. Most likely, this is because of the inherent bias that this is a disease of those who are late middle-aged and older. Approach each patient with chest symptoms as an individual who could have the disease.

Unfortunately, in a series of missed MI, the failure to recognize ischemic changes is frequent. The inferior leads, in particular, must be scrutinized carefully for any evidence of ST-segment elevation by using a straight edge across the T-P segments. Another common error is to recognize ischemic changes and then discharge the patient without definitively proving that the changes were pre-existent. Nonischemic causes of ST-segment elevation include LVH, pericarditis, ventricular-paced rhythms, hypothermia, hyperkalemia, and LV aneurysm. Nonischemic causes may lead to overtreatment.

The diagnosis of an MI may be missed in the setting of a left bundle-branch block, and there may be delays in, or a failure of, administering thrombolytic agents or initiating PCI. This is usually because of delays in ECG performance, interpretation, and decision-making, and it is also affected by the availability of thrombolytics in the ED. Excluding patients based on age alone will deny some the significant benefit of thrombolysis.

Differential Diagnoses