Differential Diagnosis of Acute Myocardial Infarction

In general, all causes of precordial and chest pain have to be considered in the differential diagnosis of an acute myocardial infarction. In persistent chest pain, which is associated with symptoms such as nausea, diaphoresis, and dyspnea, the following acute diseases are the most important to consider in the differential diagnosis:

➤ Pulmonary embolism: a massive pulmonary embolism can simulate a myocardial infarction. Chest pain and the imminent sense of doom are main symptoms of a massive pulmonary embolism, too. A sinus tachycardia, hypotension, and peripheral vasoconstriction are typical signs found during physical examination. In addition, tachypnea, distended jugular veins, and cyanosis are often present. In the ECG a rotation of the frontal QRS axis to the right (resulting in a SI/QIII type), a clockwise rotation of the horizontal axis, and often unspecific ST−T changes are typical signs of pulmonary embolism. The chest radiograph may show wedge-shaped or linear opacities of any size or shape, a pleural effusion, or an elevated hemidiaphragm. Blood gases show a low PaO2 and a low PaCO2. D-dimers are elevated in the plasma (_500 ng/L). The diagnosis of pulmonary embolism is most often confirmed by a spiral CT, occasionally by lung scintigraphy, or pulmonary angiography.

➤ Pericarditis: the changes of the intensity of chest pain with posture or breathing, in addition to the typical signs in the ECG, aremost helpful to differentiate pericarditis from myocardial infarction.

➤ Aortic dissection: an aortic dissection has to be considered in case of chest pain in the back or radiating to the back. The diagnosis is confirmed or excluded by computed tomography, transesophageal echocardiography, or MRI.

➤ A spontaneous pneumothorax  or a tachycardic arrhythmia can result in precordial tightening and a tendency for collapse or syncope.