Massive pulmonary embolism with anterolateral ST-segment elevation: electrocardiogram limitations and the role of echocardiogram.

Although acute pulmonary embolism (PE) may give rise to certain electrocardiographic (ECG) changes, most of these changes have low sensitivity and specificity and are of limited value alone in the diagnosis. Possible ECG changes with acute PE include S(1)Q(3)T(3) pattern, atrial tachyarrhythmias, incomplete right bundle-branch block, or negative T wave over right and midprecordial leads. Elevation of ST segment is a rare ECG manifestation with PE. We present a case of PE that went unrecognized in the emergency department (ED). The patient presented with anterior chest pain and dyspnea, and ECG showed ST elevation in V3 through V6. The differential diagnosis included acute coronary syndrome and acute pericarditis. Echocardiography revealed dilatation and dysfunction of right ventricle. Emergent computed tomographic pulmonary angiography showed bilateral pulmonary artery thrombosis and confirmed the diagnosis. Thrombolytic therapy with tissue plasminogen activator was initiated, and symptoms subsided dramatically. We proposed that the ST elevation in anterolateral leads might be the reciprocal changes of myocardial strain in the interventricular septum or right ventricle lateral wall. In a patient with such a critical condition and a confusing ECG, echocardiography played an important role in the diagnostic procedure, enabling prompt therapeutic intervention.