Atrial Repolarization as a Rare Mimicker of ST-Segment Elevation Myocardial Infarction

Figures

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  Figure 1. Depiction of the Patient's Complex Congenital Heart Anatomy (A) Transthoracic echocardiography demonstrated single-ventricle physiology with double-outlet right ventricle, mitral valve atresia, LV hypoplasia, L-malposition of the great arteries, large secundum ASD, inlet to outlet VSD, pulmonic stenosis, biatrial enlargement, and severe tricuspid regurgitation. (B) Right heart catheterization demonstrated severe pulmonic stenosis with a transpulmonary systolic gradient of ∼50 mm Hg. The systemic right ventricle was markedly dilated, with an end-diastolic pressure of 15 mm Hg. (C) Chest computed tomography angiography cross-sectional slice at the level of the great vessels, demonstrating L-malposition of the great arteries with the aorta located anteriorly and leftward of the pulmonary artery. Ao = aorta; ASD = atrial septal defect; DORV = double-outlet right ventricle; LA = left atrium; LAA = left atrial appendage; LV = left ventricle; PA = pulmonary artery; RA = right atrium; TV = tricuspid valve; VSD = ventricular septal defect.

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  Figure 2. Serial Standard 12-Lead ECGs (A) The index ECG demonstrated ST-segment elevations in the inferior leads (II, III, aVF) and lateral leads (V4-V6) (arrows) preceded by a large negative deflection that was initially misconstrued for a pathologic Q wave. Crochetage sign is also seen in the inferior leads (star). (B) Repeat ECG within 30 minutes demonstrated normalization of the ST-segment elevations (arrowheads). P waves are now evident (from sinus vs high atrial origin) with a longer PR interval and discordant ST-segment depressions in the inferior leads. ECG = electrocardiogram.

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  Figure 3. Outpatient 12-Lead ECG During Hospital Follow-Up The patient remained in normal sinus rhythm. Interestingly, the Crochetage sign is no longer evident in the inferior leads as was seen on the index ECG, likely reflecting improvement in right-sided cardiac pressure and volume following diuresis. ECG = electrocardiogram.

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  Visual Summary. Serial 12-Lead ECGs Performed 30 Minutes Apart in a Patient With Transposed Great Arteries Presenting With Chest Pain (Left) The initial 12-lead ECG demonstrates Q waves and ST-segment elevations in the inferior and lateral leads and absence of a distinct P wave, raising concern for STEMI. (Right) Repeat ECG following activation of the cardiac catheterization laboratory showed clear P waves and normalization of the ST segments. The initial ECG was determined to represent a pseudo-inferolateral infarct pattern given low atrial ectopic rhythm and a large atrial repolarization wave. ECG = electrocardiogram; STEMI = ST-segment elevation myocardial infarction.