Atrial Flutter Masquerading as an ST-segment-elevation Myocardial Infarction in a Patient with Dextrocardia

Abstract

Electrocardiogram (ECG) findings suggestive of an ST-segment-elevation myocardial infarction (STEMI) often lead to emergent left heart catheterization. Occasionally, non-coronary conditions mimic ECG findings of STEMI, resulting in an increased risk and expenses from emergent transportation and procedures. In this report, we describe diagnostic and management strategies for a case of 1:1 atrial flutter in a patient with dextrocardia presenting as a STEMI.

Keywords: Atrial flutter; catheter ablation; congenital heart disease; intracardiac electrophysiology; mapping.

Figure 1:

A: Narrow complex tachycardia with deep Q-waves across the precordium from leads V2–V6, I, II, and aVL along with inferolateral ST-segment elevation, raising the possibility of a large transmural infarct. B: After adenosine and lead reversal, the Q-waves previously seen in leads I, II, aVL, and V2–V6 had disappeared, further supporting the diagnosis of atrial flutter.

Figure 2:

A right anterior oblique projection (A) and a left anterior oblique projection (B) are shown. Activation maps in A and B illustrate counterclockwise atrial flutter, with red and purple interfaces exhibiting the early and late components of the re-entry circuit, respectively. C: Computed tomography imaging confirming dextrocardia with situs inversus in addition to continuity of the inferior vena cava in the right atrium is depicted.

Figure 3:

A: The precordial leads were reversed, and the entrainment attempt terminated the tachycardia as the patient was under anesthesia, but atrial ectopy caused atrial fibrillation, which organized into multiple types of flutter after a few minutes. Clockwise cavotricuspid isthmus (CTI) flutter was confirmed via activation mapping. B: With precordial leads still reversed, counterclockwise CTI flutter was also confirmed via activation mapping.