A 64-year-old man with ischemic cardiomyopathy (left ventricular ejection fraction, 20%) and coronary artery disease that had necessitated coronary artery bypass grafting was hospitalized because of progressive angina and decompensated heart failure. Inotropic support improved his hemodynamic status. However, before he could be discharged from the hospital on a maintenance infusion of dopamine, he had recurrent, sustained wide-complex tachycardia (WCT) that was associated with hypotension and refractory to amiodarone therapy. His electrolyte levels were normal.

The patient's electrocardiogram (ECG) showed a regular wide-complex rhythm characterized by right bundle branch block morphology with a rightward/superior axis (Fig. 1).

What is the diagnosis for the wide-complex tachycardia?

  • A)

    Supraventricular tachycardia with conduction over an antegrade accessory atrioventricular pathway

  • B)

    Supraventricular tachycardia with QRS aberrancy

  • C)

    Drug-induced wide-complex tachycardia

  • D)

    Ventricular tachycardia

Focus on ECGs: Answer #25

B) Supraventricular tachycardia with QRS aberrancy

The differential diagnosis of WCT includes supraventricular tachycardia (SVT) with aberrancy, SVT with conduction over an accessory pathway, and ventricular tachycardia (VT). Morphologic criteria initially suggest VT, as does the baseline ECG that shows only a nonspecific intraventricular conduction defect (Fig. 2).

In Figure 1, the ECG shows a broad R wave with atypical right bundle features in lead V1 and Q waves in leads V4 through V6, suggesting VT in accordance with the Brugada criteria.1  The only pattern 100% specific for VT across multiple algorithms is atrioventricular association.1,2  However, in this case, atrial activity in lead III preceded each QRS interval (arrows), an argument against VT (Fig. 3A). The P waves associated with the QRS pattern cannot exclude SVT with aberrancy despite the VT morphologies. An electrophysiologic study (EPS) induced no VT, and atrial pacing reproduced the clinical QRS pattern without any evident pre-excitation (Fig. 3B). This confirmed that an ectopic atrial rhythm caused the WCT.

The Brugada criteria and the single-lead aVR algorithm, two widely used contemporary methods for diagnosing WCT, vary in sensitivity and specificity.13  The atrioventricular association led us to conclude that the patient's clinical arrhythmia was atrial tachycardia with QRS aberrancy, as confirmed during the EPS.

Section editors: Yochai Birnbaum, MD, FACC; Mohammad Saeed, MD, FACC

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