FIGURE 64-1 ECG of the wide complex tachycardia. There are more QRS complexes than P-wave complexes (arrow), essentially clinching that the mechanism of the wide complex tachycardia is ventricular tachycardia.

EXPERT OPINION

• The differential diagnosis for a wide complex tachycardia include:

Ventricular tachycardia (VT)

Supraventricular tachycardia (SVT) with aberrancy (ie, LBBB or RBBB)

Paced tachycardia

Antidromicatrial ventricular reciprocating tachycardia (AVRT)

SVT with a bystander accessory pathway

• Patients with previous MI or impaired ejection fraction are at higher risk for VT.

• Paced tachycardias should have pacing spikes before each QRS.

• Antidromic AVRT and SVT with a bystander accessory pathway are seen in Wolff-Parkinson-White patients who should have a delta wave on baseline ECG.

• In this patient, VT was suspected based on the history of MI. Furthermore, there were more QRS complexes than P waves seen on the presenting ECG (see arrows in Figure 64-1), essentially clinching the diagnosis of VT. Rarely, SVTs such as AVNRT with upper common final pathway block or junctional tachycardia with retrograde block in the AVN can have more ventricular depolarizations than atrial depolarizations; however, one would not expect a wide QRS complex different than the native QRS in that case.

• For patients with incessant VT, antiarrhythmics are typically tried first to suppress the VT.

• When antiarrhythmics are not successful, emergent ablation is necessary.

• Although ICD implantation may be eventually necessary, it is not the next step in management of patients with incessant VT since it would lead to multiple shocks.

PATHOPHYSIOLOGY AND MANAGEMENT

• The patient was brought to the EP Laboratory in stable VT.

• A diagnosis of VT was confirmed with intracardiac recordings.

• Mapping of the tachycardia started in the LV since the patient had a scar in the LV from a previous anterior wall MI.

• Voltage mapping of the LV showed low voltages in the apical septum corresponding to scar from the previous MI (Figure 64-2).

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