What is the default assumption for wide complex tachycardia?

Assume VT until proven otherwise, especially in patients with a history of MI or structural heart disease. Treating VT as SVT can be fatal.

What ECG features favor VT?

AV dissociation, fusion or capture beats, QRS > 140 ms, extreme axis deviation, concordance across precordial leads (all up or all down), and a prior MI history.

What is the treatment for stable VT?

Amiodarone 150 mg IV over 10 min, or procainamide 20–50 mg/min. Prepare for synchronized cardioversion if the patient decompensates.

When do you cardiovert vs defibrillate wide complex?

Pulseless VT or VF → defibrillate (unsynchronized). Unstable but perfusing wide complex → synchronized cardioversion at 100 J biphasic.

ECG reference

Wide complex tachycardia.

Assume VT. Treat VT. Sort it out at the hospital.

The default rule

Any regular wide-complex tachycardia (QRS > 120 ms, HR > 100) is VT until proven otherwise. Especially in patients over 50, with a history of MI, CHF, or structural heart disease — the pretest probability of VT is above 90%.

ECG clues that favor VT

AV dissociation — P waves marching through independently.
Fusion or capture beats — narrow beat in the middle of a wide run.
QRS > 140 ms (RBBB pattern) or > 160 ms (LBBB pattern).
Extreme axis (northwest quadrant).
Concordance — all V leads positive or all negative.
Prior MI, ICD, or CHF history.

Brugada 4-step (simplified)

Absence of RS complex in all precordial leads → VT.
RS interval > 100 ms in any precordial lead → VT.
AV dissociation → VT.
Morphology criteria for VT in V1/V2 and V6 → VT.

Treatment

Pulseless

VF/pVT algorithm: CPR, defibrillate (unsynchronized, 200 J biphasic), epi, amiodarone 300 mg.

Unstable, perfusing

Synchronized cardioversion at 100 J biphasic. Sedate if time permits.

Stable

Amiodarone 150 mg IV over 10 min, or procainamide. 12-lead. Prepare for cardioversion.

Torsades caveat

Polymorphic VT with a long QT is torsades. Treatment is magnesium sulfate 2 g IV, defibrillation if pulseless, correction of electrolytes, and stopping any QT-prolonging drugs.

Frequently asked

What is the default assumption for wide complex tachycardia?: Assume VT until proven otherwise, especially in patients with a history of MI or structural heart disease. Treating VT as SVT can be fatal.
What ECG features favor VT?: AV dissociation, fusion or capture beats, QRS > 140 ms, extreme axis deviation, concordance across precordial leads (all up or all down), and a prior MI history.
What is the treatment for stable VT?: Amiodarone 150 mg IV over 10 min, or procainamide 20–50 mg/min. Prepare for synchronized cardioversion if the patient decompensates.
When do you cardiovert vs defibrillate wide complex?: Pulseless VT or VF → defibrillate (unsynchronized). Unstable but perfusing wide complex → synchronized cardioversion at 100 J biphasic.

More cardiac drills

Amiodarone dosing →Practice test