Monomorphic VT
- Identical from beat to beat
- Typically re-entry around a fixed scar
- Prior myocardial infarction
- Ischemic cardiomyopathy
- Structural heart disease
- Ventricular scar from myocarditis or surgery
- Frequently more amenable to catheter ablation
Polymorphic VT
- Typically due to ACUTE ischemia or repol abnormalities
- Acute MI
- Long QT syndrome
- Electrolyte abnormalities
- Drug-induced QT prolongation
- Often hemodynamically unstable
- Higher risk to degenerate into VFIB
Cheat Sheet
| Feature | Monomorphic VT | Polymorphic VT |
|---|---|---|
| QRS morphology | Same every beat | Changes beat to beat |
| Mechanism | Scar reentry | Ischemia or repolarization instability |
| Typical setting | Prior MI / structural heart disease | Acute ischemia, long QT |
| Stability | Often more stable | Often unstable |
| Example | Scar-related VT | Torsades de pointes |