If the VT is non-inducible, pace mapping can be used during sinus rhythm to map.

• A. True
• B. False
• C. Not possible
• D. Only with drugs

Answer: (A)

Pace mapping during sinus rhythm can localize the VT origin when the arrhythmia cannot be induced. By pacing from multiple ventricular sites and comparing the resulting QRS shapes to the VT morphology, the site whose paced QRS most closely matches the VT is likely near the VT exit or origin. This works because the local activation vector generated by pacing reflects local conduction paths, so a match suggests you're at or near the substrate driving the VT. Even when VT is non-inducible, this approach provides a practical way to identify ablation targets. Keep in mind that exact matches aren’t always possible due to differences in activation during pacing versus actual VT, scar-related conduction, and other factors, but a close morphologic match is still the best guide available in this situation.