In VT mapping, what region is identified as the exit site?

• A. The region where the VT circuit exits into viable tissue.
• B. The center of the scar.
• C. The earliest activation within the VT circuit.
• D. A distant region far from scar.

Answer: (B)

In VT mapping, the exit site is the region where the reentrant VT wavefront leaves scar tissue and propagates into viable (healthy) myocardium. This border between scar (slow-conducting tissue) and normal tissue is where the activation that sustains the tachycardia emerges into a broader, faster-conducting substrate, making it a key target for ablation. The center of the scar is often the scar core that supports the circuit, but the exit site is specifically at the boundary where the circuit’s activity exits into viable tissue. The earliest activation point inside the VT circuit identifies timing within the circuit itself, not the location where the wavefront exits to healthy tissue, and a region far from scar is not typically involved in sustaining the VT.