Substrate Mapping Alters Ventricular Tachycardia Inducibility

Area of Science:

• Cardiology
• Electrophysiology
• Medical Devices

Background:

• Programmed electrical stimulation (PES) is crucial for initiating ventricular tachycardia (VT) to guide mapping and assess ablation success.
• The study investigates whether substrate mapping, a common electrophysiological technique, influences VT inducibility through mechanical manipulation of critical cardiac sites.

Purpose of the Study:

• To test the hypothesis that substrate mapping alters VT inducibility by mechanically affecting critical sites.
• To evaluate the impact of substrate mapping on the success of VT ablation procedures.

Main Methods:

• Twenty-eight patients with scar-related left ventricular VT underwent repeated PES.
• Group I (n=14) had PES after substrate mapping; Group II (n=14) had PES after a period of sedation/anesthesia without mapping.
• VT inducibility was categorized as same VT (type I), different VT (type II), or no VT (type III) after the second PES.

Main Results:

• Group I showed significantly lower VT inducibility (21% same VT, 64% different VT, 14% no VT) compared to Group II (71% same VT, 21% different VT, 7% no VT) after the second PES (P=0.017).
• Patients in Group I also had a shorter initial VT cycle length and required more extrastimuli for induction in the first PES.
• No significant differences were observed in patient demographics or baseline characteristics between the groups.

Conclusions:

• The mechanical aspects of substrate mapping frequently change VT inducibility.
• These findings have significant implications for planning catheter ablation procedures and evaluating their immediate outcomes.
• Altered VT inducibility may also explain some cases of recurrent VT that are not identified during the initial procedure.