VT substrate in post MI VT
VT substrate in post MI VT
Circuit and the ECG
Isthmus pacing during tachycardia
Some times VT is
- Not inducible
- Not mappable
Pacing in sinus rhythm - Attractive idea
Pacing in sinus rhythm - Reality
Pacing in sinus rhythm useful to delineate isthmus
- Do not expect perfect pace match
- Adjacent bystander cannot be differentiated
Evidence
Parts of VT reentry circuit isthmuses can be traced during sinus rhythm
- 11 patients
- Match defined as 10/12
- Pace match at short S-QRS - 85%
- Pace match at long S-QRS - only 27%
Corrina B …. Williaim Stevenson. Identification of the ventricular tachycardia isthmus after infarction by pace mapping. Circ 2004;110:652-659
Pacemapping matches
- Isthmus exit - 84%
- Isthmus entrance - 32%
- Central isthmus - 59%
Christian de Chillou … Francis Marchlinski. Localizing the critical isthmus of post infarct ventricular tachycardia: The value of pace-mapping during sinus rhythm. Heart Rhythm 2014;11:175-181
Color coding the match - Pacemapping map
Christian de Chillou … Francis Marchlinski. Localizing the critical isthmus of post infarct ventricular tachycardia: The value of pace-mapping during sinus rhythm. Heart Rhythm 2014;11:175-181
Practical ? - Old AWMI with recurrent VT of one morphology
Delineating the circuit
Usefulness
- Most post MI VT, substrate based ablation superior to targeting specific VTs (1)
- But some patients with single dominant VT, useful to target VT
- In these cases, when VT is not inducible / not mappable / to deduce circuit in SR
- But be aware of limitations when using pacemapping
- Di Biase …. Natale. VISTA multicenter randomized trial. JACC 2015;66:2872-2882