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Electroanatomic characterization and ablation outcome of non-lesion related left atrial macroreentrant tachycardia in patients without obvious structural heart disease
Journal of Cardiovascular Electrophysiology, 08/16/2012
Zhang J et al. – Extensive scarring of the LA formed arrhythmogenic substrates of LAMRT in this group of patients. Ablation targeting these narrow, slow conduction zones eliminated AT in all patients.
Methods- Ten of 226 patients (7 women, mean age 57±14) with LAMRT underwent electroanatomic mapping and catheter ablation.
- None of the 10 patients had structural heart disease or history of previous surgery or catheter ablation.
- In all patients, the reentry circuits were located within a large low– voltage (bipolar voltage≤0.5 mV) area in left atrium (LA),which contained 2.6±1.2 electrically silent areas (ESAs) and/or lines of double potentials(LDPs).
- The tachycardia circuit propagated through a narrow isthmus (<5mm width) bounded by ESAs/LDPs and /adjacent anatomical barriers (e.g., mitral annulus).
- In these isthmus, low amplitude (0.21±0.05 mV), long–duration (123±14 msec) fractionated electrograms were found in 8 tachycardias, accounting for 43±5% of the tachycardia cycle length. li>
- In two other tachycardias without fractionated electrograms,the electrogram amplitude in the isthmus were extremely low (<0.1 mV).
- RF energy was delivered at the isthmuses and terminated all 10 tachycardias.
- After ablation, the original LAMRT was not inducible in all patients.
- During follow–up (mean14± 10 months), 2 patients developed recurrence of ATs and were sucessfully ablated.
