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Heart Rhythm. 2010 Dec;7(12):1817-24. doi: 10.1016/j.hrthm.2010.07.032. Epub 2010 Aug 1.

Distribution of late potentials within infarct scars assessed by ultra high-density mapping.

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1
UCLA Cardiac Arrhythmia Center, David Geffen School of Medicine at UCLA, Los Angeles, California 90095-1679, USA.

Abstract

BACKGROUND:

Late potential (LP) electrograms represent areas of slow conduction and are often sites critical to reentrant tachycardia circuits. The distribution of LPs within infarct scar is not known.

OBJECTIVE:

The purpose of this study was to delineate infarct heterogeneity using ultra high-density mapping and to determine the location of LPs with respect to scar architecture.

METHODS:

Detailed endocardial (n = 21) and epicardial (n = 8) ultra high-density mapping was performed to delineate the substrate for ventricular tachycardia (VT) in 21 patients with ischemic cardiomyopathy. LP was defined as a low-voltage electrogram (< 1.5 mV) with distinct onset after the QRS. Very late potentials (vLPs) were classified as LPs with onset > 100 ms after the QRS.

RESULTS:

A mean of 787 ± 391 and 810 ± 375 points in the LV endocardium and epicardium were sampled. Multipolar mapping identified heterogeneous islets (HIs) with relatively preserved electrogram amplitudes (≥ 0.51 mv) within dense scar (8.5 ± 4.9/4.5 ± 2.6 HIs per endocardium/epicardium) in all patients. In maps on which putative VT isthmuses were identified (25/29), 57% of vLP were recorded in or adjacent to HI. An LP-targeted ablation strategy combined with pace mapping achieved acute success in all patients (complete success in 52% and partial success in 48%). After 15 ± 7 months, 65% of patients remained free of VT episodes.

CONCLUSION:

Ultra high-density mapping with a multipolar catheter facilitates the delineation of heterogeneous scar architecture at higher resolution. Electrograms within and adjacent to HIs have a higher incidence of vLP, and these sites are frequently critical to reentry. These findings have important implications for substrate-based ablation strategies.

PMID:
20682358
DOI:
10.1016/j.hrthm.2010.07.032
[Indexed for MEDLINE]
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