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Currently, the decision to implant an implantable cardiac defibrillator (ICD) as primary prevention (PP) of sudden cardiac death (SCD) is based on the presence of severe left ventricle dysfunction and the New York Heart Association functional class. However, only a minority of PP patients with an indication for an ICD based on these variables will require ICD therapies during follow-up, especially those experiencing nonischemic cardiomyopathy. Thus, better risk stratification tools are needed to improve the identification of patients at SCD risk who could benefit from ICD implant. See Article by Jablonowski et al Myocardial scar provides the substrate for the vast majority of life-threatening ventricular arrhythmias (VAs) and reentry circuits contained in the scar tissue are essential for ventricular tachycardia to occur. Late gadolinium enhancement (LGE) by Cardiac magnetic resonance (CMR) allows identification and quantification of myocardial scar and enables classification into 2 types of tissues: dense scar and border zone (BZ) depending on the signal intensity produced by LGE. BZ tissue can be distributed around the scar as the transition toward normal myocardium and can also be located in the scar thereby creating corridors of BZ inside the scar that connect with normal myocardium. These BZ corridors have a reasonably good correlation with conducting channels on the electroanatomical maps and have been shown to be the substrate for ventricular tachycardias. …

Background— Scar heterogeneity identified with contrast-enhanced cardiac magnetic resonance (CE-CMR) has been related to its arrhythmogenic potential by using different algorithms. The purpose of the study was to identify the algorithm that best fits with the electroanatomic voltage maps (EAM) to guide ventricular tachycardia (VT) ablation. Methods and Results— Three-dimensional scar reconstructions from preprocedural CE-CMR study at 3T were obtained and compared with EAMs of 10 ischemic patients submitted for a VT ablation. Three-dimensional scar reconstructions were created for the core (3D-CORE) and border zone (3D-BZ), applying cutoff values of 50%, 60%, and 70% of the maximum pixel signal intensity to discriminate between core and BZ. The left ventricular cavity from CE-CMR (3D-LV) was merged with the EAM, and the 3D-CORE and 3D-BZ were compared with the corresponding EAM areas defined with standard cutoff voltage values. The best match was obtained when a cutoff value of 60% of the maximum pixel signal intensity was used, both for core ( r 2 =0.827; P r 2 =0.511; P =0.020), identifying 69% of conducting channels (CC) observed in the EAM. Matching improved when only the subendocardial half of the wall was segmented (CORE: r 2 =0.808; P r 2 =0.485; P =0.025), identifying 81% of CC. When comparing the location of each bipolar voltage intracardiac electrogram with respect to the 3D CE-CMR–derived structures, a Cohen κ coefficient of 0.70 was obtained. Conclusions— Scar characterization by means of high resolution CE-CMR resembles that of EAM and can be integrated into the CARTO system to guide VT ablation.

The usefulness of contrast-enhanced cardiac magnetic resonance (ce-CMR) to guide the ventricular tachycardia (VT) ablation procedure has not been yet studied. Applied to tissue characterization, ce-CMR has demonstrated its ability to differentiate between normal and scarred tissue, providing details that also permit us to identify dysfunctional but viable myocardium. It has been suggested that the zones characterized as viable myocardium are probably the substrate for the VT reentry circuits.1 On the other hand, it has been described that the lesions produced by radiofrequency (RF) application in the myocardium may be detected by ce-CMR in animal experiments.2,3 However, there is no evidence showing that RF lesions can be observed in vivo in humans. We report the case of a 79-year-old patient with normal coronary arteries and 48% left ventricular (LV) ejection fraction, who presented with repetitive episodes of well tolerated VT (Figure 1). A 1.5-T ce-CMR study was performed the day before the ablation and repeated 24 hours after the procedure. Ten minutes after intravenous administration of gadolinium (gadodiamide, GE Healthcare) at a dose of 0.2 mmol/kg, sequential short axis …