Delayed-enhanced magnetic resonance imaging in nonischemic cardiomyopathy: utility for identifying the ventricular arrhythmia substrate.

OBJECTIVES The purpose of this study was to assess the value of delayed-enhanced magnetic resonance imaging (DE-MRI) to guide ablation of ventricular arrhythmias in patients with nonischemic cardiomyopathy (NIC). BACKGROUND In patients with NIC, ventricular arrhythmias often are associated with scar tissue. DE-MRI can be used to precisely define scar tissue. METHODS DE-MRI was performed in 29 consecutive patients (mean age 50 +/- 15 years) with NIC (mean ejection fraction 37 +/- 9%) referred for catheter ablation of ventricular tachycardia (VT) or premature ventricular complexes (PVCs). Scar was extracted from DE-MRIs and was then integrated into the electroanatomic map. Mapping data were correlated with respect to the localization of scar tissue. RESULTS Scar was identified by DE-MRI in 14 of 29 patients. Nine of these patients had VT and 5 had PVCs. In 5 of the patients there was predominantly endocardial scar, and mapping and ablation of arrhythmias was effectively performed from the endocardium in all 5 patients. In 2 patients scar was either intramural or epicardial with extension to the endocardium. In both patients with partial endocardial scar extension, the ablation was effective in eliminating some but not all arrhythmias. In 2 patients most of the scar tissue was confined to the epicardium; mapping identified and eliminated an epicardial origin in both patients. No effect on arrhythmias could be achieved in the other 5 patients with predominantly intramural scar. CONCLUSIONS DE-MRI in patients without prior infarctions can help to identify the arrhythmogenic substrate; furthermore, it helps to plan an appropriate mapping and ablation strategy.