Abstract 2739: First Clinical Experience With Integration of Three-Dimensional, Delayed Enhancement MRI Scar in Patients With ICD for Guidance of Ventricular Tachycardia Ablation
Introduction: Magnetic resonance imaging (MRI) is contraindicated in patients with ICDs. However, delayed-enhanced (DE) MRI is able to accurately delineate the three dimensional (3D) architecture of myocardial scar, which is the target of substrate-guided VT ablations. This study sought to assess the feasibility of DE MRI in ICD patients, the ability to integrate 3D MRI scar maps and its utility for VT ablations.
Methods: Nine patients with ischemic cardiomyopathy and recurrent ICD shocks underwent DE MRI with a specific absorption rate of < 2.0W/kg. Using a voxel-based, semi-automatic algorithm endocardial/epicardial surfaces and 3D scar were reconstructed. MRI-based cardiac anatomy and 3D scar were registered with a clinical mapping system using a developmental software application (Carto IPE). High resolution voltage maps were performed guided by the integrated 3D scar maps and compared with the detailed MRI-defined anatomy.
Results: MRI was safely performed in all patients (p > 0.05 for pre/post-MRI battery voltage, P/R wave, thresholds). Adjusting for the metal-induced artifact MRI scar maps could be registered with a registration error of 3.9±1.1mm. MRI predicted correctly decreasing endocardial voltage with increasing scar transmurality (p < 0.05) and eliminated falsely-low voltage points due to suboptimal catheter contact (6%). Inversely, MRI was able to identify surviving anatomic areas with normal voltage (e.g. papillary muscle). Bipolar/unipolar voltages of 1.4±0.4mV/4.5±1.2mV correlated best with the MRI-defined scar area. Fractionated potential were found more frequently within 10mm of the border zone than within the scar center (67% vs. 33%) as were diastolic potentials (73% vs. 26%; p < 0.05 for both). 62% of fractionated potentials and 88% of diastolic potentials were found in areas of 75–100% transmural MRI-defined scar.
Conclusions: DE MRI can be safely performed in selected ICD patients. The registration of detailed 3D scar maps into clinical mapping systems provides a supplementary scar characterization and allows to target high-resolution voltage mapping. This suggests a possible role of DE-MRI integration to facilitate and shorten ischemic VT ablations.
This research has received full or partial funding support from the American Heart Association, National Center.