Characterization of ARVC substrate on MRI and electrophysiological mapping

Methods We studied consecutive patients with definite ARVC diagnosis according to Task Force criteria (TFC), undergoing electrophysiological study for ventricular tachycardia. CMR imaging was performed on a 1.5T system (Avanto, Siemens, Erlangen, Germany). SSFP cine imaging was performed in 2 stacks of contiguous 6 mm-thick slices encompassing the whole ventricles in short axis and 4-chamber orientations. BH-LGE imaging was performed 10 min after the injection of 0.2 mmol/Kg gadoterate meglumine using a 3D turbo FLASH sequence in 3 stacks of contiguous 6 mm-thick slices encompassing the whole ventricles in short axis, 2-chamber and 4-chamber orientations (pixel size 1.6 × 1.6 × 6 mm). FB-LGE acquisition was initiated 15 min after contrast using an inversion recovery-prepared and respiratory navigated 3D Turbo FLASH sequence with fat saturation, in order to acquire a whole heart volume at higher spatial resolution (pixel size 1.25 × 1.25 × 2.5mm). Wall motion abnormalities (WMA) and LGE were assessed by 2 observers analyzing the images in consensus. This substrate was distributed over a biventricular 16-segment model: the RV and LV free walls comprised 7 segments each (3 basal, 3 midventricular and 1 apical), and the septum comprised 2 segments (basal and midventricular). All patients underwent electrophysiological contact mapping during sinus rhythm on RV endocardium and RV and LV epicardium. Low bipolar voltage and local abnormal ventricular activity (LAVA) were distributed over the same segmentation.