Right ventricular epicardial arrhythmogenic substrate in long-QT syndrome patients at risk of sudden death

Figures

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  Figure 1. Epicardial arrhythmogenic substrate. Patient #3. LQTS Male patient (QTc 535 ms, ECG top panel; paper speed 25 mm/sec, two major marks in the time scale indicate 1 s). surviving a previous cardiac arrest and experiencing several appropriate ICD shocks (ICD recording, top panel). Epicardial mapping identified abnormal electrograms characterizing the arrhythmogenic substrate (CARTO map, bottom panel). The abnormal signals present an abnormal amplitude (<1.0 mV) and are characterized by multiple fragmented and double components (bottom panel on the left side). The distribution of abnormal signals extended from the epicardial outflow tract to the infero-lateral peri-tricuspid region including part of the anterior wall. These abnormalities accounted for a surface area of 20.4 cm2.

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  Figure 2. Effect of arrhythmogenic substrate elimination. Patient #4. LQTS female patient experiencing ICD shocks. The 12-lead ECGs show QTc shortening from 525 ms, recorded at the beginning of the procedure (top panel on the left), to 482 ms, obtained after ablation (bottom panel on the left). The epicardial mapping (top panel on the right) showed a large arrhythmogenic substrate (17.8 cm2) involving a wide surface of the RVOT and anterior RV epicardium. The region depicted in red represents a low-voltage area (<0.5 mV), indicating the progression of the disease towards fibrosis. The abnormal potentials presented fragmentation and multiple components over this area (same characteristics described in Figure 1). Catheter ablation over the arrhythmogenic substrate area resulted in the disappearance of the abnormal electrogram fragmentation (EGM example, bottom panel on the right). In the bottom panel on the left, transient ST-segment elevation is observed in V1-V3 lead due to the epicardial ablation over the anterior RV epicardium, which completely solved during the follow-up (see Supplementary material online, Figure S4). The ECGs are shown at 25 and 50 mm/sec paper speed; two major marks…

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  Figure 3. Cluster of epicardial electrogram abnormalities in LQTS. Schematic representation of the electrogram abnormalities described in patients with LQTS (double abnormal electrical activities, fragmentation, and low-voltage/microstructural damage). The epicardial mapping shows example of three LQTS patients (#3, 6 and 5, respectively) featured by abnormal electrograms with different characteristics. The abnormal signals present multiple and discrete components (circle and star; left panel) expression of the local electrical delay. The overall amplitude is still partially preserved. The electrophysiological substrate may progress to more advanced microstructural functional remodelling initially characterized by electrogram fragmentation (circle and star; middle panel), and lately by low-voltage (<0.5 mV) and epicardial structural fibrosis (circle and star; right panel). This represents a hypothesis to explain why we have a pronounced delayed component and signal fragmentation in some patients and a significant reduction in signal voltage (< 0.5 mV) in others. We do not yet have a definitive explanation for the nature of such electrograms, yet the morphology and characteristics of the…