ST-Segment Elevation and Fractionated Electrograms in Brugada Syndrome Patients Arise From the Same Structurally
Judith N Ten Sande1, Ruben Coronel1, Chantal E Conrath1
1From the Heart Center, Department of Clinical and Experimental Cardiology, Academic Medical Center, University of Amsterdam, Amsterdam (J.N.t.S., R.C., C.E.C., A.H.G.D., J.R.d.G., H.L.T., A.A.M.W., J.M.T.d.B., P.F.H.M.v.D.); Interuniversity Cardiology Institute of the Netherlands, Utrecht, the Netherlands (J.N.t.S., J.M.T.d.B.); L'Institut de RYthmologie et de modélisation Cardiaque (LIRYC), Université Bordeaux Segalen, Bordeaux, France (R.C.); and Pacific Rim Electrophysiology Research Institute, Los Angeles, CA (K.N.).
Background:
Brugada syndrome (BrS) is characterized by a typical ECG pattern. We aimed to determine the pathophysiologic basis of the ST-segment in the BrS-ECG with data from various epicardial and endocardial right ventricular activation mapping procedures in 6 BrS patients and in 5 non-BrS controls.
Methods And Results:
In 7 patients (2 BrS and 5 controls) with atrial fibrillation, an epicardial 8×6 electrode grid (interelectrode distance 1 mm) was placed epicardially on the right ventricular outflow tract (RVOT) before video-assisted thoracoscopic surgical pulmonary vein isolation. In 2 other BrS patients, endocardial, epicardial RV (CARTO), and body surface mapping was performed. In 2 additional BrS patients, we performed decremental preexcitation of the RVOT before endocardial RV mapping. During video-assisted thoracoscopic surgical pulmonary vein isolation and CARTO mapping, BrS patients (n=4) showed greater activation delay and more fractionated electrograms in the RVOT region than controls. Ajmaline administration increased the region with fractionated electrograms, as well as ST-segment elevation. Preexcitation of the RVOT (n=2) resulted in ECGs that supported the current-to-load mismatch hypothesis for ST-segment elevation. Body surface mapping showed that the area with ST-segment elevation anatomically correlated with the area of fractionated electrograms and activation delay at the RVOT epicardium.
Conclusions:
ST-segment elevation and epicardial fractionation/conduction delay in BrS patients are most likely related to the same structural subepicardial abnormalities, but the mechanism is different. ST-segment elevation may be caused by current-to-load mismatch, whereas fractionated electrograms and conduction delay are expected to be caused by discontinuous conduction in the same area with abnormal myocardium.
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