A three-dimensional computed model of ST segment abnormality in type 1 Brugada Pattern: A key role of right ventricular outflow tract orientation?

Since its first description, Brugada Syndrome is characterized by definite ECG abnormalities (J wave, elevated ST segment) confined in right precordial leads. Brugada Pattern (BP) could be found in one or more right precordial leads, at conventional or higher intercostal spaces. A recent study, conducted by our group, reported that slightly less than one half of patients with type 1 BP show a definite ST segment depression (≥0.1 mV with duration ≥ 0.08 s) in the inferior leads. With these premises, 4 distinct ST abnormalities phenotypes can be recognizable in Type 1 BP. We speculated the key role of orientation of right ventricular outflow tract in the thorax, particularly the inclination of anterior wall compared to the sternum, contributing to the determination of these various ECG phenotypes. An interactive program, ECGsim, able to simulate ECG appearance in several anatomical and electrical models, confirmed this assumption. This computed model affirmed the strict relationship between ST segment depression in the inferior leads and the ST segment elevation in right precordial leads, typical of type 1 BP. A horizontal right ventricular outflow tract, in fact, gives raise to abnormal BP vector directed both superiorly and anteriorly, explaining, at the same time, typical BP appearance in right precordial leads and ST segment depression in the inferior leads.