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Brugada syndrome (BrS) is a controversial disease whose pathophysiology is still far from being fully understood. Unlike other cardiological disorders, a definite etiology has not yet been established so that it could be summarized under two main chapters: "functional" or "organic", "repolarization" or "depolarization" disorder. Despite initial descriptions leaned towards the organic substrate and delayed depolarization features, functional and repolarization theories have attracted most of the Cardiological attention for many years. Data from electrocardiography, endocavitary tracings, electroanatomic mapping and histopathology, however, demonstrated that BrS is mainly characterized by structural myocardial changes mostly at the right ventricular outflow tract (RVOT), but also at the right ventricle (RV) and by delayed conduction at the same sites. Conduction disorders at different levels may also be present and identify patients at high risk for major arrhythmic events. The aim of the present review is to provide the current state of art of the pathophysiology of BrS, focusing on electro-vectorcardiography and electrophysiological features, histopathology, echocardiography, and cardiac magnetic resonance imaging (CMRI)., (© 2022 Wiley Periodicals LLC.)

Primary ventricular fibrillation (PVF) may occur in the early phase of ST-elevation myocardial infarction (STEMI) prior to primary percutaneous coronary intervention (PCI). Multiple electrocardiographic STEMI patterns are associated with PVF and short-term mortality including the tombstone, Lambda, and triangular QRS-ST-T waveform (TW). We aimed to compare the predictive value of different electrocardiographic STEMI patterns for PVF and 30-day mortality. We included a consecutive cohort of 407 STEMI patients (75% males, median age 66 years) presenting within 12 h of symptoms onset. At first medical contact, 14 (3%) showed the TW or Lambda ECG patterns, which were combined in a single group (TW-Lambda pattern) characterized by giant R-wave and downsloping ST-segment. PVF prior to primary PCI occurred in 39 (10%) patients, significantly more often in patients with the TW-Lambda pattern than those without (50% vs. 8%, p < 0.001). For the multivariable analysis, Killip class ≥3 (OR 6.19, 95% CI 2.37–16.1, p < 0.001) and TW-Lambda pattern (OR 9.64, 95% CI 2.99–31.0, p < 0.001) remained as independent predictors of PVF. Thirty-day mortality was also higher in patients with the TW-Lambda pattern than in those without (43% vs. 6%, p < 0.001). However, only LVEF (OR 0.86, 95% CI 0.82–0.90, p < 0.001) and PVF (OR 4.61, 95% CI 1.49–14.3, p = 0.042) remained independent predictors of mortality. A mediation analysis showed that the effect of TW-Lambda pattern on mortality was mediated mainly via the reduced LVEF. In conclusion, among patients presenting with STEMI, the electrocardiographic TW-Lambda pattern was associated with both PVF before PCI and 30-day mortality. Therefore, this ECG pattern may be useful for early risk stratification of STEMI. [ABSTRACT FROM AUTHOR]

The so-called Brugada syndrome (BS), first called precordial early repolarization syndrome (PERS), is characterized by the association of a fascinating electrocardiographic pattern, namely an aspect resembling right bundle branch block with a coved and sometime upsloping ST segment elevation in the precordial leads, and major ventricular arrhythmic events that could rarely lead to sudden death. Its electrogenesis has been related to a conduction delay mostly, but not only, located on the right ventricular outflow tract (RVOT), probably due to a progressive fibrosis of the conduction system. Many tests have been proposed to identify people at risk of sudden death and, among all, ajmaline challenge, thanks to its ability to enhance latent conduction defects, became so popular, even if its role is still controversial as it is neither specific nor sensitive enough to guide further invasive investigations and managements. Interestingly, a type 1 pattern has also been induced in many other cardiac diseases or systemic diseases with a cardiac involvement, such as long QT syndrome (LQTS), arrhythmogenic right ventricular cardiomyopathy (ARVC), hypertrophic cardiomyopathy (HCM) and myotonic dystrophy, without any clear arrhythmic risk profile. Evidence-based studies clearly showed that a positive ajmaline test does not provide any additional information on the risk stratification for major ventricular arrhythmic events on asymptomatic individuals with a non-diagnostic Brugada ECG pattern. [ABSTRACT FROM AUTHOR]