Transient left septal fascicular block in the setting of acute coronary syndrome associated with giant slurring variant J‐wave

Abstract

We report a case of acute coronary syndrome with transient prominent anterior QRS forces (PAF) caused by proximal subocclusion of the left anterior descending (LAD) coronary artery before the first septal perforator branch. The ECG change indicates left septal fascicular block (LSFB) with associated slurring-type giant J-wave. Currently, this J-wave variant is considered as a lambda-like wave or QRS-ST-T "triangulation". Its presence is indicative of poor prognosis because of the risk for cardiac arrest as a consequence of ventricular tachycardia/ventricular fibrillation (VT/VF).

Variant Angina with Spontaneously Documented Ischemia- and Tachycardia-induced "Lambda" Waves

“…In contrast, the existence of conduction defects of the LSF remains controversial. Pérez-Riera et al reported several cases of transient PAF thought to be caused by LSFB in the setting of proximal LAD disease and have stated that the characteristic ECG feature of LSFB is PAF on the horizontal plane (21,22). These ECG findings should be distinguished from other conditions that also produce PAF, such as right ventricular enlargement, lateral myocardial infarction, right bundle branch block, Wolff-Parkinson-White syndrome, hypertrophic cardiomyopathy, and Chagas cardiomyopathy in Latin America.…”

Forças Anteriores Proeminentes do QRS Durante Suboclusão Transitória do Tronco da Coronária Esquerda

“…Vários manuscritos sucessivos do nosso grupo e de outros mostraram que uma grande proporção de casos com LSFB, manifestado por forças anteriores proeminentes do QRS, é causada por obstrução proximal crítica da DAE antes de seu primeiro ramo perfurante septal. [6][7][8][9] Como a DAE é uma continuação do TCE, uma obstrução significativa do TCE pode levar à isquemia na porção média e no território apical do ventrículo esquerdo, onde fica o fascículo septal esquerdo, causando a LSFB.…”

Transient left septal fascicular block in a patient with stable effort angina and critical proximal obstruction of left anterior descending coronary artery

“…Successive publications from our group [6][7][8][9][10][11] and others [12] have provided ECG evidence that blockage of the LSF of the LBB is an incontestable reality. Consequently, the term "hemiblock", unfortunately still the predominant term [13] to denominate the blockages of the LBB fascicles, can be inappropriate according to the new evidence [14], because the LBB is not divided into two but into three fascicles.…”