ABC | Volume 114, Nº4, Suplement, April 2020

Case Report Alencar Neto et al. A painful left bundle branch block syndrome case Arq Bras Cardiol 2020; 114(4Suppl.1):34-37 The best theory so far was proposed by Virtanen et al., 3 who speculated that the pain could be induced by abnormal systolic motion of the septum in ventriculography. An inferior axis which presented uniformly in a series of cases made the authors hypothesize that this could reflect a specific contractility pattern. Shvlikin et al. 7 proposed criteria to the diagnosis of painful LBBB syndrome (Table 1). 7 Similar to the memory T waves of paced patients, chronic LBBB has lower amplitude T waves than acute LBBB. In a prospective study, a S/T ratio < 2.5 in precordial leads proved to be useful (100% sensitivity and 89% specificity) to help distinguish between new-onset or chronic LBBB, 8 which refers to one of the items of the criteria proposed in Table 1. The patient described in this paper was referred to EPS because of the mistaken hypothesis of supraventricular tachycardia with aberrancy. During the study, with continuous atrial pacing, we had the opportunity to register the exact moment of left bundle branch blockade and the immediate complain about the same pain she referred to as chronic. Regarding the criteria proposed by Schvilkin et al., 8 our case matches all but one criterion: the “inferior axis criterion”. However, other publications evidenced superior QRS complex axis as well. 9,10 The S/T wave ratio was 1,33 in V2 (Figure 3), which is compatible with acute onset LBBB. The patient had abrupt onset of pain, as registered by the members of our team in our electrophysiology lab; the resolution of the symptoms occurred immediately after the resolution of the LBBB; The basal 12-lead ECG was normal. A stress test discarded myocardial ischemia and the CT angiography evidenced normal coronary arteries. Echocardiography and cardiac resonance were both normal, excluding secondary causes of angina. Conclusion We reported the case of a patient with painful LBBB who was referred to electrophysiology study. The abrupt onset of pain immediate after left bundle blockade is incompatible with ischemia and the patient underwent exams that discarded coronary and myocardial involvement. The best hypothesis for the pathophysiology of this syndrome is painful desynchrony of the heart due to acute onset LBBB. To our knowledge, this is the first case report of this syndrome in a Brazilian medical journal. Author contributions Conception and design of the research: Alencar Neto JN, Cirenza C, Paola AAV; Acquisition of data: Alencar Neto JN, Sakai MH, Moraes SRR; Writing of the manuscript: Alencar Neto JN, Sakai MH, Moraes SRR, Paola AAV; Critical revision of the manuscript for intellectual content: Cirenza C, Paola AAV. Potential Conflict of Interest No potential conflict of interest relevant to this article was reported. Sources of Funding There were no external funding sources for this study. Figure 3 – S/T ratio < 1.8 in V2. 36