Electrocardiographic signs of acute myocardial infarction in left bundle branch block.

Introduction: Acute myocardial infarction is characterized by typical chest pain, electrocardiographic changes in terms of lesion and/or myocardial ischemia and increased cardiac enzymes. It is often difficult to make diagnosis in the presence of non-specific chest pain, the short duration of symptoms and electrocardiographic signs of a complete left bundle branch block.

Literature Review: Many authors have tried to set the electrocardiographic criteria that can increase the possibility of correct diagnosis of acute myocardial infarction in such situations. The most widely used and recognized criterion is Sgarbossa scoring system that includes concordant ST segment elevation > 1 mm ST segment, disconcordant denivelation of ST segment > 1 mm in the leads V1-V3 and disconcordant ST segment elevation > 5 mm with acceptable sensitivity and specificity. In subsequent studies, the sensitivity and specificity increased by replacing the third criterion with ST/S ratio < -0.25.

Conclusion: The knowledge of certain electrocardiographic signs in patients with acute coronary syndrome and left bundle branch block increases the chances of early diagnosis and the possibility of better and timely treatment.