Cardiovascular diseases are the leading cause of death in Chile. Acute Coronary Syndrome (ACS) forces health systems to allocate high-cost resources for diagnosis. Procedures like Electrocardiogram (ECG) and cinecoronariography (CCG) guide the diagnosis of these pathologies, with ECG being a non- invasive exam easy to perform and of low cost. The aim of this study was to connect ECG exams with CCG to improve the diagnostic accuracy of coronary obstruction. This was a descriptive cross-sectional study, consisting of 44 adult patients of both sexes which presented myocardial infarction with ST-segment elevation (STEMI) referred to the Hemodynamic Service from Iquique Clinic, Chile, for coronary operation. All 44 patients had previous ECG and they were conducted a CCG. Results established a strong correlation between ECG and CCG diagnosis from the total of Clogged Arteries (according to Pearson correlation test = 0.80; p < 0.001). The correlation demonstrated in both exams was 92.3 % (p = 0.001) for blockage in the right coronary artery (RCA) with electrocardiographic finding corresponding to inferior wall infarction. 100 % relationship for the obstruction of the circumflex branch of the left coronary artery (LCA) (p = 0.036) and 100 % for the obstruction of RCA anterior interventricular branch or anterior descending coronary artery (p = 0.001) corresponding to a lateral wall infarction. It is concluded that there is a significant relationship between anterior wall infarction according to electrocardiographic findings and RCA obstruction and LCA circumflex branch according to CCG. In addition, there is a significant relationship between lateral wall infarction and interior walls by ECG findings and the obstruction of the anterior interventricular branch of the left coronary artery diagnosed by CCG. The correct interpretation of ECG is essential to improve the care of acute myocardial infarction.