AIM: To analyze the risk of cardiovascular complications in patients with indication for surgical treatment of Chagasic esophageal achalasia and to correlate the surgical risks with the degree of esophageal dilation,thereby proposing a risk scale index.METHODS: One hundred and twenty-four patients with Chagasic esophageal achalasia, who received surgical treatment at the Hospital das Clinicas of the Federal patients were mostly related to the postoperative complications due to the cardiovascular system. All the patients were submitted to: (1) clinical history to define the cardiac functional class (New York Heart Association);(2) conventional 12-lead electrocardiogram at rest; and (3) contrast imaging of the esophagus to determine esophageal dilatation according to Rezendes classification of Chagasic megaesophagus.RESULTS: An assessment of the functional classification (FC) of heart failure during the preoperative period determined that 67 patients (54.03%) were assigned functional class Ⅰ (FC Ⅰ), 46 patients (37.09%) were assigned functional class Ⅱ (FC Ⅱ), and 11 patients (8.87%) were assigned functional class Ⅲ (FC Ⅲ). None of the patients were assigned to functional class Ⅳ (FC Ⅳ). There was a positive correlation between the functional class and the postoperative complications (FC ⅠxFC Ⅱ: P＜0.001; FC ⅠxFC Ⅲ: P＜0.001). The ECG was normal in 44 patients (35.48%) and presented abnormalities in 80 patients (64.52%). There was a significant statistical correlation between abnormal ECG (arrhythmias and primary change in ventricular repolarization) and postoperative complications (P＜0.001).With regard to the classification of the Chagasic esophageal achalasia, the following distribution was observed: group Ⅱ, 53 patients (42.74%); group Ⅲ, 37 patients (29.83%);and group Ⅳ, 34 patients (27.41%). There was a positive correlation between the degree of esophageal dilation and the increase in postoperative complications (grade Ⅱxgrade Ⅲ achalasia: P＜0.001; grade Ⅱ×grade Ⅳ achalasia: P＜0.001; and grade Ⅲxgrade Ⅳ achalasia:P = 0.017). Analyzing these results and using a multivariate regression analysis associated with the probability decision analysis, a risk scale was proposed as follows: up to 21 points (mild risk); from 22 to 34 points (moderate risk);and more than 34 points (high risk). The scale had 82.4% accuracy for mild risk patients and up to 94.6% for the high risk cases.CONCLUSION: The preoperative evaluation of the cardiovascular system, through a careful anamnesis, an ECG and contrast imaging of the esophagus, makes possible to estimate the surgical risks for Chagas disease patients who have to undergo surgical treatment for esophageal achalasia.