Risk factors associated with long QT syndrome in cardiovascular anesthesia

Introduction: The long QT syndrome is a channelopathy characterized by a serious alteration in ventricular repolarization. Objective: To determine the risk factors associated with prolonged QT interval in cardiovascular anesthesia. Methods: Descriptive, cross-sectional study from May 2014 to May 2016, in patients scheduled for cardiac surgery under extracorporeal circulation. The attributable risk and the confidence interval were evaluated for 95% and in variables with p value under 0.05. Results: 483 patients were included, with a mean age of 62 years, of whom 57 (12 %) had prolonged QTc. Advanced age (RA: 1.8, 95 % CI: 0.86-2.67), chronic renal failure (RA: 2.7, 95 % CI: 0.82-4.96), type 2 diabetes mellitus (RA: 1.7, 95 % CI: 1.01-2.15), ischemic heart disease (RA: 3.5, 95 % CI: 1.60-4.02), left ventricular hypertrophy (RA: 2.2, 95 % CI: 2.53-3.15), calcium-lactam antibiotics (RA: 1.5, 95 % CI: 0.92-2.98), balanced orotracheal general anesthesia (RA: 2.1, 95 % CI: 2.92-2.35), ondansetron (RA: 1.7, 95 % CI: 0.98-2.74), droperidol (RA: 1.8, 95 % CI: 2.18-3.94) ), extracorporeal circulation time (RA: 2.5, 95 % CI: 1.02-3.62), hypokalemia (RA: 1.4, 95 % CI: 1.03-2.91) and severe bradycardia (RA: 1.8, 95 % CI: 1.12-3.86) were associated with a high risk of QT prolongation. The complications were more significant in this group, with a mortality of 23%. Conclusions: Advanced age, chronic renal failure, type 2 diabetes mellitus, ventricular hypertrophy, and ischemic heart disease facilitate the prolongation of QT induced by calcium blockers. The longer time of extracorporeal circulation, the balanced anesthesia with isoflurane, the use of droperidol and ondansetron, bradycardia and postoperative hypokalemia are variables associated with the extension of the QT interval, with an increase in complications. Ventricular tachyarrhythmias and mortality were higher in this subgroup of patients.