Atrioventricular block in the postoperative period of heart valve surgery: incidence, risk factors and hospital evolution.

Introduction: Disturbances of the cardiac conduction system are potential complications after cardiac valve surgery. Objectives: This study was designed to investigate the association between perioperative factors and atrioventricular block, the need for temporary cardiac artificial pacing and, if necessary, permanent pacemaker implantation after cardiac valve surgery. Methods: Retrospective analysis of the Cardiac Surgery Database - Hospital So Lucas/PUCRS. The data are collected prospectively and analyzed retrospectively. Results: Between January 1996 and December 2008 were included 1102 valve surgical procedures: 718 aortic valves (65.2%), 407(36.9%) mitral valve and 190(17.2%) coronary artery bypass grafting combined with valve repair and 23 (2.1%) aortic and mitral combined surgery. 187 patients (17%) showed clinical and electrocardiographic pattern of atrio-ventricular block requiring artificial temporary pacing. Of these, 14 patients (7.5%) required permanent pacemaker implantation (1.27% of the total valve surgery patients). Multivariate analysis showed association of the incidence of atrio-ventricular block and temporary pacing with mitral valve surgery (OR 1,76; Cl 95% 1.08-2.37; P=0.002), implantation of bioprosthetic devices (OR 1.59; Cl 95% 1.02-3.91; P=0,039), age over 60 years (OR 1.99; Cl 95% 1.35-2.85; P<0.001), prior use of anti-arrhythmic drugs (OR 1.86; Cl 95% 1.04-3.14; P=0.026) and previous use of b-blocker (OR 1.76; Cl 95% 1.25-2.54; P=0.002). Remarkably the presence of atrio-ventricular block did not significantly show association with increased mortality, but significantly prolonged (P<0.0001) hospital length-of-stay and, therefore, hospital costs. Conclusions: Our study presents a group of predictive factors referring to a specific patient profile by which high risk of atrio-ventricular block and the need of temporary cardiac pacing after cardiac valve surgery it is determined.