Asymptomatic New-Onset Left Bundle Branch Block in a Preanesthetic Evaluation for Noncardiac Surgery: Does it Matter?

Background and Objectives: To determine the prevalence of and risk factors for cardiovascular abnormalities of asymptomatic newonset left bundle branch block (LBBB) in elective noncardiac surgery. Methods: This study was a retrospective chart review about the preanesthetic evaluation center at a medical center in southern Taiwan. The charts of 87,185 patients who underwent elective noncardiac surgery in were reviewed. Patients who showed LBBB in the preanesthetic electrocardiogram were enrolled and analyzed. Patients with positive findings in the preanesthetic cardiovascular examination were categorized into the positive group, while the others were placed in the negative group. Prevalence of asymptomatic new-onset LBBB, risk factors for positive findings, and adverse postoperative outcomes. Results: The prevalence rates of new-onset LBBB and asymptomatic new-onset LBBB were 0.042% and 0.031%, respectively. Among those patients, positive findings were detected in 64% of preoperative cardiovascular examinations. Age was a risk factor for cardiovascular abnormality; being older than 63.5 years was a risk factor for positive findings in a preanesthetic cardiovascular examination with a sensitivity of 88% and a specificity of 56%. The prevalence of adverse outcomes was 25.0% in the positive group and 22.2% in the negative group (no significant difference). Conclusion: The prevalence of LBBB in this Asia population was relatively low. It is suggested that preanesthetic cardiovascular examinations should be performed in patients older than 63.5 years.