The prognostic value of new left bundle branch block in patients with acute myocardial infarction : a systematic review and meta-analysis -

Abstract

Background: Bundle branch block (BBB) is a conduction disorder that affects one or both branches of the bundle of His. Several factors were found to be associated with the development of BBB including acute myocardial infarction (AMI). Contradictory data exist concerning the independent contribution of left BBB to the risk of death among patients with AMI.Objective: To assess the prognostic value of new LBBB in patients who present with AMI.Methods: A systematic search of Medline, PubMed, CINAHL, and EMBASE was conducted without using any restrictions. Screening of the retrieved citations was made independently and in duplicate by the main investigator and five team members. Inverse variance meta- analysis was performed and summary effects presented as odds ratios and confidence intervals. Summary effects were presented for adjusted effect estimates when available; otherwise adjusted and unadjusted effect estimates were pooled. The I2 statistic was used to assess heterogeneity. Assessment of risk of bias was made by two authors independently.Results: The included eight eligible studies involved a total of 105,861 participants. New LBBB was associated with a statistically significant risk of mortality at 30 days (OR: 2.10, 95percent CI 1.27 to 3.48; I2: 85percent) and one year follow up (OR: 2.81, 95percent CI 1.64 to 4.80; I2: 4percent). Also, new LBBB was associated with a statistically significant increase in the risk of development of congestive heart failure (OR: 2.64, 95 percent CI: 1.84 to 3.77; I2: 79percent.Conclusion: New LBBB is associated with higher risk of mortality both at 30 days and one year follow up, and a higher risk of developing congestive heart failure. However, these results should be interpreted with caution due to the small number of studies and risk of bias in some of studies. More research is needed on this topic.