title: Diagnosis of myocardial infarction and ischemia in the setting of bundle branch block and cardiac pacing.
abstract: The diagnosis of myocardial infarction (MI) in the presence of left bundle branch block (LBBB) or during ventricular pacing (VP) is challenging because of inherent changes in the sequence of ventricular depolarization and repolarization associated with both conditions. Although LBBB and right ventricular (RV) pacing may both produce abnormalities in the ECG, it is often possible to diagnose an acute MI (AMI) or an old MI based on selected morphologic changes. Primary ST-segment changes scoring 3 points or greater according to the Sgarbossa criteria are highly predictive of an AMI in patients with LBBB or RV pacing. The modified Sgarbossa criteria are useful for the diagnosis of AMI in patients with LBBB; however, these criteria have not yet been studied in the setting of RV pacing. Although changes of the QRS complex are not particularly sensitive for the diagnosis of an old MI in the setting of LBBB or RV pacing, the qR complex and Cabrera sign are highly specific for the presence of an old infarct. Diagnosing AMI in the setting of biventricular (BiV) pacing is challenging. To date there is minimal evidence suggesting that the traditional electrocardiographic criteria for diagnosis of AMI in bundle branch block may be applicable to patients with BiV pacing and positive QRS complexes on their ECG in lead V1. This report is a careful review of the electrocardiographic criteria facilitating the diagnosis of acute and remote MI in patients with LBBB and/or VP.
authors.affiliation: Department of Cardiovascular Disease, University of South Florida Morsani College of Medicine, South Tampa Campus (5th floor), Two Tampa General Circle, FL 33606, Tampa, FL, USA. Bherweg@health.usf.edu.
authors.forename: B
authors.initials: B
authors.lastname: Herweg
authors.affiliation: Department of Cardiovascular Disease, University of South Florida Morsani College of Medicine, South Tampa Campus (5th floor), Two Tampa General Circle, FL 33606, Tampa, FL, USA. marshallmarcus@health.usf.edu.
authors.forename: M B
authors.initials: MB
authors.lastname: Marcus
authors.affiliation: Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA. Ssbarold@aol.com.
authors.forename: S S
authors.initials: SS
authors.lastname: Barold
mesh_terms: D000465:Algorithms; D002037:Bundle-Branch Block / Q000150:complications / Q000175:diagnosis* / Q000517:prevention & control*; D003936:Diagnosis, Computer-Assisted / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D006801:Humans; D009203:Myocardial Infarction / Q000150:complications / Q000175:diagnosis* / Q000517:prevention & control*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Cardiac arrhythmias; Cardiac resynchronization therapy; Heart block; Heart diseases; Sgarbossa criteria