Vectorcardiographic monitoring of patients with acute myocardial infarction and chronic bundle branch block

AIM: This study was set up to describe vectorcardiographic patternsin patients with bundle-branch block and acute myocardial infarction. METHODS AND RESULTS: Sixty-five patients admitted to the coronary care unit withbundle-branch block and suspected acute myocardial infarctionwere monitored by dynamic vectorcardiography with trend analysis.In 28 patients, a clinical diagnosis of acute myocardial infarctionwas made. In patients with left bundle-branch block and acutemyocardial infarction, the pattern of QRS vector-differenceevolution was similar to that in patients with the narrow QRScomplex, while ST vector-magnitude changes increased over time.Using a cut-off value for QRS vector-difference at 12 h of morethan 20 µVs and a specific trend curve pattern, acutemyocardial infarction in the presence of left bundle-branchblock could be diagnosed with an accuracy of 71%. For patientswith right bundle branch block, using a maximum ST vector-magnitudeof >200 µV during the first 4 h, acute myocardial infarctioncould be diagnosed with a 78% accuracy. CONCLUSION: Our results indicate that dynamic vectorcardiography is a valuabletool in diagnosing and monitoring acute myocardial infarctionin patients with bundle branch block.