title: False-positive posterior myocardial infarct criteria during left anterior descending coronary angioplasty.
abstract: In reviewing ECG change during acute anterior myocardial infarction (AMI) and during transluminal coronary angioplasty of the left anterior descending (LAD) coronary artery, QRS changes mimicking posterior myocardial infarct (PMI) and false-positive points for PMI using the QRS infarct size scoring system were observed in about 20% of patients. Nineteen patients in whom a three-lead electrocardiogram (ECG) was continuously recorded during transluminal coronary angioplasty of a proximal left anterior descending (LAD) coronary artery were reviewed. All but two had significant ST-segment shifts in V2 within a few seconds of balloon occlusion of a proximal LAD. In many such patients the R wave amplitude in V2 measured from the PR segment baseline remained relatively stable and the S amplitude tracked with the J. point. However, of the 19 patients studied, 11 had transient QRS changes greater than could be accounted for by baseline shift alone and 4 had transient false-positive PMI points by QRS MI size score. Transient QRS changes were observed as follows: (1) significant increase in R waves and/or decrease in S waves in V2 due to right septal block (or conduction delay) occurred in 3 of 11 patients and was the cause of the false-positive criteria for PMI; (2) 5 of 11 patients had a major decrease in R waves in V2 due to left septal block; (3) 2 of 11 patients had both (1) and (2); and (4) 1 of 11 had transient frontal plane axis shifts with the QRS configuration of anterosuperior fascicular block plus right and left septal block.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Medicine, University of Southern California/Rancho Los Amigos Medical Center, Downey 90242.
authors.forename: R H
authors.initials: RH
authors.lastname: Selvester
authors.forename: N B
authors.initials: NB
authors.lastname: Wagner
authors.forename: G S
authors.initials: GS
authors.lastname: Wagner
mesh_terms: D000800:Angioplasty, Balloon; D003327:Coronary Disease / Q000628:therapy; D003331:Coronary Vessels; D004562:Electrocardiography; D005189:False Positive Reactions; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D007430:Intraoperative Care; D008991:Monitoring, Physiologic; D009203:Myocardial Infarction / Q000175:diagnosis*