Methodology of serial ECG classification using an adaptation of the NOVACODE for Q wave myocardial infarction in the bypass angioplasty revascularization investigation (BARI)

• Published in: Journal of electrocardiology 1996-10, Vol.29 (4), p.265-277
• Main Authors: Chaitman, Bernard R., Zhou, Sophia H., Tamesis, Beaver, Rosen, Allan, Terry, Art B., Zumbehl, Kim M., Stocke, Karen, Takase, Bonpei, Gussak, Ihor, Rautaharju, Pentti M.
• Format: Article
• Language: English
• Subjects: Algorithms; Angioplasty, Balloon, Coronary; Biological and medical sciences; Canada; Cardiology. Vascular system; clinical trial methodology; Coronary Disease - classification; Coronary Disease - diagnosis; Coronary Disease - therapy; Coronary heart disease; ECG classification; Electrocardiography - classification; Electrocardiography - instrumentation; Electrocardiography - methods; Electrocardiography - statistics & numerical data; Follow-Up Studies; Heart; Humans; Medical sciences; myocardial infarction; Myocardial Infarction - classification; Myocardial Infarction - diagnosis; Observer Variation; Signal Processing, Computer-Assisted - instrumentation; Software - statistics & numerical data; United States
• ISSN: 0022-0736; 1532-8430
• DOI: 10.1016/S0022-0736(96)80091-4

Serial electrocardiographic (ECG) changes are a critical component of the diagnostic algorithm for classification of myocardial ischemic events in large-scale clinical trials. This study describes a computerized serial ECG classification program developed at the St. Louis University Core ECG Laboratory for use in the Bypass Angioplasty Revascularization Investigation (BARI) trial, in which patients with multivessel coronary artery disease were randomized to receive either coronary artery bypass grafting or percutaneous transluminal coronary angioplasty. The St. Louis University program detects and codes serial changes in Q, ST, and T wave items according to Minnesota code (MC) criteria using a modified NOVACODE hierarchical classification system. Measurements using a seven-power calibrated coding loupe are used to generate the MC from a customized software program. Significant minor or major changes are detected by the serial comparison program and referred to a physician coder for verification. Serial comparison coding rules are used to adjust for weaknesses in the standard MC classification system resulting from instability at decision boundaries. Of 4,244 BARI randomized and registry study participants with follow-up ECGs received at the Core ECG Laboratory as of March 1995, a grade 2 MC Q wave progression was noted in 568 participants (13.4%) using MC criteria alone, as compared with 367 (8.6%) after the St. Louis University coding rules were applied. The incidence of grade 1 MC Q wave progressions was 16.4% (697/4,244) versus 6.1% (259/4,244) when the St. Louis University program was applied. Intraobserver variability for grade 2 Q wave progression codes determined from a sample of 812 serial ECG comparisons revealed kappa statistics of 0.88, 0.84, and 1.0 for the anterior, inferior, and lateral lead groups, respectively. In conclusion, the use of the standard MC in this multicenter clinical trial of patients with multivessel coronary disease indicates that additional coding rules are necessary to adjust for intrinsic weaknesses and instability at decision boundaries in the code resulting from biologic variability and coding variation.