Evaluation of a QRS scoring system for estimating myocardial infarct size. VI: Identification of screening criteria for non-acute myocardial infarcts

Abstract

Each of the 54 criteria in the Selvester 32-point QRS scoring system for estimation of myocardial infarct (MI) size has attained ≥95% specificity in normal subjects. This study was performed to identify a subset of those criteria with cumulative specificity ≥95% and maximal sensitivity for use in screening for the presence of non-acute MI. Coronary angiography and left ventriculography were used to identify 500 normal subjects, 60 patients with isolated anterior MI and 62 patients with isolated inferior MI. Patients with the QRS confounding factors of ventricular hypertrophy, fascicular block or bundle branch block on their electrocardiogram were not included. Using stepwise logistic regression analysis, the screening criteria identified were: (1) Q ≥30 ms in aVF, (2) R ≤10 ms and ≤0.1 mV in V₂ and (3) R ≥40 ms in V₁ Cumulatively, these 3 screening criteria achieved 84% and 77% sensitivities for inferior and anterior MI groups, respectively. Thus, a set of 3 criteria from the Selvester QRS scoring system is capable of identifying single non-acute anterior or inferior MI in 80% of patients, and falsely indicating presence of MI in only 5% of normal subjects.