Effects of pulmonary emphysema on QRS infarct size score.

Pulmonary emphysema can produce false-positive electrocardiographic (ECG) changes of anterior myocardial infarction (MI). This problem was not addressed in earlier studies of the Selvester 54 Criteria/32 Point QRS score for MI size. The purpose of this study was to examine an automated Hewlett Packard ECG Computer Language (HP-ECL) implementation of the QRS score in the following groups of subjects. Patients who had been studied for possible lung disease with pulmonary tests, including lung volumes, were divided into two groups: group 1 (n = 133), with abnormal tests (emphysema); and group 2 (n = 102), with normal tests (no emphysema). Two other groups were studied: group 3 (positive controls, n = 44), with greater than 3 QRS points for MI on ECG and documented coronary disease with wall motion abnormalities on angiography; and group 4 (negative controls, n = 146), 49 house staff and 97 clinically normal men. A frontal plane P axis greater than 65 separated 90% of patients with emphysema from those without. Of 133 patients with emphysema, 60 (45%) had greater than 3 QRS points for MI on ECG, mainly from Q criteria in aVL and V1-V3; decreased R criteria 1 in V2, V3, and V6; and abnormal R/S criteria in V4-V6. Using HP-ECL, the QRS score was readily modified so that when P axis was greater than 65 these MI size criteria were suppressed. This resulted in a more appropriate incidence of MI diagnoses: 2% (down from 45%) in emphysema patients, no change in specificity, and minor reduction in sensitivity to MI in infarct controls from 100% to 96%.(ABSTRACT TRUNCATED AT 250 WORDS)