An ischemic index from the electrocardiogram to select patients with low left ventricular ejection fraction for coronary artery bypass grafting

Abstract

Patients who have a decreased left ventricular (LV) ejection fraction (EF) may be denied coronary by-pass grafting (CABG) because it is assumed that improvement in function is unlikely. If the low LVEF were due to myocardial necrosis, this assumption would be valid. If the dysfunction were due to both necrosis and ischemia, however, then improvement may be possible with CABG. A method capable of identifying such patients would be useful. In this study, an "ischemic index" was determined for 37 patients based on the difference between the presurgical LVEF estimated from the standard 12-lead electrocardiogram by the Selvester QRS score (indicating the extent of dysfunction due to necrosis) and the presurgical LVEF measured from resting multigated radionuclide angiography (indicating dysfunction due to both necrosis and ischemia). It was hypothesized that a high ischemia index, that is, a large discrepancy between estimated and measured LVEF, would be associated with an improved post-surgical measured LVEF. The results showed that patients with an ischemic index of less than or equal to 0 had a mean decrease in LVEF of 8% (p = 0.02) and those with an index between 0 and 10 had no mean change. Patients with an index greater than or equal to 11, however, had a mean increase of 5% (p = 0.02), suggesting that depressed LVEF may improve following CABG among patients whose low function is due primarily to reversible ischemia as indicated by a high ischemic index.