An estimate of the prevalence of reversible left ventricular dysfunction in patients referred for coronary artery bypass surgery

Background. The prevalence of reversible left ventricular function through revascularization has been difficult to assess because of the referral bias inherent in patients undergoing viability-targeted preoperative testing. Methods and Results. Rest and exercise gated equilibrium radionuclide angiography was performed in 86 patients within 6 months before and any time after coronary artery bypass. Clinical characteristics were recorded for each patient before each of the two radionuclide ventriculograms. Global left ventricular ejection fraction (LVEF) was calculated for each patient at rest. A definite change in LVEF was defined as 0.08 or more points and a probable change as 0.04 or more points. Only patients with a resting LVEF of 0.50 or less were eligible for the study. There was no significant group change in LVEF (0.39 ± 0.08 before surgery vs 0.38 ± 0.11 after surgery; difference not significant). However, a definite improvement in LVEF was seen in 18 patients (21%) and a probable change in an additional 10 (12%). Consequently, one third of the patients had at least a probable improvement in resting left ventricular function. These prevalences were not related to any change in medical therapy. Conclusion. According to a test not specifically designed to evaluate myocardial viability, the prevalence of reversible left ventricular dysfunction is not uncommon, occurring in up to one third of patients referred for coronary revascularization