Abstract 101: Is The Question Of Viability Imaging In Patients With Left Ventricular Dysfunction Relevant? Predictors Of Post-viability Imaging Referral To Revascularization

Abstract

Background . In light of the recent STICH trial results, the clinical practice of viability imaging in patients (pts) with reduced left ventricular (LV) function has been called to question. Whether measures of hibernating myocardium alter pt management is unknown. We explored the impact of the results of cardiac positron emission tomography (PET) perfusion and viability imaging on short-term referral to revascularization. Methods . We identified 586 consecutive patients with LV ejection fraction (EF) <50% who underwent Rb-82 dipyridamole stress/rest perfusion imaging with fluorodeoxyglucose (FDG) PET between March, 2006 and May, 2009. Automated quantitative software with user defined limits was used to determine the amount of myocardium that was scar, ischemic, or hibernating based on these results. Early revascularization (EREV) was performed within 90 days of PET in 198 patients (34%). Multiple logistic regression was used to model the association between the results of PET imaging and EREV after adjusting for potential confounders. Results . Overall, pts were 65±12 years, 23% female, with mean LVEF 31±12%. Expressed as %total myocardium, PET results revealed 6.0±8.1% scar, 9.1±8.5% ischemia, and 14.7%±11.6% hibernation (total defect size 29.8±16.6%). Logistic regression revealed that after adjusting for pt age, sex, prior MI, BMI, diabetes, beta-blocker use, race, residence location, prior REV, chest pain, and LV end-diastolic volumes, ischemia was the single most powerful predictor of EREV [adjusted odds ratio (OR) and 95%CI: 2.6 (2.0-3.3) per 10% ischemia], while hibernation was not a predictor of EREV (p=0.77). The presence of scar reduced EREV [0.48 (0.34-0.66) per 10% scar]. Conclusion. Although assessment of ischemia and hibernation is often considered to be a standard part of the evaluation of pts with LV dysfunction, hibernating myocardium extent measured by cardiac PET does not influence subsequent referral to revascularization.