Objective: We aimed to differentiate ischemic heart failure (HF) from non-ischemic HF in patients presenting with non-acute onset exertional dyspnea using technetium-99m methoxyisobutylisonitrile gated single photon emission tomography (Tc-99m-MIBI gSPET) imaging. Subjects and Methods: One hundred and seventy nine consecutive patients with exertional dyspnea without concomitant chest pain referred to Tc-99m-MIBI gSPET imaging were included in this study. All patients had a newly diagnosed HF with reduced ejection fraction (HFrEF). Imaging findings were compared between ischemic HF and non-ischemic HF groups. Results: Of the 179 patients, 127 had ischemic HF and 52 had non-ischemic HF. There was no difference between ischemic and non-ischemic groups in terms of age, gender, body mass index, any smoking history, diabetes mellitus, history of hypertension and hyperlipidemia. Global dysfunction of left ventricle was more common in non-ischemic HF group than ischemic HF group (82.7% vs 41.7% respectively, P8 had 65.4% sensitivity and 75.0% specificity (AUC=0.732, 95% CI: 0.661-0.795, P<0.001). Conclusion: Absence of global dysfunction and SSS on SPET imaging were the independent predictors of ischemic etiology of HF presenting with dyspnea without concomitant chest pain. These findings had a low sensitivity, but acceptable specificity
