IJCS | Volume 32, Nº1, January/ February 2019

75 Figure 4 - Interaction between mismatch on 18 FDG PET (hibernating myocardium) and clinical outcome. A) Various levels of mismatch and its hazards ratios and 95% CI. For patients with mismatch > 7% there was improvement in the primary outcome (cardiac death, myocardial infarction and cardiac hospitalization at 1 year) (with permission from D’Egidio et al. 7 ). B) Relationship between % of mismatch and adjusted HR for all cause of death in patients who received medical therapy or early revascularization. Greater amounts of hibernating myocardium related with increased risk of medical therapy (with permission from Ling et al. 12 ). C) Relationship between amount of mismatch and improvement in functional status after revascularization (with permission from Di Carli et al., Circulation 10 ). CI: confidence interval; HR: hazard ratio. Erthal et al. Myocardial viability: from PARR-2 to IMAGE HF - current evidence and future directions Int J Cardiovasc Sci. 2019;32(1)70-83 Review Article adjustment for baseline characteristics. 35 More recently, the 10-year follow-up of the original trial, STICHES (STICH Extension Study) 37 has shown the benefit of revascularization for all-cause death, cardiovascular death and cardiovascular hospitalization over optimal medical therapy alone. 37 In the STICH viability substudy, while viability did predict outcome, it was not independent of other parameters and did not predict outcome benefit from revascularization, leaving questions yet to be answered. The greater long-termbenefit in the revascularization arm in the main trial indeed highlights the need for a careful assessment of patients with ischemic HF, balancing the risks and benefits in short and long term. Although the ISCHEMIA trial (NCT01288560) does not specifically evaluate viability, its results may assist in understanding the role of ischemia imaging in guiding revascularization. Currently, more than 5,000 patients have been randomized worldwide to an invasive strategy +/- revascularization versus optimal medical management. There was also a small randomized blinded study (total of 103 patients) comparing FDG PET to MIBI perfusion imaging to detect viability. While FDG PET appeared to have better outcomes, this did not reach statistically significance. The small sample size and the fact that < 1/3 of patients had significant left ventricular dysfunction limit conclusions from this study. 38,39