Abstract 2429: Non-Revascularized Human Hibernating and Chronically Stunned Myocardium Can Adapt to Long-Term Chronic Ischemia
Background: It is unknown whether human chronically ischemic dysfunctional myocardium degenerates over time or adapts to chronic ischemia through cell survival mechanisms. We studied whether perfusion, metabolism, and contractile function and reserve can be preserved in non-revascularized human chronically stunned (CST) and hibernating myocardium (HIB).
Methods and Results: We studied 16 event-free, medically treated patients with EF 31%±2% and CST or HIB in 56%±5% of the left ventricle on 99mTechnetium-Sestamibi single photon emission computed tomography (SPECT)/18F-flouro-deoxyglucose (FDG) positron emission tomography (PET). The patients underwent repeat SPECT, PET, resting and stress tissue-Doppler echocardiography at follow-up after 25±4 months and we investigated whether measures of myocardial viability remained stable over time. The patients were stable with respect to NYHA class and global left ventricular function (30%±2%, P=0.81). Wall motion score was unaltered in HIB and CST regions and a contractile reserve by tissue-Doppler stress echocardiography was preserved. Overall, 74% of HIB and CST regions retained their initial perfusion / metabolism pattern at follow-up. In HIB, initial and follow-up Sestamibi uptake (53%±1% and 53%±2%, P=0.85) and FDG uptake (76%±1% and 74%±1%, P=0.21) did not differ. In CST, Sestamibi uptake displayed a minor decrease at follow-up (70%±1% vs. 67%±1%, P=0.01) and FDG uptake remained constant (68%±2% and 67%±1%, P=0.21).
Conclusions: Myocardial perfusion, FDG uptake, and contractile function in non-revascularized human CST and HIB can adapt to chronic ischemia. In CST adaptation may be less complete than in HIB.