Myocardial Viability Assessment by Nuclear Techniques

Abstract

Abstract Viability assessment with cardiac FDG-PET/CT is commonly applied in ischemic cardiomyopathy patients with an LVEF of 35% or less and pronounced segmental wall-motion disturbances (severe hypokinesis to akinesis, or dyskinesis). The combined application of rest perfusion imaging and FDG-PET/CT may unmask “match” findings between perfusion and viability assessment, indicative of transmural necrosis or non-transmural necrosis and no ischemic component, and “mismatch” findings, denoting non-transmural necrosis with viable but ischemic, compromised myocardium, or completely viable and ischemic, and compromised myocardium. In about 20% to 40% of these patients, FDG-PET/CT is likely to detect a sufficient amount of viable myocardium, unmasking viable but ischemic, compromised myocardium. Cardiomyopathy patients with mismatch-defined hibernating-stunned myocardium in dysfunctional wall segments, if large enough (at least four segments), who undergo coronary revascularization are likely to benefit in terms of both recovery of LV function and clinical outcome. However, no such benefit is commonly observed for those with “match” findings, and optimized medical heart failure treatment may be preferred. Predominantly viable but ischemic, compromised myocardium may have a positive predictive value of up to 74% for functional recovery after coronary revascularization. Thus, in about 16% of patients with classical “mismatch” findings, the restoration of coronary flow may not translate into recovery of LV function due to an advanced remodeling process with interstitial fibrosis and structural disintegration of cardiomyocytes, whereas improvement in clinical outcome may still ensue.