Abstract
Heart failure reduces longevity. The most frequent cause of heart failure in women is a longstanding hypertension while in men it is an ischemic heart disease.
It was originally thought that dysfunctional myocardium after an infarction was irreversibly damaged. It was recognized, thanks to revascularization techniques, that some of the involved tissue remains viable and contractility may be restored with revascularization.
Dobutamine stress echocardiography examines myocardial contractile reserve. An improvement of wall motion in akinetic regions with low dose dobutamine signifies viability.
Myocardial perfusion imaging performed by SPECT is based on the fact that accumulation of 99mTc-MIBI depend on perfusion, cell membrane integrity and mitochondrial function, and indicates viable tissue. 201Tl-chloride enters myocardial cells by active transportation, which increases its accuracy for detecting viability myocardium. 18F-FDG PET is considered the gold standard. It is used to evaluate the metabolism of cardiac glucose.
Delayed enhancement CT detects myocardial scarring. Cardiac magnetic resonance imaging (CMR) employs late gadolinium enhancement (LGE) imaging using gadolinium-based contrast agents (GBCA), which accumulates in the scar, however, there are several limitations.
Echocardiography may be the method of choice in the screening for the presence of viability, however, it is not frequently used in practice. Nuclear methods could be used in a second line, especially 18F-FDG PET, for its higher sensitivity.
Through its ability to directly visualize scar and evaluate its transmural extent, CMR seems to be a central player in viability assessment. Myocardial viability is still a subject of clinical importance and a focus of clinical trials.
The detection of myocardial viability may be a valuable predictor of the response to revascularization and long-term prognosis and, thereby, contribute to the decision-making in the medical practice. Use of appropriate method should be centered to particular patient according to local expertise and availability.