Assessment of Myocardial Viability in Patients with Heart Failure

Abstract

The prognosis for patients with chronic ischemic left ventricular dysfunction is poor, despite advances in different therapies. Noninvasive assessment of myocardial viability may guide patient management. Multiple imaging techniques have been developed to assess viable and nonviable myocardium by evaluating perfusion, cell membrane integrity, mitochondria, glucose metabolism, scar tissue, and contractile reserve. PET, 201 Tl and 99m Tc scintigraphy, and dobutamine stress echocardiography have been extensively evaluated for assessment of viability and prediction of clinical outcome after coronary revascularization. In general, nuclear imaging techniques have a high sensitivity for the detection of viability, whereas techniques evaluating contractile reserve have a somewhat lower sensitivity and a higher specificity. MRI has a high diagnostic accuracy for assessment of the transmural extent of myocardial scar tissue. Patients with a substantial amount of dysfunctional but viable myocardium are likely to benefit from coronary revascularization and may show improvements in regional and global contractile function, symptoms, exercise capacity, and long-term prognosis.

Hybrid PET/MR Imaging of the Heart: Potential, Initial Experiences, and Future Prospects

“…Viable but dysfunctional myocardium has the potential to recover after revascularization (60). Among the different imaging modalities available to assess myocardial viability, 18 F-FDG PET is considered to be the gold standard (61,62). The results of several studies have proven the value of 18 F-FDG PET imaging in identifying those patients who would benefit from revascularization, based on a prediction of improved LV function (63)(64)(65).…”

“…The presence of even a small amount of enhanced myocardium carries prognostic significance in patients with suspected CAD but without known prior myocardial infarction (68). A metaanalysis investigated the capabilities of imaging to predict functional recovery after revascularization; specificity for 18 F-FDG PET and delayed-enhancement MR imaging was comparable (63%), whereas the nuclear medicine technique had higher sensitivity (92% vs. 84%) (61).…”

Combined Positron Emission Tomography and Magnetic Resonance as Translational Tool in Cardiology

“…7 With the clinical acceptance of reversible dysfunction as a therapeutic target in patients with heart failure, several imaging methods competed for clinical application, from which FDG-PET and cardiac MR imaging with late gadolinium enhancement (LGE) emerged as "gold standards" for tissue viability and scar formation, respectively. 8 However, the lower risk of revascularization either by percutaneous techniques or by surgery has reduced the clinical imperative for viability studies in recent years. In addition, a large prospective trial (Surgical Treatment to Ischemic Heart Failure [STICH] trial) suggested that the delineation of myocardial viability did not significantly affect clinical outcome of patients considered for revascularization.…”

Cardiac Magnetic Resonance and Myocardial Viability: Why Is It so Important?

“…Even when the infarcted area is around 1-25%, and the chances of recovery decrease to 60%, viability is still preserved and it remains preserved at a percentage of delayed enhancement of around 26-50%, but a higher percentage is strongly correlated with non-viable myocardial muscle. 12,21,28 The transmurality of late gadolinium enhancement is an important prognostic factor in an acute myocardial infarction. Bodi et al demonstrated that there is a meaningful difference between major cardiovascular events when comparing patients with 5 or more segments of transmural infarction with those with less involved myocardium (23% vs. 5%, p <0.001).…”

“…Even if the wall thickness is bigger than 5.5 mm after revascularization, an improvement in contractility is not always revealed. 3,13,[19][20][21] DE-MRI is the most common noninvasive technique that can accurately identify the fibrotic myocardial tissue following a myocardial infarction. Gadolinium-diethylenetriamine pentaacetic acid is the contrast agent used for MRI examinations, which is able to diffuse and accumulate in myocardial tissue.…”