Multimodality imaging in the assessment of myocardial viability

Abstract

The prevalence of heart failure due to coronary artery disease continues to increase, and it portends a worse prognosis than non-ischemic cardiomyopathy. Revascularization improves prognosis in these high-risk patients who have evidence of viability; therefore, optimal assessment of myocardial viability remains essential. Multiple imaging modalities exist for differentiating viable myocardium from scar in territories with contractile dysfunction. Given the multiple modalities available, choosing the best modality for a specific patient can be a daunting task. In this review, the physiology of myocardial hibernation and stunning will be reviewed. All the current methods available for assessing viability including echocardiography, cardiac magnetic resonance imaging, nuclear imaging with single photon emission tomography and positron emission tomography imaging and cardiac computed tomography will be reviewed. The effectiveness of the various techniques will be compared, and the limitations of the current literature will be discussed.

Fig. 1

The relation between myocardial perfusion and contractile function and the series of intermediate steps. Images adapted and reproduced with permission from Taegtmeyer [5]

Fig. 2

Images comparing contrast-enhanced 3D echocardiography and a CMR LGE in a patient with an old infarction (a anterior infarct, b inferior infarct, and c lateral infarct) and a control subject (d). Images reproduced with permission from Montant et al. [18]

Fig. 3

Echocardiographic assessment of global strain using speckle tracking technology to assess myocardial viability. Normal strain is represented in red; decreased (less negative) strain is represented in blue. In this patient, after an acute anteroseptal myocardial infarction, the amount of strain is decreased in the anteroseptal segments of the left ventricle (apical long axis views) consistent with a region of infarction. In addition, global left ventricular strain (polar plot) is decreased (GLPS_Avg −14.4%; normal values range from −20.3 to −24.1%). Images reproduced with permission from Mollema et al. [13]

Fig. 4

CMR LGE short axis image demonstrating LGE involving >75% transmural thickness of the anteroseptal and anterior walls

Fig. 5

Rubidium-82 and F-18 FDG PET in a 78-year-old woman presenting with non ST elevation myocardial infarction. The short axis and vertical long axis images demonstrate a perfusion defect in the anterior and anteroseptal walls (Rubidium-82) with a mismatch (increased FDG uptake on the FDG images), consistent with hibernating myocardium in the left anterior descending coronary distribution

Fig. 6

A CT coronary angiogram demonstrating an anomalous coronary artery as a cause of cardiomyopathy. There is a single coronary artery ostium originating from the right coronary cusp. The left anterior descending artery is a small vessel and courses between the aorta and the right ventricle, and the left circumflex artery has a retro-aortic course

Fig. 7

Cardiac MR compared to cardiac CT to assess for viable myocardium. Panel a The percent signal intensity (SI) and the contrast noise ratio (CNR) was higher with CE-MR (contrast-enhanced magnetic resonance image) than CEMDCT (contrast-enhanced multidetector CT). The images in panel b illustrate the same findings. Images adapted and reproduced with permission from Gerber et al. [65]

Fig. 8

Recovery of function following revascularization as a function of magnitude of scar. The CMR LGE findings are shown on the left and thallium rest-redistribution findings are shown on the right panel. Myocardial segments with dense scar (<40% thallium uptake or >75% transmural scar) were unlikely to recover, whereas normal myocardial segments (>80% thallium uptake or 0% transmural scar) improved significantly. Intermediate degrees of scar (non-transmural) showed a graded recovery of function following revascularization. Images adapted and reproduced with permission from Dilsizian et al. [67]