From the Guidelines
A CMR viability study is primarily used to assess myocardial viability and guide management in patients with chronic secondary mitral regurgitation (MR) and suspected coronary artery disease (CAD), as it helps determine the potential for recovery of left ventricular (LV) function after revascularization. This is based on the 2014 AHA/ACC guideline for the management of patients with valvular heart disease, which recommends noninvasive imaging, including CMR, to establish the etiology of chronic secondary MR and assess myocardial viability 1. The study involves the use of contrast agents like gadolinium to analyze patterns of enhancement in heart tissue, with areas of delayed enhancement typically representing scarred, non-viable tissue, and areas without enhancement or with minimal enhancement representing viable tissue that could benefit from restored blood flow.
Key points to consider when using CMR viability studies include:
- The ability to distinguish between permanently damaged heart tissue and tissue that is temporarily dysfunctional but salvageable
- The potential for improvement in LV function after revascularization in patients with viable tissue
- The use of late-enhancement gadolinium imaging in combination with information on regional function available with cine techniques to identify hibernating myocardium and potential reversibility of LV dysfunction 1
- The value of CMR in postinfarction risk stratification with pharmacologic stress CMR and diagnosing CAD with dobutamine stress CMR
In clinical practice, CMR viability studies are particularly valuable for patients with coronary artery disease and heart failure, as they help guide treatment decisions and distinguish between permanently damaged heart tissue and tissue that is temporarily dysfunctional but salvageable. This distinction is crucial because revascularization procedures are most beneficial when directed at areas with viable tissue that can recover function.
From the Research
CMR Viability Study
A CMR viability study is used to assess the viability of the myocardium in patients with chronic ventricular dysfunction due to coronary artery disease. The study uses cardiac magnetic resonance (CMR) imaging to evaluate the diagnostic accuracy of different techniques in assessing myocardial viability, including:
- End-diastolic wall thickness (EDWT)
- Low-dose dobutamine (LDD)
- Contrast delayed enhancement (DE) 2
Purpose of CMR Viability Study
The purpose of a CMR viability study is to determine the best CMR strategy to evaluate patients being contemplated for revascularization. The study aims to compare the diagnostic accuracy of different CMR techniques in assessing myocardial viability and to identify the most effective method for predicting improved segmental left ventricular contractile function after revascularization 2.
Clinical Utility of CMR Viability Study
CMR viability studies have been shown to be useful in clinical practice, particularly in patients with heart failure and coronary artery disease. The studies have demonstrated that CMR can provide valuable information on myocardial viability, which can help guide revascularization decisions and improve patient outcomes 3, 4, 5, 6.
Key Findings
Key findings from CMR viability studies include:
- DE CMR provides the highest sensitivity and negative predictive value (NPV) for predicting improved segmental left ventricular contractile function after revascularization 2
- LDD CMR offers the highest specificity and positive predictive value (PPV) for predicting improved segmental left ventricular contractile function after revascularization 2
- CMR viability studies can help identify patients who are likely to benefit from revascularization and those who may not benefit from the procedure 3, 4, 5, 6