Myocardial viability: heart failure perspective Purpose of review This review highlights the different imaging modalities available to assess myocardial viability in patients with heart failure and coronary artery disease (CAD) being considered for revascularization. Recent findings Myocardial viability can be determined by a variety of cardiac imaging modalities. Recent studies have confirmed the use of cardiovascular magnetic resonance imaging (CMR) in patients with heart failure and CAD, suggesting that those who undergo revascularization but have evidence of residual viable or ‘jeopardized’ myocardium have increased mortality compared with those who achieve complete revascularization. The PET and Recovery Following Revascularization (PARR)-2 trial assessed whether viability noted on PET imaging in patients with severe LV dysfunction correlated with recovery of LV function and response to revascularization. The 5-year extension of the PARR-2 study noted a significant decrease in the composite outcome of cardiac death, myocardial infarction, or cardiac hospitalization in patient assessments adherent to PET-guided viability recommendations. Summary On the basis of the current available data, viability testing is reasonable in individuals with ICM, as identified by coronary angiography in whom complete revascularization can be achieved. Whenever available, the use of CMR or PET is preferred because of better resolution and increased sensitivity to detect myocardial viability.

Assessment of myocardial viability by PET Purpose of review Viability assessment has a key role in the management of patients with ischemic heart disease. Positron emission tomography (PET) is a unique modality that evaluates myocardial viability via assessing the tissues metabolic and perfusion properties. The mainstay of metabolic imaging relies on glucose metabolism using 18fluorodeoxyglucose, a radiolabeled glucose analog. Mismatch in perfusion metabolism data denotes hibernating myocardium with a high likelihood of functional recovery following revascularization. Matched absence or reduction in perfusion metabolism data represents scar with a low likelihood of functional recovery following revascularization. This review will focus on PET radiotracers and techniques used to assess myocardial viability. Recent findings Single-center studies have shown that patients with PET mismatch undergoing bypass grafting had improved survival compared with those on medical therapy. In addition to survival benefit, the patients who underwent PET-guided revascularization had significant improvement in angina and heart failure symptomology. Recent technological advancements in the field of PET-magnetic resonance (MR) opens a new frontier in the field of advanced imaging as it combines anatomical, functional, tissue characterization, and metabolic perfusion data obtained in one setting. The incremental value of PET/MRI is best established in diagnosing and monitoring disease activity in patients with cardiac sarcoidosis and occult malignancies, but more studies are needed to assess it value in viability assessment. Summary In conclusion, imaging myocardial viability by PET provides assessment of both physiological perfusion and myocardial tissue's metabolic activity to differentiate hibernating from scarred myocardium.

Assessment of myocardial viability using single-photon emission computed tomography myocardial perfusion imaging Purpose of review The assessment of myocardial viability continues to be a pressing and sometimes challenging clinical question. Among other imaging modalities proven to be useful in the assessment of myocardial viability, single-photon emission computed tomography (SPECT) instrumentation and expertise continue to be the most widely available to the practicing physicians. Understanding the utility of SPECT myocardial perfusion imaging in this domain is an enduring need. Recent findings A wealth of basic science and clinical data established the value of a variety of Tl-201 and Tc-99m SPECT protocols in the assessment of myocardial viability. The diagnostic performance for Tl-201 and Tc-99m imaging protocols for identifying viable myocardium is very good and is comparable for both agents. Quantitative assessment of radiotracer uptake can predict, in an objective manner, the probability of recovery of myocardial function following revascularization. Summary SPECT myocardial perfusion imaging with Tl-201 and Tc-99m tracers can provide an objective and quantifiable assessment of myocardial viability, which can help predict the likelihood of myocardial function recovery following coronary revascularization. Effective application of this imaging technique can guide clinical decision-making for coronary revascularization.

Dobutamine echocardiography for assessment of viability in the current era Purpose of review Studies from the 1990s and early 2000s documented the utility of dobutamine echocardiography for the prediction of functional recovery and prognosis with revascularization. The results of The Surgical Treatment of Ischemic Heart Failure (STICH) trial called into question the value of viability assessment using dobutamine echocardiography. The purpose of this review is to re-examine the literature on dobutamine echocardiography, put into context the STICH results, and provide insight into the current role of dobutamine echocardiography viability testing. Recent findings In contrast to the results of previous nonrandomized trials, the STICH trial showed that patients with viability defined by nuclear perfusion imaging or dobutamine echocardiography did not have improved survival with CABG compared with optimal medical therapy. Viability by dobutamine echocardiography was defined as the presence of contractile reserve in at least five segments with baseline dysfunction. The results of dobutamine echocardiography studies published before and after initiation of the STICH trial suggest that the definition of viability utilized in that trial may be suboptimal for assessment of improvement in global function and prognosis in patients undergoing revascularization. Assessment of global contractile reserve using wall motion score (WMS) or ejection fraction may be superior to utilization of a binary definition of viability confined to assessment of contractile reserve in a fixed number of segments because these indices provide information on both the magnitude and extent of contractile reserve of the entire left ventricle (LV). Summary Assessment of WMS or ejection fraction with dobutamine echocardiography may be the optimal means of evaluating the impact of viability on prognosis. Video abstract http://links.lww.com/HCO/A56

Imaging and heart failure: myocardial strain Purpose of review To summarize literature on the application of myocardial strain in patients with heart failure published since 2018. Recent findings Left ventricular (LV) and right ventricular strain provides important prognostic information in patients with acute and chronic heart failure and new insights in disease mechanisms in amyloidosis. The addition of left atrial strain to current societal diastolic dysfunction criteria may improve detection of clinically relevant diastolic dysfunction. The recently developed method for noninvasive estimation of myocardial work incorporates loading conditions into the evaluation of LV performance that may be important for selection of patients for cardiac resynchronization therapy. Summary Evidence linking myocardial strain to adverse outcomes in heart failure is steadily being developed. Although GLS seems to be ready for clinical use, further validation and standardization of RV, LA strain and myocardial work is needed.

Assessment of myocardial viability by myocardial contrast echocardiography: current perspectives Purpose of review The current guidelines recommend the use of myocardial contrast echocardiography (MCE) to assess myocardial viability. There are two clinical scenarios where detection of myocardial viability has clinical significance: in ischemic cardiomyopathy and following acute myocardial infarction with significant left ventricular dysfunction. Myocardial contrast echocardiography (MCE), which utilizes microbubbles can assess the integrity of the microvasculature, which sustains myocardial viability in real time and can hence rapidly provide information on myocardial viability at the bedside without ionizing radiation. Recent findings We discuss the value of MCE to predict myocardial viability through the detection of the integrity of myocardial microvasculature, the newer evidences behind the MCE-derived coronary flow reserve and use of MCE postmyocardial infarction to detect no-reflow. Newer studies have also demonstrated the comparable sensitivities and specificities of MCE to single photon-emission computed tomography (SPECT), cardiac myocardial resonance imaging and PET for the detection of myocardial viability. Summary Ample evidence now exist that supports the routine use of MCE for the detection of viability as laid down in recent guidelines.

Assessment of myocardial viability by cardiac MRI Purpose of review Left ventricular systolic dysfunction because of coronary artery disease is common, and ascertaining which patients will benefit from revascularization can be challenging. Viability testing is an accepted means by which to base this decision, with multiple noninvasive imaging modalities available for this purpose. This review aims to highlight the key role of cardiac magnetic resonance in myocardial viability assessment, with a focus on its unique strengths over other imaging modalities. Recent findings Transmural extent of hyperenhancement with late gadolinium imaging has been shown to be greater acutely in ST elevation myocardial infarction patients undergoing primary percutaneous coronary intervention and regress at follow-up studies. An explanation for this reported phenomenon and an argument against redefining CMR viability criteria in the acute setting will be offered. Summary Although not universally available, cardiac magnetic resonance is an exceptionally powerful and well tolerated imaging modality that should be considered when viability testing will influence patient management. Although observational outcomes data suggest a promising prognostic role for viability, randomized studies in this area are needed.

Aspirin for primary prevention of cardiovascular disease: is it time to move on? Purpose of review Aspirin has been used for decades for the primary prevention of cardiovascular disease. However, several recent trials evaluating the benefits and risks of aspirin for primary prevention have been published, creating the need to reevaluate this important topic. Recent findings Three large randomized trials studying aspirin in various primary prevention populations including individuals with diabetes, an elderly population, and middle-aged adults at high cardiovascular risk have recently been completed. These trials found a small benefit for individuals with diabetes and no benefit in the elderly and high risk middle-aged adult populations. Additionally, all three trials demonstrated a clear increase in risk for bleeding events. Summary The recent trials confirm that, in modern primary prevention populations, the cardiovascular benefit of aspirin is small and comes with a clear increase in risk for bleeding. For the majority of adults without established cardiovascular disease, the risk of a daily aspirin outweighs the benefit.

Current and future role of lipoprotein(a) in preventive cardiology Purpose of review The purpose of this review is to highlight our emerging understanding of lipoprotein(a) [Lp(a)]'s role in atherosclerotic cardiovascular disease (ASCVD), its structure–function relationship, and promising developments within the therapeutic pipeline. Recent findings Elevated levels of Lp(a) are strongly associated with an increased risk of coronary heart disease, calcific aortic valve stenosis, and ischemic stroke. With circulating levels almost exclusively genetically mediated, increased levels of Lp(a) contribute significantly to the residual cardiovascular disease risk in individuals with otherwise well controlled risk factors. The unique structure of Lp(a) – comprised of a genetically heterogeneous apolipoprotein(a) molecule bound to an LDL-like moiety – provides insight into its pathogenic role in cardiovascular disease and also complicates its accurate measurement. Emerging therapies targeting the apolipoprotein(a) component of Lp(a) have the potential to revolutionize the management of individuals with elevated Lp(a). Summary With promising therapies on the horizon, there has been a renewed focus on the role of Lp(a) in ASCVD. Given Lp(a)'s strong and independent association with key cardiovascular outcomes, it is hopeful that these promising targeted therapies will add another therapeutic option for the prevention of cardiovascular disease.