The patient with new-onset heart failure

KEY POINTS

Noninvasive imaging plays an important role in the evaluation of patients with new-onset HF.
Documentation of angiographic CAD is often a first-line test and is supported by guidelines.
The presence of angiographic CAD does not establish a causal relationship between CAD and LV dysfunction.
Demonstration of ischemia and/or scar with radionuclide MPI (or other techniques) plays an important role both in the diagnosis of ICM and in guiding management, especially the possible need for revascularization.
FDG PET imaging is emerging as a complementary tool to CMR in the evaluation of myocardial inflammation in patients with suspected myocarditis. As in cardiac sarcoidosis, quantification of myocardial inflammation may also be used to monitor response to anti-inflammatory therapies.
The potential role of quantitative MBF by PET for risk prediction and as a potential therapeutic target in patients with idiopathic DCM warrants further investigation.

Introduction

Heart failure (HF) is a clinical syndrome characterized by typical symptoms of breathlessness, ankle swelling, and fatigue. It may result from disorders of the pericardium, myocardium, endocardium, or heart valves, but because most patients have symptoms related to impaired left ventricular (LV) myocardial function, we will focus mainly on clinical scenarios characterized by abnormalities of systolic and/or diastolic LV function.

In patients with HF symptoms, the main classification is based on a measurement of the LV ejection fraction (LVEF) generally performed by echocardiography. Radionuclide ventriculography or magnetic resonance imaging (MRI) can be useful to assess LVEF and volumes when echocardiography is inadequate. HF in patients with LVEF equal to or greater than 50% is defined as HF preserved ejection fraction (HFpEF), whereas in patients with LVEF equal to or less than 40%, it is defined as HF reduced ejection fraction (HFrEF). The intermediate LVEF range represents a “gray area,” which is referred to as HF midrange ejection fraction (HFmrEF). Differentiation of patients with HF based on LVEF is important because it helps guide identification of its etiology and define management. Compared with HFrEF, patients with HFpEF are older, more often women, and more often have a history of hypertension and atrial fibrillation, but a history of myocardial infarction (MI) is less common. Biochemical and imaging findings support the initial diagnosis of HF, including elevated levels of natriuretic peptide and objective evidence of cardiac structural (including left atrial enlargement or increased LV mass) or functional abnormalities associated with systolic and/or diastolic ventricular dysfunction.

Practice guidelines from the American College of Cardiology/American Heart Association (ACC/AHA) and the European Society of Cardiology (ESC) provide clinicians with an evidence-based approach to the evaluation of patients with acute or HF. These guidelines are updated regularly, incorporating, when necessary, new evidence published in the interim. ACC/AHA and ESC guidelines have many similarities ; differences will also be mentioned when relevant.

The initial diagnosis and management of HF relies heavily on cardiac imaging. Because of the rapid evolution of imaging technologies and multimodality options, professional societies have developed appropriate use criteria (AUC) to assist clinicians with the choice of imaging approaches in different clinical scenarios. The ACC/AHA and the ESC/European Association of Cardiovascular Imaging (EACVI) AUC for multimodality imaging are based on available evidence and, when evidence is lacking, on expert and national society consensus opinion. ^,

New-onset heart failure

New-onset (so-called de novo) HF may present acutely (e.g., as a consequence of acute myocardial infarction [AMI]) or subacutely e.g., gradually, as in patients with dilated cardiomyopathy, who often have symptoms for weeks or months before the diagnosis becomes clear). Symptoms and signs of new-onset HF, as well as the underlying cause, may resolve with treatment (e.g., acute myocarditis, takotsubo cardiomyopathy). On the other hand, the underlying cardiac cause may not resolve (e.g., amyloidosis) or may resolve partially (e.g., treated coronary artery disease [CAD]), potentially causing recurrent symptoms. Other conditions, such as idiopathic dilated cardiomyopathy (DCM), may show substantial or even complete recovery with therapy or may further progress to end-stage HF.

Thus the demonstration of the underlying cause of new-onset HF is central for appropriate early management of these patients to improve prognosis. The cardiac cause of HF is usually a myocardial abnormality producing systolic and/or diastolic ventricular dysfunction because of an ischemic (obstructive and/or functional/microvascular coronary disease) or nonischemic etiology (primary/genetic, inflammatory, infiltrative myocardial disease). Nevertheless, abnormalities of the valves, pericardium, endocardium, heart rhythm, and conduction system can also cause HF, and more than one abnormality can be present.

In this chapter, we will discuss the applications of radionuclide imaging in the evaluation of patients with new-onset HF. Although the focus will be on the role of radionuclide imaging, we will also highlight applications of other imaging techniques. We will use case vignettes to illustrate how imaging can be used to answer fundamental questions in the patient with new-onset HF.

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