Steven Promislow

The evolving landscape of nuclear imaging in cardiac amyloidosis

Amyloidosis is an infiltrative disease characterized by the extracellular deposition of abnormal protein fibrils in various organ systems, including the heart. While there are multiple proteins which can form amyloid fibrils, the vast majority of patients with cardiac amyloidosis (CA) have one of two types: immunoglobulin light chain-associated amyloid (AL) or transthyretin amyloid (ATTR). ATTR amyloid is further subdivided into a hereditary form associated with a pathogenic transthyretin mutation (‘‘mutant’’ TTR, or TTR-m) and a ‘‘wild-type’’ form (TTR-wt) in which a mutation is not identified and which tends to present later in life. AL CA is a relatively rare condition, with approximately 3000 new cases per year in the United States; of these, 30%-50% have symptomatic cardiac involvement. By contrast, ATTR CA is being increasingly recognized as a more common cause of heart failure with preserved ejection fraction (HFpEF), with transthyretin amyloid deposits found at autopsy in over 30% of patients over the age of 75 with HFpEF. While the age of presentation and associated organ involvement can provide clues as to the type of amyloid present, cardiac involvement in both AL CA and ATTR CA can manifest similarly clinically (typically progressive heart failure, occasionally with arrhythmias or conduction disease, and rarely with chest pain) and on cardiac imaging. However, distinguishing between the different types of CA is absolutely crucial; treatment is entirely dependent on the amyloid type, and the prognosis of AL CA differs substantially from that of ATTR CA. While treatment of AL CA, including autologous stem cell transplantation, chemotherapy, and cardiac transplantation in highly selected cases, has improved over the past decade, it is generally associated with a poor prognosis, with 12-month mortality remaining high at 24% in recent years. Patients with more advanced cardiac disease have worse survival, highlighting the importance of early diagnosis. In patients with ATTR CA, survival is measured in years rather than months but does still result in reduced life expectancy and can have a significant impact on quality of life. Liver and/or cardiac transplantation for patients with ATTR-m is well studied and reported, but pharmacological therapies have generally remained limited until recently. Emerging therapies currently undergoing clinical trials include transtheyretin stabilizers, such as difunisal and tafamidis, as well as microRNA inhibitors that interrupt the production of amyloid proteins, which may shape the management of ATTR amyloid in the near future. With improving therapies for AL amyloid and promising new treatment options for ATTR amyloid on the horizon, the need for early and accurate diagnosis of CA, including the ability to distinguish between AL CA and ATTR CA, is becoming paramount.

Myocardial Viability: From PARR-2 to IMAGE HF - Current Evidence and Future Directions

Ischemic heart failure is a growing disease with high morbidity and mortality. Several studies suggest the benefit of viability imaging to assist revascularization decision, but there is controversy. Multiple imaging modalities can be used to accurately define hibernating myocardium; however, the best approach remains uncertain. This review will highlight current evidence and future directions of viability imaging assessment.

Radionuclide Imaging in Decision-Making for Coronary Revascularization in Stable Ischemic Heart Disease

Purpose of the ReviewThis review will discuss the current nuclear imaging techniques for defining ischemia and hibernation/viability, their advantages and disadvantages, and the data related to their use to direct revascularization decisions.Recent FindingsRecent interventional trials highlight the importance of functional imaging in trying to determine who may benefit from revascularization. Outcome benefit from revascularization has previously been shown in patients with significant ischemia, and flow quantification from positron emission tomography (PET) may allow for further risk stratification; similar data may soon be available with single-photon emission computed tomography (SPECT) as well using the newer cadmium-zinc-telluride (CZT) cameras. Some degree of equipoise still exists regarding the utilization of myocardial viability to guide revascularization in patients with ischemic cardiomyopathy, with recent studies presenting conflicting results.SummaryThere is a niche for radionuclide imaging in helping to guide revascularization decision-making, and advances in recent years are providing new mechanisms by which we may better clarify the particular circumstances in which it can and should be applied. However, most data at this time is limited to observational cohorts and inferences from other randomized trials. The results of upcoming trials like ISCHEMIA and AIMI-HF will hopefully provide the needed evidence to support current clinical practice, or may change our algorithms altogether.

Recurrence of a Thymic Carcinoid Tumour 15 Years After Resection With Multiple Myopericardial Cardiac Metastases: The Role of Multimodality Imaging

Carcinoid tumours arising from the thymus are exceedingly rare, and cardiac metastases have not previously been described in the setting of a primary thymic carcinoid tumour. We present a patient with recurrence of a carcinoid tumour initially resected from the thymus 15 years earlier, with multiple cardiac metastases. These metastatic tumours were visualized using multiple imaging modalities, including computed tomography, transthoracic echocardiogram, magnetic resonance imaging, and octreotide scan. A subsequent biopsy confirmed recurrence of his carcinoid tumour. This case highlights the role of multimodality imaging for diagnosis and the need for continued long-term surveillance in these patients.

How to Write a Good Myocardial Perfusion Imaging Report: Current North American Reports

Myocardial perfusion imaging (MPI) reports play a critical role in communicating results to referring physicians. A well-structured report is succinct, easy to understand and guides physicians in appropriate decision-making. Although the structure of MPI reports may differ across institutions and countries, they serve a common goal of informing the referring physician. In Japan, there are no standard reporting guidelines. However it is desirable to follow standards published in peer-reviewed consensus statements and guidelines. We review current North American reporting methods in hopes that can better guide trainees and imaging physicians toward simple standardized and informative MPI reports that will ultimately improve patient care.