Faculty Bibliography

MR imaging is increasingly used in evaluation of patients with known or suspected hypertrophic cardiomyopathy (HCM), as it provides useful information on cardiac structure, function, and tissue characterization that is complementary to echocardiography. While the adverse effect of left ventricle (LV) outflow tract obstruction on blood flow patterns is well characterized by the midsystolic drop in LV ejection velocities and flow, flow patterns in HCM with mid-LV obstruction, with or without apical aneurysm, are less well characterized. MR imaging can provide additional information on alterations of blood flow patterns in these HCM phenotypes and "paradoxic" flows associated with apical aneurysms.

Ischemic heart disease is the leading cause of heart failure with reduced ejection fraction in the developed world. An evolution of background medical therapy over the past decade has spurred improvement in symptoms and a reduction in morbidity and mortality with ischemic cardiomyopathy. However, there is still ongoing debate about the role and impact of revascularization. Much of the societal guidance regarding revascularization with coronary artery bypass grafting in ischemic cardiomyopathy comes from the STICH trial (Surgical Treatment for Ischemic Heart Failure) which predates improvements in medical therapy. More recently, the REVIVED-BCIS2 trial (Revascularization for Ischemic Ventricular Dysfunction-British Cardiovascular Intervention Society) failed to show a benefit of percutaneous coronary intervention on heart failure hospitalization and mortality in ischemic cardiomyopathy over contemporary medical therapy alone. Yet, there are outstanding questions regarding the role and modality of revascularization required to improve outcomes. We review current data and future directions in the management of ischemic cardiomyopathy and the potential role of revascularization.

Cardiomyopathies represent a diverse group of heart diseases that can be broadly classified into ischemic and nonischemic etiologies, each requiring distinct diagnostic approaches. Noninvasive imaging modalities, such as computed tomography (CT) and magnetic resonance imaging (MRI), play a pivotal role in the diagnosis, risk stratification, and prognosis of these conditions. This paper reviews the characteristic CT and MRI findings associated with ischemic cardiomyopathy (ICM) and nonischemic cardiomyopathy (NICM), focusing on their ability to provide detailed anatomical, functional, and tissue characterization. In ICM, CT and MRI reveal myocardial scarring, infarct size, and coronary artery disease, while MRI further distinguishes tissue viability through late gadolinium enhancement (LGE). Conversely, nonischemic cardiomyopathies demonstrate a wide array of findings, with MRI's LGE pattern analysis being particularly critical for identifying specific subtypes, such as restrictive, hypertrophic, or dilated cardiomyopathies. By comparing the strengths and limitations of these modalities, this paper highlights their complementary roles in improving diagnostic accuracy, risk stratification, prognosis, and therapeutic decision making in both ischemic and nonischemic cardiomyopathies.

Thanks to recent developments in Cardiovascular magnetic resonance (CMR), cardiac diffusion-weighted magnetic resonance is fast emerging in a range of clinical applications. Cardiac diffusion-weighted imaging (cDWI) and diffusion tensor imaging (cDTI) now enable investigators and clinicians to assess and quantify the 3D microstructure of the heart. Free-contrast DWI is uniquely sensitized to the presence and displacement of water molecules within the myocardial tissue, including the intra-cellular, extra-cellular and intra-vascular spaces. CMR can determine changes in microstructure by quantifying: a) mean diffusivity (MD) -measuring the magnitude of diffusion; b) fractional anisotropy (FA) - specifying the directionality of diffusion; c) helix angle (HA) and transverse angle (TA) -indicating the orientation of the cardiomyocytes; d) E2A and E2A mobility - measuring the alignment and systolic-diastolic mobility of the sheetlets, respectively. This document provides recommendations for both clinical and research cDWI and cDTI, based on published evidence when available and expert consensus when not. It introduces the cardiac microstructure focusing on the cardiomyocytes and their role in cardiac physiology and pathophysiology. It highlights methods, observations and recommendations in terminology, acquisition schemes, post-processing pipelines, data analysis and interpretation of the different biomarkers. Despite the ongoing challenges discussed in the document and the need for ongoing technical improvements, it is clear that cDTI is indeed feasible, can be accurately and reproducibly performed and, most importantly, can provide unique insights into myocardial pathophysiology.

While there have been many descriptions of characteristic motion findings in left bundle branch block (LBBB), there are few published descriptions of such findings in right bundle branch block (RBBB). The purpose of this study was to assess the frequency of particular regional motion findings in cardiac magnetic resonance imaging (CMR) studies of patients with RBBB, compared with normal subjects. We focused on three distinctive motion patterns that can be seen in RBBB during early systole: delayed apex-ward motion of the RV base, "reverse septal flash", and "basal bulge". The presence and relative magnitude of these findings were independently scored by four experienced observers, in 3-chamber and 4-chamber CMR cines, for both normal subjects and patients with RBBB. These motion patterns were found to be strongly associated with the presence of RBBB. While only moderately sensitive, they were quite specific for RBBB, when present. In particular, with ROC analysis, a combined feature set of the findings in the 4-chamber view had an area under the curve of 0.81.This previously undescribed set of RBBB-associated early-systolic regional motion features (delayed apex-ward motion of the RV base, "reverse septal flash", and "basal bulge") is strongly suggestive of RBBB when present, particularly in the 4-chamber view. Although here evaluated with CMR, it is also likely to be associated with RBBB when seen with other cardiac imaging modalities.

BACKGROUND/UNASSIGNED:There is controversy about risk of malignant arrhythmias and stroke in patients with apical aneurysms in hypertrophic cardiomyopathy (HCM). OBJECTIVES/UNASSIGNED:The aim of this study was to estimate the associations of aneurysm size and major HCM risk factors with the incidence of lethal and potentially lethal arrhythmias and to estimate incidence of unexplained stroke. METHODS/UNASSIGNED:In 108 patients (age 57.4 ± 13.5 years, 37% female) from 3 HCM centers, we assessed American Heart Association/American College of Cardiology guidelines risk factors and initial aneurysm size by echocardiography and cardiac magnetic resonance imaging and assessed outcomes after median 5.9 (IQR: 3.7-10.0) years. RESULTS/UNASSIGNED:and also without risk factors VT, VF, or SCD occurred in only 2.5%. Clinical atrial fibrillation (AF) was prevalent, occurring in 49 (45%). Stroke was commonly associated with AF. Stroke without conventional cause had an incidence of 0.5%/year. Surgery in 19% was effective in reducing symptoms. VT ablation and surgery were moderately effective in preventing recurrent VT. CONCLUSIONS/UNASSIGNED:Risk factors and aneurysm size were associated with subsequent VT, VF, or SCD. Patients with aneurysms in the lowest tercile of size have a low cumulative 5-year risk. Clinical AF occurred frequently. Stroke prevalence in absence of known stroke etiologies is uncommon and comparable to risk of severe bleeding.

BACKGROUND:Late gadolinium enhancement (LGE) is a valuable part of cardiac magnetic resonance imaging (CMR). In particular, inversion-recovery imaging of LGE, with nulling of the signal from reference areas of myocardium, can have a distinctive pattern in some patients with cardiac amyloid, including both diffuse (relatively faint) subendocardial LGE and a relatively dark appearance of the blood. However, the underlying reasons for this distinctive appearance have not previously been well investigated. Pharmacokinetic modeling of myocardial contrast enhancement kinetics can potentially provide insight into the mechanisms of the distinctive LGE appearance that can be seen in cardiac amyloid, as well as why it may be unreliable in some patients. METHODS:An interactive three-compartment pharmacokinetic model of the dynamics of myocardial contrast enhancement in CMR was implemented, and used to simulate LGE dynamics in normal, scar, and cardiac amyloid myocardium; the results were compared with previously published values. RESULTS:The three-compartment model is able to capture the qualitative features of LGE, in patients with cardiac amyloid. In particular, the characteristic "dark blood" appearance of PSIR images of LGE in cardiac amyloid is seen to likely primarily reflect expansion of the extravascular extracellular space (EES) by amyloid in the "reference" myocardium; the cardiac amyloid contrast enhancement dynamics also reflect expansion of the body EES. CONCLUSION:The distinctive appearance of LGE in cardiac amyloid is likely due to a combination of diffuse expansion by amyloid of the EES of the reference myocardium and of the body EES.

PURPOSE/UNASSIGNED:Cardiac radioablation is an emerging therapy for recurrent ventricular tachycardia. Electrophysiology (EP) data, including electroanatomic maps (EAM) and electrocardiographic imaging (ECGI), provide crucial information for defining the arrhythmogenic target volume. The absence of standardized workflows and software tools to integrate the EP maps into a radiation planning system limits their use. This study developed a comprehensive software tool to enable efficient utilization of the mapping for cardiac radioablation treatment planning. METHODS AND MATERIALS/UNASSIGNED:After the scar area is outlined on the mapping surface, the tool extracts and extends the annotated patch into a closed surface and converts it into a structure set associated with the anatomic images. The tool then exports the structure set and the images as The Digital Imaging and Communications in Medicine Standard in Radiotherapy for a radiation treatment planning system to import. Overlapping the scar structure on simulation CT, a transmural target volume is delineated for treatment planning. RESULTS/UNASSIGNED:The tool has been used to transfer Ensite NavX EAM data into the Varian Eclipse treatment planning system in radioablation on 2 patients with ventricular tachycardia. The ECGI data from CardioInsight was retrospectively evaluated using the tool to derive the target volume for a patient with left ventricular assist device, showing volumetric matching with the clinically used target with a Dice coefficient of 0.71. CONCLUSIONS/UNASSIGNED:HeaRTmap smoothly fuses EP information from different mapping systems with simulation CT for accurate definition of radiation target volume. The efficient integration of EP data into treatment planning potentially facilitates the study and adoption of the technique.