The Role and Advantages of Cardiac Magnetic Resonance in the Diagnosis of Myocardial Ischemia.

Ischemic heart disease continues to be the leading cause of death and disability worldwide. For the diagnosis of ischemic heart disease, some form of cardiac stress test involving exercise or pharmacological stimulation continues to play an important role, despite advances within modalities like computer tomography for the noninvasive detection and characterization of epicardial coronary lesions. Among noninvasive stress imaging tests, cardiac magnetic resonance (CMR) combines several capabilities that are highly relevant for the diagnosis of ischemic heart disease: assessment of wall motion abnormalities, myocardial perfusion imaging, and depiction of replacement and interstitial fibrosis markers by late gadolinium enhancement techniques and T1 mapping. On top of these qualities, CMR is also well tolerated and safe in most clinical scenarios, including in the presence of cardiovascular implantable devices, while in the presence of renal disease, gadolinium-based contrast should only be used according to guidelines. CMR also offers outstanding viability assessment and prognostication of cardiovascular events. The last 2019 European Society of Cardiology guidelines for chronic coronary syndromes has positioned stress CMR as a class I noninvasive imaging technique for the diagnosis of coronary artery disease in symptomatic patients. In the present review, we present the current state-of-the-art assessment of myocardial ischemia by stress perfusion CMR, highlighting its advantages and current shortcomings. We discuss the safety, clinical, and cost-effectiveness aspects of gadolinium-based CMR-perfusion imaging for ischemic heart disease assessment.

Diffuse Myocardial Fibrosis and Cardiomyocyte Diameter Are Associated With Heart Failure Symptoms in Chagas Cardiomyopathy.

Background: Chronic Chagas cardiomyopathy (CCC) constitutes the most life-threatening consequence of the Trypanosoma cruzi infection. Our goal was to test in CCC the associations of the myocardial tissue phenotype with cardiac dysfunction, and heart failure (HF) severity, using cardiac magnetic resonance (CMR). Methods: We performed a prospective observational cohort of patients with consecutive CCC with a CMR protocol, including ventricular function, myocardial T1, and late gadolinium enhancement (LGE). Extracellular volume (ECV), and intracellular water lifetime, τic, a measure of cardiomyocyte diameter, were compared to CCC disease progression, including Rassi score and New York Heart Association (NYHA) class. An exploratory prognostic analysis was performed to investigate the association of both ECV and τic with CV death. Results: A total of 37 patients with intermediate-to-high-risk CCC were enrolled (Chagas Rassi score ≥7, mean left ventricle (LV) ejection fraction (EF) 32 ± 16%). Myocardial ECV (0.40 ± 0.07) was correlated with Rassi score (r = 0.43; P = 0.009), higher NYHA class, and LV EF (r = -0.51; P = 0.0015). τic decreased linearly with NYHA class (P = 0.007 for non-parametric test of linear trend) and showed a positive association with LV EF (r = 0.47; P = 0.004). Over a median follow-up of 734 days (range: 6-2,943 days), CV death or cardiac transplantation occurred in 10 patients. The Rassi score (heart rate [HR] = 1.3; 95% CI = [1.0, 1.8]; P = 0.028) and ECV (HR = 3.4 for 0.1 change, 95% CI = [1.1, 11.0], P = 0.039) were simultaneously associated with CV death. Conclusion: In patients with intermediate-to-high-risk CCC, an expanded ECV and regression of cardiomyocyte diameter were associated with worsening systolic function and HF severity, respectively. The exploratory analysis indicates that ECV may have a prognostic value to identify patients with CCC at a higher risk for cardiovascular events.

Noninvasive imaging assessment of rehabilitation therapy in heart failure with preserved and reduced left ventricular ejection fraction (IMAGING-REHAB-HF): design and rationale.

BACKGROUND: Studies have shown significant benefits of exercise therapy in heart failure (HF) with a reduced ejection fraction (HFrEF) and HF with a preserved ejection fraction (HFpEF). The mechanisms responsible for the beneficial effect of exercise in HFrEF and HFpEF are still unclear. We hypothesized that the effect of exercise on myocardial remodeling may explain its beneficial effect. METHODS: IMAGING-REHAB-HF is a single-center, randomized, controlled clinical trial using cardiac magnetic resonance imaging, vasomotor endothelial function, cardiac sympathetic activity imaging and serum biomarkers to compare the effect of exercise therapy in HFpEF (LVEF ≥ 45%) and HFrEF (LVEF < 45%). Subjects will be assessed at baseline and after 4 months. The exercise program will consist of three 60-min exercise sessions/week. The primary endpoints are the effect of exercise on myocardial extracellular volume (ECV), left ventricular (LV) systolic function, LV mass, LV mass-to-volume and LV cardiomyocyte volume. Secondary endpoints include the effect of exercise on vasomotor endothelial function, cardiac sympathetic activity and plasmatic biomarkers. Patients will be allocated in a 2:1 fashion to supervised exercise program or usual care. A total sample size of 90 patients, divided into two groups according to LVEF:HFpEF group (45 patients:30 in the intervention arm and 15 in the control arm) and HFrEF group (45 patients:30 in the intervention arm and 15 in the control arm) - will be necessary to achieve adequate power. CONCLUSION: This will be the first study to evaluate the benefits of a rehabilitation program on cardiac remodeling in HF patients. The unique design of our study may provide unique data to further elucidate the mechanisms involved in reverse cardiac remodeling after exercise in HFpEF and HFrEF patients.

Ressonância magnética e doença coronariana: quando o exame faz a diferença? / Magnetic resonance and coronary disease: when does the test make a difference?

O diagnóstico de doença coronariana e a quantificação de isquemia miocárdica tem se tornado cada vez mais necessário. Apesar de ainda haver controvérsia, estudos clínicos têm demonstrado que pacientes com carga isquêmica moderada ou alta têm pior prognóstico, a despeito de terapia clínica considerada adequada. Neste cenário, a ressonância magnética cardíaca (RMC) com estresse farmacológico tem despontado como método singular. Com relação aos outros exames disponíveis, a RMC apresenta vantagens teóricas e práticas, pois acumula características de outros métodos e os resume em um só. Proporciona excelente resolução espacial e temporal, possibilidade de avaliação da contratilidade global e segmentar e da espessura da parede do miocárdio em repouso e durante estresse, avaliação da perfusão e da viabilidade miocárdica, além de quantificação da área infartada com a técnica do realce tardio. Os avanços recentes nas sequências para avaliação da perfusão miocárdica permitiram que essa metodologia se tornasse uma importante ferramenta na prática clínica. Estudos multicêntricos confirmam a excelente sensibilidade e especificidade em pacientes submetidos à imagem de perfusão com estresse farmacológico pela RMC e o método se estabelece a passos largos como padrão­ouro na detecção da doença arterial coronária

The diagnosis of coronary artery disease and the quantification of myocardial ischemia has become increasingly vital. Although controversy remains, clinical studies have shown that patients with a moderate or high ischemic burden have a poorer prognosis, despite clinical therapy that is considered adequate. In this scenario, cardiac magnetic resonance imaging (CMR) with pharmacological stress has been highlighted as a unique method. In relation to the other tests available, CMR presents theoretical and practical advantages, as it takes the characteristics of other methods and combines them into one. It provides excellent spatial and temporal resolution, enabling the evaluation of global and segmental contractility and myocardial wall thickness, at rest and during stress, evaluation of perfusion and myocardial viability, and quantification of the infarcted area by the technique of delayed gadolinium enhancement. Recent advances in sequences for evaluation of myocardial perfusion have led to this method becoming an important tool in clinical practice. Multicenter studies confirm the excellent sensitivity and specificity in patients submitted to perfusion imaging with pharmacological stress by CMR, and the method is fast becoming established as the gold standard for the detection of coronary arterial disease