Prognostic Significance of Myocardial Ischemia Detected by Single-Photon Emission Computed Tomography in Children with Hypertrophic Cardiomyopathy.

Myocardial ischemia caused by microvascular dysfunction is an important pathophysiologic component of hypertrophic cardiomyopathy (HCM), promoting myocardial fibrosis, adverse left ventricular remodeling, and impacting on clinical course and outcome in HCM patients. The aim of study was to assess the prevalence and clinical significance of myocardial ischemia in children with HCM using 99mTc-MIBI single-photon emission computed tomography (SPECT). Ninety-one children with HCM, median age 13.6 years, underwent SPECT evaluation from 2006 to 2017. Imaging was performed at rest and after maximal exercise. Myocardial perfusion defects were identified in 70 children (76.9%; group I), median age 13.8 years. Fixed perfusion defects were evident in 22 of them, while reversible at rest in 48. In 21 children (23.1%; group II), median age 11 years, myocardial perfusion defects were not detected. Patient demographics, echocardiography, resting electrocardiogram (ECG), 24-h Holter ECG, myocardial fibrosis in cardiovascular magnetic resonance imaging, and cardiovascular events were analyzed and compared between the groups. During follow-up at a median of 8.3 years in children with myocardial ischemia, clinical endpoints occurred more often (47 vs. 5; p = 0.02) and more patients reached a clinical endpoint (28 [40%] vs. 3 [14.3%]; p = 0.036). In children with myocardial ischemia, myocardial fibrosis was observed with greater frequency. Myocardial perfusion defects may reflect an ischemic process which (1) affects the clinical manifestations and (2) is an important predictor of adverse clinical events and risk of death in children with HCM. Myocardial ischemia in HCM patients frequently correlates with myocardial fibrosis.

Right-ventricular mechanics assessed by cardiovascular magnetic resonance feature tracking in children with hypertrophic cardiomyopathy.

BACKGROUND: Although hypertrophic cardiomyopathy (HCM) is considered a disease of the left ventricle (LV), right ventricular (RV) abnormalities have also been reported on. Cardiovascular magnetic resonance feature tracking (CMR-FT) accurately and reproducibly quantifies RV myocardial deformation. AIM: To investigate RV deformation disorders in childhood HCM using CMR-FT. MATERIAL AND METHODS: Consecutive subjects aged <18 years with echocardiographic evidence of HCM were enrolled. Cardiovascular magnetic resonance (CMR) was performed including RV volumetric and functional assessment, and late gadolinium enhancement (LGE) imaging. RESULTS: We included 54 children (37 males, 68.5%) with HCM, of which 28 patients (51.8%; mean extent of 2.18 ± 2.34% of LV mass) had late gadolinium enhancement. LV outflow tract obstruction (LVOTO) was detected in 19 subjects (35.2%). In patients with LVOTO, RV global longitudinal strain (RVGLS) (-16.1±5.0 vs. -20.7±5.3, p<0.01), RVGLS rate (-1.05±0.30 vs. -1.26±0.40, p = 0.03), RV radial strain (RVR) (15.8±7.7 vs. 22.1±7.0, p<0.01) and RVR rate (0.95±0.35 vs. 1.6±0.44, p<0.01) were lower than in patients without LVOTO. The RVR rate (p<0.01) was lower in patients with LGE in comparison to patients without LGE. CONCLUSIONS: Children with HCM, especially with LVOTO, have significantly reduced indices of RV mechanics despite normal RV systolic function. It seems that the degree of LVOT obstruction is responsible for compromising the RV dynamics, rather than either mass or the amount of LV fibrosis.

The Indices of Cardiovascular Magnetic Resonance Derived Atrial Dynamics May Improve the Contemporary Risk Stratification Algorithms in Children with Hypertrophic Cardiomyopathy.

INTRODUCTION: The most efficient risk stratification algorithms are expected to deliver robust and indefectible identification of high-risk children with hypertrophic cardiomyopathy (HCM). Here we compare algorithms for risk stratification in primary prevention in HCM children and investigate whether novel indices of biatrial performance improve these algorithms. METHODS AND RESULTS: The endpoints were defined as sudden cardiac death, resuscitated cardiac arrest, or appropriate implantable cardioverter-defibrillator discharge. We examined the prognostic utility of classic American College of Cardiology/American Heart Association (ACC/AHA) risk factors, the novel HCM Risk-Kids score and the combination of these with indices of biatrial dynamics. The study consisted of 55 HCM children (mean age 12.5 ± 4.6 years, 69.1% males); seven had endpoints (four deaths, three appropriate ICD discharges). A strong trend (DeLong p = 0.08) was observed towards better endpoint identification performance of the HCM Risk-Kids Model compared to the ACC/AHA strategy. Adding the atrial conduit function component significantly improved the prediction capabilities of the AHA/ACC Model (DeLong p = 0.01) and HCM Risk-Kids algorithm (DeLong p = 0.04). CONCLUSIONS: The new HCM Risk-Kids individualised algorithm and score was capable of identifying high-risk children with very good accuracy. The inclusion of one of the atrial dynamic indices improved both risk stratification strategies.

Comparison of echocardiography with tissue Doppler imaging and magnetic resonance imaging with delayed enhancement in the assessment of children with hypertrophic cardiomyopathy.

INTRODUCTION: In children with hypertrophic cardiomyopathy (HCM) there often occurs a non-ischemic pattern of myocardial fibrosis, which could be the cause of impaired left ventricular (LV) diastolic function assessed by tissue Doppler imaging (TDI). The aim of the study was to determine the prevalence of myocardial fibrosis in children with HCM, and to evaluate its relationship with echocardiographic parameters including LV diastolic dysfunction. MATERIAL AND METHODS: Sixty-three children with HCM, mean age 12.2 ±4.5 years, underwent magnetic resonance imaging (MRI) and echocardiographic study from January 2010 to April 2014. The results of MRI, echocardiography, and TDI velocities were analyzed and compared between children with and without myocardial fibrosis. Moreover, correlations between the results of echocardiography and MRI were assessed. RESULTS: Our results showed a significant correlation between magnetic resonance and echocardiographic measurements of septal wall thickness, posterior wall thickness, LV mass and left atrial dimension. Children with myocardial fibrosis (60%) had a significantly thicker interventricular septum (21.3 vs. 1.8 mm; p < 0.0001) and larger left atrial dimension (36.7 vs. 27.8 mm; p = 0.0004) and volume index (42.0 vs. 26.6 ml/m²; p = 0.0011). Tissue Doppler imaging demonstrated significantly decreased lateral E' (9.02 vs. 13.53 cm/s; p < 0.0001) and septal E' (7.05 vs. 9.36 cm/s; p = 0.0082) velocities and a significantly increased transmitral lateral (10.34 vs. 6.68; p = 0.0091) and septal (13.1 vs. 9.8; p = 0.046) E/E' ratio in children with myocardial fibrosis. CONCLUSIONS: Myocardial fibrosis in children with hypertrophic cardiomyopathy was associated with markers for disease severity such as larger septum thickness, enlargement of the left atrium as well as impairment of left ventricular diastolic function. Tissue Doppler imaging is a helpful tool to detect the presence of left ventricular diastolic dysfunction in children with hypertrophic cardiomyopathy and myocardial fibrosis.

The usefulness of cardiovascular magnetic resonance imaging in children with myocardial diseases.

BACKGROUND: Cardiovascular magnetic resonance (CMR) imaging is a clinically proven and reliable diagnostic method for the assessment of morphology, function, and characteristics of myocardial tissue in patients with myocardial diseases. The use of gadolinium contrast agents has created new diagnostic possibilities for tissue characterisation in patients with suspected or known cardiomyopathy, myocarditis, and cardiac tumours. AIM: To evaluate the usefulness of CMR in the diagnostic process in children with myocardial diseases and to compare the results of CMR and other non-invasive cardiovascular methods, including echocardiography. METHODS: The study included 112 children, with an average age of 12 ± 4.64 years, with various forms of myocardial disease: 63 children with hypertrophic cardiomyopathy (HCM), 9 with suspected myocarditis, 5 with history of myocarditis, 4 with dilated cardiomyopathy (DCM), 9 with suspected arrhythmogenic right ventricular cardiomyopathy (ARVC), 6 with left ventricular non-compaction cardiomyopathy (LVNC), 9 with suspected restrictive cardiomyopathy (RCM) to be differentiated with constrictive pericarditis (CP), and 7 with cardiac tumours. RESULTS: CMR confirmed the echocardiographic diagnosis of HCM in 92% of children and ruled it out in 8%, and in three children apical hypertrophy was found. CMR revealed the presence of myocardial fibrosis in 60% of patients with HCM. In 33% of children with clinically suspected myocarditis CMR confirmed this diagnosis, while in 44% of them DCM was recognised. Of the five children with a history of myocarditis, in one patient CMR performed 13 years after myocarditis revealed features of post-inflammatory DCM. In 75% of patients with the echocardiographic diagnosis of post-inflammatory DCM the result of CMR was consistent. CMR ruled out the presence of ARVC in 89% of children. Echocardiographic and CMR diagnosis of LVNC was consistent in 67% of children. CMR confirmed the clinical diagnosis of RCM in 63% of patients, and in one patient CP was recognised. CMR confirmed the presence of cardiac tumour in 57% of children and excluded it in 43% of patients. CONCLUSIONS: CMR is increasingly recognised as an important tool in the investigation of myocardial disease and should be part of routine clinical work-up. CMR provides an additional diagnostic technique to assess the presence or exclusion of an active myocarditis. In children with clinical and echocardiographic suspicion of LVNC, ARVC, RCM, CP, and cardiac tumours CMR can conclusively confirm the presence of the disease.