The aim of this study was to evaluate whether left ventricular (LV) systolic strain in children and young adults with congenital aortic stenosis (AS) and preserved ejection fraction was different ...from normal subjects and to determine whether any alterations in strain were related to myocardial fibrosis. In this retrospective study, 29 patients with congenital AS with a median age of 15.3 years (range 1.7 to 23.7), highest lifetime AS peak Doppler gradient of 73 mm Hg (22 to 110), most recent AS peak Doppler gradient of 49 mm Hg (0 to 90), and ejection fraction of 65 (55 to 79) were included. Strain was measured using 2-dimensional speckle-tracking echocardiography. Cardiac magnetic resonance was used to identify focal fibrosis by late gadolinium enhancement (LGE) and diffuse fibrosis by calculating the extracellular volume fraction (ECV) from T1 measurements. Compared to age-matched controls (n = 29), patients with AS had reduced LV longitudinal (17.0 ± 3.0% vs 20.6 ± 2.2%, p <0.001) and radial strain (28.8 ± 8.6% vs 34.9 ± 8.5%, p = 0.01), and similar circumferential strain (26.2 ± 5.9% vs 26.4 ± 3.9%, p = 0.79). Median ECV in patients with AS was 0.27 (0.22 to 0.38) and was not significantly correlated with systolic strain. Patients with LGE (n = 7) had lower longitudinal strain than those without LGE (n = 21; 15.0 ± 2.2 vs 17.7 ± 3.1, p = 0.036). In conclusion, in this cohort of children and young adults with congenital AS and preserved ejection fraction, longitudinal and radial strain were reduced, and decreased longitudinal strain was associated with LGE but not ECV.
Objectives The major aim of this study is to test the hypothesis that stress cardiac magnetic resonance (CMR) imaging can provide robust prognostic value in women presenting with suspected ischemia, ...to the same extent as in men. Background Compelling evidence indicates that women with coronary artery disease (CAD) experience worse outcomes than men owing to a lack of early diagnosis and management. Numerous clinical studies have shown that stress CMR detects evidence of myocardial ischemia and infarction at high accuracy. Compared to nuclear scintigraphy, CMR is free of ionizing radiation, has high spatial resolution for imaging small hearts, and overcomes breast attenuation artifacts, which are substantial advantages when imaging women for CAD. Methods We performed stress CMR in 405 patients (168 women, mean age 58 ± 14 years) referred for ischemia assessment. CMR techniques included cine cardiac function, perfusion imaging during vasodilating stress, and late gadolinium enhancement imaging. All patients were followed for major adverse cardiac events (MACE). Results At a median follow-up of 30 months, MACE occurred in 36 patients (9%) including 21 cardiac deaths and 15 acute myocardial infarctions. In women, CMR evidence of ischemia (ISCHEMIA) demonstrated strong association with MACE (unadjusted hazard ratio: 49.9, p < 0.0001). While women with ISCHEMIA(+) had an annual MACE rate of 15%, women with ISCHEMIA(−) had very low annual MACE rate (0.3%), which was not statistically different from the low annual MACE rate in men with ISCHEMIA(−) (1.1%). CMR myocardial ischemia score was the strongest multivariable predictor of MACE in this cohort, for both women and men, indicating robust cardiac prognostication regardless of sex. Conclusions In addition to avoiding exposure to ionizing radiation, stress CMR myocardial perfusion imaging is an effective and robust risk-stratifying tool for patients of either sex presenting with possible ischemia.
Anatomically Oriented Right Ventricular Volume Measurements With Dynamic Three-Dimensional Echocardiography Validated by 3-Tesla Magnetic Resonance Imaging Petra S. Niemann, Luiz Pinho, Thomas ...Balbach, Christian Galuschky, Michael Blankenhagen, Michael Silberbach, Craig Broberg, Michael Jerosch-Herold, David J. Sahn The right ventricle (RV) is anatomically complex, and although magnetic resonance imaging (MRI) has been used to evaluate its anatomy and function, the accuracy of 3-dimensional/4-dimensional (4D) echocardiography (echo) for evaluating the RV has not been clearly established. We studied normal subjects and others with congenital heart disease both by 4D echo and with a multiplanar set of cine magnetic resonance images. Results from both studies could be analyzed with the same anatomically oriented new RV analysis software method. The method was easily and reproducibly used for evaluation of the RV both by MRI and 4D echo, documenting the accuracy of 4D echo for RV volume determination when compared with multiplanar MRI.
Background Atrial fibrillation ( AF ) is associated with myocardial infarction, and patients with AF and no obstructive coronary artery disease can present with symptoms and evidence of cardiac ...ischemia. We hypothesized that microvascular coronary dysfunction underlies these observations. Methods and Results Myocardial blood flow ( MBF ) at baseline and during adenosine stress and left ventricular and left atrial function were evaluated by magnetic resonance in 49 patients with AF (25 paroxysmal, 24 persistent) with no history of epicardial coronary artery disease or diabetes mellitus, before and 6 to 9 months after ablation. Findings were compared with those obtained in matched controls in sinus rhythm (n=25). Before ablation, patients with AF had impaired left atrial function and left ventricular ejection fraction and strain indices (all P<0.05 versus controls). MBF was impaired in patients both under baseline conditions (1.21±0.24 mL/min per g·mm Hg·bpm/10
versus 1.34±0.28 mL/min per g·mm Hg·bpm/10
in controls, P=0.044) and during adenosine stress (2.29±0.48 mL/min per g versus 2.73±0.37 mL/min per g in controls, P<0.001). Under baseline conditions, MBF correlated with left ventricular strain and left atrial function (all P≤0.001), so that cardiac function was most impaired in patients with the lowest MBF . Baseline and stress MBF remained unchanged postablation (both P=ns), and baseline MBF showed similar correlations with functional indices to those present preablation (all P≤0.001). Conclusions Baseline and stress MBF are significantly impaired in patients with AF but no epicardial coronary artery disease. Reduction in MBF is proportional to severity of left ventricular and left atrial dysfunction, even after successful ablation. Coronary microvascular dysfunction may be a relevant pathophysiological mechanism in patients with a history of AF .
Magnetic resonance (MR) imaging during the first pass of an injected contrast agent has been used to assess myocardial perfusion, but the quantification of blood flow has been generally judged as too ...complex for its clinical application. This study demonstrates the feasibility of applying model-independent deconvolution to the measured tissue residue curves to quantify myocardial perfusion. Model-independent approaches only require minimal user interaction or expertise in modeling. Monte Carlo simulations were performed with contrast-to-noise ratios typical of MR myocardial perfusion studies to determine the accuracy of the resulting blood flow estimates. With a B-spline representation of the tissue impulse response and Tikhonov regularization, the bias of blood flow estimates obtained by model-independent deconvolution was less than 1% in all cases for peak contrast to noise ratios in the range from 15:1 to 20:1. The relative dispersion of blood flow estimates in Monte Carlo simulations was less than 7%. Comparison of MR blood flow estimates against measurements with radio-isotope labeled microspheres indicated excellent linear correlation
(R
2
=0.995,
slope: 0.96, intercept: 0.06). It can be concluded from these studies that the application of myocardial blood flow quantification with MRI can be performed with model-independent methods, and this should support a more widespread use of blood flow quantification in the clinical environment.
In cardiac magnetic resonance (CMR) imaging, the T1 relaxation time for the 1H magnetization in myocardial tissue may represent a valuable biomarker for a variety of pathological conditions. This ...possibility has driven the growing interest in quantifying T1, rather than just relying on its effect on image contrast. The techniques have advanced to where pixel-level myocardial T1 mapping has become a routine component of CMR examinations. Combined with the use of contrast agents, T1 mapping has led an expansive investigation of interstitial remodeling in ischemic and nonischemic heart disease. The purpose of this review was to introduce the reader to the physical principles of T1 mapping, the imaging techniques developed for T1 mapping, the pathophysiological markers accessible by T1 mapping, and its clinical uses.
Two-dimensional echocardiography is currently the standard test for the clinical diagnosis of hypertrophic cardiomyopathy (HCM). The present study was undertaken to determine whether cardiac MRI ...(CMR) affords greater accuracy than echocardiography in establishing the diagnosis and assessing the magnitude of left ventricular (LV) hypertrophy in HCM.
Forty-eight patients (age 34+/-16 years) suspected of having HCM (or with a confirmed diagnosis) were imaged by both echocardiography and CMR to assess LV wall thickness in 8 anatomic segments (total n=384 segments) and compared in a blinded fashion. Maximum LV thickness was similar by echocardiography (21.7+/-9.1 mm) and CMR (22.5+/-9.6 mm; P=0.21). However, in 3 (6%) of the 48 patients, echocardiography did not demonstrate LV hypertrophy, and CMR identified otherwise undetected areas of wall thickening in the anterolateral LV free wall (17 to 20 mm), which resulted in a new diagnosis of HCM. In the overall study group, compared with CMR, echocardiography also underestimated the magnitude of hypertrophy in the basal anterolateral free wall (by 20+/-6%; P=0.001), as well as the presence of extreme LV wall thickness (> or =30 mm) in 10% of patients (P<0.05).
CMR is capable of identifying regions of LV hypertrophy not readily recognized by echocardiography and was solely responsible for diagnosis of the HCM phenotype in an important minority of patients. CMR enhances the assessment of LV hypertrophy, particularly in the anterolateral LV free wall, and represents a powerful supplemental imaging test with distinct diagnostic advantages for selected HCM patients.
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