Islets of heterogeneous myocardium within the scar in cardiac magnetic resonance predict ventricular tachycardia after myocardial infarction.

INTRODUCTION: We assessed findings in cardiac magnetic resonance (CMR) as predictors of ventricular tachycardia (VT) after myocardial infarction (MI), which could allow for more precise identification of patients at risk of sudden cardiac death. METHODS: Forty-eight patients after prior MI were enrolled and divided into two groups: with (n = 24) and without (n = 24) VT. VT was confirmed by electrophysiological study and exit site was estimated based on 12-lead electrocardiogram. All patients underwent CMR with late gadolinium enhancement. RESULTS: The examined groups did not differ significantly in clinical and demographical parameters (including LV ejection fraction). There was a significant difference in the infarct age between the VT and non-VT group (15.8 ± 8.4 vs 7.1 ± 6.7 years, respectively; P = .002), with the cut-off point at the level of 12 years. In the scar core, islets of heterogeneous myocardium were revealed. They were defined as areas of potentially viable myocardium within or adjacent to the core scar. The number of islets was the strongest independent predictor of VT (odds ratio [OR], 1.42; confidence interval [CI], 1.17-1.73), but total islet size and the largest islet area were also significantly higher in the VT group (OR, 1.04; CI, 1.02-1.07 and OR, 1.16; CI, 1.01-1.27, respectively). Myocardial segments with fibrosis forming 25%-75% of the ventricular wall were associated with a higher incidence of VT (7.5 ± 2.1 vs 5.7 ± 2.6; P = .014). Three-dimension CMR reconstruction confirmed good correlation of the location of the islets/channels with VT exit site during electroanatomical mapping in five cases. CONCLUSIONS: The identification and quantification of islets of heterogeneous myocardium within the scar might be useful for predicting VT in patients after MI.

Clinical aspects of myocardial fibrosis in adults with Ebstein's anomaly.

Heart failure and arrhythmia are common complications in adults with Ebstein's anomaly. They may result not only from hemodynamic alterations, but also from myocardial fibrosis. Late gadolinium enhancement (LGE) by CMR enables the evaluation of myocardial fibrosis. The aim of the study was to asses the presence of LGE and its relation to clinical outcome. We studied a group of 37 unoperated adults aged 43.0 ± 14.4 years with Ebstein's anomaly from the congenital heart disease outpatient clinic. Study protocol included: cardiopulmonary test, assessment of supraventricular arrhythmia (SVA), and CMR with evaluation of cardiac chambers' morphology and function, and presence of LGE. Variables following normal distribution were shown as mean ± SD if otherwise median (range) was applied. Fibrosis was found in 18 patients (48.6%) and was distributed as follows: 12 patients (32.4%) in the right atrium, 12 (32.4%) in the atrialized right ventricle, and 2 (5.4%) in the functional right ventricle. In patients with fibrosis, the tricuspid regurgitation fraction was bigger (48.3 ± 19.7 vs. 36.1 ± 22.6%, p = 0.048) and SVA was more frequent [12 (66.7%) vs. 6 (31.6%), p = 0.046] when compared to patients without fibrosis. However, exercise capacity did not differ between patients with and without LGE (peak VO2 24.0 ± 4.7 vs. 23.7 ± 4.4, p = 0.87). In adults with Ebstein's anomaly fibrosis estimated by LGE-CMR was localized in the right atrium and the right ventricle only. Volume overload resulting from tricuspid regurgitation might be a factor conducive to fibrosis. Myocardial fibrosis did not influence exercise capacity. Association between myocardial fibrosis and supraventricular arrhythmia was confirmed.

Distinguishing high-flow from low-flow vascular malformations using maximum intensity projection images in dynamic magnetic resonance angiography - comparison to other MR-based techniques.

BACKGROUND: In addition to ultrasound, magnetic resonance imaging (MRI) is considered a suitable, non-invasive technique to assess the type and extent of vascular malformations. The distinction between low- and high-flow lesions is crucial because it determines appropriate patient treatment. PURPOSE: To distinguish high-flow from low-flow lesions on the basis of the enhancement pattern on MIP images acquired from dynamic time-resolved MR angiography (MRA) and compare it with previously described MR-based methods. MATERIAL AND METHODS: We examined 25 consecutive patients with previously diagnosed vascular malformations. Next, each malformation was classified as "high-flow" or "low-flow" using the following criteria: (i) findings on T1-weighted (T1W) and T2-weighted (T2W) imaging (signal voids, signal intensity); (ii) the time interval between the start of arterial enhancement and the onset of lesion enhancement (artery-lesion time); (iii) the time of maximum lesion enhancement; and (iv) analysis of the slope of the enhancement curve. RESULTS: Of the 25 patients, seven had high-flow and 18 had low-flow malformations. Signal voids on spin-echo T1W images were observed only in four of seven high-flow malformations and in two of 18 low-flow malformations. Analysis of signal intensity on T2W images showed increased signal intensity in 17 of 18 low-flow malformations, and in two of seven high-flow lesions. Calculation of the artery-lesion time, maximum enhancement time, and slope revealed significant differences between the high- and low-flow groups. CONCLUSION: In conclusion, the slope of the enhancement curve appears to be useful in distinguishing between high- and low-flow vascular malformations. Standardization of MR image evaluation criteria is essential.

Comparison of diffusion-weighted with T2-weighted imaging for detection of edema in acute myocardial infarction.

BACKGROUND: Recent studies, performed with the use of a commercially available diffusion weighted imaging (DWI) sequence, showed that they are sensitive to the increase of water content in the myocardium and may be used as an alternative to the standard T2-weighted sequences. The aim of this study was to compare two methods of myocardial edema imaging: DWI and T2-TIRM. METHODS: The study included 91 acute and post STEMI patients. We applied a qualitative and quantitative image analysis. The qualitative analysis consisted of evaluation of the quality of blood suppression, presence of artifacts and occurrence of high signal (edema) areas. On the basis of edema detection in AMI and control (post STEMI) group, the sensitivity and specificity of TIRM and DWI were determined. Two contrast to noise ratios (CNR) were calculated: CNR1--the contrast between edema and healthy myocardium and CNR2--the contrast between edema and intraventricular blood pool. The area of edema was measured for both TIRM and DWI sequences and compared with the infarct size in LGE images. RESULTS: Edema occurred more frequently in the DWI sequence. A major difference was observed in the inferior wall, where an edema-high signal was observed in 46% in T2-TIRM, whereas in the DWI sequence in 85%. An analysis of the image quality parameters showed that the use of DWI sequence allows complete blood signal suppression in the left ventricular cavity and reduces the occurrence of motion artifacts. However, it is connected with a higher incidence of magnetic susceptibility artifacts and image distortion. An analysis of the CNRs showed that CNR1 in T2-TIRM sequence depends on the infarct location and has the lowest value for the inferior wall. The area of edema measured on DWI images was significantly larger than in T2-TIRM. CONCLUSIONS: DWI is a new technique for edema detection in patients with acute myocardial infarction which may be recommended for the diagnosis of acute injuries, especially in patients with slow-flow artifacts in TIRM images.

Severity Scores for Ebstein Anomaly: Credibility and Usefulness of Echocardiographic vs Magnetic Resonance Assessments of the Celermajer Index.

BACKGROUND: The severity score of Ebstein anomaly (EA) that corresponds to clinical status is still under research, with the Celermajer index (Cel-ind) being one of those. The agreement between echocardiographic and cardiac magnetic resonance (CMR) assessment of Cel-ind is not known. We determined the agreement between echocardiography- and CMR-derived Cel-ind and its relationship with heart failure markers. METHODS: A total of 37 unoperated adults with EA (mean age, 43.0 ± 14.4 years) underwent echocardiography, CMR, and cardiopulmonary tests. For the Cel-ind, end-diastolic areas in echocardiography or end-diastolic volumes in CMR were used according to the following formula: Cel-ind = (right atrium + atrialized right ventricle)/(functional right ventricle + left atrium + left ventricle). On the basis of this assumption, patients were classified as follows: grade 1 = Cel-ind < 0.5, grade 2 = 0.5 to 0.99, grade 3 = 1.0 to 1.49, grade 4 > 1.5. The agreement between echocardiographic and CMR was determined with the intraclass correlation coefficient or Cohen's kappa (<0.2 poor agreement; 0.2-0.4 fair agreement; 0.4-0.6 moderate agreement; 0.6-0.8 good agreement; 0.8-1.0 very good agreement). RESULTS: The median echoCel-ind was 0.9 (range, 0.4-2.3), and the median cmrCel-ind was 0.7 (range, 0.3-5.3). Grade 1 or 2 was found in 19 patients (51.3%) by echocardiography and in 27 patients (72.9%) by CMR. The agreement between imaging methods was only fair (kappa = 0.39, P = 0.002) for the 4-grade classification and moderate (intra-class correlation coefficient = 0.43; 95% confidence interval, 0.13-0.66) for Cel-ind calculation. Significant correlations between Cel-ind in CMR and cardiopulmonary parameters were found (for peak oxygen uptake: R = -0.35, P = 0.034; for the ventilation/carbon dioxide slope: R = 0.46, P = 0.005). Neither of them correlated with echocardiographic severity score. CONCLUSIONS: The agreement between echocardiographic and CMR assessment of the Cel-ind is at most moderate; echocardiography usually overestimates, but rarely underestimates, EA severity. Cel-ind by CMR seems to be more valuable, because it is associated with heart failure markers.

The Usefulness of Magnetic Resonance Imaging of the Cardiovascular System in the Diagnostic Work-Up of Patients With Turner Syndrome.

Cardiovascular defects occur in 50% of patients with Turner syndrome (TS). The aim of the study was to estimate the usefulness of cardiac magnetic resonance imaging (CMR) and magnetic resonance angiography (angio-MR) as diagnostics in children and adolescents with TS. Forty-one females with TS, aged 13.9 ± 2.2 years, were studied. CMR was performed in 39 patients and angio-MR in 36. Echocardiography was performed in all patients. The most frequent anomalies diagnosed on CMR and angio-MR were as follows: elongation of the ascending aorta (AA) and aortic arch, present in 16 patients (45.7%), a bicuspid aortic valve (BAV), present in 16 patients (41.0%), and partial anomalous pulmonary venous return (PAPVR), present in six patients (17.1%). Aortic dilatation (Z-score > 2) was mostly seen at the sinotubular junction (STJ) (15 patients; 42.8%), the AA (15 patients; 42.8%), the thoracoabdominal aorta at the level of a diaphragm (15 patients; 42.8%), and the transverse segment (14 patients; 40.0%). An aortic size index (ASI) above 2.0 cm/m2 was present in six patients (17.1%) and above 2.5 cm/m2 in three patients (8.6%). The left ventricular end-diastolic volume (EDV), end-systolic volume (ESV), and stroke volume (SV) were diminished (Z-score < -2) in 10 (25.6%), 9 (23.1%), and 8 patients (20.5%), respectively. A webbed neck was correlated with the presence of vascular anomalies (p = 0.006). The age and body mass index (BMI) were correlated with the diameter of the aorta. Patients with BAV had a greater aortic diameter at the ascending aorta (AA) segment (p = 0.026) than other patients. ASI was correlated with aortic diameter and descending aortic diameter (AD/DD) ratio (p = 0.002; r = 0.49). There was a significant correlation between the right ventricular (p = 0.002, r = 0.46) and aortic diameters at the STJ segment (p = 0.0047, r = 0.48), as measured by echocardiography and CMR. Magnetic resonance can identify cardiovascular anomalies, dilatation of the aorta, pericardial fluid, and functional impairment of the ventricles not detected by echocardiography. BMI, age, BAV, and elongation of the AA influence aortic dilatation. The ASI and AD/DD ratio are important markers of aortic dilatation. The performed diagnostics did not indicate a negative influence of GH treatment on the cardiovascular system.

Cardiovascular magnetic resonance imaging in asymptomatic acute heart rejection: a case report.

BACKGROUND: Diagnosis of rejection is a major objective in the management of heart transplant recipients. It has been reported that one-third of protocol biopsies in asymptomatic, biochemically stable organ transplant recipients in the first 6 months show unsuspected subclinical graft rejection. CASE REPORT: We present the case of a 43-year-old man suffering from dilated cardiomyopathy who underwent orthotropic heart transplantation. The patient was admitted for a protocol endomyocardial biopsy and magnetic resonance imaging (MRI) on the 4th postoperative month as a protocol procedure. The examination revealed clinical status NYHA I with no signs of fatigue, diminution of exercise tolerance, or shortness of breath. His body temperature was not raised. He was referred for endomyocardial biopsy and cardiovascular magnetic resonance (CMR) imaging. CMR imaging showed good left and right ventricle function and contractility. T2 imaging revealed increased signal in the area of the right ventricular free wall, seen both in 4-chamber and short axis views. The patient underwent an endomyocardial biopsy, which demonstrated diffuse infiltrate with multifocal miocyte damage and cellular edema recognized as acute rejection (3a ISHLT grade). Consequently, he was treated with parenteral methylprednisolone administration. The CMR study performed after 1 week of therapy showed that the signal intensity of the edematous areas was significantly decreased. Repetitive endomyocardial biopsy revealed no signs of rejection. CONCLUSIONS: CMR can be helpful in graft monitoring following heart transplantation. It gives a whole-heart perspective that can be competitive with and/or complementary to endomyocardial biopsy. As a noninvasive study it can be applied more often and facilitates diagnosis of asymptomatic rejection episodes.

Value of rotational angiography (3D-ATG) with contrast agent administration into the right atrium during atrial fibrillation ablation procedures: a preliminary report.

BACKGROUND: Efficacy and safety of radiofrequency (RF) ablation in patients with atrial fibrillation (AF) strongly depend on the possibility of three-dimensional (3D) visualisation of atria as well as the ostia of pulmonary veins. Current angiographic systems allow 3D visualisation of anatomical heart structures using rotational angiography. AIM: To evaluate clinical usefulness of rotational angiography (3D-ATG) after contrast agent administration into the right atrium for the purpose of evaluating left atrial anatomy in patients undergoing RF ablation of AF. METHODS: We also compared images obtained using 3D-ATG with magnetic resonance imaging (MRI). In 18 consecutive patients undergoing RF ablation of AF or left-atrial tachycardia, 3D-ATG was performed uneventfully, followed by 3D reconstruction of the left atrium and the aorta. Ablation using the CARTO 3 system was successful in 17 patients. Total ablation time was 127 ± 28 min, fluoroscopy time 31 ± 8 min, and radiation dose was 413 ± 170 mGy. Mean fluoroscopy time for 3D-ATG was 1.75 ± 0.4 min and the mean radiation dose was 159 ± 57 mGy. Appropriate 3D visualisation of the left atrium was possible in 17 patients, including 16 patients in whom all 4 pulmonary venous ostia were imaged. In 1 patient, all right-sided pulmonary veins were located outside the scan area. In 1 case, 3D-ATG did not allow visualisation of the right inferior pulmonary vein, and in another case the left-sided veins had a common ostium as shown in MRI but not visualised in 3D-ATG. RESULTS: Pulmonary vein diameter assessed by 3D-ATG was slightly higher than by MRI (16.6 ± 3.2 vs. 15.2 ± 3.6 mm, p = 0.28), although this was mainly related to a single nonvisualised right inferior pulmonary vein. Good agreement (< 2 mm) between the two methods for the assessment of pulmonary venous ostia was higher for the right-sided than the left-sided veins (62.5% vs. 44%, p = 0.03). CONCLUSIONS: We conclude that 3D-ATG after contrast agent administration into the right atrium seems to be a safe and effective method to visualise pulmonary venous ostia and left atrial anatomy. It remains to be established whether it enables evaluation of anatomical anomalies.

Magnetic resonance imaging in the diagnostics of myocardial infarction.

Cardiovascular magnetic resonance (CMR) has a growing application in the diagnostics of myocardial infarction (MI). It is a non-invasive method that can be used regardless of the shape of patient's body. A single study allows assessment of the morphology and function of the cardiac muscle. It visualizes many pathophysiologic changes such as edema, microvascular obstruction (MVO) or necrosis, and complications of MI, like myocardial hemorrhage (MH) or thrombus, which are very difficult to diagnose using other methods. An obvious advantage of CMR is the possibility to differentiate an acute MI from the chronic one and to identify the etiology of fibrosis. All the aforementioned features of CMR have made it a useful tool in planning the treatment and assessing the prognosis of patients after MI.