Comparison of Native T1, Strain, and Traditional Measures of Cardiovascular Structure and Function by Cardiac Magnetic Resonance Imaging in Patients With Anderson-Fabry Disease.

Cardiovascular magnetic resonance imaging (CMR) has emerged as a powerful tool to illuminate cardiovascular pathology in Anderson-Fabry disease (AFD); however, further study is required to develop clinically useful monitoring paradigms. The objective of this study was to retrospectively evaluate strain, native septal T1 values, and standard CMR measurements in a cohort of AFD patients to characterize useful measures of cardiovascular dysfunction that may be derived from a CMR platform. Eighteen patients were identified (n = 8 males) and divided according to presence or absence of left ventricular hypertrophy (LVH). Biometric data were gathered and native T1 and strain values were measured for all patients. Patients with LVH were older and had significantly lower native T1 measured at the apical septal (893 ± 78 vs 1044 ± 217 ms, p = 0.035), midventricular septal (864 ± 76 vs 988 ± 67 ms, p = 0.016), and basal septal (867 ± 58 vs 1027 ± 84 ms, p = 0.006) regions. Circumferential strain was more positive in patients with LVH (-13.5% ± 5.0% vs -18.7% ± 2.7%, p = 0.042), but longitudinal strain was not significantly different between groups. Patients with LVH had higher stroke volumes (114.5 ± 9.7 vs 96.7 ± 17.8 ml, p = 0.050), but other standard CMR measures were not significantly different. In conclusion, AFD patients with LVH have reduced native T1 and more positive circumferential strain compared to those without. The basal septum may be an appropriate region for standard measure of native T1 in this population.

Myocardial strain pattern in patients with cardiac amyloidosis secondary to multiple myeloma: a cardiac MRI feature tracking study.

Cardiac MRI is frequently used in the diagnosis of cardiac amyloidosis. Feature tracking is a novel method of analyzing myocardial strain at the myocardial borders. We investigated myocardial deformation mechanics of both the right and left ventricles in patients with multiple myeloma with suspected cardiac amyloidosis. Comprehensive strain analysis was performed in 43 patients with multiple myeloma and suspected cardiac amyloidosis. MRI strain by feature tracking was measured using 2D cardiac performance analysis MR software (Tomtec, Germany). Global longitudinal (GLS) and global circumferential (GLC) strain were calculated in endo and epicardium. In addition, right ventricular longitudinal strain was measured in the endocardium only. All patients later underwent endomyocardial biopsy. Average wall thickness in biopsy proven cardiac amyloidosis group (22 patients) was 1.4 ± 0.4 cm with wall thickness ≤ 1.2 cm in 36 %. LGE was present in all patients with biopsy confirmed disease. There was significantly decreased global longitudinal strain and strain rate in the epicardial and endocardial layers. Global circumferential strain was significantly reduced in the epicardial layer but not the endocardium. GLS was significantly decreased at the base in both layers compared to the mid and apical regions of the myocardium. However, the base to apex GLS gradient was suggestive of apical sparing in the endocardial layer among patients with amyloidosis (-8.2 ± 2 vs. -2.7 ± 1; p = 0.001) but not the epicardial layer. Apical sparing was evident even in those with normal thickness CA. This feature tracking MRI analysis sheds light on strain mechanics in a cohort of multiple myeloma associated cardiac amyloidosis with a significant number of cases with normal LV wall thickness and explains mechanism of apical sparing effect.

Low-Volume Contrast CT Angiography Via Pulmonary Artery Injection for Measurement of Aortic Annulus in Patients Undergoing Transcatheter Aortic Valve Replacement.

OBJECTIVES: To investigate the feasibility and image quality of low-dose contrast computed tomography (CT) angiography with pulmonary artery (PA) protocol. BACKGROUND: Aortic stenosis is the most common valvular heart disease and transcatheter aortic valve replacement (TAVR) has evolved as an alternative method for surgical valve replacement in intermediate-risk and high-risk surgical patients. CT is essential for measurement of aortic annulus prior to TAVR. METHODS: Twenty patients underwent a low-dose contrast study with PA protocol and 20 patients underwent a traditional-dose study (traditional protocol). In PA protocol, the pigtail catheter was advanced in the main pulmonary artery under fluoroscopic guidance, with a second pigtail placed in the abdominal aorta. The pigtail catheter and sheath were secured in position and the patient was taken to the CT scan area for CT angiography of the chest (with injection from the PA catheter), abdomen, and pelvis (with injection from abdominal aortic catheter). RESULTS: The amount of contrast used was significantly lower in the PA protocol vs the traditional protocol (40 mL vs 99.50 ± 6.87 mL; P<.001) at the cost of reduced average signal (265 ± 60 HU vs 371 ± 70 HU; P<.001), but without affecting measurements of the aortic annulus. Furthermore, no statistically significant difference in serum creatinine concentration was observed before and 48 hours after contrast administration in the PA group. CONCLUSION: Our data provide evidence that the new PA technique can be performed safely with much lower volume of CT contrast without affecting assessment of aortic annulus size.

Cardiac magnetic resonance tissue tracking in right ventricle: Feasibility and normal values.

PURPOSE: To investigate right ventricular (RV) strain in patients without identified cardiac pathology using cardiac magnetic resonance tissue tracking (CMR TT). METHODS: A total of 50 consecutive patients with no identified cardiac pathology were analyzed. RV longitudinal and circumferential strain was assessed by CMR TT. The age range was 4-81years with a median of 32years (interquartile range, 15 to 56years). RESULTS: Analysis time per patient was <5min. The peak longitudinal strain (Ell) was -22.11±3.51%. The peak circumferential strains (Ecc) for global, basal, mid-cavity and apical segments were as follows: -11.69±2.25%, -11.00±2.45%, -11.17±3.36%, -12.90±3.34%. There were significant gender differences in peak Ecc at the base (P=0.04) and the mid-cavity (P=0.03) with greater deformation in females than in males. On Bland-Altman analysis, peak Ell (mean bias, 0.22±1.67; 95% CI -3.05 to 3.49) and mid-cavity Ecc (mean bias, 0.036±1.75; 95% CI, -3.39 to 3.47) had the best intra-observer agreement and inter-observer agreement, respectively. CONCLUSIONS: RV longitudinal and circumferential strains can be quickly assessed with good intra-observer and inter-observer variability using TT.

Relationship of Right Ventricular Size and Function with Respiratory Status in Duchenne Muscular Dystrophy.

The relationship between pulmonary function and right ventricle (RV) in Duchenne muscular dystrophy (DMD) has not been evaluated. Using cardiac magnetic resonance (CMR), we describe the relationship of RV size and function with spirometry in a DMD cohort. Fifty-seven boys undergoing CMR and pulmonary function testing within 1 month at a single center (2013-2015) were enrolled. Comparisons of RV ejection fraction (RVEF) and end-diastolic volume index (RVEDVI) were made across categories of percent forced vital capacity (FVC%), and relationships were assessed. Mean age was 15.5 ± 3.5 years. Spirometry and CMR were performed within 3.9 ± 4.1 days. Median FVC% was 92.0 % (67.5-116.5 %). Twenty-three (40 %) patients had abnormal FVC% (<80 %) of which 13 (57 %) had mild (FVC% 60-79 %), 6 (26 %) had moderate (FVC% 40-59 %), and 4 (17 %) had severe (FVC <40 %) reductions. Mean RVEF was 58.3 ± 3.7 %. Patients with abnormal FVC% were older and had lower RVEF and RVEDVI. Both RVEF and RVEDVI were significantly associated with FVC% (r = 0.31, p = 0.02 and r = 0.39, p = 0.003, respectively). In a large DMD cohort, RVEF and RVEDVI were related to FVC%. Worsening respiratory status may guide monitoring of cardiac function in these patients.