Search

Introduction: Relative apical sparing of longitudinal strain (RALS, the ratio of apical strain vs the rest of the heart) on echocardiography has been found to have high sensitivity and specificity for differentiating cardiac amyloidosis (CA) from other causes of left ventricular hypertrophy. Previous studies have shown no significant difference between amyloid subtypes, systemic light-chain amyloidosis (AL) and transthyretin amyloidosis (ATTR) Hypothesis: There will be a significant difference in sensitivity and specificity of RALS to detect CA across amyloid subtypes. Methods: A cohort of patients with either AL or ATTR amyloid was identified, with a control cohort of patients with left ventricular hypertrophy (LVH) of other etiologies. Speckle tracking echocardiography was performed on EchoPAC (GE Medical Systems) software to obtain values of basal, mid, and apical longitudinal strain for each patient; relative apical strain was then calculated. Results: The TTR group (n=22) was older (66.4±7.9, 76.6±11.6, p=0.001) and more likely to be female (p=0.009) than the AL group (n=30), both groups had similar rates of hypertension, diabetes mellitus, and end stage renal disease. Echocardiographic markers of diastolic function were decreased in both groups; the AL group had decreased left ventricle end diastolic volume (60.9±25.5, 94.9±50.2, p=0.012) and mean wall thickness (1.4±0.3, 1.6±0.4 p=0.017). ROC analysis using a RALS cutoff of 2 to differentiate AL and ATTR from the LVH control group revealed similar specificity (AL 85%, ATTR 85%) and sensitivity (AL 40%, ATTR 50%). Difference in area-under-curve (AUC) was not significant (p=0.2) (figure). Conclusions: ATTR and AL amyloid have similar specificity, but ATTR has a trend towards improved sensitivity over AL for detection of CA using RALS with the previously validated threshold of 2. This might become significant with a larger sample, work that is currently on-going..

Introduction: Relative apical longitudinal strain (RALS) is defined as (average apical LS/(average basal & mid-ventricular LS)). A threshold of 2 has been found to have high sensitivity and specificity for differentiating cardiac amyloidosis (CA) from other causes of left ventricular hypertrophy (LVH). This threshold was developed using General Electric (GE) software, and its reproducibility among different software vendors is unknown. Hypothesis: In patients with CA, regional segmental LS patterns and relative apical longitudinal strain will vary among software vendors. Methods: Speckle-tracking echocardiography was retroactively performed by an experienced technician on two patient cohorts, CA (n=52) and LVH (n=52), using software from two independent vendors: EchoPAC (GE Medical Systems) and TomTEC (TOMTEC Imaging Systems GMBH). For each vendor and patient, strain values for the basal, mid, and apical segments were averaged to obtain three regional LS values which were then used to calculate global longitudinal strain (GLS) and RALS. Results: EchoPAC demonstrated greater average apical LS (-16.5±5.7 vs -13.1±6.6, p Conclusions: Software measurements of regional LS and thus RALS vary between vendors. Further efforts are needed for intervendor regional strain fidelity. For now, different RALS thresholds to diagnose CA may be needed for various vendors.

Introduction Right ventricular failure (RVF) is a major cause of morbidity and mortality after left ventricular assist device (LVAD), however predicting RVF remains challenging. Hypothesis We hypothesized that an analysis of late gadolinium enhancement (LGE) patterns on pre-operative cardiac MRI (cMRI) could identify patients at risk for RVF after LVAD. Methods We analyzed reports for cMRIs performed on patients within one year prior to LVAD at our institution and abstracted LGE patterns using the 17-segment model. Patients were then grouped into clusters by similarities in LGE patterns using an unsupervised machine learning (ML) algorithm of hierarchical agglomerative clustering. Statistical comparison of the resulting clusters was then performed. Results Patients (N=31) were grouped into 3 clusters (Figure) with varying patterns of LGE. Cluster 1 patients (n=16) had no LGE or atypical LGE patterns and were significantly younger (age 42 ± 18) than other clusters (p=0.029). Cluster 2 patients (n=11) had extensive transmural LGE patterns and were more likely to have hypertension (p=0.006) and dyslipidemia (p=0.002) than other groups. Cluster 3 patients (n=4) had some degree of subendocardial LGE but no extensive transmural LGE patterns. No patients in cluster 2 developed RVF after LVAD, while 4 patients (25%) in cluster 1 and 2 patients in cluster 3 (50%) had RVF after LVAD, though the difference between groups did not reach statistical significance due to small number of patients in the cohort overall (p=0.058). Importantly, traditional factors associated with RVF including hemodynamics and echocardiographic/MRI parameters of LV and RV function were not significantly different between clusters. Further, LGE enhancement of the RV myocardium or RV insertion points were not associated with RVF after LVAD. Conclusions Unsupervised ML of LGE patterns on cMRI can identify clusters of patients at risk for RVF. LGE patterns on cMRI may identify patients with non-ischemic (cluster 1) and mixed (cluster 3) etiologies of their heart failure who are at higher risk for developing RVF due to global biventricular myocardial involvement than patients with a truly ischemic etiology of their heart failure (cluster 2). Future research in a larger cohort is needed to confirm this hypothesis. Figure: Dendrogram produced from agglomerative hierarchal clustering of LGE analysis of cardiac MRIs using standardized myocardial segmentation

Background Right ventricular failure (RVF) following left ventricular assist device (LVAD) implantation is an important source of morbidity and mortality but is difficult to predict. Right atrial (RA) strain by echocardiography is a novel hemodynamic parameter likely indicative of atrial functional capacity and RV diastolic function. Previous studies have suggested that pre-LVAD RV strain may be a predictor of RVF, but no studies have systematically evaluated the association of RA strain with outcomes after LVAD. We hypothesized that pre-LVAD RA strain may improve the ability to predict RVF after LVAD. Methods We evaluated 31 adults who received continuous flow LVAD between 2008-2018. Peak RA and RV strain values were measured by two-dimensional speckle-tracking echocardiography. RA strain was measured during three phases: reservoir phase (end-diastole to onset of ventricular filling), conduit phase (onset of ventricular filling to onset of atrial contraction), and contractile phase (onset of atrial contraction to end-diastole). RVF was defined as need for inotropic support longer than 14 days, inhaled nitric oxide for longer than 48 hours, or unplanned RVAD. Pearson correlation was used to compare RA and RV strain parameters. Logistic regression was performed for the outcome of RVF. Cox-proportional hazards modelling was performed for the outcome of survival free from transplant or device explant/exchange and hazard ratios were calculated per standard deviation change in regressors. Results Four patients (13%) developed RVF. Median time from echo to LVAD was 31 days. Correlation between RV free wall longitudinal strain (FWLS) and RA reservoir (R=-0.45, p=0.01), conduit (R=-0.30, p=0.10), and contractile strain (R=-0.27, p=0.15) was modest at best. None of the RA strain parameters were associated with RVF. Lower RA reservoir strain (HR 2.26, p=0.003) and RA conduit strain (HR 3.63, p=0.004) were associated with decreased survival free from transplant or device explant/exchange, while RA contractile strain was not. Conclusions In this small cohort, RA strain parameters were not associated with early RVF following LVAD implant. However, RA reservoir strain and RA conduit strain were strongly associated with post LVAD long term survival. RA strain parameters may represent a form of RV diastolic dysfunction that impacts long term outcomes more so than early post operative events. The utility of RA strain parameters for predicting outcomes following LVAD implant deserves further investigation and validation in a larger cohort.

Cerebral palsy (CP) is the most common developmental motor disorder in children characterized by atypical or abnormal muscle tone, weakness, and reduced selective motor control. This results in abnormal movements and postures. Augmented therapeutic modalities to train selective motor control are needed in CP rehabilitation. We investigated motor learning in children with CP (n=9, ages 8-12, GMFCS =I,II) by providing feedback in a virtual reality (VR) environment of reduced dimensions consisting only of the first two principal components (PCs) of the space of target postures from a group of typically developing children (n=8, ages 8-12). After six training sessions we observed the following changes in the children’s motor control: a) increased variance in the first principal component; b) reduced variance in the non- relevant principal components; and c) increased the number of target matches. These results suggest that feedback of reduced dimensions by remapping space into its main principal components in a game like environment may increase selective motor control in children with CP.