This study aims to evaluate the feasibility of turbulent kinetic energy (TKE) assessments using compressed sensing (CS)-accelerated three-dimensional time-resolved phase-contrast magnetic resonance imaging (4D flow MRI) in patients with aortic stenosis (AS). Conventional and CS 4D flow MRI (R = 2 with GRAPPA and R = 7.7 with CS, respectively) were sequentially acquired for voxel-wise comparison in healthy participants and patients. Total TKE was measured in both the ascending aorta (AAo) and the whole aortic region. The difference between GRAPPA and CS was expressed as the ratio of (CS 4D flow - Conventional 4D flow) to (Conventional 4D flow). A two-tailed paired t-test was used to assess statistical significance. In healthy participants, the maximum total TKE (TKEmax) measured by CS 4D flow MRI was substantially higher than that obtained with conventional 4D flow MRI, showing a 95.4% increase in the AAo region (0.74 ± 0.43 mJ by GRAPPA vs. 1.17 ± 0.72 mJ by CS; P = 0.053) and a 207.7% increase in the whole aortic region (1.13 ± 0.73 mJ by GRAPPA vs. 2.13 ± 0.95 mJ by CS; P = 0.006). In patients with AS, CS 4D flow MRI showed good agreement with conventional imaging, with only a 5.0% difference in TKEmax at the AAo (14.0 ± 4.6 mJ by GRAPPA vs. 14.8 ± 5.5 mJ by CS; P = 0.129) and a 7.4% difference in the whole region (16.3 ± 5.5 mJ by GRAPPA vs. 17.6 ± 6.5 mJ by CS; P = 0.050). CS 4D flow MRI demonstrated agreement, showing insignificant differences in total TKE measurements specifically within the AAo for AS patients. In healthy participants, CS-based TKE assessment showed larger relative differences compared with conventional 4D flow MRI, likely reflecting a low-TKE effect.

Diffuse myocardial fibrosis, as measured by T1 (longitudinal relaxation time) mapping and extracellular volume, may be associated with ventricular dysfunction in the Fontan circulation. However, the relationship between diffuse myocardial fibrosis and exercise tolerance, an early and clinically meaningful marker of Fontan physiology, remains incompletely characterized, particularly in pediatric populations. To evaluate the association between CMR-derived markers of diffuse myocardial fibrosis (native T1 and ECV) and exercise tolerance in pediatric patients with Fontan circulation compared with healthy controls. A retrospective cohort study of pediatric patients with Fontan circulation who underwent clinically indicated cardiovascular magnetic resonance (CMR) with native and post-contrast T1 mapping between 2019 and 2022 was performed. Global native T1 and ECV were quantified and compared with age- and scanner-matched controls. Cardiopulmonary exercise testing–derived VO₂ max and catheterization parameters obtained within 24 months of CMR were analyzed. Associations between myocardial fibrosis markers and functional measures were assessed using correlation analyses. A cohort of 64 pediatric Fontan patients (median age 11.0 years, interquartile range 7.0—14.0; age range <18 years), and 41 pediatric controls, was stratified by field strength and ventricular dominance. Fontan patients demonstrated increased native T1 values across varying field strengths of 1.5 T (1,035.9 ± 48.7 ms vs 983.8 ± 29.0 ms, P<0.001) and 3 T (1,292.8 ± 53.5 ms vs 1,257.8 ± 41.5 ms, P=0.033), and significantly elevated ECV compared to controls (25.6 ± 3.5

Examine the relationship between the inter-superior vena cava (SVC) distance and pulmonary blood flow (PBF) splitting, post-Fontan outcomes, hemodynamics, Fontan geometry, and pulmonary artery (PA) growth in bilateral bidirectional Glenn (BBDG) patients compared to unilateral bidirectional Glenn (BDG) patients. A single center retrospective cohort study comparing demographic, hemodynamic, and post-Fontan outcome variables between BBDG patients and a randomized cohort of BDG patients was conducted. A simple linear regression model was created to evaluate the relationship between Fontan geometry and PBF splitting. Cardiac magnetic resonance images were segmented using Slicer 5.6.2 and center line distance between the right and left SVC was calculated using an in-house code. The relationship between SVC distance and PBF was examined. The Nakata index was compared for BBDG and BDG patients. 42 patients (21 BBDG and 21 BDG) were included. Demographics, post-Fontan complications, and hemodynamics between groups were not different. PBF flow splitting increased as a function of inter-SVC distance. Patients with BBDG experienced a decrease in PA size over time with the mean difference in Nakata index between groups of 128.5 ± 23.73 (95

Pulmonary hemodynamics are necessary to measure for lifelong surveillance of cardiovascular function in children with tetralogy of Fallot (TOF). To measure cardiac index, invasive cardiac catheterization using the Fick principle or phase-contrast MRI (PC-MRI) can be used. However, estimates of oxygen consumption and other assumptions used in the Fick method may lead to significant inaccuracy, which are further exacerbated by disease characteristics such as pulmonary regurgitation. By comparison, PC-MRI can directly measure blood flow and regurgitant fraction. To investigate the potential complications of using the Fick principle, flow hemodynamics in 33 repaired TOF patients (7.6 ± 3.9 years) were investigated in patients who underwent cardiac catheterization and cardiac MRI. Pulmonary blood flow (Qp) measured by catheterization and PC-MRI showed poor agreement with an absolute bias of 0.80 ± 0.910 L/min/m2. Qp by Fick was significantly higher than PC-MRI (3.15 ± 0.60 L/min/m2 vs. 2.35 ± 0.95 L/min/m2 [p < 0.001]). Patients were also stratified by the presence of severe pulmonary regurgitant fraction (RF > 40

Introduction and Objective: Type 2 diabetes (T2D) and obesity are associated with left ventricular (LV) dysfunction, but the impact of exercise interventions on LV function remains unclear. This study aims to assess LV function in individuals with obesity, with and without T2D via supervised aerobic exercise training, using cardiac MRI and time-resolved three-dimensional phase-contrast MRI (4D flow MRI). Methods: 16 overweight controls (OWC; HbA1c = 5.3 ± 0.2%; age = 42.8 ± 6.0 years; 56% female) and 7 individuals with obesity and T2D (HbA1c = 6.8 ± 0.8%; age = 48.3 ± 6.0 years; 57%) completed 15 weeks of exercise training. Maximal oxygen consumption was measured as a marker of cardiorespiratory fitness. Global LV function and strain were analyzed using cardiac MRI. E/A velocity, a standard echocardiographic marker, was assessed using 4D flow MRI. Participants were categorized into low SVi (20.5 ± 3.0 mL/m2) and high SVi groups (30.1 ± 3.6 mL/m2) based on an SVi threshold of 25 mL/m2. Pre- and post-exercise data were compared using paired t-tests. Results: Reclassifying the cohort by SVi showed a significant increase in E/A velocity only in the high SVi group after exercise, with no other biomarkers showing significant changes in either group. Conclusion: Early LV function changes via exercise intervention may be detectable in E/A velocity in individuals with high SVi. S. Park: None. E.K. Englund: None. T. Fujiwara: None. D. Enge: Employee; Epic. M. Schäfer: None. B.M. Fonseca: Consultant; Siemens Healthcare Diagnostics. K.S. Hunter: None. J.G. Regensteiner: None. J.E.B. Reusch: Advisory Panel; Medtronic. A.J. Barker: None. American Diabetes Association (4-24-PDF-51)

Este consenso de nomenclatura y clasificación para la válvula aórtica bicúspide congénita y su aortopatía está basado en la evidencia y destinado a ser utilizado universalmente por médicos (tanto pediatras como de adultos), médicos ecocardiografistas, especialistas en imágenes avanzadas cardiovasculares, cardiólogos intervencionistas, cirujanos cardiovasculares, patólogos, genetistas e investigadores que abarcan estas áreas de investigación clínica y básica. Siempre y cuando se disponga de nueva investigación clave y de referencia, este consenso internacional puede estar sujeto a cambios de acuerdo con datos basados en la evidencia1.

Objective:Aortic shape and geometry after surgical reconstruction have been shown to be important determinants of flow hemodynamics, aortic remodeling, and clinical outcomes. In this study, we investigated aortic shapes post-frozen elephant trunk (FET) reconstruction using statistical shape modeling by principal component analysis and correlated discovered shape variations with the postoperative outcomes. Methods:Patients from 3 institutions who underwent computed tomography (CT) angiography post-FET aortic reconstruction for type A dissection or ascending thoracic aortic aneurysms were included. A 3-dimensional aortic model was generated from CT angiography, and the aortic centerline was calculated for each subject. Principal components describing aortic shape variations were then correlated with the cumulative rate of postoperative aortic events requiring intervention. Results:A total of 135 subjects across 2 sites with postoperative CT and surveillance data were included in the study. Identified first principal component accounting for 31.6% of geometric shape variation in the entire cohort described angle variability at the region of the aortic isthmus. On the basis of the degree of isthmic angulation quantitatively defined by the principal component score, we separated the cohort into high and low isthmic angle groups. Patients with high isthmic angle had greater 5-year freedom from aortic events with 49.5% compared with 78.6% in the low isthmic angle group (P = .024). Conclusions:Aortic shape variation defined by the acute angle of the aortic isthmus has been associated with aortic events and lower freedom from intervention post-FET operation. These results add to the increasing amount of evidence implicating acute isthmic angle from overt downstream aortic remodeling postcomplex aortic repair. Further biomechanical studies are required to identify the mechanistic link between isthmic geometry and patient-specific aortic remodeling.

This International evidence-based nomenclature and classification consensus on the congenital bicuspid aortic valve and its aortopathy recognizes 3 types of bicuspid aortic valve: 1. Fused type, with 3 phenotypes: right-left cusp fusion, right-non cusp fusion and left-non cusp fusion; 2. 2-sinus type with 2 phenotypes: Latero-lateral and antero-posterior; and 3. Partial-fusion or forme fruste. This consensus recognizes 3 bicuspid-aortopathy types: 1. Ascending phenotype; root phenotype; and 3. extended phenotypes.

Fetal cardiac MRI using Doppler US gating is an emerging technique to support prenatal diagnosis of congenital heart disease and other cardiovascular abnormalities. Analogous to postnatal electrocardiographically gated cardiac MRI, this technique enables directly gated MRI of the fetal heart throughout the cardiac cycle, allowing for immediate data reconstruction and review of image quality. This review outlines the technical principles and challenges of cardiac MRI with Doppler US gating, such as loss of gating signal due to fetal movement. A practical workflow of patient preparation for the use of Doppler US-gated fetal cardiac MRI in clinical routine is provided. Currently applied MRI sequences (ie, cine or four-dimensional flow imaging), with special consideration of technical adaptations to the fetal heart, are summarized. The authors provide a literature review on the clinical benefits of Doppler US-gated fetal cardiac MRI for gaining additional diagnostic information on cardiovascular malformations and fetal hemodynamics. Finally, future perspectives of Doppler US-gated fetal cardiac MRI and further technical developments to reduce acquisition times and eliminate sources of artifacts are discussed. Keywords: MR Fetal, Ultrasound Doppler, Cardiac, Heart, Congenital, Obstetrics, Fetus Supplemental material is available for this article. © RSNA, 2024.

AIM:Type 1 diabetes (T1D) increases the risk of morbidity and mortality from cardiovascular disease, and insufficient sleep is prevalent. Emerging evidence suggests a link between sleep and cardiometabolic health, but this has not been examined across the lifespan in individuals with T1D. We aimed to examine associations between sleep and cardiometabolic health in adolescents and adults with T1D in a secondary analysis of data from a 4-week double-blind, random-order, placebo-controlled crossover trial of bromocriptine quick release (BCQR) therapy with a 4-week washout in between conditions. MATERIALS AND METHODS:Forty-two adults (19-60 years) and 42 adolescents (12-18 years) with T1D >9 months completed 1 week of home monitoring with wrist-worn actigraphy to estimate sleep duration and continuous glucose monitoring, anthropometrics, arterial stiffness, magnetic resonance imaging (adolescents only), and fasting laboratory testing at each treatment phase. RESULTS:Sixty-two per cent of adolescents and 74% of adults obtained <7 h of sleep per night at baseline. After adjustment for age, sex and diabetes duration, baseline sleep <7 h per night was associated with a higher body mass index, a higher waist circumference, a higher systolic blood pressure, worse arterial stiffness and a lower estimated insulin sensitivity (all p < .05). When examined by age group, associations between sleep duration and cardiometabolic health outcomes remained significant, predominantly for adolescents. In adolescents only, wake time was significantly later (p = .027) and time in bed was significantly longer with BCQR versus placebo (p = .049). CONCLUSIONS:Objectively measured sleep <7 h per night was prevalent in adolescents and adults with T1D and associated with poorer cardiometabolic health markers. Small changes in sleep were seen following BCQR treatment in adolescents only. Sleep may be an important and novel target for improving cardiometabolic health in individuals with T1D.

Introduction & Objective: Diabetes and SARS-CoV-2 target the endothelium, causing microvascular dysfunction. We present a novel test to measure recovery dynamics of blood flow post-isometric exercise in the leg. We hypothesized that T2D related microvascular injury would augment perfusion abnormalities in people with COVID-19. Methods: 14 hospitalized adults with COVID-19 and acute hypoxemia (7 with DM) underwent vPIVOT MRI on a 3T scanner 1 month post hospitalization. Scans were compared to 4 healthy controls (no DM or severe COVID-19). vPIVOT is an MRI sequence that simultaneously measures micro- and macrovascular blood flow and oxygenation, enabling quantification of integrated peripheral vascular responses to hyperemic stimuli, such as exercise. Here, the perfusion response following a 90s isometric plantar flexion contraction at 70% maximum effort was analyzed. Results: Quantitative analysis of the MRI data was performed as shown (Figure). Significant between group differences of area under the curve (AUC, p=0.021) and time to recovery (TTR, p=0.024) were observed by ANOVA. Post-hoc comparisons did not detect any significant differences in COVID-19 participants with or without T2DM in this limited sample. Conclusion: We demonstrate a novel MRI exam can elucidate total perfusion after exercise, and preliminary results show that it is reduced in time and in magnitude for people post severe COVID-19 infection. Disclosure E. Englund: None. A.J. Barker: None. G.I. Medrano: None. M. Cree-Green: Consultant; Pollie, Inc. Research Support; Amino Co. R. Maicki: None. I.S. Douglas: None. J.E.B. Reusch: Advisory Panel; Medtronic. Funding NIH (R01 DK130351); NIH/NCATS Colorado CTSA (KL2TR002534); American Heart Association (853697)

Purpose To provide reference values for four-dimensional (4D) flow MRI in healthy fetuses and evaluate reliability of fetal 4D flow MRI hemodynamics in third trimester fetuses with normal cardiovascular development or suspected coarctation of the aorta (CoA). Materials and Methods Pregnant patients with healthy fetuses or fetuses with echocardiographic concern for CoA were prospectively recruited between May 2021 and October 2023. Doppler US-gated fetal 4D flow MRI was performed at 3 T. Repeated 4D flow (time permitting) and two-dimensional (2D) phase contrast (PC) MRI data were acquired. Net flow was quantified, and the reliability of 4D flow measurement was evaluated by using precision across adjacent measurement planes, internal consistency based on conservation of mass, comparison of net flow from 4D flow MRI versus 2D PC MRI, and repeatability of 4D flow from separate acquisitions. Results Data were obtained in 34 pregnant participants (mean maternal age, 33 years ± 5 [SD]; mean gestational age, 35 weeks ± 2; n = 22 healthy fetuses and 12 fetuses with suspected CoA). Precision was high across all vascular segments (mean within-subject coefficient of variation = 7%). For mass conservation, there was an average difference of 19% ± 12 between ductus arteriosus plus isthmus flow versus descending aorta flow (r = 0.76). Net flow measured with 4D flow MRI correlated with that measured with 2D PC MRI (r = 0.51) but was underestimated relative to 2D PC MRI by approximately 34%. Hemodynamic parameters quantified from repeated 4D flow acquisitions had good agreement, with an intraclass correlation coefficient of 0.94 between test and retest data. Conclusion Hemodynamic measurements derived from fetal 4D flow MRI were reliable, showing good internal consistency, precision, and repeatability; however, as expected, 4D flow MRI underestimated absolute blood flow relative to 2D PC MRI. Keywords: Fetal MRI, Cardiac, Aorta, Hemodynamics/Flow Dynamics, Pulmonary Arteries Supplemental material is available for this article. © RSNA, 2024.

The purpose of this study was to investigate neo-aortic curvature and diameter variation using the principal component analysis in patients who underwent a Norwood procedure for hypoplastic left heart syndrome. We further assessed whether neo-aortic curvature and diameter features are associated with clinical outcomes, single right ventricle function and flow hemodynamic patterns derived by 4D-Flow MRI. 55 patients with Fontan circulation who underwent a Norwood procedure in infancy underwent cardiac MRI as part of surveillance of their Fontan circulation. Neo-aortic models segmented from the MRI angiography were subjected to principal component analysis. Principal component (PC) score values representing curvature and diameter variability were compared between patients with and without composite clinical event and correlated with standard cardiac hemodynamics. Fourteen patients experienced composite adverse clinical events. The PCs describing the variations in aortic curvature were not associated with cardiac MRI hemodynamics or clinical events. The diameter-based 2nd PC describing the degree of aortic tapering was significantly associated with the end-systolic volume index (R = 0.34, P = 0.011), ejection fraction (R = -0.44, P = 0.001), and viscous energy loss measured in the ascending aorta (R = 0.45, P = 0.009). High 2nd PC score values describing abrupt diameter changes were also associated with worse freedom from clinical events (P = 0.042). Neo-aortic shape variation described by gradual diameter tapering is strongly linked to better clinical and hemodynamic outcomes. Neo-aortic curvature and luminal trajectory seems to have less impact on the overall hemodynamics and long-term outcomes.

Background: Aortic dilation is seen in pediatric/young adult patients with bicuspid aortic valve (BAV), and hemodynamic markers to predict aortic dilation are necessary for monitoring. Although promising hemodynamic metrics, such as abnormal wall shear stress (WSS) magnitude, have been proposed for adult BAV patients using four-dimensional (4D) flow cardiovascular magnetic resonance, those for pediatric BAV patients have less frequently been reported, partly due to scarcity of data to define normal WSS range. To circumvent this challenge, this study aims to investigate if a recently proposed 4D flow-based hemodynamic measurement, abnormal flow directionality, is associated with aortic dilation in pediatric/young adult BAV patients. Methods: 4D flow scans for BAV patients (< 20 years old) and age-matched controls were retrospectively enrolled. Static segmentation for the aorta and pulmonary arteries was obtained to quantify peak systolic hemodynamics and diameters in the proximal aorta. In addition to peak velocity, WSS, vorticity, helicity, and viscous energy loss, direction of aortic velocity and WSS in BAV patients were compared with that of control atlas using registration technique; angle differences of > 60 deg and > 120 deg were defined as moderately and severely abnormal, respectively. The association between the obtained metrics and normalized diameters (Z-scores) was evaluated at the sinotubular junction, mid-ascending aorta, and distal ascending aorta. Results: Fifty-three BAV patients, including 18 with history of repaired aortic coarctation, and 17 controls were enrolled. Correlation between moderately abnormal velocity/WSS direction and aortic Z-scores was moderate to strong at the sinotubular junction and mid-ascending aorta (R = 0.62-0.81; p < 0.001) while conventional measurements exhibited weaker correlation (|R| = 0.003-0.47, p = 0.009-0.99) in all subdomains. Multivariable regression analysis found moderately abnormal velocity direction and existence of aortic regurgitation (only for isolated BAV group) were independently associated with mid-ascending aortic Z-scores. Conclusion: Abnormal velocity and WSS directionality in the proximal aorta were strongly associated with aortic Z-scores in pediatric/young adult BAV patients.

This study aims to assess whether the On-X aortic valved conduit better restores normal valvular and ascending aortic hemodynamics than other commonly used bileaflet mechanical valved conduit prostheses from St. Jude Medical and Carbomedics by using same-day transthoracic echocardiography (TTE) and 4D flow magnetic resonance imaging (MRI) examinations. TTE and 4D flow MRI were performed back-to-back in 10 patients with On-X, six patients with St. Jude (two) and Carbomedics (four) prostheses, and 36 healthy volunteers. TTE evaluated valvular hemodynamic parameters: transvalvular peak velocity (TPV), mean and peak transvalvular pressure gradient (TPG), and effective orifice area (EOA). 4D flow MRI evaluated the peak systolic 3D viscous energy loss rate (VELR) density and mean vorticity magnitude in the ascending aorta (AAo). While higher TPV and mean and peak TPG were recorded in all patients compared to healthy subjects, the values in On-X patients were closer to those in healthy subjects (TPV 1.9 ± 0.3 vs. 2.2 ± 0.3 vs. 1.2 ± 0.2 m/s, mean TPG 7.4 ± 1.9 vs. 9.2 ± 2.3 vs. 3.1 ± 0.9 mmHg, peak TPG 15.3 ± 5.2 vs. 18.9 ± 5.2 vs. 6.1 ± 1.8 mmHg, p < 0.001). Likewise, while higher VELR density and mean vorticity magnitude were recorded in all patients than in healthy subjects, the values in On-X patients were closer to those in healthy subjects (VELR: 50.6 ± 20.1 vs. 89.8 ± 35.2 vs. 21.4 ± 9.2 W/m 3 , p < 0.001) and vorticity (147.6 ± 30.0 vs. 191.2 ± 26.0 vs. 84.6 ± 20.5 s-1, p < 0.001). This study demonstrates that the On-X aortic valved conduit may produce less aberrant hemodynamics in the AAo while maintaining similar valvular hemodynamics to St. Jude Medical and Carbomedics alternatives.

Objective: The frozen elephant trunk procedure is a well-established technique for the repair of type A ascending aortic dissection and complex aortic arch pathology. The ultimate shape created by the repair may have consequences in long-term complications. The purpose of this study was to apply a machine learning technique to comprehensively describe 3-dimensional aortic shape variations after the frozen elephant trunk procedure and associate these variations with aortic events. Methods: Computed tomography angiography acquired before discharge of patients (n = 93) who underwent the frozen elephant trunk procedure for type A ascending aortic dissection or ascending aortic arch aneurysm was preprocessed to yield patient-specific aortic models and centerlines. Aortic centerlines were subjected to principal component analysis to describe principal components and aortic shape modulators. Patient-specific shape scores were correlated with outcomes defined by composite aortic event, including aortic rupture, aortic root dissection or pseudoaneurysm, new type B dissection, new thoracic or thoracoabdominal pathologies, residual descending aortic dissection with residual false lumen flow, or thoracic endovascular aortic repair complications. Results: The first 3 principal components accounted for 36.4%, 26.4%, and 11.6% of aortic shape variance, respectively, and cumulatively for 74.5% of the total shape variation in all patients. The first principal component described variation in arch height-to-length ratio, the second principal component described angle at the isthmus, and the third principal component described variation in anterior-to-posterior arch tilt. Twenty-one aortic events (22.6%) were encountered. The degree of aortic angle at the isthmus described by the second principal component was associated with aortic events in logistic regression (hazard ratio, 0.98; 95% confidence interval, 0.97-0.99; P = .046). Conclusions: The second principal component, describing angulation at the region of the aortic isthmus, was associated with adverse aortic events. Observed shape variation should be evaluated in the context of aortic biomechanical properties and flow hemodynamics.

BackgroundModern CT scanners with lower radiation doses have resulted in large numbers of cardiac CTs being performed in children. As seen in adults, pediatric cardiac CT has the potential to demonstrate extracardiac variants and pathology that can occur in conjunction with congenital heart disease (CHD). Prior publications demonstrated a high incidence of extracardiac findings in various locations but the prevalence of urgent unexpected extracardiac findings in children is unknown.ObjectiveThe purpose of this study was to describe the incidence, distribution and clinical significance of the extracardiac findings on pediatric cardiac CT at a tertiary referral center.Materials and methodsWe reviewed all reports (n = 648) for 554 children through young adults who received a cardiac CT study between Jan. 2, 2018, and March 10, 2020, at our tertiary referral pediatric hospital. We interrogated CT reports for extracardiac findings and categorized them by system (airway, pulmonary, abdomen, malpositioned lines and musculoskeletal). We then subclassified each of these findings by level of clinical importance based upon the need for intervention or treatment into low, medium or high importance. High-importance findings were confirmed with a focused chart review. If a patient had more than one CT with a persistent extracardiac finding, the finding was only counted once.ResultsWe identified 562 individual extracardiac findings, with one or more extracardiac findings present in 91% of the study population. Extracardiac findings with high clinical importance, requiring urgent attention or intervention, were present in 10% (57/554) of cases. The most common location of extracardiac findings was pulmonary (50%; 280/562), followed by airway (22%; 125/562) and abdomen (9%; 52/562).ConclusionUnexpected highly important extracardiac findings were found in 10% of patients. Therefore, extracardiac structures should be scrutinized for the timely identification of potentially highly important findings.

Myocardial deformation analysis by cardiac MRI (CMR) yielding global circumferential and longitudinal strain (GCS and GLS) is an increasingly utilized method to accurately quantify systolic function and predict clinical events in patients with Fontan circulation. The purpose of this study was to use principal component analysis (PCA) to investigate myocardial temporal deformation patterns derived from strain–time curves to learn about latent strain features beyond peak values. We conducted the study with specific attention to dominant single left or right ventricle (SLV and SRV) morphologies. Methods and Results: Patients remote from Fontan operation who underwent follow-up CMR were analyzed for standard volumetric and function hemodynamics including myocardial deformation parameters including GCS and GLS. We applied PCA to investigate in an unbiased fashion the strain–time curve morphology and to calculate patient specific shape scores. All variables were subjected to single variable Cox regression analysis to detect composite clinical outcome including death, heart transplant, protein losing enteropathy and plastic bronchitis. A total of 122 patients, (SLV = 67, SRV = 55) with a mean age of 12.7 years underwent comprehensive CMR analysis. The PCA revealed 3 primary modes of strain-curve variation regardless of single ventricle morphology and type of strain investigated. Principle components (PCs) described changes in (1) strain–time curve amplitude, (2) time-to-peak strain, and (3) post-systolic slope of the strain–time curve. Considering only SLV patients, GCS was only CMR variable predictive of clinical events (HR 1.46, p = 0.020). In the SRV group, significant CMR predictors of clinical events were derived indexed end-diastolic (HR 1.02, p = 0.023) and end-systolic ( HR 1.03, p = 0.022) volumes, GCS ( HR 1.91, p = 0.003) and its related first component score (HR 1.20, p = 0.005), GLS (HR 1.32, p = 0.029) and its third component score (HR 1.58, p = 0.017). CMR derived global strain measures are sensitive markers of clinical outcomes in patients with Fontan circulation, particularly in patients with the SRV morphology. Myocardial strain–time curve morphology specific to SLV and SRV patients inspired by unbiased PCA technique can further aid with predicting clinical outcomes.