Objective: Diagnosing cardiac sarcoidosis (CS), giant cell myocarditis (GCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC) is difficult because all 3 cardiomyopathies can involve both the right and left ventricles, leading to arrhythmias and heart failure. Notably, the extent and pattern of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) for each condition remain poorly characterized which further complicates their differentiation. This study aimed to evaluate the diagnostic efficacy of CMR parameters to improve the accuracy of their differential diagnosis. Methods: Twelve patients with CS, 8 with GCM, and 30 with ARVC in Fuwai Hospital who underwent CMR between July 2011 and May 2024 were retrospectively analyzed in this study. Cardiac structure, function, and scar quantification were performed on a post-processing software. LGE in the left ventricle was visually classified by layer: subepicardial, intramural, transmural, and subendocardial. Left ventricle segmentation followed the American Heart Association 17-segment model. Results: Patients with CS had the greatest left ventricular mass compared to those with GCM or ARVC (111.2 (84.7, 155.8)g vs. 77.3 (63.6, 103.5)g vs. 64.4 (54.3, 81.4)g, P = 0.002). Meanwhile, those with ARVC had the largest right ventricular dimension and outflow tract (P < 0.001), along with the most extensive right ventricular global longitudinal strain impairment compared with the CS or GCM group (-6.1% +/- 4.9% vs. -14.8% +/- 7.3% vs. -11.9% +/- 4.9%, P < 0.001). CS patients presented with more LGE in the insertion area and less LGE in the right ventricular free wall than GCM and ARVC (all P < 0.001). The left ventricular layers showing the greatest vulnerability varied by condition: subepicardial for CS, subendocardial for GCM, and transmural for ARVC (all P < 0.02). Patients with CS and GCM presented with more extensive LGE than those with ARVC in the septal and anterior wall segments at the basal (segments 1-3) and mid-cavity (segments 7 and 8) levels of the left ventricle (all P < 0.05). However, at the apical level, patients with CS had less fibrotic involvement in segment 14 than patients with GCM or ARVC (P = 0.039). Conclusion: The 3 cardiomyopathies differed in the pattern and extent of lesion involvement. Insertion point enhancement favors a diagnosis of CS. More extensive right ventricular transmural LGE should prompt consideration of GCM or ARVC. At the basal and mid-cavity levels, the extent of LGE in anteroseptal segments was significantly reduced in patients with ARVC relative to that in patients with CS or GCM.

AIMS:The prognostic value of late gadolinium enhancement (LGE) phenotypes-particularly subendocardial involvement-for sudden cardiac death (SCD) remains unclear in dilated cardiomyopathy (DCM). Whether LGE phenotype integrating pattern and location can improve SCD risk stratification is an unmet need. METHODS AND RESULTS:DCM patients who underwent cardiac MRI were retrospectively enrolled. The endpoint was a composite of SCD and surrogate SCD events. Among 902 patients (mean age 46 ± 14 years, 78.7% men), subendocardium-involved and mid-wall LGE were observed in 129 (14.3%) and 263 (29.1%) patients, predominantly involving the lateral (65.1%) and septal wall (97.7%), respectively. During a median follow-up of 77 months (IQR 40-92 months), 51 (5.7%) patients experienced SCD events. Multivariable analysis identified septal mid-wall LGE (HR 3.59; 95% CI 1.73-7.47; P = 0.001) and lateral subendocardium-involved LGE (HR 3.07; 95% CI 1.39-6.75; P = 0.005) as independent predictors. A three-tier risk stratification model was developed, classifying patients into: lowest risk (neither septal mid-wall nor lateral subendocardium-involved LGE; reference), intermediate risk (either phenotype alone; HR 4.8, 95% CI 2.2-10.46, P < 0.001), and highest risk (both phenotypes; HR 10.71, 95% CI 3.53-32.46, P < 0.001). The model showed the best improvement in model discrimination and reclassification over left ventricular ejection fraction (C-statistic improvement: 0.23; net reclassification improvement = 0.67; integrative discrimination index = 0.27; all P < 0.05). CONCLUSION:SCD was predicted by both lateral subendocardium-involved LGE and septal mid-wall LGE in DCM. The novel SCD risk model integrating these phenotypes demonstrated superior prognostic performance compared with conventional prognosticators.

AIMS:To evaluate the prognostic value of cardiac magnetic resonance (CMR) feature tracking-derived left ventricular global longitudinal strain (FT-LVGLS) for adverse outcomes in patients with chronic moderate to severe aortic regurgitation (AR), and to further assess its incremental prognostic value in predicting adverse outcomes beyond the 2025 ESC/EACTS Class I/IIb surgical indication parameters. METHODS AND RESULTS:This retrospective cohort study initially screened 707 patients with at least moderate chronic AR who underwent CMR between 2010 and 2024, of whom 385 with no or minimal symptoms (NYHA class I-II; mean age 54.1 ± 13.5 years; 329 male) constituted the primary study cohort. The primary endpoint was major adverse cardiac events (MACE), defined as all-cause mortality, heart transplantation, unplanned hospitalization for heart failure, or implantable cardioverter defibrillator discharge. During a median follow-up of 52.9 months, 45 patients experienced MACE. Multivariable Cox regression identified FT-LVGLS as independently associated with MACE (adjusted HR: 1.210 per 1% decrease in absolute FT-LVGLS, P < 0.007). Incorporating FT-LVGLS into prognostic models containing each ESC/EACTS Class I/IIb surgical indication parameter (dichotomized by guideline-recommended thresholds) consistently improved model discrimination for MACE, with C-index increasing from 0.730-0.768 to 0.783-0.791 and likelihood ratio χ2 values from 36.04-41.12 to 50.10-52.07. Kaplan-Meier survival curves demonstrated that an absolute FT-LVGLS cut-off of 12% further refined risk stratification. CONCLUSION:In NYHA class I-II patients with chronic moderate-to-severe AR, FT-LVGLS was independently associated with MACE and provided incremental prognostic value beyond ESC/EACTS guideline-based surgical indication parameters, supporting its potential role in improving risk identification.

Objective To evaluate the potential mediating role of left ventricular ejection fraction (LVEF) in the relationship between replacement fibrosis (assessed by late gadolinium enhancement (LGE)) and sudden cardiac death (SCD) post-myocardial infarction (MI) and also to assess this mediation effect in subgroups based on LVEF ≤ 35% and > 35% according to implantable cardioverter-defibrillator (ICD) selection criterion.Methods A retrospective analysis was conducted on 917 post-MI patients (mean age: 56.3±11.0 years, 88.8% male) who underwent cardiac MR from January 2017 to August 2021. The endpoint for SCDs included SCD, aborted SCD and appropriate ICD discharges. The association of LGE with LVEF was quantified using linear regression models. The associations of LGE and LVEF with SCDs were evaluated using competing risk models. Mediation analysis was then used to decompose the total effect of LGE on SCDs into direct and indirect (mediated through LVEF) effects using accelerated failure time models.Results Over a median follow-up of 63.3 (IQR, 43.6 to 76.6) months, 65 patients (7.1%) experienced SCDs. In all patients, LGE was significantly associated with lower LVEF (β=-0.35, p<0.001). Both LGE and LVEF independently predicted SCDs (subdistribution hazard ratio (sHR)=1.06, p<0.001; sHR=0.95, p=0.03, respectively). Mediation analysis showed that LVEF accounted for 19.7% of the total effect of LGE on SCDs (p<0.001). This mediation effect was 40.4% in patients with LVEF > 35% (p = 0.02), while no mediation was observed in patients with LVEF ≤ 35% (p = 0.08).Conclusion LVEF partially mediated the effect of LGE on the SCD, accounting for less than one-fifth of the total effect. LVEF alone inadequately captured the whole SCD risk, irrespective of whether LVEF is greater than 35% or 35% or less.

BACKGROUND:The prognostic value of persistent microvascular obstruction (persistent-MVO) in ST-segment elevation myocardial infarction (STEMI) patients after percutaneous coronary intervention (PCI) remains unclear. OBJECTIVES:To investigate the prognostic value of persistent-MVO in reperfused STEMI. METHODS:Retrospectively analyzed 504 STEMI patients with primary PCI who underwent a follow-up cardiac magnetic resonance at ≥60 days after PCI. Persistent-MVO was defined as the presence of MVO on late gadolinium enhancement (LGE) imaging, which served as the study baseline. The endpoint was composite events of heart failure (HF), including HF-related death, heart transplantation, left ventricular assist device implantation, and HF hospitalization. Competing risk analysis was performed to address the possible influences of competing events. RESULTS:Persistent-MVO was detected in 44 of 504 patients (8.7%). These patients demonstrated lower left ventricular ejection fraction, larger end-diastolic volume index, and larger LGE extent (all P < 0.05), compared with those without. During a median follow-up of 64.5 months (IQR: 45.0-79.4), 91 of 504 patients (18.1%) experienced the endpoint. Adding persistent-MVO to a model with NYHA functional class, left ventricular ejection fraction, and LGE extent improved model discrimination (C-index: from 0.78 [95% CI: 0.73-0.83] to 0.82 [95% CI: 0.77-0.86], P = 0.01), model fit (-2 log-likelihood: from 996.7 to 984.8, P < 0.001), and risk reclassification (continuous net reclassification improvement: 8.56% [95% CI: 2.60%-16.23%], P < 0.01), with decision curve analysis confirming net clinical benefit at 5 years. CONCLUSIONS:Persistent-MVO was observed in 8.7% of STEMI patients at least 60 days after PCI and provided incremental value beyond established risk markers for predicting HF-related events.

Rationale and Objectives To evaluate the discriminative performance of right atrial (RA) phasic function in arrhythmogenic right ventricular cardiomyopathy (ARVC) patients with preserved right ventricular (RV) function. Materials and Methods Right atrial and ventricular strain, together with conventional cardiac MRI (CMR) parameters, were assessed in 38 patients with ARVC and preserved RV function, 38 patients with ARVC and reduced RV function, and 38 healthy controls between January 2012 and May 2021. Results Compared to controls, ARVC patients with preserved RV function showed impaired RA reservoir and conduit strain, as well as reduced RA passive emptying fraction, despite normal RA size. RA conduit strain <17% showed discriminative performance for identifying ARVC with preserved RV function (AUC = 0.79). The combination of RA conduit strain and RV global longitudinal strain (RVGLS) further improved discriminative performance (AUC = 0.89, P < 0.001). Multivariable logistic regression identified RA conduit strain (OR = 0.88, P = 0.005) and RVGLS (OR = 1.37, P < 0.001) as independently associated factors. In addition, RA conduit strain impairment showed modest incremental diagnostic value beyond RVGLS (χ² increased from 31.6 to 41.3, P = 0.002) and correlated with more advanced RV dysfunction and higher N-terminal pro-brain natriuretic peptide (NT-proBNP) levels across the overall ARVC cohort. Conclusion RA phasic strain is impaired in ARVC even when RV function is preserved. In combination with RVGLS, RA conduit strain showed improved diagnostic performance and may serve as a potential adjunctive imaging marker, although further evaluation is required.

To evaluate whether cardiac diffusion tensor imaging (cDTI) can discriminate hypertrophic cardiomyopathy (HCM) from hypertensive heart disease (HHD) based on microstructural alterations. This prospective study enrolled 40 HCM patients and 14 HHD patients who underwent 3.0T cardiac magnetic resonance (CMR), including cDTI, T1 mapping and late gadolinium enhancement (LGE). Parameters of cDTI (mean diffusivity [MD], secondary eigenvector [E2A], helix angel [HA)] and fractional anisotropy [FA]) were compared across groups using analysis of covariance. Diagnostic performance was assessed using receiver operating characteristic analysis. A subgroup analysis was performed in HCM patients with mild hypertrophy (left ventricular wall thickness [LVWT] 13–19 mm). Compared to patients with HHD, those with HCM showed significantly greater LVWT, LGE extent, native T1 and extracellular volume fraction (ECV, all p < 0.05). cDTI revealed significant microstructural alterations in HCM, characterized by reduced FA (p = 0.001) and elevated E2A p < 0.001). Analysis of covariance confirmed these differences after adjusting for LVWT, native T1, and ECV. ROC analysis demonstrated that E2A (AUC = 0.88) and FA (AUC = 0.79) had superior diagnostic performance for distinguishing HCM from HHD, outperforming native T1 (AUC = 0.76), ECV (AUC = 0.75), and LGE extent (AUC = 0.67). In the HCM subgroup, E2A maintained the highest diagnostic performance (AUC = 0.86), followed by FA and ECV (both AUC = 0.73). E2A and FA derived from cDTI were robust biomarkers of microstructural alterations, enabling superior differentiation of HCM from HHD beyond conventional hypertrophy and fibrosis indices. These findings support the potential utility of cDTI in diagnosis of ambiguous hypertrophy. Fractional anisotropy (FA) and diastolic secondary eigenvector angle (E2A) derived from cDTI demonstrate excellent accuracy in differentiation among hypertrophic cardiomyopathy (HCM), hypertensive heart disease (HHD) and healthy controls compared to other cardiovascular magnetic resonance (CMR) parameters. FA (p = 0.01) and diastolic E2A (p = 0.001) act as independent discriminators between HCM and HHD after adjusting for hypertrophy and fibrosis, offering a novel insight into myocardial microstructural alterations of HCM and HHD.

BACKGROUND:Pediatric and adolescent arrhythmogenic cardiomyopathy (ACM) is a clinically severe phenotype that remains underrepresented in cardiac magnetic resonance (CMR) research. The prognostic value of CMR-derived right ventricular deformation analysis in this population is unclear. OBJECTIVES:This study sought to describe the burden of severe cardiac outcomes in pediatric and adolescent ACM, and to assess the prognostic and incremental value of CMR-derived right ventricular global longitudinal strain (RVGLS) for risk stratification when incorporated into conventional clinical and CMR markers. METHODS:This multicenter study included consecutive pediatric and adolescent patients (aged ≤21 years) with ACM who underwent baseline CMR evaluation. We assessed clinical, electrocardiographic, and CMR parameters according to the 2010 Task Force Criteria, along with biventricular strain parameters. Severe cardiac outcomes were defined as a composite of malignant ventricular arrhythmias (MVAs), heart transplantation, and heart failure-related death. RESULTS:The cohort included 102 patients (16.3 ± 3.4 years; 72% male) and 95 controls (mean age: 15.6 ± 3.3 years; 70% male). During a median of 58-month follow-up, 51 (50%) patients experienced severe cardiac outcomes and 28 (27.5%) MVA outcomes. Reduced RVGLS was independently associated with severe cardiac outcomes (HR: 1.14; P = 0.004) and MVA outcomes (subdistribution HR: 1.15; P < 0.001) after adjustment for clinical and conventional CMR parameters. Incorporation of RVGLS significantly improved prediction of severe cardiac outcomes beyond both right ventricular-based and left ventricular-based multivariable models, with significant improvement in discrimination and reclassification. Kaplan-Meier analysis further showed that RVGLS ≥-12.2% identified patients at higher risk of severe cardiac outcomes and MVA outcomes (both log-rank P < 0.001). CONCLUSIONS:Pediatric and adolescent ACM manifests a malignant phenotype with high burden of heart failure and arrhythmia. RVGLS provides independent and incremental prognostic value beyond conventional CMR markers and could improve risk stratification in this high-risk population.

BACKGROUND:The prognostic value of serial myocardial fibrosis assessments in hypertrophic cardiomyopathy (HCM) remains to be elucidated. OBJECTIVES:The study aims to investigate late gadolinium enhancement (LGE) progression via follow-up cardiac magnetic resonance (CMR) in HCM patients and its prognostic value. METHODS:Retrospective analysis included 313 HCM patients with 2 CMR studies (between 2010 and 2019). LGE mass progression (ΔLGE mass/y) was defined as the increase in grams of enhanced myocardium divided by interval scan years. The primary endpoint included all-cause mortality, heart transplantation, aborted sudden cardiac death, unscheduled hospitalization for heart failure, and stroke. The secondary endpoint included all-cause mortality, aborted sudden cardiac death, and heart transplantation. Maximally selected rank statistical analysis was conducted to identify the optimal cutoff for ΔLGE mass/y. RESULTS:LGE mass progressed from a median of 2.9 g at the first CMR study to 8.3 g at the second CMR study (median scan interval 4.2 years). During a median follow-up period of 3.4 years after the second CMR study, 69 patients reached the primary endpoint, 17 of whom reached the secondary endpoint. For the primary and secondary endpoints, the optimal cutoffs for ΔLGE mass/y were >1.50 and 3.75 g/y, respectively. Multivariable Cox regression analysis showed that ΔLGE mass/y >1.50 g/year was an independent predictor of the primary endpoint (HR: 2.22 [95% CI: 1.13-4.34]; P = 0.02). The addition of ΔLGE mass/y to the baseline model improved the discrimination (C-statistic = 0.81 vs 0.84) and risk reclassification (net reclassification improvement = 0.27, integrated discrimination improvement = 0.02; P < 0.001 for both). External validation in 6 multicenter data sets confirmed the prognostic value of ΔLGE mass/y. CONCLUSIONS:In HCM patients, myocardial fibrosis increased over time. Serial assessments of myocardial fibrosis on CMR may improve risk stratification and clinical decision-making.

To validate the use of full free-breathing (FB) motion-corrected (MoCo) cardiac MRI examinations in assessing biventricular systolic function and tissue characterization compared with the reference standard breath-hold (BH) examination. In this prospective study, 216 patients underwent 3-T cardiac MRI. Of these patients, 113 underwent FB motion-corrected cardiac cine imaging in addition to standard BH cine imaging; the remaining 103 patients underwent FB motion-corrected late gadolinium enhancement (LGE) imaging in addition to standard BH LGE imaging. Image quality was assessed with a five-point scale (1 = nondiagnostic, 5 = very good). Left ventricular (LV) and right ventricular (RV) functional parameters and LGE mass in BH and FB examinations were analyzed using Wilcoxon signed-rank test, Bland-Altman plots, and linear regression. Subjective image quality between the FB and BH groups was comparable for cine imaging (4.02 ± 0.81 vs. 4.14 ± 0.79, P = 0.220) but was significantly better in the FB group for LGE (4.79 ± 0.46 vs. 4.16 ± 0.79, P < 0.001). Scan times for both cine (149.46 ± 32.29 s vs. 392.61 ± 47.02 s, P < 0.001) and LGE (198.12 ± 41.90 s vs. 361.69 ± 46.17 s, P < 0.001) were consistently shorter in the FB group than in the BH group. No significant differences were found in biventricular volumetric parameters or LGE mass measurements between FB and BH groups. Bland-Altman plots and linear regression analysis showed good agreement for LV and RV functional parameters and LGE mass in BH and FB sequences. Full FB cardiac MRI produces high-quality images and could be a suitable alternative for patients who cannot tolerate multiple BHs or long examination times.

PURPOSE:This study aimed to assess the utility of myocardial tissue characteristics, as identified by cardiac magnetic resonance T1 mapping, in detecting heart failure with preserved ejection fraction (HFpEF) in patients with hypertrophic cardiomyopathy (HCM). METHODS:A total of 133 consecutive patients with HCM were prospectively enrolled for biomarker testing to measure N-terminal pro-brain natriuretic peptide (NT-proBNP) concentrations, echocardiography to evaluate the diastolic function, and cardiac MRI to access tissue characteristics including native T1 values, extracellular volume fraction (ECV), and indexed ECV (iECV). RESULTS:Seventy-five (56.4 %) HCM patients were diagnosed with HFpEF based on the 2019 ESC HFA-PEFF diagnostic algorithm. Compared to HCM patients without HF, HFpEF-HCM subjects demonstrated greater native T1, ECV, and iECV (all p < 0.05). Native T1, ECV, and iECV were positively correlated with NT-proBNP and elevated in those with diastolic dysfunction (all p < 0.05). In ROC analysis, native T1 value (AUC: 0.723; p < 0.001) was a stronger discriminator among cardiac MRI-derived LV parameters and remained independently related to the diagnosis of HFpEF after adjusting for other clinical and imaging variables (odds ratio: 2.41; 95 % confidence interval: 1.32-4.39, per 1 standard deviation increase). Furthermore, native T1 had incremental value to the traditional markers for identifying HFpEF in HCM. CONCLUSIONS:In HCM, prolonged native T1 and elevated extracellular volume correlated with the diagnosis of HFpEF. Native T1 was an independent discriminator and may have supplementary value in identifying HFpEF-HCM.

BACKGROUND:Left ventricular (LV)-global longitudinal strain (GLS) assessed by cardiac magnetic resonance (CMR) feature tracking is an emerging marker for predicting adverse outcomes in hypertrophic cardiomyopathy (HCM), but its incremental prognostic value and mechanistic role in sudden cardiac death (SCD) risk stratification remain unclear. OBJECTIVES:The study sought to evaluate whether LV-GLS adds prognostic value beyond current ESC (European Society of Cardiology) and ACC (American College of Cardiology)/AHA (American Heart Association) SCD risk models, and mediates the relationship between myocardial abnormalities and SCD risk in HCM. METHODS:The authors retrospectively analyzed 2,009 patients with HCM (mean age: 50 ± 14 years, 70% men) who underwent CMR between 2010 and 2017. LV-GLS was quantified using cine CMR feature tracking. The primary endpoint included SCD and aborted SCD. Prognostic performance was assessed using time-dependent receiver-operating characteristic analysis and competing risk regression. Mediation analysis was used to investigate how LV-GLS mediated associations between myocardial hypertrophy, fibrosis, and SCD. RESULTS:Over a median follow-up of 88.2 months, 85 (4.2%) patients experienced SCD events. These patients had significantly lower absolute LV-GLS values (9.0% ± 3.6% vs 11.1% ± 3.6%; P < 0.001). In competing-risk regression, LV-GLS independently predicted SCD after adjustment for ESC (subdistribution HR [sHR]: 1.12 per 1% decrease [95% CI: 1.06-1.22]; P < 0.001) and ACC/AHA risk factors (sHR: 1.09 [95% CI: 1.02-1.18]; P = 0.016). Adding LV-GLS improved the 5-year predictive accuracy of both ESC and ACC/AHA models (AUC from 0.72 to 0.77 and from 0.71 to 0.76, respectively). Absolute LV-GLS with a cutoff of 9.23% further stratified risk in patient subgroups with either class II or class III implantable cardioverter-defibrillator indications (all log-rank P < 0.001). Mediation analysis showed LV-GLS partially mediated the effect of maximum wall thickness and extent of fibrosis on SCD (proportion-mediated: 17.5% and 23.1%, respectively; both P < 0.001). CONCLUSIONS:In patients with HCM, CMR-derived LV-GLS is an incremental predictor of SCD beyond current guideline-based risk models and partially mediates the association between myocardial abnormalities and SCD.

To assess the left ventricular remodeling index (LVRI) for predicting ventricular tachyarrhythmia (VTA) in patients with dilated cardiomyopathy (DCM) with left ventricular ejection fraction (LVEF) < 35

In hypertrophic cardiomyopathy, myocardial microstructural alterations could be detected by in vivo cardiac diffusion-tensor imaging even before the appearance of cardiac MRI findings of hypertrophy or fibrosis.

Background Although chest X-rays (CXRs) are widely used, diagnosing mitral stenosis (MS) based solely on CXR findings remains challenging in some cases.Objective This study aimed to develop a deep learning-based artificial intelligence (AI) model to detect MS using CXR.Methods In this retrospective study, 515 posteroanterior CXR images were analysed, including 285 from patients with MS and 230 from healthy controls. The dataset was randomly divided into training, validation and test datasets at a 7:2:1 ratio. An AI model was formulated by using the training dataset, and model performance was evaluated on the validation and test datasets using the area under the receiver operating characteristic curve (AUC), precision, recall, F1-score and accuracy. Saliency maps were generated to visualise the regions prioritised by the model.Results The model achieved an AUC of 0.99 on the validation dataset, with a precision of 0.96, recall of 0.96, F1-score of 0.96 and accuracy of 0.96. On the test dataset, the model achieved an AUC of 0.99, with a precision of 0.95, recall of 0.94, F1-score of 0.94 and accuracy of 0.94. Saliency maps highlighted regions consistent with known radiographic features of MS.Conclusion The developed deep learning-based AI model demonstrated high performance in detecting MS from CXR. This approach may provide a convenient and accessible screening tool for MS, particularly in resource-limited areas.

Background:Recently, late gadolinium enhancement (LGE) has been identified as an important risk factor in pediatric hypertrophic cardiomyopathy (HCM). However, its prognostic significance in pediatric HCM remains to be fully validated, particularly in Asian population. This study aims to assess the prognostic value of LGE and explore its incremental utility in predicting sudden cardiac death (SCD) in pediatric HCM using data from a Chinese cohort. Methods:231 primary HCM patients ≤18 years of age with cardiac magnetic resonance (CMR) were retrospectively and consecutively enrolled in a single center. The composite outcomes included SCD or equivalent events and heart failure-related events. Findings:Of 231 patients (median age 15, IQR: 12-16), LGE was present in 195 (84.4%) with a median LGE extent of 4.7% (IQR: 2.0%-9.2%). During a median follow-up of 62 months (IQR: 39-85), 26 (11.3%) patients reached composite outcomes, and 13 (5.6%) patients experienced SCD events. Kaplan-Meier analysis showed a significantly increased risk of composite outcomes (log-rank P < 0.001) and SCD (log-rank P < 0.001) in the group with LGE extent ≥5%. In multivariable Cox analysis adjusted by clinical and imaging factors, LGE extent was independently associated with composite outcomes (adjusted HR: 1.15; P < 0.001) and SCD (adjusted HR: 1.11; P = 0.009). For SCD events, the addition of LGE extent could improve the model performance of HCM Risk-Kids model (C-statistics: 0.65 versus 0.79, P = 0.015) and PRIMaCY model (C-statistics: 0.62 versus 0.82, P = 0.002), respectively. Interpretation:In Chinese pediatric HCM, LGE serves as a risk factor in predicting adverse outcomes and may enhance SCD risk stratification strategies. Funding:This study was funded by the National Key Research and Development Program of China (2021YFF0501400 and 2021YFF0501404), the Key Project of the National Natural Science Foundation of China (82430066), and the Yunnan Province Science and Technology Platform and Talent Project (202305AF150033).

Motivation: The association of preoperative LA strain assessed by cardiac magnetic resonance (CMR)-FT with the late outcome of HOCM patients after myectomy remains unknown. Goal(s): To evaluate the prognostic value of preoperative LA strain in HOCM following myectomy. Approach: In this retrospective, single-center study, 802 adult patients with HOCM after myectomy were included, who underwent preoperative CMR with clinical outcome follow-up. Results: LA reservoir strain ≤ 22.9% was independently associated with postoperative adverse outcomes. Incorporating LA reservoir strain, the performance of the HCM Risk-SCD score improved for SCD prediction (C-statistic: from 0.62 to 0.69; log-likelihood: from -110.31 to -108.27, P=.04). Impact: HOCM patients with reduced preoperative LA reservoir strain tend to have poor postoperative outcomes, so reinforced follow-ups may be required in those patients.