5-year Sudden Cardiac Death Research Articles

Distinct phenotypic groups and related clinical outcomes in patients with hypertrophic cardiomyopathy

Abstract Background Hypertrophic cardiomyopathy (HCM) is a heterogeneous disorder with varying risks of clinical outcomes, including sudden cardiac death (SCD). Purpose We aimed to identify distinct phenotypes among patients with HCM in relation to SCD risk factors, interpret their clinical characteristics, and examine their outcomes. Methods This retrospective study analyzed 1,231 consecutive patients with HCM from two tertiary hospitals. We performed latent class analysis (LCA) to categorize patients into phenotypic groups, which is a probabilistic modeling technique that reveals hidden patterns and subgroups within a dataset. Results Three distinct phenotypic groups were identified using LCA. Group 1 (n=554) consisted of young patients with HCM with minimal SCD risk factors and favorable cardiac remodeling. Group 2 (n=114) comprised young patients with HCM and a high prevalence of SCD risk factors, whereas Group 3 (n=563) included older patients (median age, 68 years). Over a median 6.5-year follow-up, 34 SCD-related events, 131 cardiovascular (CV) events, 133 all-cause mortality, and 70 non-CV mortality were observed. Group 2 exhibited the highest rate of SCD-related events (5-year SCD rate: Group 1 vs. 2 vs. 3: 0.8% vs. 8.2% vs. 4.0%, respectively, p<0.001), and CV events were more frequent in Group 2 and 3 compared to Group 1 (Figure 1). All-cause and non-CV mortality were the most frequent in Group 3. A simplified decision tree was developed for the straightforward assignment of phenotypic group membership, demonstrating fair concordance. The phenotypic categorization and the decision tree is shown in Figure 2. Conclusions This study identified three distinct clinical phenotypes in patients with HCM, each associated with different SCD risks and outcomes. Data-driven phenotyping of patients with HCM offers effective risk stratification and may optimize patient management.

Distinct Phenotypic Groups and Related Clinical Outcomes in Patients With Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is a heterogeneous disorder with varying risks of clinical outcomes, including sudden cardiac death (SCD). We aimed to identify distinct phenotypes among patients with HCM in relation to SCD risk factors, interpret their clinical characteristics, and examine their outcomes. This retrospective study analyzed 1231 consecutive patients with HCM from 2 tertiary hospitals. We performed latent class analysis to categorize patients into phenotypic groups. Three distinct phenotypic groups were identified using latent class analysis. Group 1 (n=554) consisted of young patients with HCM with minimal SCD risk factors and favorable cardiac remodeling. Group 2 (n=114) comprised young patients with HCM and a high prevalence of SCD risk factors, whereas Group 3 (n=563) included older patients (median age, 68 years). Over a median 6.5-year follow-up, 34 SCD-related events, 131 cardiovascular events, 133 all-cause mortality events, and 70 noncardiovascular mortality events were observed. Group 2 exhibited the highest rate of SCD-related events (5-year SCD rate: Group 1 versus 2 versus 3: 0.8% versus 8.2% versus 4.0%, respectively, P<0.001), and cardiovascular events were more frequent in Groups 2 and 3 compared with Group 1. All-cause and noncardiovascular mortality were the most frequent in Group 3. A simplified decision tree was developed for the straightforward assignment of phenotypic group membership, demonstrating fair concordance. This study identified 3 distinct clinical phenotypes in patients with HCM, each associated with different SCD risks and outcomes. Data-driven phenotyping of patients with HCM offers effective risk stratification and may optimize patient management.

Enhanced detection of damaged myocardium and risk stratification in hypertrophic cardiomyopathy using integrated [68Ga]Ga-FAPI-04 PET/CMR imaging.

This study aims to explore the correlation between PET and CMR in integrated [68Ga]Ga-FAPI-04 PET/CMR multimodal imaging and its value in the diagnosis and risk assessment of hypertrophic cardiomyopathy (HCM). This study included 20 HCM patients and 11 age- and gender-matched controls. PET analysis evaluated left ventricular (LV) [68Ga]Ga-FAPI-04 uptake, including SUVmax, TBR, cardiac fibroblast activity (CFA) and volume (CFV), and total SUV of the 16 segments. CMR tissue characterization parameters included cardiac function, myocardial thickness, late gadolinium enhancement (LGE), relaxation time, extracellular volume (ECV), and peak strain parameters. The 5-year sudden cardiac death (SCD) risk score and the 2-year and 5-year atrial fibrillation (AF) risk scores were calculated for each patient. The study analyzed differences between HCM patients and controls, the correlation between [68Ga]Ga-FAPI-04 PET and concurrent CMR imaging results, and the predictive value of PET/CMR. The FAPI uptake, myocardial mass, myocardial thickness, and T1/T2 mapping values were significantly higher in HCM patients compared to controls. Twenty HCM patients and their 320 myocardial segments were discussed. Increased [68Ga]Ga-FAPI-04 uptake in the left ventricular wall was observed in 95% (19/20) of the patients, covering 48.8% (156/320) of the segments. On concurrent CMR, 80% (16/20) of the patients showed LGE, including 95 (29.7%) segments. The FAPI(+)LGE(+) segments exhibited the highest myocardial PET uptake, greatest thickness, longest T1/T2 native values, largest ECV value and the greatest loss of myocardial strain capacity (P < 0.05). There was a significant correlation between FAPI uptake and CMR parameters (P < 0.05). Higher [68Ga]Ga-FAPI-04 uptake showed a positive correlation with SCD and AF risk scores (P < 0.05). The number of LGE(+) segments, mapping parameters, and ECV values in CMR also had prognostic significance. Combining PET with CMR aided in further risk stratification of HCM. [68Ga]Ga-FAPI-04 PET/CMR multimodal imaging has potential value in the detection of damaged myocardial lesions and risk assessment of HCM patients. [68Ga]Ga-FAPI-04 PET can detect more affected myocardium compared to CMR, and segments with abnormalities in both PET and CMR show more severe myocardial damage.

Additional factors associated with sudden cardiac death in HCM patients

Abstract Background Hypertrophic cardiomyopathy (HCM) is a primary myocardial disease characterized by an increase in the thickness of the left ventricular (LV) wall, which is not explained only by abnormal loading conditions. Sudden cardiac death (SCD) is the most devastating complication of HCM occurring in asymptomatic or younger patients without warning. Purpose To evaluate additional SCD risk factors in Ukrainian population of HCM patients. Materials and methods We retrospectively evaluated 350 consecutive HCM patients that were followed from 2006 to 2021 in our Cardiological Department. General clinical examination, standard 12-lead ECG, transthoracic echocardiography and 24 hours Holter ECG monitoring data were estimated. The 5-year SCD risk was calculated according to the HCM Risk-SCD score. The endpoint of the study was SCD and its surrogates, including adequate performance of the implantable cardioverter-defibrillator and successful resuscitation. Results Follow-up time was 5.0 (1.5-9.5) years. During this time, 16 patients (4.6%) reached the end point, which was 0.9%/year. According to the HCM Risk-SCD score, 5 (31.3%) of this group had a high risk of SCD (≥ 6%) and 3 (18.8%) had an intermediate risk (≥ 4% and &amp;lt; 6%). In multivariable Cox regression analysis adjusted for conventional SCD risk factors it was found that independent predictors of SCD were unexplained syncope (HR 3.81, 95% CI 1.11-13.12, p=0.034), systolic blood pressure (SBP) (HR 0.97 , 95% CI 0.94- 0.99, p=0.026), "infarct-like" ST elevation on ECG (HR 6.81, 95% CI 2.09-22.16, p=0.001) and PQ interval duration (HR 1.03, 95% CI 1.01-1.05, p=0.002), Harrell's C-index 0.84, 95% CI 0.73-0.95, p &amp;lt; 0.0001). Conclusions In our study HCM Risk-SCD score predicted SCD or surrogates only in 50% of cases. In order to improve the risk stratification some additional independent predictors of SCD can be proposed. ECG parameters ("infarct-like" ST elevation and PQ interval duration) and level of SBP were found to have SCD predictive value.

The China Hypertrophic Cardiomyopathy Project (CHCMP): The Rationale and Design of a Multicenter, Prospective, Registry Cohort Study.

Hypertrophic cardiomyopathy (HCM) is associated with adverse outcomes, such as heart failure, arrhythmia, and mortality. Sudden cardiac death (SCD) is a common cause of death in HCM patients, and identification of patients at a high risk of SCD is crucial in clinical practice.The China Hypertrophic Cardiomyopathy Project is a hospital-based, multicenter, prospective, registry cohort study of HCM patients, covering a total of 3000 participants and with a 5-year follow-up plan. A large number of demographic characteristics and clinical data will be fully collected to identify prognostic factors in Chinese HCM patients. Furthermore, the main purpose of this study is to integrate demographic and clinical characteristics to establish new 5-year SCD risk predictive equations for Chinese HCM patients by the use of machine learning technologies.The project has crucial clinical significance for risk stratification and determination of HCM patients with high risk of adverse outcomes. CLINICAL TRIALS REGISTRATION: ChiCTR2300070909.

Performance of the PRIMaCY sudden death risk prediction model for childhood hypertrophic cardiomyopathy: implications for implantable cardioverter-defibrillator decision-making.

The validated HCM Risk-Kids model provides accurate individualized estimates of sudden cardiac death risk in children with hypertrophic cardiomyopathy (HCM). A second validated model, PRIMaCY, also provides individualized estimates of risk, but its performance and clinical impact has not been independently investigated. The aim of this study was to investigate the clinical impact of using the PRIMaCY sudden cardiac death (SCD) risk model in childhood HCM. The estimated 5-year SCD risk was calculated for children meeting diagnostic criteria for HCM in a large single-centre cohort using PRIMaCY (clinical and genetic) and HCM Risk-Kids model, and model performance was assessed. Three hundred one patients [median age 10 (interquartile range 4-14)] were followed up for an average of 4.9 (±3.8) years, during which 30 (10.0%) reached the SCD or equivalent event endpoint. Harrell's C-statistic for the clinical and genetic models was 0.66 [95% confidence interval (CI) 0.52-0.8] and 0.66 (95% CI 0.54-0.80) with a calibration slope of 0.19 (95% CI 0.04-0.54) and 0.26 (95% CI -0.03-0.62), respectively. The number needed to treat to potentially treat one life-threatening arrhythmia for the PRIMaCY clinical, PRIMaCY genetic, and HCM Risk-Kids models was 13.7, 14.5, and 9.4, respectively. Although PRIMaCY has a similar discriminatory ability to that reported for HCM Risk-Kids, estimated risk estimates did not correlate well with observed risk. A higher proportion of patients met implantable cardioverter-defibrillator thresholds using PRIMaCY model compared with HCM Risk-Kids. This has important clinical implications as these patients will be exposed to a lifetime risk of complications and inappropriate therapies.

Performance of 2020 AHA/ACC HCM Guidelines and Incremental Value of Myocardial Strain for Predicting SCD

The 2020 American Heart Association (AHA)/American College of Cardiology (ACC) guidelines for sudden cardiac death (SCD) risk stratification in hypertrophic cardiomyopathy (HCM) need further international validation. Performance of the guidelines and the incremental value of myocardial strain for predicting SCD in HCM were investigated. In 1,416 HCM patients, SCD risk was stratified according to the 2020 AHA/ACC and 2014 European Society of Cardiology (ESC) guidelines. Left ventricular (LV) global longitudinal strain (GLS) and left atrial reservoir strain (LARS) were measured. The main outcome consisted of SCD events. Overall, 29.1% had major risk factors (RFs), and 14.7% had nonmajor RFs in the absence of major RFs; estimated 5-year SCD event rates were 6.8% and 2.3%, respectively. SCD risk was significantly increased in the former group but not in the latter. When stratified by the number of RFs, 5-year SCD event rates were 1.9%, 3.0%, 4.9%, and 18.4% for patients with 0, 1, 2, and 3 or more RFs, respectively. SCD risk was elevated in patients with multiple RFs but not in those with a single RF. Performance of the AHA/ACC and ESC guidelines did not differ significantly over 10 years (5-year time-dependent area under the curve: 0.677 vs 0.724; P=0.235). Decreased LV GLS and LARS were independently associated with SCD events with optimal cutoffs of LV GLS<13% and LARS<21%. Adding LV GLS and LARS to the guidelines had incremental predictive value. The 2020 AHA/ACC guidelines were predictive of SCD events with modest power in a large Asian HCM cohort. Implantable cardioverter-defibrillators are reasonable in patients with multiple RFs, and consideration of myocardial strain can improve SCD prediction.

PO-04-075 TRANSVENOUS CARDIAC DEFIBRILLATOR WITHOUT INTERACTION WITH THE MAGNETIC TITANIUM BEADS SYSTEM FOR GASTROESOPHAGEAL REFLUX DISEASE

Gastroesophageal reflux is increasingly treated with LINX®, a flexible bracelet of magnetic titanium beads (not MRI compatible) that is laparoscopically implanted to wrap around the gastroesophageal junction for providing tone/support aiding passive relaxation of a weak lower esophageal sphincter with peristalsis. The FDA currently cautions against concurrent use of the LINX® system with cardiac implantable electronic devices (CIEDs) given that the risk of electromagnetic interference (EMI) is unknown, and safety has not been established. We assessed the safety of a transvenous ICD in a patient with the LINX® system. Case Report 59 year old male who previously had the LINX® system implanted after hiatal hernia repair for refractory reflux. Shortly after, he was then diagnosed with apical hypertrophic cardiomyopathy with obstruction (NYHA Class I, genetic testing revealed VUS in CSRP3). Given non-sustained VT on cardiac event monitoring, family history of sudden cardiac death (SCD) and late gadolinium enhancement on cardiac magnetic resonance imaging with a calculated 5-year SCD risk 4.1%, he was recommended ICD implantation for primary prevention. Patient underwent an uneventful transvenous dual chamber defibrillator implantation. Although we do not routinely perform (DFT) testing at our institution, given the coexisting LINX® system in close proximity to the RV lead, we elected to proceed with DFT Testing, which was successful (1 induction: T-wave shock from sinus to VF, 30J delivered successfully to sinus with 7s charge time, no ATP, 70 ohms impedance). Patient underwent routine remote device interrogations and at 1-year follow up (which included an in-person device interrogation), continues to have normal lead parameters (sensing, impedance, threshold), minimal atrial or ventricular pacing, and no recurrent arrhythmias including NSVT (was started on verapamil). Specifically, patient received no inappropriate shocks, and no high frequency noise episodes were detected. We present the first case report of a patient who had a concomitant dual chamber ICD that was implanted shortly after a LINX device placement. We demonstrate normal DFTs at implant and no device interaction at 1 year follow-up, suggesting that ICD implantation without removal of the LINX device might be reasonable. Decision-making for cardiac device implantation decisions in such patients should consider additional theoretical risks until additional data with more patients is available.

Rare Case of Pediatric Hypertrophic Obstructive Cardiomyopathy (HOCM) in A 6-year-old Boy: How to Recognize, Assess, and Manage the Risk?

Highlights: It discusses pediatric HCM which is usually caused by autosomal dominant traits caused by mutation in cardiac sarcomere protein genes. It explains how to recognize the cardiac risk Abstract: Hypertrophic Obstructive Cardiomyopathy (HOCM) is a disease characterized by increased left ventricular (LV) wall thickness and accompanied by obstructive physiology measured by increased LV outflow tract gradient. It is mainly inherited in autosomal dominant traits caused by a mutation in cardiac sarcomere protein genes. In pediatrics, HOCM is rare and comprises a different diagnosis and management approach compared to adults. The risk of sudden cardiac death (SCD) is also higher in the pediatric population. Case Summary. This report is about a case of HOCM found incidentally in a 6-year-old boy and a discussion based on the latest literature review. The patient first came for evaluation for cardiac murmur and abnormality in ECG and chest x-ray. Diagnosis of HOCM was made through echocardiography assessment. Discussion. ICD implantation for primary prevention of SCD was considered based on individualized 5-year SCD risk assessment which is around 7%. Optimal pharmacological therapy with beta-blocker, careful planning of ICD implantation with balanced benefit and risk, and septal reduction surgery when indicated should extend the life expectancy and quality of life of pediatric HOCM. It is both essential and interesting to recognize pediatric HOCM diagnostic findings and to pursue further research about therapies of this rare disease.

Updated risk assessments for sudden cardiac death in hypertrophic cardiomyopathy patients with implantable cardioverter-defibrillator.

Hypertrophic cardiomyopathy (HCM) is a genetic disease associated with a risk of malignant ventricular tachyarrhythmias and sudden cardiac death (SCD). Assessment of the SCD risk is crucial for its clinical management, and there has been considerable interest in developing risk stratification strategies. An implantable cardioverter-defibrillator (ICD) is a life-saving treatment for patients with HCM who are at a high-risk of ventricular tachyarrhythmias and SCD. However, a substantial number of ICD recipients experience adverse effects arising from inappropriate device therapy and implant-related complications. This has led to numerous investigations of the risk of SCD and the indications for ICD implantation. American guidelines were recently updated to include new risk markers, including left ventricular systolic dysfunction, apical aneurysm, and extensive late gadolinium enhancement, while European guidelines recommend individualized estimated 5-year SCD risk assessment models. Studies evaluating other risk factors for SCD in patients with HCM have also been published. Drawing on recent guidelines and publications on clinical risk factors, we focus this review on updated risk assessments for SCD with ICD therapy in patients with HCM.

Myocardial Activity at 18F-FAPI PET/CT and Risk for Sudden Cardiac Death in Hypertrophic Cardiomyopathy.

Background Myocardial fibrosis contributes to adverse cardiovascular events in hypertrophic cardiomyopathy (HCM). Purpose To explore the characteristics of cardiac fibroblast activation protein inhibitor (FAPI) PET/CT imaging and its relationship with the risk of sudden cardiac death (SCD) in HCM. Materials and Methods In this prospective study from July 2021 to January 2022, participants with HCM and healthy control participants underwent cardiac fluorine 18 (18F)-labeled FAPI PET/CT imaging. Myocardial FAPI activity was quantified as intensity (target-to-background uptake ratio), extent (the percent of FAPI-avid myocardium of the left ventricle [LV]), and amount (the percent of FAPI-avid myocardium of LV × target-to-background ratio). Regional wall thickness was analyzed at cardiac MRI. The 5-year SCD risk score was calculated from the 2014 European Society of Cardiology guidelines. Univariable and multivariable linear regression analyses were used to identify factors related to the FAPI amount. The correlation between FAPI amount and 5-year SCD risk was explored. Results Fifty study participants with HCM (mean age, 43 years ± 13 [SD]; 32 men) and 22 healthy control participants (mean age, 45 years ± 17; 14 men) were included. All participants with HCM had intense and inhomogeneous cardiac FAPI activity in the LV myocardium that was higher than that in healthy control participants (median target-to-background ratio, 8.8 vs 2.1, respectively; P < .001). In HCM, more segments with FAPI activity were detected than the number of hypertrophic segments (median, 14 vs five, respectively; P < .001); 84% of nonhypertrophic segments showed FAPI activity. Log-transformed FAPI amount had a positive relationship with log-transformed N-terminal probrain natriuretic peptide, high-sensitive troponin I, and left atrial diameter and a negative relationship with LV ejection fraction z-score. Degree of FAPI activity positively correlated with the 5-year SCD risk score (r = 0.32; P = .03). Conclusion Fibroblast activation protein inhibitor (FAPI) PET/CT imaging indicated intense and heterogeneous activity in hypertrophic cardiomyopathy, and FAPI uptake was associated with 5-year risk of sudden cardiac death. © RSNA, 2022 Online supplemental material is available for this article.

Clinical Characteristics and Prognostic Importance of Left Ventricular Apical Aneurysms in Hypertrophic Cardiomyopathy

Left ventricular (LV) apical aneurysms in hypertrophic cardiomyopathy (HCM) are a recognized risk marker for adverse cardiovascular events. There is variable practice among clinicians and discordance between international guidelines regarding treatment recommendations and prognostication for this important phenotype. The authors sought to describe the morphology, clinical course, and risk of adverse events in a large single-center cohort of HCM patients with LV apical aneurysms. This study analyzed 160 HCM patients with an LV apical aneurysm who were evaluated in our dedicated HCM clinic between January 1997 and April2021. Mean age was 59.1 ± 13.6 years, and 71% of these patients were male. Mean aneurysm size was 1.77 ± 1.04cm. Over 6.2 ± 4.8 years, 14 (9%) patients had a sudden cardiac death (SCD) event, including appropriate therapy from an implantable cardioverter-defibrillator (ICD) or resuscitation from cardiac arrest (annualized event rate 1.77%/y), 39 (24%) had either a thromboembolic stroke or apical thrombus formation (2.9%/y), and 14 (9%) developed LV systolic dysfunction with an ejection fraction (EF)<50% (1.28%/y). HRs for SCD, stroke or thrombus, and EF<50% per 1-cm increase in aneurysm size were 1.69 (P = 0.007), 1.60 (P = 0.0002), and 1.63 (P = 0.01), respectively. Aneurysm size≥2cm was associated with a 5-year SCD rate of 9.7%, compared with 2.9% for aneurysm size<2cm (log-rank P = 0.037). Thissubgroup also had higher risk of stroke/thrombus formation (HR: 2.20; P = 0.002), with an annualized event rate of 2.7%/year. A total of 39 (24%) patients reached the combined end point of SCD, stroke, or LV dysfunction (2.12%/y) with an HR of 1.47/cm increase in aneurysm size (P = 0.003) and an HR of 2.22 for patients with aneurysm size≥2cm (P = 0.02). Increasing aneurysm size confers poorer prognosis. Aneurysm size≥2cm should alert potential consideration for prophylactic anticoagulation and primary prevention ICDs.

Clinical impact of the pathological quantification of myocardial fibrosis and infiltrating T lymphocytes using an endomyocardial biopsy in patients with hypertrophic cardiomyopathy

The impact of quantitative pathological findings derived from endomyocardial biopsies (EMB) on clinical prognosis in patients with hypertrophic cardiomyopathy (HCM) remains unclear. We retrospectively studied 55 consecutive HCM patients who underwent EMB. We quantified the collagen area fraction (CAF), the cardiomyocyte diameter, the nuclear area and circularity, and the number of myocardial infiltrating CD3+ cells using EMB samples by image analyzing software. The primary clinical endpoint was defined as a composite including cardiovascular death, admission due to heart failure and ventricular arrhythmia. During the median follow-up of 37.2 months, the primary endpoint was found in 12 patients. No significant difference in the risk score of 5-year sudden cardiac death was observed between the event-occurrence group and the event-free group. In the multivariable Cox proportional-hazard analysis, CAF [hazard ratio (HR) per 10% increase: 1.555, 95% CI: 1.014-2.367, p = 0.044] and the number of infiltrating CD3+ cells (HR per 10% increase: 1.231, 95% CI: 1.011-1.453, p = 0.041) were the independent predictors of the primary endpoint, while the myocardial diameter and the nuclear irregularity had no significant prognostic impact. Kaplan-Meier survival curves demonstrated that patients with both higher CAF and higher number of CD3+ cells had the worst prognosis (log-rank, P < 0.001). The higher CAF and the higher number of infiltrating CD3+ cells quantified using EMB samples were the independent predictors of poor clinical outcomes in patients with HCM. Cardiomyocyte diameter and nuclear irregularity did not significantly impact the clinical prognosis.

Ventricular Repolarization Dispersion is a Potential Risk for the Development of Life-Threatening Arrhythmia in Children with Hypertrophic Cardiomyopathy.

The risk stratification and early interventions are necessary in patients with hypertrophic cardiomyopathy (HCM), as life-threatening arrhythmia (LTA) is a leading cause of death. This study aimed to explore whether an interval between the peak of the T wave to the end terminal of the T wave (Tp-e), which represents ventricular repolarization dispersion, could predict the risk for LTA in children with HCM. We analyzed electrocardiography at the first and last visits in children (aged < 15years) with HCM, and compared Tp-e interval and theratio of Tp-e interval to QT interval (Tp-e/QT) between children with and without LTA. We studied 25 children with HCM. During the follow-up of 85 (38-146) months, there were 7 children with LTA. The 5-year sudden cardiac death (SCD) risk was 1.4 (1.1-2.5) %, which suggested that our cohort consisted of patients at a lower risk for SCD. Age was significantly older in children with LTA compared to those without it (12.5 vs.1.0years, P = 0.037), although sex, the presence of family history and symptoms at diagnosis, the maximum left ventricular wall thickness Z-score did not differ between the groups. At the last electrocardiography before LTA, corrected Tp-e interval and Tp-e/QT ratio were significantly greater in patients with LTA compared to those in patients without LTA (corrected Tp-e: 103 vs. 78ms, P = 0.020; Tp-e/QT: 0.28 vs. 0.22, P = 0.046). Corrected Tp-e and Tp-e/QT ratio cutoff values of 91ms and 0.28 yielded as the predictors for LTA with sensitivity of 85% and 72%, specificity of 71% and 89%, respectively. Prolonged absolute and corrected Tp-e intervals and an increase in the Tp-e/QT ratio can be useful predictors for LTA in children with HCM. We offer temporal assessments of ventricular repolarization dispersion to stratify the risk for the development of LTA/SCD among children with HCM.

Major Clinical Issues in Hypertrophic Cardiomyopathy.

Hypertrophic cardiomyopathy (HCM) is one of the most common inheritable cardiomyopathies. Contemporary management strategies, including the advent of implantable cardioverter-defibrillators and effective anticoagulation, have substantially improved the clinical course of HCM patients; however, the disease burden of HCM is still high in Korea. Sudden cardiac death (SCD), atrial fibrillation and thromboembolic risk, dynamic left ventricular outflow tract (LVOT) obstruction, and heart failure (HF) progression remain important issues in HCM. SCD in HCM can be effectively prevented with implantable cardioverter-defibrillators. However, appropriate patient selection is important for primary prevention, and the 5-year SCD risk score and the presence of major SCD risk factors should be considered. Anticoagulation should be initiated in all HCM patients with atrial fibrillation regardless of the CHA2DS2-VASc score, and non-vitamin K antagonist oral anticoagulants are the first option. Symptomatic dynamic LVOT obstruction is first treated medically with negative inotropes, and if symptoms persist, septal reduction therapy is considered. The recently approved myosin inhibitor mavacamten is promising. HF in HCM is usually related to diastolic dysfunction, while about 5% of HCM patients show reduced left ventricular ejection fraction <50%, also referred to as "end-stage" HCM. Myocardial fibrosis plays an important role in the progression to advanced HF in patients with HCM. Patients who do not respond to guideline-directed medical therapy can be considered for heart transplantation. The development of imaging techniques, such as myocardial deformation on echocardiography and late gadolinium enhancement on cardiac magnetic resonance, can provide better risk evaluation and decision-making for management strategies in HCM.

Worldwide differences in primary prevention implantable cardioverter defibrillator utilization and outcomes in hypertrophic cardiomyopathy.

Risk stratification algorithms for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) and regional differences in clinical practice have evolved over time. We sought to compare primary prevention implantable cardioverter defibrillator (ICD) implantation rates and associated clinical outcomes in US vs. non-US tertiary HCM centres within the international Sarcomeric Human Cardiomyopathy Registry. We included patients with HCM enrolled from eight US sites (n = 2650) and five non-US (n = 2660) sites and used multivariable Cox-proportional hazards models to compare outcomes between sites. Primary prevention ICD implantation rates in US sites were two-fold higher than non-US sites (hazard ratio (HR) 2.27 [1.89-2.74]), including in individuals deemed at high 5-year SCD risk (≥6%) based on the HCM risk-SCD score (HR 3.27 [1.76-6.05]). US ICD recipients also had fewer traditional SCD risk factors. Among ICD recipients, rates of appropriate ICD therapy were significantly lower in US vs. non-US sites (HR 0.52 [0.28-0.97]). No significant difference was identified in the incidence of SCD/resuscitated cardiac arrest among non-recipients of ICDs in US vs. non-US sites (HR 1.21 [0.74-1.97]). Primary prevention ICDs are implanted more frequently in patients with HCM in US vs. non-US sites across the spectrum of SCD risk. There was a lower rate of appropriate ICD therapy in US sites, consistent with a lower-risk population, and no significant difference in SCD in US vs. non-US patients who did not receive an ICD. Further studies are needed to understand what drives malignant arrhythmias, optimize ICD allocation, and examine the impact of different ICD utilization strategies on long-term outcomes in HCM.

Sudden cardiac death risk in hypertrophic cardiomyopathy: comparison between echocardiography and magnetic resonance imaging

In hypertrophic cardiomyopathy (HCM) patients, left ventricular (LV) maximal wall thickness (MWT) is one of the most important factors determining sudden cardiac death (SCD) risk. In a large unselected sample of HCM patients, we aimed to simulate what changes would occur in the calculated SCD risk according to the European HCM Risk-SCD calculator when MWT measured using echocardiography was changed to MWT measured using MRI. All consecutive patients with HCM who underwent cardiac MRI were included. MWT measured with echocardiography and MRI were compared, and 5-year SCD risk according to the HCM Risk-SCD calculator was computed using four different models. The final population included 673 patients [389 (57.8%) males, median age 50 years, interquartile range (36–60)]. The median MWT was lower measured by echocardiography than by MRI [20 (17–24) mm vs 21 (18–24) mm; p < 0.0001]. There was agreement between echocardiography and MRI in the measurement of maximal LV wall thickness in 96 patients (14.3%). The largest differences between echo and MRI were − 13 mm and + 9 mm. The differences in MWT by echocardiography and MRI translated to a maximal difference of 8.33% in the absolute 5-year risk of SCD, i.e., the echocardiography-based risk was 8.33% lower than the MRI-based estimates. Interestingly, 13.7% of patients would have been reclassified into different SCD risk categories if MRI had been used to measure MWT instead of echocardiography. In conclusion, although there was high general intermodality agreement between echocardiography and MRI in the MWT measurements, the differences in MWT translated to significant differences in the 5-year risk of SCD.

The role of the electrocardiographic phenotype in risk stratification for sudden cardiac death in childhood hypertrophic cardiomyopathy.

AimsThe 12-lead electrocardiogram (ECG) is routinely performed in children with hypertrophic cardiomyopathy (HCM). An ECG risk score has been suggested as a useful tool for risk stratification, but this has not been independently validated. This aim of this study was to describe the ECG phenotype of childhood HCM in a large, international, multi-centre cohort and investigate its role in risk prediction for arrhythmic events.Methods and resultsData from 356 childhood HCM patients with a mean age of 10.1 years (±4.5) were collected from a retrospective, multi-centre international cohort. Three hundred and forty-seven (97.5%) patients had ECG abnormalities at baseline, most commonly repolarization abnormalities (n = 277, 77.8%); left ventricular hypertrophy (n = 240, 67.7%); abnormal QRS axis (n = 126, 35.4%); or QT prolongation (n = 131, 36.8%). Over a median follow-up of 3.9 years (interquartile range 2.0–7.7), 25 (7%) had an arrhythmic event, with an overall annual event rate of 1.38 (95% CI 0.93–2.04). No ECG variables were associated with 5-year arrhythmic event on univariable or multivariable analysis. The ECG risk score threshold of >5 had modest discriminatory ability [C-index 0.60 (95% CI 0.484–0.715)], with corresponding negative and positive predictive values of 96.7% and 6.7%ConclusionIn a large, international, multi-centre cohort of childhood HCM, ECG abnormalities were common and varied. No ECG characteristic, either in isolation or combined in the previously described ECG risk score, was associated with 5-year sudden cardiac death risk. This suggests that the role of baseline ECG phenotype in improving risk stratification in childhood HCM is limited.

Management and outcomes of hypertrophic cardiomyopathy in young adults

Management of young adults with hypertrophic cardiomyopathy (HCM) is challenging. To evaluate the profile of young adults (16-25 years) with HCM included in the French prospective HCM registry. Patients were compared according to occurrence of major adverse cardiac events (MACE), comprising sudden cardiac death (SCD) events (implantable cardioverter defibrillator [ICD] discharge, SCD, sustained ventricular tachycardia), atrial fibrillation/embolic stroke, heart failure hospitalisation and unexplained syncope, at a mean follow-up of 4.4±2.2 years. At baseline, among 61 patients (20.5±3.0 years; 16 women, 26.2%), 13 (21.3%) had a prophylactic ICD, 24.6% a family history of SCD, 29.5% obstruction, 86.0% magnetic resonance imaging myocardial fibrosis, 11.8% abnormal exercise blood pressure and 52.8% a European Society of Cardiology (ESC) 5-year SCD score<4% (24.5%≥6%). At follow-up, 15 patients (24.6%; seven women; all with fibrosis) presented 17 MACE, comprising: SCD events (n=7, 41.2%; including three patients with an ICD, five with at least one SCD major classical risk factor and an ESC score≥5% and two with no risk factors and an ESC score<4%); atrial fibrillation/stroke (n=6, 35.3%); heart failure (n=1, 5.9%); syncope (n=3, 17.6%). An ICD was implanted in 11 patients (four for secondary prevention), but in only 61.5% of patients with a score≥6%. Only obstruction significantly increased MACE risk (odds ratio 3.96; P=0.035), with a non-significant trend towards a lower risk in men (OR 0.29; P=0.065). In young adults with HCM, MACE are common in the short term, especially in obstructive HCM and women, mostly arrhythmic in origin. Prophylactic ICD implantation is frequent and does not strictly follow the guidelines, while the use of European/USA guidelines is helpful but imperfect in identifying SCD risk.

Gaps in Evidence for Risk Stratification for Sudden Cardiac Death in Hypertrophic Cardiomyopathy.

Gaps in Evidence for Risk Stratification for Sudden Cardiac Death in Hypertrophic Cardiomyopathy.