Multimodality Imaging in Hypertrophic Cardiomyopathy for Risk Stratification

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

BACKGROUND

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.

METHODS AND RESULTS

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.

CONCLUSIONS

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.

Austrian consensus statement on the diagnosis and management of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease that is characterized by left ventricular hypertrophy unexplained by secondary causes. Based on international epidemiological data, around 20,000-40,000 patients are expected to be affected in Austria. Due to the wide variety of clinical and morphological manifestations the diagnosis can be difficult and the disease therefore often goes unrecognized. HCM is associated with a substantial reduction in quality of life and can lead to sudden cardiac death, especially in younger patients. Early and correct diagnosis, including genetic testing, is essential for comprehensive counselling of patients and their families and for effective treatment. The latter is especially true as an effective treatment of outflow tract obstruction has recently become available in the form of a first in class cardiac myosin ATPase inhibitor, as a noninvasive alternative to established septal reduction therapies. The aim of this Austrian consensus statement is to summarize the recommendations of international guidelines with respect to the genetic background, pathophysiology, diagnostics and management in the context of the Austrian healthcare system and resources, and to present them in easy to understand algorithms.

Three-Tesla Magnetic Resonance Imaging Characteristics of Hypertrophic Cardiomyopathy: A Comparison with Several Echocardiography Parameters

Background

Hypertrophic cardiomyopathy (HCM) is a primary cardiac disorder characterized by myocardial hypertrophy without increased afterload. This study set out to describe the cardiac magnetic resonance (CMR) imaging characteristics of HCM and to evaluate correlations of selected CMR parameters with echocardiography.

Methods

This cross-sectional study enrolled 46 patients diagnosed at the Vietnam Heart Institute with HCM and underwent CMR at the Radiology Center, Bach Mai Hospital, from July 2021 to September 2022.

Results

A left ventricular outflow tract (LVOT)/aortic valve (AO) diameter ratio of ≥0.38 on CMR was consistent with an LVOT pressure gradient (PG) of <30 mmHg on echocardiography. The LVOT diameter and the LVOT/AO diameter ratio differed significantly between obstructive and non-obstructive HCM. The predominant phenotypes were diffuse asymmetric HCM (32.6%) and septal HCM (37%), followed by apical HCM (6.5%). Most late gadolinium enhancement (LGE) lesions were observed in the mid-wall of the hypertrophic segments. The mean LGE mass was significantly higher in the obstructive group than in the non-obstructive HCM group (p < 0.05). A strong negative correlation (r = -0.66) was found between the LVOT/AO diameter ratio on the CMR and the LVOT PG via echocardiography. Moreover, echocardiography detected morphologic risk factors for sudden cardiac death (SCD) in 80.4% of patients, whereas the corresponding proportion detected by CMR was 91.3%. Patients with systolic anterior motion (SAM) had a risk for a LVOT/AO diameter ratio <0.38, which was 5.7 times the risk observed in their counterparts without SAM.

Conclusions

The LVOT/AO diameter ratio detected by CMR is a precise index for classifying hemodynamic HCM groups. CMR was better than echocardiography for SCD risk stratification.

Quantitative Late Gadolinium Enhancement Cardiac Magnetic Resonance and Sudden Death in Hypertrophic Cardiomyopathy: A Meta-Analysis

BACKGROUND

Quantitative late gadolinium enhancement (LGE) cardiac magnetic resonance provides important prognostic information for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM). However, it has not been fully integrated into clinical practice.

OBJECTIVES

The purpose of this study was to assess the prognostic value of LGE extent in predicting SCD in adults with HCM across different methods of quantification, thresholds, and patients' clinical profile.

METHODS

The authors searched PubMed, Web of Science, and Cochrane Library for studies investigating the prognostic value of LGE% in predicting SCD in HCM. Pooled ORs were calculated with 95% CIs. The optimal threshold was determined using a multiple cutoffs model.

RESULTS

Eleven studies were included in the meta-analysis with a total of 5,550 patients and a median follow-up time of 5.2 years. Two studies quantified LGE manually, 7 studies used the 6 SD technique, 1 study used the 4 SD technique, and 1 study the 2 SD technique. There was no statistically significant difference in predicting SCD between these 4 methods (P = 0.443). Optimal cutoff could be determined only for the 6 SD technique. LGE 10% was the optimal threshold of the 6 SD technique with sensitivity 0.73 and specificity 0.67.

CONCLUSIONS

The different LGE quantification techniques have comparable accuracy in predicting SCD. When the more extensively studied 6 SD technique is used, LGE 10% is the optimal cutoff and can effectively restratify intermediate-risk patients. LGE extent can improve HCM risk stratification, but it is unlikely to become a standalone tool.

Apical hypertrophic cardiomyopathy: pathophysiology, diagnosis and management

Since the first description of apical hypertrophic cardiomyopathy (ApHCM) in 1976, contrasting information from all over the world has emerged regarding the natural history of the disease. However, the recommended guidelines on hypertrophic cardiomyopathy (HCM) pay a cursory reference to ApHCM, without ApHCM-specific recommendations to guide the diagnosis and management. In addition, cardiologists may not be aware of certain aspects that are specific to this disease subtype, and a robust understanding of specific disease features can facilitate recognition and timely diagnosis. Therefore, the review covers the incidence, pathogenesis, and characteristics of ApHCM and imaging methods. Echocardiography and cardiovascular magnetic resonance imaging (CMR) are the most commonly used imaging methods. Moreover, this review presents the management strategies of this heterogeneous clinical entity. In this review, we introduce a novel transapical beating-heart septal myectomy procedure for ApHCM patients with a promising short-time result.

Role of Imaging in the Diagnosis, Evaluation, and Management of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is increasingly recognized and may benefit from the recent approval of new, targeted medical therapy. Successful management of HCM is dependent on early and accurate diagnosis. The lack of a definitive diagnostic test, the wide variation in phenotype and the commonness of phenocopy conditions, and the presence of normal or hyperdynamic left ventricular function in most patients makes HCM a condition that is highly dependent on imaging for all aspects of management including, diagnosis, classification, predicting risk of complications, detecting complications, identifying risk for ventricular arrhythmias, evaluating choice of therapy and monitoring therapy, intraprocedural guidance, and screening family members. Although echocardiographic imaging remains the mainstay in the diagnosis and subsequent management of HCM, this disease clearly requires multimethod imaging for various aspects of optimal patient care. Advances in echocardiography hardware and techniques, development and refinement of imaging with computed tomography, magnetic resonance, and nuclear scanning, and the emergence of very focused assessments such as diastology and fibrosis imaging have all advanced the diagnosis and management of HCM. In this review, we discuss the relative utility and evidence support for these imaging approaches to contribute to improve patient outcomes.

Complete Heart Block After Aortic Valve Repair and Septal Myectomy in a Patient With Rheumatic Heart Disease

Surgical myectomy with concomitant valvular repair has been demonstrated to be safe in the treatment of hypertrophic obstructive cardiomyopathy (HOCM). It is unclear which risk factors predispose patients to develop complete heart block (CHB). We present a unique case of a 66-year-old female with rheumatic heart disease and HOCM admitted for aortic valve (AV) repair and septal myectomy, complicated by a presentation of complete heart block. The histology slide showed fibrosis of the septum, suggesting atrioventricular conduction disease from rheumatic fever, which likely contributed to her presentation. This case highlights the importance of elucidating the etiology of HOCM before undergoing cardiac surgery to guide postsurgical management and improve clinical outcomes.

Relationship between myocardial bridging and fatal ventricular arrhythmias in patients with hypertrophic cardiomyopathy: the HCM-MB study

BACKGROUND

Myocardial bridging (MB) and hypertrophic cardiomyopathy (HCM) are associated with the risk of fatal ventricular arrhythmias (VAs). The goal of the study was to determine the relationship between MB and fatal VAs in HCM patients with implantable cardiac defibrillators (ICD).

METHODS

A total of 108 HCM patients (mean age: 46.6 ± 13.6 years; male: 73) were enrolled in this retrospective study. All patients underwent transthoracic echocardiography and coronary computed tomography angiography. Fatal VAs including sustained ventricular tachycardia and ventricular fibrillation were documented in ICD records.

RESULTS

There were documented fatal VAs in 29 (26.8%) patients during a mean follow-up time of 71.3 ± 30.9 months. Compared with the other groups, the fatal VA group had a higher incidence of the following: presence of MB (82.8 vs. 38%, p < 0.001), deep MB (62.1 vs. 6.3%, p < 0.001), very deep MB (24.1 vs. 0%, p < 0.001), long MB (65.5 vs. 11.4%, p < 0.001), presence of > 1 MB (17.2 vs. 0%, p = 0.001), and MB of the left anterior descending artery (79.3 vs. 17.7%, p < 0.001) . Sudden cardiac death (SCD) risk score (hazard ratio: 1.194; 95% CI: 1.071-1.330; p = 0.001) and presence of MB (hazard ratio: 3.815; 95% CI: 1.41-10.284; p = 0.008) were found to be independent predictors of fatal VAs in HCM patients.

CONCLUSIONS

The current data suggest that the SCD risk score and presence of MB were independent risk factors for fatal VAs in patients with HCM. In addition to conventional risk factors, the coronary anatomical course can provide clinicians with valuable information when assessing the risk of fatal VAs in HCM patients.

Cardiac Remodeling and Functional Changes in Patients With Hypertrophic Cardiomyopathy: A Longitudinal Observational Study

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a hereditary cardiac disorder characterized by abnormal thickening of the left ventricular myocardium. This can lead to various clinical manifestations, including sudden death.

AIM

To investigate the cardiac remodeling and functional changes in patients with HCM over a specific time period and explore the impact of different treatment regimens on disease progression.

METHODS

We conducted a prospective longitudinal observational study involving 100 patients diagnosed with HCM. Baseline clinical data, including demographics, medical history, and echocardiographic measurements, were collected. Follow-up assessments were performed at regular intervals over 24 months to track changes in cardiac structure, function, and clinical status. Statistical analysis, including paired t-tests and subgroup analysis, was conducted to identify significant associations and differences between treatment groups.

RESULTS

A total of 100 patients (mean age = 55 years, 50% male) were enrolled in the study. At baseline, echocardiography revealed increased left ventricular wall thickness (mean = 18.5 mm), left atrial dimensions (mean = 39 mm), and ventricular mass (mean = 230 g). During the follow-up period, there was a progressive increase in left ventricular wall thickness (mean change = 1.0 mm/year, p < 0.001), left atrial dimensions (mean change = 3.0 mm/year, p < 0.001), and ventricular mass (mean change = 8 g/year, p = 0.003). Additionally, alterations in diastolic and systolic function parameters were noted, with a decline in E/A ratio (mean change = -0.1 units/year, p = 0.008) and a reduction in ejection fraction (mean change = -2.0% per year, p = 0.001).

CONCLUSION

Our longitudinal observational study provides important insights into the cardiac remodeling and functional changes in patients with HCM over time. The progressive increase in cardiac parameters indicates ongoing disease progression. Additionally, beta-blocker therapy was associated with a slower rate of left ventricular wall thickening. These findings contribute to a better understanding of HCM's natural history and may guide targeted therapeutic approaches to improve patient outcomes.

Imaging of left ventricular outflow tract obstruction in hypertrophic cardiomyopathy

PURPOSE OF REVIEW

The current article reviews obstructive forms of hypertrophic cardiomyopathy and associated morphologic cardiac abnormalities. It focuses on echocardiographic imaging of the left ventricular (LV) outflow tract obstruction, its evaluation, prognostication, and differentiation from other conditions mimicking obstructive hypertrophic cardiomyopathy.

RECENT FINDINGS

Symptomatic patients with LV outflow tract (LVOT) gradients at least 50 mmHg on maximally tolerated medical therapy are candidates for advanced therapies. Resting echocardiography may only identify 30% of patients with obstructive physiology. Provocative maneuvers are essential for symptomatic patients with hypertrophic cardiomyopathy (HCM). Exercise echocardiography is recommended if they fail to provoke a gradient. Although dynamic LV tract obstruction is seen with obstructive HCM, it is not specific to this condition and exists in other physiologic and pathophysiologic states. Careful clinical evaluation and imaging techniques aid in the differentiation of HCM from these conditions.

SUMMARY

Imaging plays an integral role in the diagnosis, prognosis, and risk stratification of HCM patients. Newer imaging technologies, including 3D transthoracic echocardiography, 3D transesophageal, speckle-derived 2D strain, and cardiac MRI, allow for a better hemodynamic understanding of systolic anterior motion and LV tract obstruction. Evolving techniques, that is, artificial intelligence, will undoubtedly further increase diagnostic capabilities. Newer medical therapies are available with the hope that this will lead to better patient management.

Increase in skeletal muscle extracellular volume as an under-recognised change detected at cardiac MRI in hypertrophic cardiomyopathy

AIM

To explore skeletal muscle change and its correlation with the myocardium in hypertrophic cardiomyopathy (HCM) using cardiac magnetic resonance imaging (cMRI) with T1 mapping and late gadolinium enhancement (LGE).

MATERIALS AND METHODS

This retrospective study enrolled 50 HCM patients and 35 healthy controls. The extracellular volume (ECV) of the skeletal muscle and myocardium, the presence and absence of LGE of the myocardium, and cardiac troponin T (cTnT), were assessed. In the HCM group, the elevated ECV_skeletal group was defined as ECV_skeletal >2 standard deviations (SD) above the mean value of the controls. Statistical analyses included Student's t-test, the Mann-Whitney U-test, and linear regression.

RESULTS

ECV_skeletal in the HCM group was higher than in the control group (mean 13.0 versus 10.9%; p<0.001), with 20 (40%) HCM patients having elevated ECV_skeletal (ECV_skeletal ≥13.7%). In the HCM group, ECV_skeletal had a positive linear correlation with global myocardial ECV (r=0.37, p=0.009). In addition, the elevated ECV_skeletal group had a higher cTnT than the non-elevated group (log cTnT, mean 1.55 versus 1.16, p=0.045). Furthermore, segmental myocardial ECV in the elevated ECV_skeletal group was higher than in the non-elevated group, despite the presence or absence of myocardial LGE (median 30.1 versus 27.2%; 26.5 versus 24.6%, both p<0.001) or hypertrophy (median 29.0 versus 26.0%; 26.8 versus 24.8%, both p<0.001).

CONCLUSION

In the HCM patients, ECV_skeletal was higher than in the healthy controls. Furthermore, some ECV_skeletal changes had corresponding changes in the cTnT and myocardium.

Hypertrophic, Dilated, and Arrhythmogenic Cardiomyopathy: Where Are We?

Cardiomyopathies are a heterogeneous group of structural, mechanical, and electrical heart muscle disorders which often correlate with life-threatening arrhythmias and progressive heart failure accounting for significant cardiovascular morbidity and mortality. Currently, cardiomyopathies still represent a leading reason for heart transplantation worldwide. The last years have brought remarkable advances in the field of cardiomyopathies especially in terms of understanding the molecular basis as well as the diagnostic evaluation and management. Although most cardiomyopathy treatments had long focused on symptom management, much of the current research efforts aim to identify and act on the disease-driving mechanisms. Regarding risk assessment and primary prevention of sudden cardiac death, additional data are still pending in order to pave the way for a more refined and early patient selection for defibrillator implantation. This review summarizes the current knowledge of hypertrophic, dilated and arrhythmogenic cardiomyopathy with a particular emphasis on their pathophysiology, clinical features, and diagnostic approach. Furthermore, the relevant ongoing studies investigating novel management approaches and main gaps in knowledge are highlighted.

Myocardial mechanics of percutaneous intramyocardial septal radiofrequency ablation

OBJECTIVE

Echocardiography-guided Percutaneous IntraMyocardial Septal Radiofrequency Ablation (PIMSRA, Liwen procedure) is a novel treatment option for hypertrophic obstructive cardiomyopathy (HOCM). The impact of PIMSRA on myocardial mechanics is unknown.

METHODS

Between October 2016 and June 2019, PIMSRA and 3-dimentional speckle tracking echocardiography were performed in 82 patients. Echocardiographic imaging, qualitative and quantitative clinical assessment were completed at baseline, immediately postprocedure and 1-year follow-up.

RESULTS

There was a significant reduction in the peak left ventricular outflow tract (LVOT) gradients immediately following PIMSRA and at 1-year follow-up (resting gradients: from 83.50 (61.25) to 23.00 (41.75) mm Hg, p<0.001 and 13.50 (21.75) mm Hg, p<0.001, respectively; stress-induced gradients: from 118.25 (96.02) to 47.00 (74.50) mm Hg (1 year), p<0.001). There was an improvement in exercise time on stress echocardiography (p<0.001) and distance by 6 min walk test (p=0.034). Immediately after PIMSRA, there was a significant reduction in radial and circumferential strain in the ablated segments (p<0.001), with no change of longitudinal strain. At 1-year follow-up, the radial and circumferential strain recovered in the ablated segments. Meanwhile, left ventricular regional and global longitudinal strain had improved significantly (p<0.05).

CONCLUSIONS

PIMSRA is an effective treatment for symptomatic HOCM that resulted in a sustained improvement in exercise capacity, a persistent decrease in LVOT gradient, and a measurable increase in myocardial contractile function.

TRIAL REGISTRATION NUMBER

NCT04777188.

Cardiac Resynchronization Therapy and Hypertrophic Cardiomyopathy: A Comprehensive Review

Hypertrophic cardiomyopathy (HCM) is an inherited primary myocardial disease characterized by asymmetrical/symmetrical left ventricle (LV) hypertrophy, with or without LV outflow tract (LVOT) dynamic obstruction, and poor prognosis. Cardiac resynchronization therapy (CRT) has emerged as a minimally invasive tool for patients with heart failure (HF) with decreased LV ejection fraction (LVEF) and prolonged QRS duration of over 120 ms with or without left bundle branch block (LBBB). Several HCM patients are at risk of developing LBBB because of disease progression or secondary to septal myomectomy, while others might develop HF with decreased LVEF, alleged end-stage/dilated HCM, especially those with thin myofilament mutations. Several studies have shown that patients with myectomy-induced LBBB might benefit from left bundle branch pacing or CRT to relieve symptoms, improve exercise capacity, and increase LVEF. Otherwise, patients with end-stage/dilated HCM and prolonged QRS interval could gain from CRT in terms of NYHA class improvement, LV systolic performance increase and, to some degree, LV reverse remodeling. Moreover, several electrical and imaging parameters might aid proper selection and stratification of HCM patients to benefit from CRT. Nonetheless, current available data are scarce and further studies are still required to accurately clarify the view. This review reassesses the importance of CRT in patients with HCM based on current research by contrasting and contextualizing data from various published studies.

Risk stratification in patients with hypertrophic cardiomyopathy: Looking beyond the left side myocardial function

BACKGROUND

Patients with hypertrophic cardiomyopathy (HCM) have heterogeneous outcomes. As risk stratification mostly focuses on left-side myocardial function, we sought to investigate the prognostic value of right ventricular (RV) function in patients with HCM.

METHODS

This retrospective cohort study included patients with HCM. Conventional ventricular functional parameters, including left ventricular ejection fraction (LVEF), tricuspid annular plane systolic excursion (TAPSE), and fractional area change were obtained. The longitudinal strain was analyzed using the speckle tracking method. The primary endpoint was defined as a composite of hospitalization for heart failure, sustained ventricular tachycardia, or all-cause death.

RESULTS

A total of 56 patients with HCM (aged 58.0 ± 14.9 years, 64.3% male) were included. After a mean follow-up duration of 30.1 ± 17.4 months, primary endpoints developed in 10 (20%) of 50 patients who were treated medically. Patients with cardiovascular events had a more reduced LV thickest segmental strain, worse TAPSE, and more impaired RV free wall strain. After adjusting for age, sex, and LVEF, TAPSE (hazard ratio [HR], 95% confidence intervals [CIs]: 0.24, 0.06-0.93) and RV free wall strain (HR, 95% CIs:1.12, 1.03-1.21) remained independent prognostic predictors. Incorporating either TAPSE or RV free wall strain provides incremental prognostic value to the LV strain alone (net reclassification improvement by 31.4% and 34.1%, respectively, both p < 0.05).

CONCLUSION

RV function assessed by TAPSE or RV free wall strain is predictive of subsequent cardiac events, suggesting that a comprehensive evaluation of RV function is useful for risk stratification in patients with HCM.

Myosin Inhibition and Left Ventricular Diastolic Function in Patients With Obstructive Hypertrophic Cardiomyopathy Referred for Septal Reduction Therapy: Insights From the VALOR-HCM Study

BACKGROUND

In the randomized phase 3 VALOR-HCM study (A Study to Evaluate Mavacamten in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy Who Are Eligible for Septal Reduction Therapy) of patients with obstructive hypertrophic cardiomyopathy, mavacamten reduced the need for septal reduction therapy. Because mavacamten improves ventricular compliance, this sub-study examined the effects of treatment with this cardiac myosin inhibitor on diastolic function.

METHODS

Symptomatic obstructive hypertrophic cardiomyopathy patients on maximally tolerated medical therapy referred for septal reduction therapy were randomized 1:1 to mavacamten or placebo. At baseline and week 16, a resting and stress echocardiogram was performed with interpretation by a core laboratory. In this exploratory substudy, the principal end point was the change in parameters used to define the grade of diastolic function in patients treated with mavacamten and placebo. A related objective was to assess the proportion of patients with an improvement in diastolic function grade. A secondary aim was to assess for correlation between diastolic function parameters and the secondary end points from VALOR-HCM: New York Heart Association class, quality of life, and cardiac biomarkers.

RESULTS

Diastolic dysfunction grade was evaluable in 98 patients at baseline and week 16. Among patients treated with mavacamten, 29.4% (15 of 51) demonstrated improvement in diastolic function grade compared with 12.8% (6 of 47) patients with placebo (P=0.05). Average E/e' ratio decreased significantly in patients treated with mavacamten (-3.4±5.3) compared with placebo (0.57±3.5; P<0.001). Indexed left atrial volumes (mL/m²) also decreased significantly in patients who received mavacamten (-5.2±7.8) compared with placebo (-0.51±8.1; P=0.005). After adjustment for change in left ventricular outflow tract gradient and mitral regurgitation, mavacamten was significantly associated with a decrease in average E/e' ratio and indexed left atrial volumes. Change in average E/e' ratio was significantly correlated with the secondary end points from VALOR-HCM.

CONCLUSIONS

In this exploratory substudy, after 16 weeks of therapy, mavacamten improved diastolic function, and this change correlated with improvement in clinical and biomarker end points.

REGISTRATION

URL: https://www.

CLINICALTRIALS

gov; Unique identifier: NCT04349072.

Prognostic role of global longitudinal strain by feature tracking in patients with hypertrophic cardiomyopathy: The STRAIN-HCM study

BACKGROUND

The assessment of myocardial fiber deformation with cardiac magnetic resonance feature tracking (CMR-FT) has shown to be promising in terms of prognostic information in several structural heart diseases. However, little is known about its role in hypertrophic cardiomyopathy (HCM). Aims of the present study were: 1) to assess the prognostic role of CMR-FT derived strain parameters in patients with HCM.

METHODS

CMR was performed in 130 consecutive HCM patients (93 males, mean age (54 ± 17 years) with an estimated 5-year risk of sudden cardiac death (SCD) <6% according to the HCM Risk-SCD calculator. 2D- and 3D-Global Radial (GRS), Longitudinal (GLS) and Circumferential (GCS) Strain was evaluated by FT analysis. The primary outcome of the study was a composite of major adverse cardiac events (MACE) including SCD, resuscitated cardiac arrest due to ventricular fibrillation (VF) or hemodynamically unstable ventricular tachycardia (VT), and hospitalization for heart failure.

RESULTS

After a median follow-up of 51.7 (37.1-68.8) months, 4 (3%) patients died (all of them suffered from SCD) and 36 (28%) were hospitalized for heart failure. After multivariable adjustment for clinical and imaging covariates, among all strain parameters, only GLS remained a significant independent predictor of outcome events in both the model including 2D strain (HR 1.12, 95% CI 1.03-1.23, p = 0.01) and the model including 3D strain (HR 1.14, 95% CI 1.01-1.30, p = 0.04). The addition of 2D-GLS into the model with clinical and imaging predictors resulted in a significant increase in the C-statistic (from 0.48 to 0.65, p = 0.03).

CONCLUSION

CMR-FT derived GLS is a powerful independent predictor of MACE in patients with HCM, incremental to common clinical and CMR risk factors including left ventricular ejection fraction and late gadolinium enhancement.

Risk stratification in cardiomyopathies (dilated, hypertrophic, and arrhythmogenic cardiomyopathy) by cardiac magnetic resonance imaging

Cardiac magnetic resonance imaging (CMR) is a non-invasive, multiplanar, and high spatial resolution imaging technique, which represents the current gold standard for the evaluation of biventricular volumes and function. Furthermore, unlike other methods, it has the great advantage of characterizing the myocardial tissue by identifying the presence of alterations, such as oedema and focal and diffuse fibrosis. In particular, the late gadolinium enhancement technique makes it possible to identify areas of focal fibrosis that often constitute the substrate for the triggering of threatening ventricular arrhythmias at the basis of sudden cardiac death. For this reason, the use of CMR in the study of cardiomyopathies has become of primary importance, both for the differential diagnosis and for patient risk stratification. In this brief review, the ability of CMR in prognostic stratification of patients with dilated, hypertrophic, and arrhythmogenic cardiomyopathy will be analysed. In particular, the role of CMR in the prediction of arrhythmic risk and in the decision-making process for the implantation of a cardiac defibrillator will be examined.

CMR-Based Risk Stratification of Sudden Cardiac Death and Use of Implantable Cardioverter-Defibrillator in Non-Ischemic Cardiomyopathy

Non-ischemic cardiomyopathy (NICM) is one of the most important entities for arrhythmias and sudden cardiac death (SCD). Previous studies suggest a lower benefit of implantable cardioverter–defibrillator (ICD) therapy in patients with NICM as compared to ischemic cardiomyopathy (ICM). Nevertheless, current guidelines do not differentiate between the two subgroups in recommending ICD implantation. Hence, risk stratification is required to determine the subgroup of patients with NICM who will likely benefit from ICD therapy. Various predictors have been proposed, among others genetic mutations, left-ventricular ejection fraction (LVEF), left-ventricular end-diastolic volume (LVEDD), and T-wave alternans (TWA). In addition to these parameters, cardiovascular magnetic resonance imaging (CMR) has the potential to further improve risk stratification. CMR allows the comprehensive analysis of cardiac function and myocardial tissue composition. A range of CMR parameters have been associated with SCD. Applicable examples include late gadolinium enhancement (LGE), T1 relaxation times, and myocardial strain. This review evaluates the epidemiological aspects of SCD in NICM, the role of CMR for risk stratification, and resulting indications for ICD implantation.

Incremental Values of T1 Mapping in the Prediction of Sudden Cardiac Death Risk in Hypertrophic Cardiomyopathy: A Comparison With Two Guidelines

Background: MRI native T1 mapping and extracellular volume fraction (ECV) are quantitative values that could reflect various myocardial tissue characterization. The role of these parameters in predicting the risk of sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) is still poorly understood.

Aim: This study aims to investigate the ability of native T1 mapping and ECV values to predict major adverse cardiovascular events (MACE) in HCM, and its incremental values over the 2014 European Society of Cardiology (ESC) and enhanced American College of Cardiology/American Heart Association (ACC/AHA) guidelines.

Methods: Between July 2016 and October 2020, HCM patients and healthy individuals with sex and age matched who underwent cardiac MRI were prospectively enrolled. The native T1 and ECV parameters were measured. The SCD risk was evaluated by the 2014 ESC guidelines and enhanced ACC/AHA guidelines. MACE included cardiac death, transplantation, heart failure admission, and implantable cardioverter-defibrillator implantation.

Results: A total of 203 HCM patients (54.2 ± 14.9 years) and 101 healthy individuals (53.2 ± 14.7 years) were evaluated. During a median follow-up of 15 months, 25 patients (12.3%) had MACE. In multivariate Cox regression analysis, global native T1 mapping (hazard ratio (HR): 1.446; 95% confidence interval (CI): 1.195–1.749; P < 0.001) and non-sustained ventricular tachycardia (NSVT) (HR: 4.949; 95% CI, 2.033–12.047; P < 0.001) were independently associated with MACE. Ten of 86 patients (11.6%) with low SCD risk assessed by the two guidelines had MACE. In this subgroup of patients, multivariate Cox regression analysis showed that global native T1 mapping was independently associated with MACE (HR: 1.532; 95% CI: 1.221–1.922; P < 0.001). In 85 patients with conflicting results assessed by the two guidelines, end-stage systolic dysfunction was independently associated with MACE (HR: 7.942, 95% CI: 1.322–47.707, P = 0.023). In 32 patients with high SCD risk assessed by the two guidelines, NSVT was independently associated with MACE (HR: 9.779, 95% CI: 1.953–48.964, P = 0.006).

Conclusion: The global native T1 mapping could provide incremental values and serve as potential supplements to the current guidelines in the prediction of MACE.

Etiology-Discriminative Multimodal Imaging of Left Ventricular Hypertrophy and Synchrotron-Based Assessment of Microstructural Tissue Remodeling

Background: Distinguishing the etiology of left ventricular hypertrophy (LVH) is clinically relevant due to patient outcomes and management. Easily obtained, echocardiography-based myocardial deformation patterns may improve standard non-invasive phenotyping, however, the relationship between deformation phenotypes and etiology-related, microstructural cardiac remodeling has not been reported. Synchrotron radiation-based X-ray phase-contrast imaging (X-PCI) can provide high resolution, three-dimensional (3D) information on myocardial microstructure. The aim of this pilot study is to apply a multiscale, multimodality protocol in LVH patients undergoing septal myectomy to visualize in vivo and ex vivo myocardial tissue and relate non-invasive LVH imaging phenotypes to the underlying synchrotron-assessed microstructure. Methods and findings: Three patients (P1-3) undergoing septal myectomy were comprehensively studied. Medical history was collected, and patients were imaged with echocardiography/cardiac magnetic resonance prior to the procedure. Myocardial tissue samples obtained during the myectomy were imaged with X-PCI generating high spatial resolution images (0.65 μm) to assess myocyte organization, 3D connective tissue distribution and vasculature remodeling. Etiology-centered non-invasive imaging phenotypes, based on findings of hypertrophy and late gadolinium enhancement (LGE) distribution, and enriched by speckle-tracking and tissue Doppler echocardiography deformation patterns, identified a clear phenotype of hypertensive heart disease (HTN) in P1, and hypertrophic cardiomyopathy (HCM) in P2/P3. X-PCI showed extensive interstitial fibrosis with normal 3D myocyte and collagen organization in P1. In comparison, in P2/P3, X-PCI showed 3D myocyte and collagen disarray, as well as arterial wall hypertrophy with increased perivascular collagen, compatible with sarcomere-mutation HCM in both patients. The results of this pilot study suggest the association of non-invasive deformation phenotypes with etiology-related myocyte and connective tissue matrix disorganization. A larger patient cohort could enable statistical analysis of group characteristics and the assessment of deformation pattern reproducibility. Conclusion: High-resolution, 3D X-PCI provides novel ways to visualize myocardial remodeling in LVH, and illustrates the correspondence of macrostructural and functional non-invasive phenotypes with invasive microstructural phenotypes, suggesting the potential clinical utility of non-invasive myocardial deformation patterns in phenotyping LVH in everyday clinical practice.

Echocardiographic evaluation of the Athlete's heart

Cardiac response to prolonged, intense exercise induces phenotypic and physiologic adaptive changes that improve myocardial ability to meet oxygen demands. These adaptations, termed "athletes' heart," have been extensively studied. The importance of this entity arises from the increasing numbers of athletes as well as the drive for physical fitness in the general population leading to adaptive cardiac changes that need to be differentiated from life-threatening cardiovascular diseases. A number of pathologic entities may share phenotypic changes with the athletes' heart such as hypertrophic cardiomyopathy, dilated cardiomyopathy, Marfan's syndrome, and arrhythmogenic right ventricular cardiomyopathy. Cardiologists need to be cognizant of these overlapping findings to appropriately diagnose diseases and prevent catastrophic outcomes especially in young and healthy individuals who may not show any symptoms until they engage in intense exercise. It is equally important to recognize and distinguish normal, exercise-adaptive cardiac changes to provide accurate screening and guidance to young elite athletes. Echocardiography is a valuable modality that allows comprehensive initial evaluation of cardiac structures, function, and response to exercise. Several different echocardiographic techniques including M-Mode, 2D echo, Doppler, tissue Doppler, color tissue Doppler, and speckle tracking have been used in the evaluation of cardiac adaptation to exercise. The following discussion is a review of literature that has expanded our knowledge of the athlete's heart.

Impaired repolarization parameters may predict fatal ventricular arrhythmias in patients with hypertrophic cardiomyopathy (from the CILICIA Registry)

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is significantly associated with high risk of fatal ventricular arrhythmias (VAs). Increased frontal QRST angle (fQRSTa), Tpe interval, and Tp-e/QTc ratio are described as ventricular repolarization parameters which are related to arrhythmias. In this study, we aimed to investigate the predictive value of these repolarization parameters for fatal VAs in patients with HCM.

METHODS

A total of 127 HCM patients (mean age: 47.9 ± 12.6 years; male:79) were enrolled in this retrospective study. All patients underwent transthoracic echocardiography. Moreover, the last electrocardiograms within 3 months prior to the fatal VA documentation were assessed. The primary outcome was the occurrence of fatal VAs including sustained ventricular tachycardia and ventricular fibrillation which were documented from implantable cardioverter defibrillator records.

RESULTS

There were documented fatal VAs in 37 (29.1%) patients during a mean follow-up time of 70.1 ± 22.6 months. The prevalence of fatal VAs was significantly higher in patients with fQRSTa ≥140 degrees (67.4 vs. 7.4%; p < 0.001) and in patients with Tp-e/QTc ratio ≥ 0.19 (61.5 vs. 6.7%; p < 0.001) as compared to others. High Tp-e/QTc ratio (hazard ratio: 1.564; 95% confidence interval: 1.086-4.796; p = 0.032) and high fQRSTa (hazard ratio: 1.864; 95% confidence interval: 1.106-8.745; p = 0.002) were found to be independent predictors of fatal VAs in HCM patients.

CONCLUSIONS

Wider fQRSTa, prolonged Tp-e interval, and increased Tp-e/QTc ratio may be associated with fatal VAs in HCM patients. In addition to traditional risk factors, these simple ECG parameters may provide valuable information during evaluation of sudden cardiac death risk in HCM patients.

Differential diagnosis of apical hypertrophic cardiomyopathy and apical displacement of the papillary muscles: a multimodality imaging point of view

Apical hypertrophic cardiomyopathy (ApHCM) and apical displacement of papillary muscles (ADPM) are two different pathologies with a number of similar imaging findings that may hamper adequate diagnosis. While ApHCM is associated with increased rate of mortality, ADPM commonly presents with a benign course and differential diagnosis is of great importance. Clinical assessment and 2D echocardiography cannot sufficiently differentiate these conditions, however, and advanced echocardiographic methods may facilitate diagnosis. Although echocardiography is the first-line imaging method in the diagnostic algorithm, cardiac magnetic resonance imaging (CMRI) is the gold standard for evaluating patients due to good spatial resolution and myocardial tissue characterization abilities. When CMRI is contraindicated, cardiac computed tomography may be an alternative reliable method that can also give information about the coronary anatomy. Nuclear imaging may also provide supplementary data regarding hypertrophy and coronary arteries when there is a suspicion of ischemia.

The Advantages of New Multimodality Imaging in Choosing the Optimal Management Strategy for Patients with Hypertrophic Cardiomyopathy

In recent years, significant advances have been made in the diagnosis and therapeutic management of hypertrophic cardiomyopathy (HCM) patients, which has led to an important improvement in their longevity and quality of life. The use of multimodality imaging has an essential role in the diagnosis, assessing the regional distribution and severity of the disease, with important prognostic implications. At the same time, imaging contributes to the identification of optimal treatment for patients with hypertrophic cardiomyopathy, whether it is pharmaceutical, interventional or surgical treatment. Novel pharmacotherapies (like myosin inhibitors), minimally invasive procedures (such as transcatheter mitral valve repair, high-intensity focused ultrasound or radiofrequency ablation) and gene-directed approaches, may soon become alternatives for HCM patients. However, there are only few data on the early diagnosis of patients with HCM, in order to initiate treatment as soon as possible, to reduce the risk of sudden cardiac death (SCD). The aim of our review is to highlight the advantages of contemporary imaging in choosing the optimal management strategies for HCM patients, considering the novel therapies which are currently applied or studied for these patients.

Hypertrophic Cardiomyopathy - A Heterogeneous and Lifelong Disease in the Real World

Hypertrophic cardiomyopathy (HCM) is the most frequent hereditary cardiomyopathy, showing an autosomal-dominant f inheritance. A great deal of attention has been paid to genetics, left ventricular tract obstruction and the prediction and prevention of sudden cardiac death in HCM. Needless to say, these are very important, but we should recognize the heterogeneity in etiology, morphology, clinical course and management of this unique cardiomyopathy. Another important perspective is that HCM causes left ventricular remodeling over time and is a disease that requires lifelong management in the real world.