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Background Cardiac MRI late gadolinium enhancement (LGE) scar volume is an important marker for outcome prediction in patients with hypertrophic cardiomyopathy (HCM); however, its clinical application is hindered by a lack of measurement standardization. Purpose To develop and evaluate a three-dimensional (3D) convolutional neural network (CNN)-based method for automated LGE scar quantification in patients with HCM. Materials and Methods We retrospectively identified LGE MRI data in a multicenter ( n = 7) and multivendor ( n = 3) HCM study obtained between November 2001 and November 2011. A deep 3D CNN based on U-Net architecture was used for LGE scar quantification. Independent CNN training and testing data sets were maintained with a 4:1 ratio. Stacks of short-axis MRI slices were split into overlapping substacks that were segmented and then merged into one volume. The 3D CNN per-site and per-vendor performances were evaluated with respect to manual scar quantification performed in a core laboratory setting using Dice similarity coefficient (DSC), Pearson correlation, and Bland-Altman analyses. Furthermore, the performance of 3D CNN was compared with that of two-dimensional (2D) CNN. Results This study included 1073 patients with HCM (733 men; mean age, 49 years ± 17 [standard deviation]). The 3D CNN-based quantification was fast (0.15 second per image) and demonstrated excellent correlation with manual scar volume quantification ( r = 0.88, P < .001) and ratio of scar volume to total left ventricle myocardial volume (%LGE) ( r = 0.91, P < .001). The 3D CNN-based quantification strongly correlated with manual quantification of scar volume ( r = 0.82-0.99, P < .001) and %LGE ( r = 0.90-0.97, P < .001) for all sites and vendors. The 3D CNN identified patients with a large scar burden (>15%) with 98% accuracy (202 of 207) (95% confidence interval [CI]: 95%, 99%). When compared with 3D CNN, 2D CNN underestimated scar volume ( r = 0.85, P < .001) and %LGE ( r = 0.83, P < .001). The DSC of 3D CNN segmentation was comparable among different vendors ( P = .07) and higher than that of 2D CNN (DSC, 0.54 ± 0.26 vs 0.48 ± 0.29; P = .02). Conclusion In the hypertrophic cardiomyopathy population, a three-dimensional convolutional neural network enables fast and accurate quantification of myocardial scar volume, outperforms a two-dimensional convolutional neural network, and demonstrates comparable performance across different vendors. © RSNA, 2019 Online supplemental material is available for this article.

Left atrial (LA) volumes are known to be increased in hypertrophic cardiomyopathy (HCM) and are a predictor of adverse outcome. In addition, LA function is impaired and is presumed to be due to left ventricular (LV) diastolic dysfunction as a result of hypertrophy and myocardial fibrosis. In the current study, we assess the incremental effect of outflow tract obstruction (and concomitant mitral regurgitation) on LA function as assessed by LA strain. Patients with HCM (50 obstructive, 50 nonobstructive) were compared to 50 normal controls. A subset of obstructive patients who had undergone septal myectomy was also studied. Utilising feature-tracking software applied to cardiovascular magnetic resonance images, LA volumes and functional parameters were calculated. LA volumes were significantly elevated and LA ejection fraction and strain were significantly reduced in patients with HCM compared with controls and were significantly more affected in patients with obstruction. LA volumes and function were significantly improved after septal myectomy. LVOT obstruction and mitral regurgitation appear to further impair LA mechanics. Septal myectomy results in a significant reduction in LA volumes, paralleled by an improvement in function.

Hypertrophic cardiomyopathy (HCM) is characterized by substantial genetic and phenotypic heterogeneity, leading to considerable diversity in clinical course including the most common cause of sudden death in young people and a determinant of heart failure symptoms in patients of any age. Traditionally, two-dimensional echocardiography has been the most reliable method for establishing a clinical diagnosis of HCM. However, cardiovascular magnetic resonance (CMR), with its high spatial resolution and tomographic imaging capability, has emerged as a technique particularly well suited to characterize the diverse phenotypic expression of this complex disease. For example, CMR is often superior to echocardiography for HCM diagnosis, by identifying areas of segmental hypertrophy (ie., anterolateral wall or apex) not reliably visualized by echocardiography (or underestimated in terms of extent). High-risk HCM patient subgroups identified with CMR include those with thin-walled scarred LV apical aneurysms (which prior to CMR imaging in HCM remained largely undetected), end-stage systolic dysfunction, and massive LV hypertrophy. CMR observations also suggest that the cardiomyopathic process in HCM is more diffuse than previously regarded, extending beyond the LV myocardium to include thickening of the right ventricular wall as well as substantial morphologic diversity with regard to papillary muscles and mitral valve. These findings have implications for management strategies in patients undergoing invasive septal reduction therapy. Among HCM family members, CMR has identified unique phenotypic markers of affected genetic status in the absence of LV hypertrophy including: myocardial crypts, elongated mitral valve leaflets and late gadolinium enhancement. The unique capability of contrast-enhanced CMR with late gadolinium enhancement to identify myocardial fibrosis has raised the expectation that this may represent a novel marker, which may enhance risk stratification. At this time, late gadolinium enhancement appears to be an important determinant of adverse LV remodeling associated with systolic dysfunction. However, the predictive significance of LGE for sudden death is incompletely resolved and ultimately future large prospective studies may provide greater insights into this issue. These observations underscore an important role for CMR in the contemporary assessment of patients with HCM, providing important information impacting diagnosis and clinical management strategies.

Background: In hypertrophic cardiomyopathy (HCM), the arrhythmic potential associated with a variety of left ventricular myocardial signal intensities evident on contrast-enhanced cardiovascular magnetic resonance with late gadolinium enhancement (LGE) is unresolved., Methods and Results: In 145 HCM patients (43±15 years old), visually identified areas of LGE in left ventricle were analyzed quantitatively for intermediate (≥4 but <6 SD) and high (≥6 SD above the mean signal intensity of normal myocardium) LGE signal intensity (LGE-SI). Ambulatory Holter ECGs were obtained within 7.8±8.3 weeks of cardiovascular magnetic resonance. HCM patients with nonsustained ventricular tachycardia, ventricular couplets, and premature ventricular contractions showed greater amounts of intermediate LGE-SI (17±7 versus 10±10 g, 16±10 versus 10±11 g, and 13±8 versus 10±13 g, respectively; P=0.003 to <0.001) and greater amounts of high LGE-SI (15±6 versus 10±8 g, 14±9 versus 10±12 g, and 12±7 versus 10±8 g, respectively; P=0.02-0.003) than patients without these arrhythmias. In HCM patients with either nonsustained ventricular tachycardia, couplets, or premature ventricular contractions, the extent of intermediate LGE-SI exceeded that of high LGE-SI (17±7 versus 15±6 g, 16±10 versus 14±9 g, and 13±8 versus 12±7 g, respectively; P=0.01-0.04). In addition, the receiver operating characteristic area under the curve established intermediate LGE-SI as a better discriminator of patients with nonsustained ventricular tachycardia than was high LGE-SI, with 7 additional patients with this arrhythmia identified., Conclusions: In patients with HCM, intermediate LGE-SI is a better predictor of ventricular tachyarrhythmias (including nonsustained ventricular tachycardia, a risk factor for sudden death) than is high LGE-SI. Longitudinal studies in larger HCM cohorts are justified to define the independent prognostic impact of intermediate LGE-SI.

Background: Whether morphological abnormalities of the mitral valve represent part of the hypertrophic cardiomyopathy (HCM) disease process is unresolved. Therefore, we applied cardiovascular magnetic resonance to characterize mitral valve morphology in a large HCM cohort., Methods and Results: Cine cardiac magnetic resonance images were obtained in 172 HCM patients (age, 42±18 years; 62% men) and 172 control subjects. In addition, 15 HCM gene-positive/phenotype-negative relatives were studied. Anterior mitral leaflet (AML) and posterior mitral leaflet lengths were greater in HCM patients than in control subjects (26±5 versus 19±5 mm, P<0.001; and 14±4 versus 10±3 mm, P<0.001, respectively), including 59 patients (34%) in whom AML length alone, posterior mitral leaflet length alone, or both were particularly substantial (>2 SDs above controls). Leaflet length was increased compared with controls in virtually all HCM age groups, including young patients 15 to 20 years of age (AML, 26±5 versus 21±4 mm; P=0.0002) and those ≥60 years of age (AML, 26±4 versus 19±2 mm; P<0.001). No relation was evident between mitral leaflet length and LV thickness or mass index (P=0.09 and P=0.16, respectively). A ratio of AML length to LV outflow tract diameter of >2.0 was associated with subaortic obstruction (P=0.001). In addition, AML length in 15 genotype-positive relatives without LV hypertrophy exceeded that of matched control subjects (21±3 versus 18±3 mm; P<0.01)., Conclusions: In HCM, mitral valve leaflets are elongated independently of other disease variables, likely constituting a primary phenotypic expression of this heterogeneous disease, and are an important morphological abnormality responsible for LV outflow obstruction in combination with small outflow tract dimension. These findings suggest a novel role for cardiac magnetic resonance in the assessment of HCM.

Purpose: To determine the most reproducible semiautomated gray-scale thresholding technique for quantifying late gadolinium enhancement (LGE) in a large cohort of patients with hypertrophic cardiomyopathy (HCM)., Materials and Methods: All study patients signed a statement approved by the internal review boards of the participating institutions, agreeing to the use of their medical information for research purposes. LGE cardiovascular magnetic resonance (MR) imaging was performed in 201 patients (71% male) with a mean age of 41.5 years ± 17.6 (standard deviation [SD]) by using standard techniques with administration of 0.2 mmol of gadopentetate dimeglumine per kilogram of body weight. The presence and quantity of LGE were determined first with visual assessment; then with gray-scale thresholds of 2 SDs, 4 SDs, and 6 SDs above the mean signal intensity for the normal remote myocardium; and then with 2 SDs above noise. The LGE quantifications were repeated 4 or more weeks apart to assess reproducibility. Bland-Altman analysis and correlation coefficients were used to compare the visual and various thresholding methods, with normally distributed variables expressed as means ± SDs., Results: LGE was identified in 103 (51%) subjects. The mean quantity of LGE at visual analysis was 13 g ± 20 compared with 12 g ± 17 at 6 SDs, 25 g ± 23 at 4 SDs, 55 g ± 31 at 2 SDs, and 64 g ± 69 at 2 SDs above noise. All gray-scale thresholds were significantly correlated with visual assessment. The 6-SD threshold had the strongest correlation (r = 0.913, P < .0001) compared with thresholds of 2 SDs (r = 0.81) and 4 SDs (r = 0.91) above the mean and 2 SDs above noise (r = 0.53) (P < .001 for all comparisons). In addition, compared with visual assessment, the 6-SD threshold yielded less intraobserver variability (difference, 0.6 g ± 8, κ = 0.66 [P < .0001] vs 1.4 g ± 9, κ = 0.49 [P < .0001]) and less interobserver variability (difference, 5.4 g ± 18, κ = 0.20 [P < .0001] vs -18.4 g ± 18, κ = 0.08 [P < .0001])., Conclusion: Semiautomated LGE cardiovascular MR gray-scale thresholding with 6 or more SDs above the mean signal intensity for the visually normal remote myocardium yields the closest approximation of the extent of LGE identified with visual assessment and is highly reproducible. This objective method should be considered for quantifying LGE in patients with HCM., (© RSNA, 2010)

Cardiovascular magnetic resonance (CMR) is a high spatial resolution, 3-dimensional tomographic imaging technique which may identify regions of massive left ventricular hypertrophy (particularly when confined to the anterolateral free wall) in which the extent of wall thickness is underestimated with traditional 2-dimensional echocardiography in patients with hypertrophic cardiomyopathy (HC). This observation may have potential implications on management strategies as extreme left ventricular hypertrophy is a primary risk factor for sudden death in HC and therefore supports an expanding role for CMR in the evaluation of HC patients.

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy with substantial heterogeneity in phenotypic expression and clinical course. Traditionally, two-dimensional echocardiography has been the easiest and most reliable technique for establishing a diagnosis of HCM. However, cardiovascular magnetic resonance (CMR) has emerged as a novel, three-dimensional tomographic imaging technique, which provides high spatial and temporal resolution images of the heart in any plane and without ionizing radiation. As a result, CMR is particularly well suited to provide detailed characterization of the HCM phenotype, including precise assessment of the location and distribution of left ventricular (LV) wall thickening. In this regard, CMR can identify hypertrophy (particularly in the anterolateral free wall and apex), not well appreciated (or underestimated) by two-dimensional echocardiography, with important implications for diagnosis. CMR can also provide detailed characterization of other myocardial structures such as the papillary muscles, which may impact on preoperative management strategies for patients who are candidates for surgical myectomy. Furthermore, CMR enables an accurate assessment of total LV mass, a robust marker of the overall extent of hypertrophy, which may have implications for risk stratification. In addition, a subgroup of HCM patients have normal LV mass (with focal hypertrophy), suggesting that a limited extent of hypertrophy is consistent with a diagnosis of HCM. Finally, following the intravenous administration of gadolinium, first-pass perfusion sequences can identify myocardial perfusion abnormalities, while late gadolinium enhancement (LGE) sequences can characterize areas of myocardial fibrosis/scarring. LGE is associated with systolic dysfunction and likelihood for ventricular tachyarrhythmias on ambulatory Holter monitoring in patients with HCM. However, the precise clinical implications of myocardial perfusion abnormalities and LGE in HCM are still uncertain; this information may have important implications with regard to identifying HCM patients at risk of sudden death and adverse LV remodeling associated with systolic dysfunction. Therefore, at present, CMR provides important information impacting on diagnosis and clinical management strategies in patients with HCM and will likely have an expanding role in the evaluation of patients with this complex disease.

Objectives: Our purpose was to characterize the pattern and distribution of left ventricular (LV) hypertrophy by cardiovascular magnetic resonance (CMR) to more precisely define phenotypic expression and its clinical implications in hypertrophic cardiomyopathy (HCM)., Background: Based on prior pathologic and 2-dimensional echocardiographic studies, HCM has been regarded as a disease characterized by substantial LV wall thickening., Methods: Cine and late gadolinium enhancement CMR were performed in 333 consecutive HCM patients (age 43 +/- 17 years)., Results: Basal anterior LV free wall and the contiguous anterior ventricular septum were the most commonly hypertrophied segments (n = 256; 77%). LV hypertrophy was focal (involving < or = 2 segments [< or = 12% of LV]) in 41 patients (12%), intermediate (3 to 7 segments [13% to 49% of LV]) in 112 patients (34%), and diffuse (> or = 8 segments [> or = 50% of LV]) in 180 patients (54%); 42 patients (13%) showed hypertrophied segments separated by regions of normal thickness. The number of hypertrophied segments was greater in patients with LV outflow tract obstruction (> or = 30 mm Hg) than without (10 +/- 4 vs. 8 +/- 4 per patient; p = 0.0001) and was associated with an advanced New York Heart Association functional class (p = 0.007). LV wall thickness was greater in segments with late gadolinium enhancement than without (20 +/- 6 mm vs. 16 +/- 6 mm; p < 0.001). We also identified 40 (12%) of HCM patients with segmental LV hypertrophy largely confined to the anterolateral free wall, posterior septum, or apex, which was underestimated or undetected by echocardiography., Conclusions: Although diverse, patterns of LV hypertrophy are usually not extensive in HCM, involving < or = 50% of the chamber in about one-half the patients, and are particularly limited in extent in an important minority. Contiguous portions of anterior free wall and septum constituted the predominant region of wall thickening, with implications for clinical diagnosis. These observations support an emerging role for CMR in the contemporary evaluation of patients with HCM.

Background: Contrast-enhanced cardiovascular magnetic resonance with delayed enhancement (DE) can provide in vivo assessment of myocardial fibrosis. However, the clinical significance of DE in hypertrophic cardiomyopathy (HCM) remains unresolved., Methods and Results: Cine and cardiovascular magnetic resonance with DE were performed in 202 HCM patients (mean age, 42+/-17 years; 71% male), DE was compared with clinical and demographic variables, and patients were followed up for 681+/-249 days for adverse disease events. DE was identified in 111 (55%) HCM patients, occupying 9%+/-11% of left ventricular myocardial volume, including >25% DE in 10% of patients. The presence of DE was related to occurrence of heart failure symptoms (P=0.05) and left ventricular systolic dysfunction (P=0.001). DE was present in all patients with ejection fraction < or =50% but also in 53% (102/192) of patients with preserved ejection fraction (P<0.001); %DE was both inversely related to (r=-0.3; P<0.001) and an independent predictor of ejection fraction (r=-0.4; P<0.001). DE (7%+/-7% of left ventricle) was present in 54 patients who were asymptomatic (and with normal ejection fraction). Over the follow-up period, the annualized adverse cardiovascular event rate in patients with DE exceeded that in patients without DE but did not achieve statistical significance (5.5% versus 3.3%; P=0.5)., Conclusions: In a large HCM cohort, DE was an independent predictor of systolic dysfunction but with only a modest relationship to heart failure symptoms. These data suggest an important role for myocardial fibrosis in the clinical course of HCM patients but are not sufficient at this time to consider DE as an independent risk factor for adverse prognosis.

Objectives: Our aim was to assess the distribution and clinical significance of left ventricular (LV) mass in patients with hypertrophic cardiomyopathy (HCM)., Background: Hypertrophic cardiomyopathy is defined echocardiographically by unexplained left ventricular wall thickening. Left ventricular mass, quantifiable by modern cardiovascular magnetic resonance techniques, has not been systematically assessed in this disease., Methods: In 264 HCM patients (age 43 +/- 18 years; 75% men), LV mass by cardiovascular magnetic resonance was measured, indexed by body surface area, and compared with that in 606 healthy control subjects., Results: The LV mass index in HCM patients significantly exceeded that of control subjects (104 +/- 40 g/m(2) vs. 61 +/- 10 g/m(2) in men and 89 +/- 33 g/m(2) vs. 47 +/- 7 g/m(2) in women; both p < 0.0001). However, values were within the normal range (< or = mean +2 SDs for control subjects) in 56 patients (21%), and only mildly increased (mean +2 to 3 SDs) in 18 (16%). The LV mass index showed a modest relationship to maximal LV thickness (r(2) = 0.38; p < 0.001), and was greater in men (104 +/- 40 g/m(2) vs. 89 +/- 33 g/m(2) in women; p < 0.001) and in patients with resting outflow obstruction (121 +/- 43 g/m(2) vs. 96 +/- 37 g/m(2) in nonobstructives; p < 0.001). During a 2.6 +/- 0.7-year follow-up, markedly increased LV mass index proved more sensitive in predicting outcome (100%, with 39% specificity), whereas maximal wall thickness >30 mm was more specific (90%, with 41% sensitivity)., Conclusions: In distinction to prior perceptions, LV mass index was normal in about 20% of patients with definite HCM phenotype. Therefore, increased LV mass is not a requirement for establishing the clinical diagnosis of HCM. The LV mass correlated weakly with maximal wall thickness, and proved more sensitive in predicting outcome.

Objectives: Our aim was to determine whether myocardial fibrosis, detected by cardiovascular magnetic resonance (CMR), represents an arrhythmogenic substrate in hypertrophic cardiomyopathy (HCM)., Background: Myocardial fibrosis is identified frequently in HCM; however, the clinical significance of this finding is uncertain., Methods: We studied prevalence and frequency of tachyarrhythmias on 24-h ambulatory Holter electrocardiogram (ECG) with regard to delayed enhancement (DE) on contrast-enhanced CMR in 177 HCM patients (age 41 +/- 16 yrs; 95% asymptomatic or mildly symptomatic)., Results: Premature ventricular contractions (PVCs), couplets, and nonsustained ventricular tachycardia (NSVT) were more common in patients with DE than those without DE (PVCs: 89% vs. 72%; couplets: 40% vs. 17%; NSVT: 28% vs. 4%; p < 0.0001 to 0.007). Patients with DE also had greater numbers of PVCs (202 +/- 655 vs. 116 +/- 435), couplets (1.9 +/- 5 vs. 1.2 +/- 10), and NSVT runs (0.4 +/- 0.8 vs. 0.06 +/- 0.4) than non-DE patients (all p < 0.0001); DE was an independent predictor of NSVT (relative risk 7.3, 95% confidence interval 2.6 to 20.4; p < 0.0001). However, extent (%) of DE was similar in patients with and without PVCs (8.2% vs. 9.1%; p = 0.93), couplets (8.5% vs. 8.4%; p = 0.99), or NSVT (8.3% vs. 8.5%; p = 0.35)., Conclusions: In this large HCM cohort with no or only mild symptoms, myocardial fibrosis detected by CMR was associated with greater likelihood and increased frequency of ventricular tachyarrhythmias (including NSVT) on ambulatory Holter ECG. Therefore, contrast-enhanced CMR identifies HCM patients with increased susceptibility to ventricular tachyarrhythmias.

Background: Myocardial scar burden quantified using late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR), has important prognostic value in hypertrophic cardiomyopathy (HCM). However, nearly 50% of HCM patients have no scar but undergo repeated gadolinium-based CMR over their life span. We sought to develop an artificial intelligence (AI)-based screening model using radiomics and deep learning (DL) features extracted from balanced steady state free precession (bSSFP) cine sequences to identify HCM patients without scar. Methods: We evaluated three AI-based screening models using bSSFP cine image features extracted by radiomics, DL, or combined DL-Radiomics. Images for 759 HCM patients (50 ± 16 years, 66% men) in a multi-center/vendor study were used to develop and test model performance. An external dataset of 100 HCM patients (53 ± 14 years, 70% men) was used to assess model generalizability. Model performance was evaluated using area-under-receiver-operating curve (AUC). Results: The DL-Radiomics model demonstrated higher AUC compared to DL and Radiomics in the internal (0.83 vs 0.77, p = 0.006 and 0.78, p = 0.05; n = 159) and external (0.74 vs 0.64, p = 0.006 and 0.71, p = 0.27; n = 100) datasets. The DL-Radiomics model correctly identified 43% and 28% of patients without scar in the internal and external datasets compared to 42% and 16% by Radiomics model and 42% and 23% by DL model, respectively. Conclusions: A DL-Radiomics AI model using bSSFP cine images outperforms DL or Radiomics models alone as a scar screening tool prior to gadolinium administration. Despite its potential, the clinical utility of the model remains limited and further investigation is needed to improve the accuracy and generalizability. [ABSTRACT FROM AUTHOR]

[Figure: see text]. [ABSTRACT FROM AUTHOR]

Background--The 2 most commonly affected genes in hypertrophic cardiomyopathy (HCM) are MYH7 (β-myosin heavy chain) and MYBPC3 (β-myosin-binding protein C). Phenotypic differences between patients with mutations in these 2 genes have been inconsistent. Scarce data exist on the genotype-phenotype association as assessed by tomographic imaging using cardiac magnetic resonance imaging. Methods and Results--Cardiac magnetic resonance imaging was performed on 358 consecutive genotyped hypertrophic cardiomyopathy probands at 5 tertiary hypertrophic cardiomyopathy centers. Genetic testing revealed a pathogenic mutation in 159 patients (44.4%). The most common genes identified were MYH7 (n=53) and MYBPC3 (n=75); 33.1% and 47% of genopositive patients, respectively. Phenotypic characteristics by cardiac magnetic resonance imaging of these 2 groups were similar, including left ventricular volumes, mass, maximal wall thickness, morphology, left atrial volume, and mitral valve leaflet lengths (all P=non-significant). The presence of late gadolinium enhancement (65% versus 64%; P=0.99) and the proportion of total left ventricular mass (%late gadolinium enhancement; 10.4±13.2% versus 8.5±8.5%; P=0.44) were also similar. Conclusions--This multicenter multinational study shows lack of phenotypic differences between MYH7- and MYBPC3- associated hypertrophic cardiomyopathy when assessed by cardiac magnetic resonance imaging. Postmutational mechanisms appear more relevant to thick-filament disease expression and outcome than the disease-causing variant per se. [ABSTRACT FROM AUTHOR]

The almost 50-year odyssey of cardiac imaging in hypertrophic cardiomyopathy (HCM), revisited and described here, has been remarkable, particularly when viewed in the timeline of advances that occurred during a single generation of investigators. At each step along the way, from M-mode to 2-dimensional echocardiography to Doppler imaging, and finally over the last 10 years with the emergence of high-resolution tomographic cardiac magnetic resonance (CMR), evolution of the images generated by each new technology constituted a paradigm change over what was previously available. Together, these advances have transformed the noninvasive diagnosis and management of HCM in a number of important clinical respects. These changes include a more complete definition of the phenotype, resulting in more reliable clinical identification of patients and family members, defining mechanisms (and magnitude) of left ventricular outflow obstruction, and novel myocardial tissue characterization (including in vivo detection of fibrosis/scarring); notably, these advances afford more precise recognition of at-risk patients who are potential candidates for life-saving primary prevention defibrillator therapy. This evolution in imaging as applied to HCM has indelibly changed cardiovascular practice for this morphologically and clinically complex genetic disease. [ABSTRACT FROM AUTHOR]

The article presents case studies related to Hypertrophic Cardiomyopathy. It presenst the case of a 62-year-old male patient, whose electrocardiogram (ECG) and Transthoracic echocardiography showed apical hypertrophy, and discusses the case of a 63-year-old male patient, who was administered to the emergency department (ED) after getting acute chest pain. It mentions case of a 60-year-old female who was suffering from palpitation, and dyspnea, and underwent intracardiac defibrillator (ICD).

In hypertrophic cardiomyopathy (HCM), heterogeneous myocardial hypertrophy and fibrosis are responsible for abnormalities of left ventricular (LV) function. We aimed to characterize LV global and regional myocardial mechanics in HCM, according to segmental hypertrophy and fibrosis.Fifty-nine patients with HCM underwent standard echocardiography, 3-dimensional speckle tracking echocardiography, and cardiac magnetic resonance with late gadolinium enhancement (LGE); all 3 tests were <24 hours apart. Longitudinal, circumferential, and area strains were investigated according to the extent of LGE (no LGE, LGE<10%, and LGE≥10%), segmental thickness (≥15 versus <15 mm), and segmental LGE (LGE versus non-LGE). Attenuated global longitudinal strain showed association with extent of hypertrophy (indexed LV mass, r=0.32, P=0.01; maximum LV wall thickness, r=0.34, P=0.009; number of segments ≥15 mm, r=0.44, P<0.001), whereas enhanced global circumferential strain was correlated to LV global functional parameters (indexed end-systolic volume, r=0.47, P<0.001; ejection fraction, r=-0.75, P<0.001). Parameters of global myocardial mechanics showed no association with the extent of LGE; in contrast, the extent of LGE was associated with the extent of hypertrophy. All 3 deformation parameters were attenuated both in segments ≥15 mm in thickness and in those with LGE; adjusted analysis demonstrated that segmental presence of LGE was associated with additional attenuation in myocardial deformation.Both hypertrophy and fibrosis contribute to regional impairment of myocardial shortening in HCM. The extent of hypertrophy is the primary factor altering global myocardial mechanics. Circumferential myocardial shortening seems to be directly involved in preservation of LV systolic performance in HCM. [ABSTRACT FROM AUTHOR]

Hypertrophic cardiomyopathy (HCM) is a heterogeneous albeit treatable cardiac disease of variable severity, with the potential for heart failure, atrial fibrillation and arrhythmic sudden death, characterized by otherwise unexplained left ventricular (LV) hypertrophy and affecting all ages and races. Over the last 30 years, several studies have estimated the prevalence of HCM in the general population, employing echocardiography and cardiac magnetic resonance imaging (CMR), as well electronic health records and billing databases for clinical diagnosis. The estimated prevalence in the general population based on the disease phenotype of LV hypertrophy by imaging is 1:500 (0.2%). This prevalence was initially proposed in 1995 in the population-based CARDIA study employing echocardiography, and more recently confirmed by automated CMR analysis in the large UK Biobank cohort. The 1:500 prevalence appears most relevant to clinical assessment and management of HCM. These available data suggest that HCM is not a rare condition but likely underdiagnosed clinically and by extrapolation potentially affects about 700,000 Americans and possibly 15 million people worldwide. Central Illustration. Spectrum of reported population prevalence estimates for HCM. The predominant and most clinically relevant (1:500) is based on the disease phenotype and documented by both echocardiography and CMR. EHR = electronic health records; MRI = magnetic resonance imaging. [Display omitted] • The estimated prevalence of HCM based on the disease phenotype by imaging is 1:500. • HCM prevalence is relevant to clinical practice, funding and public awareness. • HCM is not rare but clinically underdiagnosed by a factor of almost 3×. [ABSTRACT FROM AUTHOR]

The authors reflect on a study by R. Wassmuth and colleagues on cardiovascular magnetic resonance imaging for bicuspid aortic valve syndrome, published within the issue. Topics discussed include the components of congenital abiscupid aortic valve, such as aortic valve stenosis, ascending aortic dilation and aortic coarctation, the use of cardiovascular magnetic resonance (CMR) as a modality, and factors affecting the role of CMR.

The authors comment on the significance of several cardiovascular imaging techniques in the diagnosis of hypertrophic cardiomyopathy (HCM), a complex and heterogeneous genetic heart disease. Included are previous approaches of HCM diagnosis such as demonstrating a pressure gradient between the left ventricular cavity and aorta. They note that the introduction of echocardiographic imaging ways led the expansion of advanced imaging methods including cardiovascular magnetic resonance (CMR).

Hypertrophic cardiomyopathy (HCM) is an important genetic heart muscle disease for which prevalence in the general population has not been completely resolved. For the past 20 years, most data have supported the occurrence of HCM at about 1 in 500. However, the authors have interrogated a number of relevant advances in cardiovascular medicine, including widespread fee-for-service genetic testing, population genetic studies, and contemporary diagnostic imaging, as well as a greater index of suspicion and recognition for both the clinically expressed disease and the gene-positive–phenotype-negative subset (at risk for developing the disease). Accounting for the potential impact of these initiatives on disease occurrence, the authors have revisited the prevalence of HCM in the general population. They suggest that HCM is more common than previously estimated, which may enhance its recognition in the practicing cardiovascular community, allowing more timely diagnosis and the implementation of appropriate treatment options for many patients. [ABSTRACT FROM AUTHOR]

In hypertrophic cardiomyopathy (HC), atrial fibrillation (AF) is an important determinant of clinical deterioration due to heart failure or embolic stroke. This study characterizes left atrial (LA) structural and functional parameters to establish markers predictive of AF risk, using cardiovascular magnetic resonance (CMR) imaging. We studied 427 consecutive patients with HC in sinus rhythm with CMR (age 44 ± 18 years), including 41 who developed clinically overt AF after study entry (2.6 ± 2.1 years), 49 patients with AF before CMR, 337 patients with HC but without AF, and 244 normal controls. LA chamber was assessed for absolute and indexed end-diastolic volume (LAEDV), end-systolic volume, and percent ejection fraction (LAEF). In the 41 prospectively studied patients with HC who developed AF during follow-up, LAEDV was significantly greater than in patients without AF (146 ± 48 vs 107 ± 37 ml) or in normal controls (81 ± 24 ml, p <0.001). Percent LAEF was lower in patients developing AF (36 ± 10%) than without AF (46 ± 12%) or controls (55 ± 9%, p <0.001). Multivariate analysis identified LAEF (<38%), LAEDV (≥118 ml), and age (≥40 years) as independently associated with AF occurrence. In conclusion, CMR measures of LA remodeling and dysfunction reliably identified patients with HC at risk for future development of AF. Decrease in LAEF represents a strong novel marker of susceptibility to AF in this disease. [ABSTRACT FROM AUTHOR]

The article focuses on hypertrophic cardiomyopathy (HCM), the most common cause of sudden death among young athletes. Topics discussed include the effectiveness of a risk stratification algorithm in identifying people who are at highest risk to develop HCM, the health effects of engaging in intense competitive sports, and the use of cardiovascular magnetic resonance (CMR) imaging.

Objectives: This study sought to assess the impact of body mass index (BMI) on cardiac phenotypic and clinical course in a multicenter hypertrophic cardiomyopathy (HCM) cohort. Background: It is unresolved whether clinical variables promoting left ventricular (LV) hypertrophy in the general population, such as obesity, may influence cardiac phenotypic and clinical course in patients with HCM. Methods: In 275 adult HCM patients (age 48 ± 14 years; 70% male), we assessed the relation of BMI to LV mass, determined by cardiovascular magnetic resonance (CMR) and heart failure progression. Results: At multivariate analysis, BMI proved independently associated with the magnitude of hypertrophy: pre-obese and obese HCM patients (BMI 25 to 30 kg/m2 and >30 kg/m2, respectively) showed a 65% and 310% increased likelihood of an LV mass in the highest quartile (>120 g/m2), compared with normal weight patients (BMI <25 kg/m2; hazard ratio [HR]: 1.65; 95% confidence interval [CI]: 0.73 to 3.74, p = 0.22 and 3.1; 95% CI: 1.42 to 6.86, p = 0.004, respectively). Other features associated with LV mass >120 g/m2 were LV outflow obstruction (HR: 4.9; 95% CI: 2.4 to 9.8; p < 0.001), systemic hypertension (HR: 2.2; 95% CI: 1.1 to 4.5; p = 0.026), and male sex (HR: 2.1; 95% CI: 0.9 to 4.7; p = 0.083). During a median follow-up of 3.7 years (interquartile range: 2.5 to 5.3), obese patients showed an HR of 3.6 (95% CI: 1.2 to 10.7, p = 0.02) for developing New York Heart Association (NYHA) functional class III to IV symptoms compared to nonobese patients, independent of outflow obstruction. Noticeably, the proportion of patients in NYHA functional class III at the end of follow-up was 13% among obese patients, compared with 6% among those of normal weight (p = 0.03). Conclusions: In HCM patients, extrinsic factors such as obesity are independently associated with increase in LV mass and may dictate progression of heart failure symptoms. [Copyright &y& Elsevier]

The article presents a study on the risk stratification and outcome of hypertrophic cardiomyopathy (HCM) patients ages over or equal to 60. The study employs coronary arteriograms, computed tomographic angiography, and Kaplan-Meier method. Results reveal that HMC patients are at low risk for disease-related mortality/morbidity even with conventional risk factors.

In hypertrophic cardiomyopathy (HCM), the clinical significance attributable to the broad range of left ventricular (LV) systolic function, assessed as the ejection fraction (EF), is incompletely resolved. We evaluated the EF using cardiovascular magnetic resonance (CMR) imaging in a large cohort of patients with HCM with respect to the clinical status and evidence of left ventricular remodeling with late gadolinium enhancement (LGE). CMR imaging was performed in 310 consecutive patients, aged 42 ± 17 years. The EF in patients with HCM was 71 ± 10% (range 28% to 89%), exceeding that of 606 healthy controls without cardiovascular disease (66 ± 5%, p <0.001). LGE reflecting LV remodeling showed an independent, inverse relation to the EF (B-0.69, 95% confidence interval −0.86 to −0.52; p <0.001) and was greatest in patients with an EF <50%, in whom it constituted a median value of 29% of the LV volume (interquartile range 16% to 40%). However, the substantial subgroup with low-normal EF values of 50% to 65% (n = 45; 15% of the whole cohort), who were mostly asymptomatic or mildly symptomatic (37 or 82% with New York Heart Association functional class I to II), showed substantial LGE (median 5% of LV volume, interquartile range 2% to 10%). This overlapped with the subgroup with systolic dysfunction and significantly exceeded that of patients with an EF of 66% to 75% and >75% (median 2% of the LV volume, interquartile range 1.5% to 4%; p <0.01). In conclusion, in a large cohort of patients with HCM, a subset of patients with low-normal EF values (50% to 65%) was identified by contrast-enhanced CMR imaging as having substantial degrees of LGE, suggesting a transition phase, potentially heralding advanced LV remodeling and systolic dysfunction, with implications for clinical surveillance and management. [Copyright &y& Elsevier]

Increased thickness of the left ventricular (LV) wall is the predominant feature of the hypertrophic cardiomyopathy (HC) phenotype. The structural characteristics of the LV papillary muscles (PMs) have received little attention. In this study, cardiovascular magnetic resonance (CMR) was used to characterize PM morphology in a large HC population. Cine and delayed enhancement (DE) CMR images were obtained in 201 patients with HC and 43 control subjects. PM number and mass index were greater in patients with HC compared with controls (2.5 vs 2.1, p <0.001, and 6 ± 2 vs 3 ± 2 g/m2, p <0.001, respectively), including 109 (54%) with PM mass ≥7 g/m2 (≥2 SDs above the mean for controls). Greater LV wall mass index was associated with more substantial PM mass (r = 0.09, p <0.001). Furthermore, 12 patients with HC (19%) had normal LV mass with localized wall thickness but increased PM mass. In patients with HC with LV outflow obstruction at rest, PMs were positioned closer to the ventricular septum (displaced anteriorly: 58% vs 42% for subjects without obstruction, p = 0.02), with more marked hypertrophy (9 ± 5 vs 6 ± 4 g/m2, p <0.001). Preoperative CMR identified 3 patients with accessory, anteriorly displaced PMs judged to contribute to outflow obstruction, which were resected during septal myectomy. DE of the PMs was identified in 13 patients with HC (6%), including 3 with DE confined to PMs. In conclusion, CMR demonstrates LV PMs to be part of the cardiomyopathic process in HC, with increases in number and mass, and not uncommonly associated with remodeling with DE. The identification of accessory PMs may be useful in planning preoperative strategy. [Copyright &y& Elsevier]

The article describes the case of a 19-year-old man with Danon disease without clinically significant skeletal myopathy or mental retardation. He disclosed no significant cardiovascular symptoms and had an active life. Also discussed are the importance of the precise diagnosis of unexplained left ventricular hypertrophy and the presence of glycogen resulting from pseudoglycogenosis.

Introduction: The Hypertrophic Cardiomyopathy Registry (HCMR) is a NHLBI-funded study of 2764 HCM patients recruited from 44 sites worldwide. Baseline clinical evaluation included echo, cardiac magnetic resonance imaging (CMR), and blood drawn for genetic and biomarker analysis. Follow-up is 1.5 years to date. CMR protocol included short axis cines, pre-and post-contrast T1 mapping, and late gadolinium enhancement (LGE). Hypothesis: We hypothesized that demographic factors may relate to extent of LGE (replacement fibrosis) and T1 mapping (interstitial fibrosis). Methods: LGE assessed visually was categorized as none, >0-5, >5-10, >10-15 and >15% of LV mass. LGE relationship to continuous demographic variables was assessed by one-way analysis of variance. The relationship of native T1 (by field strength) and extracellular volume (ECV) with baseline variables were assessed by Pearson correlations, unpaired t-tests, or analysis of variance. Results: Of 2764 patients, 2556 (92%) had valid LGE values and 50% had any LGE. (Table) Only 2% of patients had LGE >15% of LV mass. Age was similar across LGE categories, but BMI declined with greater LGE extent. There were smaller % of whites and blacks with >15% LGE, but a larger % of other races (primarily Asian). With more LGE, a family history of HCM was more likely and hypertension less likely. The greater the LGE extent, the lower the LVEF. 2122 patients (77%) had valid native T1 and 1988 (72%) valid ECV measures. There was no relationship between age, BMI, or race with either T1 or ECV. Females had longer native T1 at 1.5T (p < 0.001), but not at 3T (p = 0.168). Females had higher ECV values (0.32±0.06 vs. 0.30±0.06, p<0.001). Conclusions: Baseline data from HCMR demonstrate that 2% of patients have LGE >15% of LV mass. These patients have more family history of HCM, are less often black or white, have less hypertension, lower BMI, and lower LVEF. These data suggest that extensive LGE, a risk factor for sudden cardiac death, may be more typical of familial, rather than sporadic or secondary disease. Ongoing genetic analysis may shed additional light. Interstitial fibrosis is greater in females with HCM. Longer follow-up is needed to demonstrate whether these baseline findings are associated with adverse cardiovascular outcome. [ABSTRACT FROM AUTHOR]