Significance of magnetic resonance imaging in apical hypertrophic cardiomyopathy

Ethnic and sex-related differences at presentation in apical hypertrophic cardiomyopathy: An observational cross-sectional study

BACKGROUND

We investigated whether ethnicity and sex are associated with different clinical presentations and cardiovascular magnetic resonance (CMR) findings in individuals with apical hypertrophic cardiomyopathy (ApHCM).

METHODS

A retrospective observational cohort study of consecutive ApHCM patients from a large tertiary referral center in the United Kingdom (UK). Demographic, clinical, 12‑lead electrocardiogram (ECG) and CMR findings were collected. Participants presented in our clinics between 2010 and 2020. 'Pure' ApHCM was defined as isolated apical hypertrophy and 'mixed' with both apical and septal hypertrophy but with the apical segments of a greater wall thickness. Deep T-wave inversion was defined as ≥5 mm in any electrocardiogram lead.

RESULTS

A total of 150 consecutive ApHCM patients (75% men, 25% women; 37% White, 25% Black, 24% Asian and 15% of Mixed/Other ethnicity) were included. Females were diagnosed at an older age compared to men, had less prominent ECG changes, had higher left atrial area index, and were more hypertensive. Black patients had higher left ventricular mass index, more hypertension, and more of the 'mixed' type of ApHCM. The majority of hypertensive male patients showed the 'mixed' phenotype.

CONCLUSIONS

Individuals of Black ethnicity and hypertensive male patients are more likely to present with mixed apical and basal hypertrophy, whereas White, Asian and non-hypertensive male patients tend to have hypertrophy limited to the apex. Females present at an older age and are less likely to have deep T wave inversion on ECG.

Myocardial deformation analysis using cardiac magnetic resonance in apical hypertrophic cardiomyopathy: is it an useful tool to predict adverse outcomes?

Apical hypertrophic cardiomyopathy (AHCM) has a broad phenotypic spectrum and still poses many diagnostic and prognostic challenges. Our team performed a retrospective study to examine the prognostic value of myocardial deformation obtained with cardiac magnetic resonance tissue tracking (CMR-TT) analysis in predicting adverse events in AHCM patients. We included patients with AHCM referred to CMR in our department from August 2009 to October 2021. CMR-TT analysis was performed to characterize the myocardial deformation pattern. Clinical, other complementary diagnostic exams characteristics and follow-up data were analysed. Primary endpoint was the composite of all-cause hospitalizations and mortality. During the 12-year period, 51 AHCM patients were evaluated by CMR, with a median age of 64 years-old and male predominance. 56,9% had an echocardiogram suggestive of AHCM. The most frequent phenotype was "the relative form" (43,1%). CMR evaluation revealed a median maximum left ventricle thickness of 15 mm and the presence of late gadolinium enhancement in 78,4%. Applying CMR-TT analysis, median global longitudinal strain was - 14,4%, with a median global radial strain of 30,4% and global circumferential strain of -18,0%. During a median follow-up of 5,3 years, the primary endpoint occurred in 21,3% of patients, with a hospitalization rate of 17,8% and all-cause mortality rate of 6,4%. After multivariable analysis, longitudinal strain rate in apical segments was an independent predictor of the primary endpoint (p = 0,023), showing that CMR-TT analysis could be useful in predicting adverse events in AHCM patients.

An Unusual Presentation of Apical Hypertrophic Cardiomyopathy in an Orthotopic Heart Transplant Recipient

In this case study, we present the evaluation of an orthotopic heart transplant (OHT) patient who presented with persistent shortness of breath and dizziness upon standing. The investigation uncovered the presence of progressive hypertrophic cardiomyopathy (HCM) in the transplanted heart, a condition first detected 11 years after the transplantation. Utilizing echocardiography with global longitudinal strain (GLS), we determined that the HCM likely originated from genetic predominance inherited from the heart donor rather than hypertensive disease. This finding highlights the significance of genetic factors in post-transplant complications and warrants further investigation into the long-term effects of heart transplantation on recipient health.

Temporal and Global Trends of the Incidence of Sudden Cardiac Death in Hypertrophic Cardiomyopathy

BACKGROUND

Since the initial clinical description of hypertrophic cardiomyopathy (HCM) over 60 years ago, sudden cardiac death (SCD) has been the most visible and feared complication of HCM.

OBJECTIVES

This study sought to characterize the temporal, geographic, and age-related trends of reported SCD rates in adult HCM patients.

METHODS

Electronic databases were systematically searched up to November 2021 for studies reporting on SCD event rates in HCM patients. Patients with SCD equivalents (appropriate implantable cardioverter-defibrillator [ICD] shocks and nonfatal cardiac arrests) were not included. A random-effects model was used to pool study estimates calculating the overall incidence rates (IR) for each time-era, geographic region, and age group. We analyzed 2 periods (before vs after 2000, following clinical implementation of ICD in HCM). Following 2000, 5-year intervals were used to demonstrate the temporal change in SCD rates.

RESULTS

A total of 98 studies (N = 70,510 patients and 431,407 patient-years) met our inclusion criteria. The overall rate of HCM SCD was 0.43%/y (95% CI: 0.37-0.50%/y; I² = 75%; SCD events: 1,938; person-years of follow-up: 408,715), with young patients (<18 years of age) demonstrating a >2-fold-risk for sudden death vs adult patients 18-60 years of age (IR: 1.09%; 95% CI: 0.69%-1.73% vs IR: 0.43%; 95% CI: 0.37%-0.50%) (P value for subgroup differences <0.01). Contemporary SCD rates from 2015 to present were 0.32%/y and significantly lower compared with 2000 or earlier (IR: 0.32%; 95% CI: 0.20%-0.52% vs IR: 0.73%; 95% CI: 0.53%-1.02%, respectively). Reported SCD rates for HCM were lowest in North America (IR: 0.28%; 95% CI: 0.18%-0.43%,) and highest in Asia (IR: 0.67%; 95% CI: 0.54%-0.84%).

CONCLUSIONS

Contemporary HCM-related SCD rates are low (0.32%/y) representing a 2-fold decrease compared with prior treatment eras. Young HCM patients are at the highest risk. The maturation of SCD risk stratification strategies and the application of primary prevention ICD to HCM are likely responsible for the notable decline over time in SCD events. In addition, worldwide geographic disparities in SCD rates were evident, underscoring the need to increase access to SCD prevention treatment for all HCM patients.

Twenty-four hour variability of inverted T-waves in patients with apical hypertrophic cardiomyopathy

Background

Patients with apical hypertrophic cardiomyopathy (ApHCM) have marked inverted T-waves that vary over several years. Inverted T-waves in ApHCM are unstable, but it is unclear whether this change is due to coronary artery disease (CAD) or if it is a characteristic of ApHCM itself. We aimed to study the characteristics of inverted T-waves in patients with ApHCM over the course of 24 h to improve the diagnostic indices of ApHCM.

Methods

We examined 83 patients with ApHCM and 89 patients with CAD (who served as the control group). All patients underwent a 24-h dynamic electrocardiogram (ECG). We analyzed the average depth of inverted T-waves per minute and sorted them from shallow to deep; the sorted ECG segments at the 10^th, 50^th, and 90^th positions of the T-wave were subsequently analyzed.

Results

The amplitudes of inverted T-waves in ApHCM corresponding to the 10^th, 50^th, and 90^th percentiles were −5.13 ± 4.11, −8.10 ± 4.55, and −10.9 ± 5.04 mm, respectively. Changes in the degree of inverted T-waves were greater in ApHCM than in CAD. T-wave amplitudes in ApHCM were strongly associated with heart rate and circadian rhythm and only weakly associated with CAD and posture. Maximum T-wave amplitudes in the CAD group were <10 mm, while 68% of patients with ApHCM had maximum T-wave amplitudes >10 mm, and all patients with ApHCM aged <50 years had maximum T-wave amplitudes >10 mm.

Conclusion

Notable variations in the T-waves of patients with ApHCM were observed over 24 h. ECG examinations during states of inactivity (comparable to sleep) improved the sensitivity of the diagnosis of ApHCM. Inverted T-wave amplitudes correlated with heart rate and circadian rhythm, where T-wave changes in ApHCM may be due to the normalization of abnormal T-waves effect. Identifying T-wave amplitudes >10 mm can effectively improve the diagnostic rate of ApHCM, especially in patients aged <50 years. The short-term change in T-waves in patients with ApHCM could serve as a novel index that will help in the diagnosis of ApHCM.

The Combination of Feature Tracking and Late Gadolinium Enhancement for Identification Between Hypertrophic Cardiomyopathy and Hypertensive Heart Disease

Background

The differentiation between hypertrophic cardiomyopathy (HCM) and hypertensive heart disease (HHD) is challenging due to similar myocardial hypertrophic phenotype. The purpose of this study is to evaluate the feasibility of cardiovascular magnetic resonance feature tracking (CMR-FT) and late gadolinium enhancement (LGE) to distinguish between HCM and HHD and the potential relationship between myocardial strain and cardiac functional parameters.

Methods

One hundred and seventy subjects (57 HCM, 45 HHD, and 68 controls) underwent 3.0 T CMR, including steady-state free precession cines and LGE images. Global and segmental (basal, mid, and apical) analyses of myocardial radial, circumferential, longitudinal strain, and left ventricular (LV) torsion, as well as global and 16 segments of LGE were assessed. The multivariate analysis was used to predict the diagnostic ability by combining comprehensive myocardial strain parameters and LGE.

Results

Global radial strain (GRS), global circumferential strain (GCS), and LV torsion were significantly higher in the HCM group than in the HHD group (GRS, 21.18 ± 7.52 vs. 14.56 ± 7.46%; GCS, −13.34 ± 3.52 vs. −10.11 ± 4.13%; torsion, 1.79 ± 0.69 vs. 1.23 ± 0.65 deg/cm, all P &lt; 0.001). A similar trend was also seen in the corresponding strain rate. As for segmental strain analysis, basal radial strain (BRS), basal circumferential strain (BCS), basal longitudinal strain (BLS), mid-radial strain (MRS), and mid-circumferential strain (MCS) were higher in the HCM group than in the HHD group (all P &lt; 0.001). The receiver operating characteristic (ROC) results showed that the area under the curve (AUC) of LGE in the mid-interventricular septum (mIVS) was the highest among global and segmental LGE analyses. On the multivariate regression analysis, a combined model of LGE (mIVS) with GRS obtained the highest AUC value, which was 0.835 with 88.89% sensitivity and 70.18% specificity, respectively. In addition, for patients with HCM, GRS, GCS, and global longitudinal strain had correlations with LV ejection fraction (LVEF), maximum interventricular septum thickness (IVST max), and left ventricular mass index (LVMi). Torsion was mildly associated with LVEF.

Conclusion

CMR-FT-derived myocardial strain and torsion provided valuable methods for evaluation of HCM and HHD. In addition, the combination of GRS and LGE (mIVS) achieved the highest diagnostic value.

Cardiac Involvement in Human Immunodeficiency Virus Infected Patients: An Observational Cardiac Magnetic Resonance Study

Objectives: To investigate the subclinical imaging changes in terms of myocardial inflammation and fibrosis and to explore the risk factors associated with myocardial fibrosis by cardiac magnetic resonance (CMR) approach in a Chinese HIV/AIDS cohort.

Methods: We evaluated myocardial function (cine), myocardial inflammation (T1, T2), and myocardial fibrosis (through extracellular volume fraction [ECV] and late gadolinium enhancement [LGE]) by a multiparametric CMR scan protocol in a total of 68 participants, including 47 HIV-infected individuals, who were divided into two groups: asymptomatic HIV (HIV+) (n = 30), and acquired immunodeficiency syndrome (AIDS) (n = 17), and 21 healthy controls.

Results: HIV-infected patients had lower left (55.3 ± 6.5 vs. 63.0 ± 7.9%, P < 0.001) and right ventricular systolic function (35.9 ± 15.7 vs. 50.8 ± 9.3%, P < 0.001). Radial systolic strain (30.7 ± 9.3 vs. 39.3 ± 9.4%, P = 0.001), circumferential systolic strain (−17.5 ± 2.6 vs. −19.4 ± 2.7%, P = 0.008), and longitudinal systolic strain (−9.4 ± 5.7 vs. −12.8 ± 3.1%, P = 0.012) were also decreased in HIV. Native T1 relaxation time (1,337.2 ± 70.2 vs. 1,249.5 ± 47.0 ms, P < 0.001), ECV value (33.5 ± 6.2 vs. 28.5 ± 2.9 ms, P = 0.026), and T2 relaxation time (45.2 ± 3.5 vs. 42.0 ± 2.6 ms, P = 0.001) were higher in HIV-infected patients compared with controls. Myocardial fibrosis, predominantly in the mid-inferior wall, was detected in 24.4% of the HIV-infected patients. HIV+ had a significantly lower value of ECV [29.1 (26.1, 31.8) vs. 35.2 (31.8, 41.9) %, P < 0.001] and frequency of LGE [3/25 (8%) vs. 7/16 (43.8%), P = 0.014)] compared with AIDS. AIDS was associated with myocardial fibrosis.

Conclusions: HIV-infected patients were associated with changes in myocardial function and higher rates of subclinical myocardial inflammation and fibrosis, which were more abnormal with greater severity of the disease. AIDS was associated with myocardial fibrosis, where the observations supported earlier initiation of antiretroviral therapy in the Chinese HIV/AIDS cohort.

Clinical, echocardiographic and cardiac MRI predictors of outcomes in patients with apical hypertrophic cardiomyopathy

Recent studies have found that some adverse cardiovascular events could also occur in patients with apical hypertrophic cardiomyopathy (ApHCM), which is different with previous studies suggesting benign nature of this condition. Therefore, the present study aimed to observe the clinical prognosis of ApHCM and to identify the predictors of poor prognosis in clinical, echocardiography and cardiac magnetic resonance (CMR). A total of 126 ApHCM patients with both echocardiography and CMR were identified retrospectively from January 2008 to December 2018. Adverse clinical events were defined as a composite of cardiac death, progressive heart failure, myocardial infarction, thromboembolic stroke, appropriate implantable cardioverter-defibrillator (ICD) interventions for ventricular tachycardia or ventricular fibrillation, and new-onset atrial fibrillation (AF). During a mean follow-up of 96.8 ± 36.0 months, clinical events were observed in 34 (27.0%) patients. As compared with patients without clinical events, patients with clinical events were older and had a higher incidence of heart failure. Moreover, patients with clinical events had a higher incidence of non-sustained ventricular tachycardia (NSVT) and had larger left atrial volume index (LAVI), thicker apical thickness, lower peak systolic mitral annular velocity (S') than those without clinical events. In addition, late gadolinium enhancement (LGE) in CMR were more frequently observed in patients with clinical events. Five predictors of poor prognosis were identified: age ≥ 55 years, LAVI ≥ 36.7 ml/m², S' ≤ 6.7 cm/s, NSVT and LGE. ApHCM was not as benign as expected. Age ≥ 55 years, LAVI ≥ 36.7 ml/m², S' ≤ 6.7 cm/s along with NSVT and LGE were independent predictors for poor prognosis of ApHCM.

MRI Characteristics, Prevalence, and Outcomes of Hypertrophic Cardiomyopathy with Restrictive Phenotype

Purpose

To investigate the MRI characteristics, prevalence, and outcomes of hypertrophic cardiomyopathy (HCM) with restrictive phenotype.

Materials and Methods

A total of 2592 consecutive patients with HCM were evaluated to identify individuals who fulfilled the diagnostic criteria of restrictive phenotype. Thirty-four patients with HCM (mean age, 41 years ± 16 [standard deviation]; range, 21-62 years, 16 men) with restrictive phenotype were retrospectively identified. Thirty-four patients with HCM with the same age and sex distributions were randomly selected as a control group. Kaplan-Meier survival curves were compared using log-rank statistics for survival analysis.

Results

The anteroposterior diameters of the left and right atria were 55 mm ± 5 and 61 mm ± 9, respectively, which were larger than those of the control group (P < .001). The maximum wall thickness in the restrictive group was lower than that in the control group (16 mm ± 2 vs 19 mm ± 3, P < .001). No significant difference was found in late gadolinium enhancement fraction between the restricted phenotype and the control group (15% ± 8 vs 13% ± 7, P = .376). The 5-year event-free survival from any cause of death and cardiac transplantation was 81% in the restrictive group, compared with 94% in the control group (log-rank P = .018).

Conclusion

Restrictive phenotype is a rare subtype of HCM and is associated with severe clinical symptoms and poor prognosis. The MRI features of this phenotype include mild to moderate left ventricular hypertrophy, markedly enlarged atria, moderate myocardial fibrosis, and pericardial effusion.© RSNA, 2020.

Syncope in the Young Adult and in the Athlete: Causes and Clinical Work-up to Exclude a Life-Threatening Cardiac Disease

Syncope is defined as a transient loss of consciousness due to cerebral hypoperfusion, characterized by a rapid onset, short duration, and spontaneous complete recovery. It is usually a benign event, but sometimes it may represent the initial presentation of several cardiac disorders associated with sudden cardiac death during physical activity. A careful evaluation is essential particularly in young adults and in competitive athletes in order to exclude the presence of an underlying life-threatening cardiovascular disease. The present review analyzes the main non-cardiac and cardiac causes of syncope and the contribution of the available tools for differential diagnosis. Clinical work-up of the athlete with syncope occurring in extreme environments and management in terms of sports eligibility and disqualification are also discussed.

MRI T1 Mapping in Hypertrophic Cardiomyopathy: Evaluation in Patients Without Late Gadolinium Enhancement and Hemodynamic Obstruction

Background The value of native myocardial T1 mapping and extracellular volume (ECV) fraction in patients who have hypertrophic cardiomyopathy (HCM) but no late gadolinium enhancement (LGE) and no hemodynamic obstruction are currently unknown. Purpose To evaluate myocardial fibrosis in patients with nonobstructive HCM and no LGE by using native myocardial T1 mapping and ECV fraction and to study their relationships to left ventricular (LV) function and LV hypertrophy. Materials and Methods Patients with HCM who underwent cardiac MRI between 2012 and 2015 were retrospectively evaluated. Patients were included if they had no LGE at MRI, LV ejection fraction greater than or equal to 45%, and no LV outflow tract obstruction. Healthy participants had similar age and sex distribution. Native myocardial T1 and ECV were measured with MRI. Results A total of 258 patients with HCM (mean age ± standard deviation, 49 years ± 15; 74% men) and 122 healthy participants (mean age, 50 years ± 14; 76% men) were evaluated. Native myocardial T1 was longer and ECV fraction was higher in the patients with HCM relative to the healthy participants (mean native T1, 950 msec ± 48 vs 913 msec ± 46; mean ECV, 24.5% ± 2.8 vs 23.0% ± 2.7; both P < .001). Maximum T1 and ECV values correlated strongly with LV mass index for the entire patient cohort with HCM (both r = 0.86; P < .001) and for the subgroups (r = 0.86 and 0.85 for interventricular septal group and r = 0.88 and 0.86 for apical group; all P < .001). Conclusion Prolonged myocardial T1 and elevated extracellular volume in hypertrophic cardiomyopathy suggests diffuse myocardial fibrosis, even in the absence of regionally apparent late gadolinium enhancement and hemodynamic obstruction, and is associated with left ventricular hypertrophy. © RSNA, 2019 See also the editorial by Bluemke and Lima in this issue.

Evaluation of Hypertrophic Cardiomyopathy: Newer Echo and MRI Approaches

PURPOSE OF REVIEW

This review discusses the basic and evolving echocardiographic and cardiac magnetic resonance (CMR) approaches in the diagnosis and management of patients with hypertrophic cardiomyopathy (HCM).

RECENT FINDINGS

Newer imaging technologies and techniques in both echocardiography and CMR have proved to add incremental value to our understanding of HCM. 3D reconstruction in echocardiography and CMR allows for more accurate morphological and volumetric assessment of the left ventricle. Echocardiographic and CMR-based left atrial assessment, including for its mechanical properties, has been shown to be correlated to outcomes and development of atrial fibrillation. Tissue characterization and scar burden quantification by late gadolinium enhancement on CMR has revolutionized our understanding of fibrotic processes in HCM and their contribution to disease severity and clinical outcomes. Cardiac imaging plays a crucial role in HCM patients. Using echocardiography and CMR as complementary modalities allows for improved diagnostics, optimization of treatment, and better prognostication.

Lack of Phenotypic Differences by Cardiovascular Magnetic Resonance Imaging in MYH7 (β-Myosin Heavy Chain)- Versus MYBPC3 (Myosin-Binding Protein C)-Related Hypertrophic Cardiomyopathy

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.

The role of imaging in the diagnosis and management of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiomyopathy, affecting approximately 1:500 people. As the yield of genetic testing is only about 35-60%, the diagnosis of HCM is still clinical and based on the demonstration of unexplained and usually asymmetric left ventricular (LV) hypertrophy by imaging modalities. In the past, echocardiography was the sole imaging modality used for the diagnosis and management of HCM. However, in recent years other imaging modalities such as cardiac magnetic resonance have played a major role in the diagnosis, management and risk stratification of HCM, particularly when the location of left ventricular hypertrophy is atypical (apex, lateral wall) and when the echocardiographic imaging is sub-optimal. However, the most unique contribution of cardiac magnetic resonance is the quantification of myocardial fibrosis. Exercise stress echocardiography is the preferred provocative test for the assessment of LV outflow tract obstruction, which is detected only on provocation in one-third of the patients.

Diagnosis of apical hypertrophic cardiomyopathy: T-wave inversion and relative but not absolute apical left ventricular hypertrophy

BACKGROUND

Diagnosis of apical HCM utilizes conventional wall thickness criteria. The normal left ventricular wall thins towards the apex such that normal values are lower in the apical versus the basal segments. The impact of this on the diagnosis of apical hypertrophic cardiomyopathy has not been evaluated.

METHODS

We performed a retrospective review of 2662 consecutive CMR referrals, of which 75 patients were identified in whom there was abnormal T-wave inversion on ECG and a clinical suspicion of hypertrophic cardiomyopathy. These were retrospectively analyzed for imaging features consistent with cardiomyopathy, specifically: relative apical hypertrophy, left atrial dilatation, scar, apical cavity obliteration or apical aneurysm. For comparison, the same evaluation was performed in 60 healthy volunteers and 50 hypertensive patients.

RESULTS

Of the 75 patients, 48 met conventional HCM diagnostic criteria and went on to act as another comparator group. Twenty-seven did not meet criteria for HCM and of these 5 had no relative apical hypertrophy and were not analyzed further. The remaining 22 patients had relative apical thickening with an apical:basal wall thickness ratio >1 and a higher prevalence of features consistent with a cardiomyopathy than in the control groups with 54% having 2 or more of the 4 features. No individual in the healthy volunteer group had more than one feature and no hypertension patient had more than 2.

CONCLUSION

A cohort of individuals exist with T wave inversion, relative apical hypertrophy and additional imaging features of HCM suggesting an apical HCM phenotype not captured by existing diagnostic criteria.

Multimodality imaging in apical hypertrophic cardiomyopathy

Apical hypertrophic cardiomyopathy (AHCM) is a relatively rare morphologic variant of HCM in which the hypertrophy of myocardium is localized to the left ventricular apex. Symptoms of AHCM might vary from none to others mimic coronary artery disease including acute coronary syndrome, thus resulting in inappropriate hospitalization. Transthoracic echocardiography is the first-line imaging technique for the diagnosis of hypertrophic cardiomyopathies. However, when the hypertrophy of the myocardium is localized in the ventricular apex might results in missed diagnosis. Aim of this paper is to review the different imaging techniques used for the diagnosis of AHCM and their role in the detection and comprehension of this uncommon disease.

Evaluation of apical subtype of hypertrophic cardiomyopathy using cardiac magnetic resonance imaging with gadolinium enhancement

Apical hypertrophic cardiomyopathy (HC) is an uncommon variant of HC. We sought to characterize cardiac magnetic resonance imaging (MRI) findings among apical HC patients. This was a retrospective review of consecutive patients with a diagnosis of apical HC who underwent cardiac MRI examinations at the Mayo Clinic (Rochester, MN) from August 1999 to October 2011. Clinical and demographic data at the time of cardiac MRI study were abstracted. Cardiac MRI study and 2-dimensional echocardiograms performed within 6 months of the cardiac MRI were reviewed; 96 patients with apical HC underwent cardiac MRI examinations. LV end-diastolic and end-systolic volumes were 130.7 ± 39.1 ml and 44.2 ± 20.9 ml, respectively. Maximum LV thickness was 19 ± 5 mm. Hypertrophy extended beyond the apex into other segments in 57 (59.4%) patients. Obstructive physiology was seen in 12 (12.5%) and was more common in the mixed apical phenotype than the pure apical (19.3 vs 2.6%, p = 0.02). Apical pouches were noted in 39 (40.6%) patients. Late gadolinium enhancement (LGE) was present in 70 (74.5%) patients. LGE was associated with severe symptoms and increased maximal LV wall thickness. In conclusion, cardiac MRI is well suited for studying the apical form of HC because of difficulty imaging the cardiac apex with standard echocardiography. Cardiac MRI is uniquely suited to delineate the presence or absence of an apical pouch and abnormal myocardial LGE that may have implications in the natural history of apical HM. In particular, the presence of abnormal LGE is associated with clinical symptoms and increased wall thickness.

Functional, morphological and electrocardiographical abnormalities in patients with apical hypertrophic cardiomyopathy and apical aneurysm: correlation with cardiac MR

Objective

The prognosis of apical hypertrophic cardiomyopathy (APH) has been benign, but apical myocardial injury has prognostic importance. We studied functional, morphological and electrocardiographical abnormalities in patients with APH and with apical aneurysm and sought to find parameters that relate to apical myocardial injury.

Methods

Study design: a multicentre trans-sectional study. Patients: 45 patients with APH and 5 with apical aneurysm diagnosed with transthoracic echocardiography (TTE) in the database of Hamamatsu Circulation Forum. Measure: the apical contraction with cine-cardiac MR (CMR), the myocardial fibrotic scar with late gadolinium enhancement (LGE)-CMR, and QRS fragmentation (fQRS) defined when two ECG-leads exhibited RSR’s patterns.

Results

Cine-CMR revealed 27 patients with normal, 12 with hypokinetic and 11 with dyskinetic apical contraction. TTE misdiagnosed 11 (48%) patients with hypokinetic and dyskinetic contraction as those with normal contraction. Apical LGE was apparent in 10 (83%) and 11 (100%) patients with hypokinetic and dyskinetic contraction, whereas only in 11 patients (41%) with normal contraction (p<0.01). Patients with dyskinetic apical contraction had the lowest left ventricular ejection fraction, the highest prevalence of ventricular tachycardia, and the smallest ST depression and depth of negative T waves. The presence of fQRS was associated with impaired apical contraction and apical LGE (OR=8.32 and 8.61, p<0.05).

Conclusions

CMR is superior to TTE for analysing abnormalities of the apex in patients with APH and with apical aneurysm. The presence of fQRS can be a promising parameter for the early detection of apical myocardial injury.

Distribution of late gadolinium enhancement in various types of cardiomyopathies: Significance in differential diagnosis, clinical features and prognosis

The recent development of cardiac magnetic resonance (CMR) techniques has allowed detailed analyses of cardiac function and tissue characterization with high spatial resolution. We review characteristic CMR features in ischemic and non-ischemic cardiomyopathies (ICM and NICM), especially in terms of the location and distribution of late gadolinium enhancement (LGE). CMR in ICM shows segmental wall motion abnormalities or wall thinning in a particular coronary arterial territory, and the subendocardial or transmural LGE. LGE in NICM generally does not correspond to any particular coronary artery distribution and is located mostly in the mid-wall to subepicardial layer. The analysis of LGE distribution is valuable to differentiate NICM with diffusely impaired systolic function, including dilated cardiomyopathy, end-stage hypertrophic cardiomyopathy (HCM), cardiac sarcoidosis, and myocarditis, and those with diffuse left ventricular (LV) hypertrophy including HCM, cardiac amyloidosis and Anderson-Fabry disease. A transient low signal intensity LGE in regions of severe LV dysfunction is a particular feature of stress cardiomyopathy. In arrhythmogenic right ventricular cardiomyopathy/dysplasia, an enhancement of right ventricular (RV) wall with functional and morphological changes of RV becomes apparent. Finally, the analyses of LGE distribution have potentials to predict cardiac outcomes and response to treatments.

Clinical implications of T-wave inversion in an asymptomatic population undergoing annual medical screening (from the Korean Air Forces Electrocardiogram Screening)

This study aimed to determine prevalence, differentiate underlying causes, and identify the benign group in subjects with asymptomatic T-wave inversion (TWI). We retrospectively read 12-lead electrocardiograms from 3,929 consecutive asymptomatic men in the air force (3,929 participants, mean age 39.3 ± 8.7 years) who underwent medical screening at the Aerospace Medical Center, Korea, from September 2010 to August 2012. TWIs other than in right precordial leads (V1 and V2) were present in 23 men (0.6%). All subjects with persistent TWI for 1 year (n = 18) underwent additional study, with the exception of 1 patient who refused further evaluation. Of 17 subjects with investigated persistent TWI, 8 (47.1%) had an apically displaced papillary muscle, 5 (29.4%) exhibited idiopathic TWI, 3 (17.6%) had apical hypertrophic cardiomyopathy, and 1 (5.9%) had Maron type 2 hypertrophic cardiomyopathy with dynamic left ventricular outflow obstruction. The depth of TWI was significantly shallow in the benign group (idiopathic TWI, 1.6 ± 0.5 mm) compared with potentially nonbenign group (the others; 5.5 ± 3.3 mm, p = 0.021). Lateral lead TWI was significantly correlated with potentially nonbenign group (46% vs 0%, p = 0.049). In conclusion, asymptomatic TWI is not rare (0.6%), even in a healthy population such as Korean Air Force society, and at least 29.4% of subjects with TWI are considered to belong to the benign group that does not require aggressive evaluation and criteria of TWI ≤2 mm other than lateral leads without co-morbidity could help to distinguish the benign group from the potentially nonbenign group.

Delay enhancement patterns in apical hypertrophic cardiomyopathy by phase-sensitive inversion recovery sequence

OBJECTIVE

Late gadolinium enhancement (LGE) patterns of cardiovascular magnetic resonance (CMR) relying on PSIR (phase-sensitive inversion recovery sequence) techniques had been used to determine the characteristics of LGE in apical hypertrophic cardiomyopathy (ApHCM).

METHODS

Forty patients pure ApHCM [age, (60.2±10.4) years, 31 men] were enrolled. LGE images were acquired using PSIR, and analyzed using a 17-segment model. Summing the LGE areas in all short axis slices yielded the total volume of late enhancement, which was subsequently presented as a proportion of total LV myocardium (% LGE).

RESULTS

Mean maximal apical wall thickness was (17.9±2.3) mm, and mean left ventricular (LV) ejection fraction was (67.7±8.0)%. LGE was detected in 130 segments of 30 patients (75.0%), occupying (4.9±5.5)% of LV myocardium. LGE was mainly detected at the junction between left and right ventricles in 12 (30%) and at the apex in 28 (70%), although LGE-positive areas were widely distributed, and not limited to the apex. Focal LGE at the non-hypertrophic LV segments was found in some ApHCM patients, even without LGE of hypertrophied apical segments.

CONCLUSIONS

LGE was frequently observed not only in the thickened apex of the heart but also in other LV segments, irrespective of the presence or absence of hypertrophy. The simple presence of LGE on CMR was not representative of adverse prognosis in this population.

Pseudonormalization of negative T wave during stress test in asymptomatic patients without ischemic heart disease: a clue to apical hypertrophic cardiomyopathy?

INTRODUCTION

Generally, apical hypertrophic cardiomyopathy (ApHCM) shows a negative T wave on an electrocardiogram (ECG), which waxes and wanes during the clinical course. However, some patients with ApHCM just have negative T waves and show no obvious diagnostic evidence on their echocardiography, so the diagnosis of ApHCM cannot be confirmed or is delayed for several years in many cases.

CASE REPORT

In our study, 2 males in their 50s showed negative T waves on their ECG precordial leads, but no diagnosis was confirmed for over 10 years, despite all efforts. Both patients showed pseudonormalization of the negative T wave during a stress test using a treadmill and dobutamine. They were finally diagnosed with ApHCM confirmed by cardiac magnetic resonance (MR).

DISCUSSION

Pseudonormalization of the negative T wave during a stress test is a quite rare phenomenon, particularly in the general population, and cardiac MR is very costly and inaccessible. Thus, when such an ECG pattern is observed without evidence of other pathology, the possibility of ApHCM should be kept in mind and the performance of cardiac MR may be considered. Furthermore, this pseudonormalization pattern could also be one possible explanation for the waxing and waning of the negative T wave during the course of ApHCM.

Contrast-enhanced cardiac magnetic resonance imaging

Cardiac magnetic resonance (CMR) imaging has significantly evolved in the past decade and is well established in the evaluation of coronary artery disease (CAD). The evaluation of cardiac anatomy and contractility by high-resolution CMR can be improved by using intravenous administration of gadolinium-based contrast agents. Delayed enhancement CMR imaging has become the gold standard for quantification of myocardial viability in CAD. Contrast-enhanced CMR imaging may circumvent the need for endomyocardial biopsy or localize the involved regions, thereby improving the diagnostic yield of this invasive procedure. The application of contrast-enhanced CMR as an advanced imaging technique for ischemic and nonischemic diseases is reviewed.

Myocardial scarring on cardiovascular magnetic resonance in asymptomatic or minimally symptomatic patients with "pure" apical hypertrophic cardiomyopathy

BACKGROUND

Late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) enables state-of-the-art in vivo evaluations of myocardial fibrosis. Although LGE patterns have been well described in asymmetrical septal hypertrophy, conflicting results have been reported regarding the characteristics of LGE in apical hypertrophic cardiomyopathy (ApHCM). This study was undertaken to determine 1) the frequency and distribution of LGE and 2) its prognostic implication in ApHCM.

METHODS

Forty patients with asymptomatic or minimally symptomatic pure ApHCM (age, 60.2 ± 10.4 years, 31 men) were prospectively enrolled. LGE images were acquired using the inversion recovery segmented spoiled-gradient echo and phase-sensitive inversion recovery sequence, and analyzed using a 17-segment model. Summing the planimetered LGE areas in all short axis slices yielded the total volume of late enhancement, which was subsequently presented as a proportion of total LV myocardium (% LGE).

RESULTS

Mean maximal apical wall thickness was 17.9±2.3 mm, and mean left ventricular (LV) ejection fraction was 67.7 ± 8.0%. All but one patient presented with electrocardiographic negative T wave inversion in anterolateral leads, with a mean maximum negative T wave of 7.2 ± 4.7 mm. Nine patients (22.5%) had giant negative T waves, defined as the amplitude of ≥ 10 mm, in electrocardiogram. LGE was detected in 130 segments of 30 patients (75.0%), occupying 4.9 ± 5.5% of LV myocardium. LGE was mainly detected at the junction between left and right ventricles in 12 (30%) and at the apex in 28 (70%), although LGE-positive areas were widely distributed, and not limited to the apex. Focal LGE at the non-hypertrophic LV segments was found in some ApHCM patients, even without LGE of hypertrophied apical segments. Over the 2-year follow-up, there was no one achieving the study end-point, defined as all-cause death, sudden cardiac death and hospitalization for heart failure.

CONCLUSIONS

LGE was frequently observed not only in the thickened apex of the heart but also in other LV segments, irrespective of the presence or absence of hypertrophy. The simple presence of LGE on CMR was not representative of adverse prognosis in this population.

Prevalence and clinical profile of myocardial crypts in hypertrophic cardiomyopathy

BACKGROUND

In hypertrophic cardiomyopathy (HCM), cardiovascular MR can detect morphological abnormalities of the left ventricle (LV) not visualized with echocardiography. Although myocardial crypts (ie, narrow, blood-filled invaginations within the LV wall) have been recognized in HCM, all clinical implications of these structural abnormalities within the broad clinical HCM spectrum are not completely resolved. Therefore, we sought to characterize the prevalence and diagnostic significance of myocardial crypts in HCM patients.

METHODS AND RESULTS

Cine and late gadolinium enhancement cardiovascular MR and 2-dimensional echocardiography were obtained in 292 consecutive patients with HCM including 31 genotype-positive/phenotype-negative family members without LV hypertrophy (28 ± 16 years; 51% male) and 261 patients with LV hypertrophy (46 ± 18 years; 60% male). Ninety-eight subjects without cardiovascular disease were controls. Myocardial crypts (1-6/patient) were identified only by cardiovascular MR in 19 of 31 genotype-positive/phenotype-negative patients (61%) compared with only 10 of 261 (4%) patients with HCM with LV hypertrophy (P<0.001) and were absent in control subjects. Twelve-lead electrocardiograms were normal in 10 (53%) of the genotype-positive/phenotype-negative patients with crypts. Crypts were confined to the basal LV, most commonly in the ventricular septum (n=21) or posterior LV free wall (n=4), and associated with normal LV contractility and absence of late gadolinium enhancement in all but one patient.

CONCLUSIONS

LV myocardial crypts represent a distinctive morphological expression of HCM, occurring with different frequency in HCM patients with or without LV hypertrophy. Crypts are a novel cardiovascular MR imaging marker, which may identify individual HCM family members who should also be considered for diagnostic genetic testing. These data support an expanded role for cardiovascular MR in early evaluation of HCM families.

Apical hypertrophic cardiomyopathy presenting as recurrent unexplained syncope

Apical hypertrophic cardiomyopathy (AHC) is a rare variant of hypertrophic cardiomyopathy. Since its description by Sakamoto in 1976 in Japanese patients, our understanding of this entity has evolved. Although cardiac magnetic resonance imaging has emerged as the gold standard for diagnosing AHC, clinical attention must be drawn to the unique electrocardiographic features that provide the initial clues to making the diagnosis. In this case, we present a 47-year-old man with AHC who presented with recurrent syncope, but anomalies on his electrocardiogram went unnoticed on two clinical encounters. He was subsequently admitted to our service and rapidly diagnosed after we observed the very classical findings in the plain twelve lead electrocardiogram done at the time of admission. In a clinical encounter involving a patient presenting with recurrent syncope, special attention must be focused on the electrocardiogram to decipher the unique diagnostic features it might show.

Clinical utility of cardiovascular magnetic resonance in hypertrophic cardiomyopathy

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.

Onset of apical hypertrophic cardiomyopathy in adulthood

The development of the hypertrophic cardiomyopathy (HC) phenotype with left ventricular (LV) hypertrophy usually occurs in adolescence, and documentation of patients with later onset of wall thickening during adulthood is rare. We report 4 patients with asymptomatic, nonobstructive HC (3 women and 1 man) who were studied with serial cardiovascular magnetic resonance imaging or echocardiography. In these patients, LV wall thickening, confined to the apex and the contiguous distal portions of the ventricular septum and free wall, appeared in midlife and beyond. These patients were >40, >50, or >70 years old when the hypertrophy became evident. The maximum LV wall thickness was 14 to 25 mm (mean 18), with a "spade" deformity of the distal chamber, associated with a nondilated cavity and normal ejection fraction (65% to 80%), in the absence of mitral valve systolic anterior motion. In each patient, similar electrocardiographic patterns with similar diffuse and marked T-wave inversion (with or without increased precordial voltages) preceded the appearance of the HC phenotype on the imaging studies. In conclusion, the recognition that the onset of LV hypertrophy in HC can be delayed well into adulthood (and even to advanced age) has important implications regarding the clinical screening practices for families, and suggests the potential value of extending prospective serial imaging beyond adolescence in some relatives. Electrocardiographic repolarization abnormalities can predict the future development of apical LV hypertrophy in adults with HC.

Delayed-enhancement MRI of apical hypertrophic cardiomyopathy: assessment of the intramural distribution and comparison with clinical symptoms, ventricular arrhythmias, and cine MRI

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is reported to show patchy midwall myocardial hyperenhancement on delayed-enhancement magnetic resonance imaging (DE-MRI). The intramural distribution of myocardial hyperenhancement and its correlation with clinical symptoms, ventricular arrhythmias, and cardiac function have not been described forsymptomatic apical HCM.

PURPOSE

To evaluate the features and significance of myocardial hyperenhancement on DE-MRI insymptomatic apical HCM.

MATERIAL AND METHODS

Thirteen patients with symptomatic apical HCM and their 65 apical segments were investigated. Myocardial hyperenhancement and regional and global functional parameters were determined with MRI. We investigated the intramural distribution and frequencies of this myocardial hyperenhancement and compared them with the patients' clinical symptoms, the presence of ventricular arrhythmias, and cine MRI.

RESULTS

Eight (61.5%) patients with symptomatic apical HCM displayed apical myocardial hyperenhancement, and 22 (33.8%) of the 65 apical segments examined showed myocardial hyperenhancement. Of the myocardial hyperenhancement observed, 81.8% showed a subendocardial pattern.The hyperenhanced apical myocardium had a lower percentage of systolic myocardial thickening, and was associated with serious symptoms (e.g. syncope) and ventricular arrhythmias.

CONCLUSION

Patients with symptomatic apical HCMshowed myocardial hyperenhancement involving the subendocardial layer, which might be related to regional systolic dysfunction, serious clinical symptoms, and ventricular arrhythmias.