Syndrome of Reversible Cardiogenic Shock and Left Ventricular Ballooning in Obstructive Hypertrophic Cardiomyopathy

Background

Cardiogenic shock from most causes has unfavorable prognosis. Hypertrophic cardiomyopathy (HCM) can uncommonly present with apical ballooning and shock in association with sudden development of severe and unrelenting left ventricular (LV) outflow obstruction. Typical HCM phenotypic features of mild septal thickening, outflow gradients, and distinctive mitral abnormalities differentiate these patients from others with Takotsubo syndrome, who have normal mitral valves and no outflow obstruction.

Methods and Results

We analyzed 8 patients from our 4 HCM centers with obstructive HCM and abrupt presentation of cardiogenic shock with LV ballooning, and 6 cases reported in literature. Of 14 patients, 10 (71%) were women, aged 66±9 years, presenting with acute symptoms: LV ballooning; depressed ejection fraction (25±5%); refractory systemic hypotension; marked LV outflow tract obstruction (peak gradient, 94±28 mm Hg); and elevated troponin, but absence of atherosclerotic coronary disease. Shock was managed with intravenous administration of phenylephrine (n=6), norepinephrine (n=6), β‐blocker (n=7), and vasopressin (n=1). Mechanical circulatory support was required in 8, including intra‐aortic balloon pump (n=4), venoarterial extracorporeal membrane oxygenation (n=3), and Impella and Tandem Heart in 1 each. In refractory shock, urgent relief of obstruction by myectomy was performed in 5, and alcohol ablation in 1. All patients survived their critical illness, with full recovery of systolic function.

Conclusions

When cardiogenic shock and LV ballooning occur in obstructive HCM, they are marked by distinctive anatomic and physiologic features. Relief of obstruction with targeted pharmacotherapy, mechanical circulatory support, and myectomy, when necessary for refractory shock, may lead to survival and normalization of systolic function.

Don't Forget Commotio Cordis

Non-penetrating chest blows can occasionally trigger fatal ventricular tachyarrhythmias and sudden death (commotio cordis). Such events were initially reported in association with sporting activities and projectiles such as baseball/lacrosse balls. However, similar potentially fatal chest blows, seemingly incapable of causing death, can occur during a variety of other circumstances such as when delivered during a fight (by a fist) such as in the accompanying paper. Notably, commotio cordis events can be reversed by resuscitation and defibrillation.

LAMP2 Cardiomyopathy: Consequences of Impaired Autophagy in the Heart

Background

Human mutations in the X‐linked lysosome‐associated membrane protein‐2 (LAMP2) gene can cause a multisystem Danon disease or a primary cardiomyopathy characterized by massive hypertrophy, conduction system abnormalities, and malignant ventricular arrhythmias. We introduced an in‐frame LAMP2 gene exon 6 deletion mutation (denoted L2^Δ6) causing human cardiomyopathy, into mouse LAMP2 gene, to elucidate its consequences on cardiomyocyte biology. This mutation results in in‐frame deletion of 41 amino acids, compatible with presence of some defective LAMP2 protein.

Methods and Results

Left ventricular tissues from L2^Δ6 and wild‐type mice had equivalent amounts of LAMP2 RNA, but a significantly lower level of LAMP2 protein. By 20 weeks of age male mutant mice developed left ventricular hypertrophy which was followed by left ventricular dilatation and reduced systolic function. Cardiac electrophysiology and isolated cardiomyocyte studies demonstrated ventricular arrhythmia, conduction disturbances, abnormal calcium transients and increased sensitivity to catecholamines. Myocardial fibrosis was strikingly increased in 40‐week‐old L2^Δ6 mice, recapitulating findings of human LAMP2 cardiomyopathy. Immunofluorescence and transmission electron microscopy identified mislocalization of lysosomes and accumulation of autophagosomes between sarcomeres, causing profound morphological changes disrupting the cellular ultrastructure. Transcription profile and protein expression analyses of L2^Δ6 hearts showed significantly increased expression of genes encoding activators and protein components of autophagy, hypertrophy, and apoptosis.

Conclusions

We suggest that impaired autophagy results in cardiac hypertrophy and profound transcriptional reactions that impacted metabolism, calcium homeostasis, and cell survival. These responses define the molecular pathways that underlie the pathology and aberrant electrophysiology in cardiomyopathy of Danon disease.

Usefulness of Global Longitudinal Strain to Predict Heart Failure Progression in Patients With Nonobstructive Hypertrophic Cardiomyopathy

While predicting prognosis to anticipate adverse disease course has long been an aspiration in hypertrophic cardiomyopathy (HC), reliable markers of progressive and unrelenting heart failure symptoms in the absence of obstruction are not well characterized. We sought to evaluate markers of systolic function, including the role of global longitudinal strain (GLS), to identify nonobstructive HC patients at risk for future heart failure. A cohort of 296 consecutive nonobstructive HC patients (42 ± 18years; 75% male) with NYHA class I/II symptoms and preserved systolic function at study entry (EF: 65 ± 6%), were followed for progressive heart failure symptoms (increase in ≥ 1 NYHA functional class) and/or development of systolic dysfunction (EF < 50%). Over median follow-up of 4 ± 3 years, 35 study patients (10%) experienced new heart failure events, including 31 with progressive symptoms and 4 who developed systolic dysfunction. Abnormal GLS < 16% was associated with a 5-fold increase in risk for heart failure compared to GLS > 18% (p < 0.001). GLS remained an independent predictor of heart failure even after adjustment for other relevant disease variables including EF (OR 1.23, p = 0.005). However, notably, when GLS and EF were combined, the prediction of heart failure for individual patients was enhanced (net reclassification improvement 0.55; p = 0.002). Together, GLS < 16% and EF 50% to 59% were associated with a 12.5-fold greater risk for heart failure versus patients with GLS > 18% and EF ≥ 60%, who were at the lowest risk. In conclusion, in nonobstructive HC with no or mild symptoms and preserved EF, abnormal GLS is a strong independent predictor for subsequent development of progressive heart failure symptoms and/or systolic dysfunction. Furthermore, the greatest power in predicting outcome in nonobstructive HC is achieved by combining GLS with EF to identify HC patients at the highest risk for heart failure progression and systolic dysfunction.

Development and Validation of a Clinical Predictive Model for Identifying Hypertrophic Cardiomyopathy Patients at Risk for Atrial Fibrillation: The HCM-AF Score

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Prognostic role of left ventricular apical aneurysm in hypertrophic cardiomyopathy: A systematic review and meta-analysis

OBJECTIVES

The aim of this study was to systematically review and quantitatively synthesize existing evidence about the prognostic value of LV apical aneurysm in patients with HCM.

BACKGROUND

Hypertrophic cardiomyopathy (HCM) represents a common inherited heart disease associated with enormous diversity in morphologic expression and clinical course. With the increasing penetration of advanced high resolution cardiovascular imaging into routine HCM practice, a subset of HCM patients with left ventricular (LV) apical aneurysm have become more widely recognized.

METHODS

Medline was searched for studies describing the prognostic implication of LV apical aneurysm in patients with HCM. In the main analysis the combined endpoint of major HCM-related outcomes was assessed. Separate analyses for sudden cardiac death (SCD) events and thromboembolic events were also performed.

RESULTS

Six studies comprising of 2382 patients met the inclusion criteria. In the pooled analysis, the presence of LV apical aneurysm was significantly associated with major adverse outcomes (pooled OR: 5.13, 95 CI: 2.85 to 9.23, I²:31%), increased risk of SCD arrhythmic events (pooled OR: 4.67, 95% CI: 2.30 to 9.48, I²: 38%) and thromboembolic events (pooled OR: 6.30, 95% CI: 1.52 to 26.19, I²: 66%).

CONCLUSIONS

These data demonstrate that LV apical aneurysm in HCM patients is associated with an increased risk for SCD events and thromboembolism. This finding might encourage the inclusion of LV apical aneurysm into the HCM SCD risk stratification algorithm as a novel risk marker that supports consideration for primary prevention implantable cardioverter defibrillator and anticoagulation for stroke prophylaxis.

Sudden Unexpected Death Due to Myocarditis in Young People, Including Athletes

Sudden deaths in young active people and athletes are distinctly uncommon and frequently related to highly visible cardiovascular conditions including hypertrophic cardiomyopathy and congenital coronary anomalies. Myocarditis is also a cause of sudden death in the young, but frequently under-recognized clinically, and therefore deserving of the present analysis. Two large registries were interrogated for cases of myocarditis, and clinical, demographic, and pathologic findings were assessed. Of 97 cases of myocarditis identified, ages were 19.3 ± 6.2 years, 76% male, and 58 were physically active at or near the time of death. Almost one-half of the 97 cases (47%) had a viral prodrome or symptoms (i.e., syncope, malaise, chest pain or palpitations). Nine were evaluated by cardiologists, but in none was a diagnosis of myocarditis established before death. The inflammatory cellular infiltrate was predominantly lymphocytic (67%), was most frequently multifocal (59%) and involved the conduction system (including atrioventricular node), 38%. In conclusion, myocarditis is an important but under-recognized cause of sudden death in young people including competitive athletes. Clinical diagnosis is difficult because symptoms are nonspecific and often ignored, requiring high index of suspicion for diagnosis. Our data support the ACC/AHA consensus guidelines recommending removal of individuals with myocarditis from competitive sports during recovery. Selective examination of conduction systems showed a number of cases with involvement of myocarditis, suggesting a novel mechanism for sudden death.

Low Risk of Hypertrophic Cardiomyopathy With Contemporary Management Strategies Implemented in Non-Referral Regional Community-Based Practices

Major advances in diagnosis and treatment have emerged for hypertrophic cardiomyopathy (HCM), largely in major tertiary referral centers dedicated to this disease. Whether these therapeutic benefits are confined to patients in such highly selected cohorts, or can be implemented effectively in independent regional or community-based populations is not generally appreciated. We assessed management and clinical outcomes in a non-referral HCM center (n = 214 patients) in Eastern Pennsylvania. Over a 6.0 ± 3.2-year follow-up, the HCM-related mortality rate was 0.1% per year attributed to a single disease-related death, in a 49-year-old man with end-stage heart failure, ineligible for heart transplant. Fifteen patients (7%) with prophylactically placed implantable cardioverter-defibrillators (ICDs) experienced appropriate therapy terminating life-threatening ventricular tachyarrhythmias. In 23 other patients (11%; 5%/year), heart failure due to left ventricular outflow obstruction was reversed by surgical septal myectomy (n = 20) or percutaneous alcohol septal ablation (n = 3). This regional HCM cohort was similar to a comparison tertiary center referral population in terms of HCM-mortality: 0.1%/year vs 0.3%/year (p = 0.3) and ICD therapy (31% vs 16% of primary prevention implants), although more frequently with uncomplicated benign clinical course (62% vs 46%; p <0.01). In conclusion, effective contemporary HCM management strategies and outcomes in referral-based HCM centers can be successfully replicated in regional and/or non-referral settings. Therefore, HCM is now a highly treatable disease compatible with normal longevity when assessed in a variety of clinical venues not limited to tertiary centers.

Individualized interactomes for network-based precision medicine in hypertrophic cardiomyopathy with implications for other clinical pathophenotypes

Progress in precision medicine is limited by insufficient knowledge of transcriptomic or proteomic features in involved tissues that define pathobiological differences between patients. Here, myectomy tissue from patients with obstructive hypertrophic cardiomyopathy and heart failure is analyzed using RNA-Seq, and the results are used to develop individualized protein-protein interaction networks. From this approach, hypertrophic cardiomyopathy is distinguished from dilated cardiomyopathy based on the protein-protein interaction network pattern. Within the hypertrophic cardiomyopathy cohort, the patient-specific networks are variable in complexity, and enriched for 30 endophenotypes. The cardiac Janus kinase 2-Signal Transducer and Activator of Transcription 3-collagen 4A2 (JAK2-STAT3-COL4A2) expression profile informed by the networks was able to discriminate two hypertrophic cardiomyopathy patients with extreme fibrosis phenotypes. Patient-specific network features also associate with other important hypertrophic cardiomyopathy clinical phenotypes. These proof-of-concept findings introduce personalized protein-protein interaction networks (reticulotypes) for characterizing patient-specific pathobiology, thereby offering a direct strategy for advancing precision medicine.

Long-Term Outcome in High-Risk Patients With Hypertrophic Cardiomyopathy After Primary Prevention Defibrillator Implants

Background:

The implantable cardioverter-defibrillator (ICD) is effective for preventing sudden death in patients with hypertrophic cardiomyopathy. However, data on performance and complications of implanted ICDs over particularly long time periods to inform clinical practice is presently incomplete.

Methods:

The study cohort comprises 217 consecutive hypertrophic cardiomyopathy patients with primary prevention ICDs implanted before 2008 and followed for ≥10 years (mean 12±4; range to 31).

Results:

Patients were 38±17 years at implant and 45 (21%) experienced appropriate interventions terminating ventricular tachycardia/ventricular fibrillation. The majority of ICD discharges occurred ≥5 years after implant (29 patients; 64%), including ≥10 years in 16 patients (36%). Initial device therapy increased in frequency from 2.3% of patients at <1 year to 8.5% of patients at ≥10-years after implant ( P =0.005). Inappropriate ICD shocks in 39 patients occurred most commonly <5 years after implant (54%) and decreased in frequency with increasing time from implant (from 9.7% of patients at <5 years to 3.8% at ≥10 years, P =0.02). Other major device complications including infection and lead fractures and dislodgement occurred in 27 patients (12%) but did not increase in frequency over follow-up after implant ( P =0.47). There were no arrhythmic sudden death events among the 217 patients with ICD.

Conclusions:

In hypertrophic cardiomyopathy, after a primary prevention implant, ICD therapy often followed prolonged periods of device dormancy and increased progressively in frequency over time, including one-third of patients with initial therapy after 5 to 9 years, and an additional one-third of patients at ≥10 years. Frequency of inappropriate shocks decreased over follow-up, likely reflecting standard changes in device programming, while occurrence of device complications, such as lead fractures/infection, did not increase during follow-up.

Adult Monozygotic Twins With Hypertrophic Cardiomyopathy and Identical Disease Expression and Clinical Course

A unique clinical circumstance involving middle-aged male identical twins with obstructive hypertrophic cardiomyopathy (HC) is reported. The concordance of morphologic (i.e., phenotype) findings and clinical course between the 2 patients is remarkable, including timing of the onset and progression of heart failure due to left ventricular outflow tract obstruction, frequency of paroxysmal atrial fibrillation and beneficial response to surgical myectomy and Cox-Maze IV procedure (performed 14 days apart). Histopathology of resected ventricular septal muscle showed identical hallmarks of HC including myocyte disorganization, small vessel disease, and myocardial fibrosis. A missense variant of the CRYAB gene was identified as potentially relevant to the pathogenesis of HC in the twins. Taken together, these observations support a powerful genetic determinant for the morphologic and clinical expression of HC, with little or no environmental influence.

Hypertrophic Cardiomyopathy and Sudden Death Initially Identified at Autopsy

Hypertrophic cardiomyopathy (HC) is associated with a well-recognized risk for unexpected sudden death (SD). Most such reported patients have been referred to dedicated centers and/or expert cardiologists for risk stratification, with the number of SDs decreasing sharply due to penetration of the implantable cardioverter-defibrillator (ICDs) into HC practice. However, the clinical circumstances, and morphologic features of HC patients who incur SD without the opportunity to be considered for preventive intervention with ICDs are largely undefined. Using the long-standing unique Jesse Edwards Registry (St. Paul, Minnesota), we studied 86 selected heart specimens from young HC patients who died suddenly and unexpectedly without prior clinical evaluation, ages 31 ± 16 years. The patients were predominantly male (87%) with only modest phenotypic expression and maximum LV wall thickening of only 18 ± 4 mm. SD events occurred predominantly with sedentary/mild activities (66%) often in bed or asleep (32%), but also during physical activity (22%) including with organized competitive sports. This largely unappreciated sub-population of patients with HC (and SD) is characterized by mild-to-moderate degree of LV hypertrophy, representing a clinical challenge which is particularly relevant in the current ICD era for HC, with the potential for SD prevention.

Enhanced American College of Cardiology/American Heart Association Strategy for Prevention of Sudden Cardiac Death in High-Risk Patients With Hypertrophic Cardiomyopathy

Importance

Strategies for reliable selection of high-risk patients with hypertrophic cardiomyopathy (HCM) for prevention of sudden cardiac death (SCD) with implantable cardioverter/defibrillators (ICDs) are incompletely resolved.

Objective

To assess the reliability of SCD prediction methods leading to prophylactic ICD recommendations to reduce the number of SCDs occurring in patients with HCM.

Design, Setting, and Participants

In this observational longitudinal study, 2094 predominantly adult patients with HCM consecutively evaluated over 17 years in a large HCM clinical center were studied. All patients underwent prospective ICD decision making relying on individual major risk markers derived from the HCM literature and an enhanced American College of Cardiology/American Heart Association (ACC/AHA) guidelines-based risk factor algorithm with complete clinical outcome follow-up. Data were collected from June 2017 to February 2018, and data were analyzed from February to July 2018.

Main Outcomes and Measures

Arrhythmic SCD or appropriate ICD intervention for ventricular tachycardia or ventricular fibrillation.

Results

Of the 2094 study patients, 1313 (62.7%) were male, and the mean (SD) age was 51 (17) years. Of 527 patients with primary prevention ICDs implanted based on 1 or more major risk markers, 82 (15.6%) experienced device therapy-terminated ventricular tachycardia or ventricular fibrillation episodes, which exceeded the 5 HCM-related SCDs occurring among 1567 patients without ICDs (0.3%), including 2 who declined device therapy, by 49-fold (95% CI, 20-119; P = .001). Cumulative 5-year probability of an appropriate ICD intervention was 10.5% (95% CI, 8.0-13.5). The enhanced ACC/AHA clinical risk factor strategy was highly sensitive for predicting SCD events (range, 87%-95%) but less specific for identifying patients without SCD events (78%). The C statistic calculated for enhanced ACC/AHA guidelines was 0.81 (95% CI, 0.77-0.85), demonstrating good discrimination between patients who did or did not experience an SCD event. Compared with enhanced ACC/AHA risk factors, the European Society of Cardiology risk score retrospectively applied to the study patients was much less sensitive than the ACC/AHA criteria (34% [95% CI, 22-44] vs 95% [95% CI, 89-99]), consistent with recognizing fewer high-risk patients.

Conclusions and Relevance

A systematic enhanced ACC/AHA guideline and practice-based risk factor strategy prospectively predicted SCD events in nearly all at-risk patients with HCM, resulting in prophylactically implanted ICDs that prevented many catastrophic arrhythmic events in this at-risk population.

Single Coil Implantable Cardioverter Defibrillator Leads in Patients With Hypertrophic Cardiomyopathy

Patients with hypertrophic cardiomyopathy (HC) may require higher energies to terminate ventricular fibrillation (VF); thus, dual coil defibrillation leads are often implanted. However, single coil leads may be preferred in young patients. All patients with HCM implanted with a transvenous ICD from years 2000 to 2014 were included. Of 249 patients, 223 underwent VF testing including 150 with a dual coil lead and 73 a single coil. Patients tested with dual coil compared with single coil had lower successful VF energies (15.7 ± 6.1 joule to 20.2 ± 7.9 joule (p <0.0001)). Adequate safety margin for defibrillation was noted in 97.3% of patients. Notably, 6 (4 with single coil leads) had inadequate safety margins (defined as ≥10 joule). Three of these 6 patients required replacement of a single coil lead with a dual coil lead. The remaining 3 underwent waveform tilt alteration, higher energy ICD, or removal of the can from the shock vector. There were no clinical or implant predictors of inadequate safety margins. In follow-up of 16 ± 30 months (range 0 to 170), there were 24 arrhythmias including 13 VF, all successfully terminated. In conclusion, in HC patients undergoing ICD implantation, single coil leads can provide adequate safety margins. In conclusion, defibrillation testing should be considered in all HC patients undergoing ICD implantation, and should be performed in those undergoing implantation with a single coil lead.

Hypertrophic Cardiomyopathy in "Real-World" Community Cardiology Practice

Differences in presentation and natural history of hypertrophic cardiomyopathy (HC) between community cardiology practice and referral centers has been a source of considerable uncertainty. We report here a cross-sectional analysis of 253 consecutive HC patients from a "real-world" clinical cardiology setting. When compared with a highly selected referral center cohort, patients in clinical practice proved to be similar with regard to disease expression such as left ventricular (LV) wall thickness, outflow obstruction, and natural history, including stable and largely benign clinical course with no or mild symptoms (61% in community practice vs. 55% in referred patients, p = 0.23), occurrence of atrial fibrillation (22% vs. 24%, p = 0.75) and nonfatal sudden death (SD) events (3% vs. 4%, p = 0.8). In contrast, progressive heart failure symptoms were most common in the referral cohort (36% vs. 26%, p = 0.04). In clinical practice, SD was prevented by prophylactic implatable cardioverter defibrillators (ICD) in 5 of 44 patients (11%), although risk was overestimated in 6 patients who were implanted with ICDs in the absence of risk markers (14%). In 16 of 61 (26%) severely symptomatic drug-refractory patients with LV outflow obstruction, recommendation for surgical myectomy (or alcohol septal ablation) was delayed. In conclusion, clinical characteristics and course of HC patients in community practice were generally similar to those in HC referral centers. Community cardiologists managed HC patients predominantly in concert with guideline-based strategies, although risk for SD could be overestimated, and the significance of outflow obstruction with timely reversal of refractory heart failure by intervention was underappreciated.