Clinical Characteristics and Prognosis of End-stage Hypertrophic Cardiomyopathy

Management of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is an important cause of heart failure and arrhythmias, including sudden death, with a major impact on the healthcare system. Genetic causes and different phenotypes are now increasingly being identified for this condition. In addition, specific medications, such as myosin inhibitors, have been recently shown as potentially able to modify its symptoms, hemodynamic abnormalities and clinical course. Our article aims to provide a comprehensive outline of the epidemiology, diagnosis and treatment of hypertrophic cardiomyopathy in the current era.

Electrocardiographic abnormalities in patients with cardiomyopathies

Abnormalities in impulse generation and transmission are among the first signs of cardiac remodeling in cardiomyopathies. Accordingly, 12-lead electrocardiogram (ECG) of patients with cardiomyopathies may show multiple abnormalities. Some findings are suggestive of specific disorders, such as the discrepancy between QRS voltages and left ventricular (LV) mass for cardiac amyloidosis or the inverted T waves in the right precordial leads for arrhythmogenic cardiomyopathy. Other findings are less sensitive and/or specific, but may orient toward a specific diagnosis in a patient with a specific phenotype, such as an increased LV wall thickness or a dilated LV. A "cardiomyopathy-oriented" mindset to ECG reading is important to detect the possible signs of an underlying cardiomyopathy and to interpret correctly the meaning of these alterations, which differs in patients with cardiomyopathies or other conditions.

Mechanisms and prognostic impact of myocardial ischaemia in hypertrophic cardiomyopathy

Despite the progress made in risk stratification, sudden cardiac death and heart failure remain dreaded complications for hypertrophic cardiomyopathy (HCM) patients. Myocardial ischaemia is widely acknowledged as a contributor to cardiovascular events, but the assessment of ischaemia is not yet included in HCM clinical guidelines. This review aims to evaluate the HCM-specific pro-ischaemic mechanisms and the potential prognostic value of imaging for myocardial ischaemia in HCM. A literature review was performed using PubMed to identify studies with non-invasive imaging of ischaemia (cardiovascular magnetic resonance, echocardiography, and nuclear imaging) in HCM, prioritising studies published after the last major review in 2009. Other studies, including invasive ischaemia assessment and post-mortem histology, were also considered for mechanistic or prognostic relevance. Pro-ischaemic mechanisms in HCM reviewed included the effects of sarcomeric mutations, microvascular remodelling, hypertrophy, extravascular compressive forces and left ventricular outflow tract obstruction. The relationship between ischaemia and fibrosis was re-appraised by considering segment-wise analyses in multimodal imaging studies. The prognostic significance of myocardial ischaemia in HCM was evaluated using longitudinal studies with composite endpoints, and reports of ischaemia-arrhythmia associations were further considered. The high prevalence of ischaemia in HCM is explained by several micro- and macrostructural pathological features, alongside mutation-associated energetic impairment. Ischaemia on imaging identifies a subgroup of HCM patients at higher risk of adverse cardiovascular outcomes. Ischaemic HCM phenotypes are a high-risk subgroup associated with more advanced left ventricular remodelling, but further studies are required to evaluate the independent prognostic value of non-invasive imaging for ischaemia.

Augmented risk of ischemic stroke in hypertrophic cardiomyopathy patients without documented atrial fibrillation

Although atrial fibrillation (AF) is a well-established risk factor for ischemic stroke (IS) in hypertrophic cardiomyopathy (HCM), the risk of IS in HCM patients without documented AF is less recognized. This nationwide population-based cohort study using Korean National Health Insurance database included 8,328 HCM patients without documented AF and 1:2 propensity score-matched 16,656 non-HCM controls between 2010 and 2016. The primary outcome was an incident IS. During a mean follow-up of 6.1 years, IS occurred in 328/8,328 (3.9%) patients with HCM and 443/16,656 (2.7%) controls. The overall incidence of IS was 0.72/100 person-years in the HCM group, which was significantly higher than that in the control group (0.44/100 person-years) (HR 1.64; 95% CI 1.424–1.895; P < 0.001). The overall incidence of IS was 1.36/100 person-years in HCM patients aged ≥ 65 and 2.32/100 person-years years in those with heart failure, respectively. In the HCM group, age ≥ 65 years (adjusted HR 2.74; 95% CI 2.156–3.486; P < 0.001) and chronic heart failure (adjusted HR 1.75; 95% CI 1.101–2.745; P = 0.018) were independent risk factors for IS. HCM patients without documented AF are at a greater risk of IS, especially in those 65 years of age or older or those with chronic heart failure.

Very long-term prognosis in patients with hypertrophic cardiomyopathy: a longitudinal study with a period of 20 years

AIMS

We aim to clarify the prognosis on patients with hypertrophic cardiomyopathy (HCM) for a follow-up period of more than 10 years.

METHODS AND RESULTS

We retrospectively analysed 102 consecutive patients with HCM diagnosed by 31 December 2000. Complete and detailed clinical records were obtained for 93 (91%) of the 102 patients. Sixty-three (68%) of the 93 patients were men, and the mean age of the patients at the initial evaluation was 51.5 ± 13.0 years. During the mean follow-up period of 19.6 ± 8.1 years (median 20.1 years), HCM-related deaths occurred in 20 patients (21% [1.1%/year]). HCM-related adverse events (including HCM-related deaths and nonfatal HCM-related events: hospitalization for heart failure, embolic stroke admission, and sustained ventricular tachycardia with haemodynamic instability or appropriate implantable cardioverter-defibrillator discharge) occurred in 45 patients (48%). The first HCM-related adverse events occurred in approximately 20% of the patients in every decade, the first decade to the third decade, from the initial evaluation. Forty-seven patients (51%) had documentation of atrial fibrillation at the last follow-up. There were seven patients in the end-stage HCM group at the initial evaluation, and 22 patients (24%) had progression to end-stage HCM during the follow-up period.

CONCLUSIONS

In our cohort of patients, HCM-related mortality was relatively favourable. However, approximately half of the patients suffered from HCM-related adverse events during the follow-up period of 20 years. It is important for HCM patients to be carefully followed up over the long-term because HCM is a lifelong disease.

Midterm Outcome After Septal Myectomy and Medical Therapy in Mildly Symptomatic Patients With Hypertrophic Obstructive Cardiomyopathy

Objective

The purpose of this study was mainly to determine the midterm outcome of septal myectomy (SM) and medical therapy (MT) in mildly symptomatic patients (NYHA class II) with hypertrophic obstructive cardiomyopathy (HOCM).

Methods

The study cohort consisted of 184 mildly symptomatic patients with HOCM evaluated in Beijing Anzhen Hospital, Capital Medical University between March 2001 and December 2017, including 82 patients in the SM group and 102 patients in the MT group. Overall survival and HCM-related survival were mainly observed.

Results

The average follow-up time was 5.0 years. Compared to patients accepting MT, patients treated with SM were associated with comparable overall survival (96.5% and 93.1% vs. 92.9% and 83.0% at 5 and 10 years, respectively; P = 0.197) and HCM-related survival (98.7% and 98.7% vs. 94.2% and 86.1% at 5 and 10 years, respectively; P = 0.063). However, compared to MT, SM was superior at improvement of NYHA class (1.3 ± 0.6 vs. 2.1 ± 0.5, P &lt; 0.001) and mean reduction of resting left ventricular outflow (LVOT) gradient (78.5 ± 18.6% vs. 28.3 ± 18.4%, P &lt; 0.001). Multivariate analysis suggested that resting LVOT gradient in the last clinical examination was an independent predictor of all-cause mortality (HR = 1.017, 95%CI: 1.000–1.034, P = 0.045) and HCM-related mortality (HR = 1.024, 95%CI: 1.005–1.043, P = 0.012) in the entire cohort.

Conclusion

Compared with MT, SM had comparable overall survival and HCM-related survival in mildly symptomatic HOCM patients, but SM had advantages on improving clinical symptoms and reducing resting LVOT gradient. Resting LVOT gradient in the last clinical examination was an independent predictor of all-cause mortality and HCM-related mortality.

Projecting the Long-term Clinical Value of Mavacamten for the Treatment of Obstructive Hypertrophic Cardiomyopathy in the United States: An Assessment of Net Health Benefit

PURPOSE

The aim of the study was to project the long-term net health benefits of mavacamten for the treatment of symptomatic obstructive hypertrophic cardiomyopathy (HCM) in the United States.

METHODS

A Markov model with 4 mutually exclusive health states (New York Heart Association [NYHA] functional classes I, II, and III/IV and death) was developed to project the life-years (LYs) and quality-adjusted life-years (QALYs) over a lifetime horizon for patients with symptomatic obstructive HCM receiving mavacamten with or without β-blocker (BB) or calcium channel blocker (CCB) monotherapy or placebo with or without BB or CCB monotherapy. The model simulated a patient cohort with a starting age of 59 years and 41% women. Transition probabilities across NYHA functional classes were estimated using data from the Phase III Clinical Study to Evaluate Mavacamten (MYK-461) in Adults With Symptomatic Obstructive Hypertrophic Cardiomyopathy (EXPLORER-HCM) and the EXPLORER long-term extension (EXPLORER-LTE) cohort from the Long-term Safety Extension Study of Mavacamten in Adults who Have Completed MAVERICK-HCM or EXPLORER-HCM (MAVA-LTE) trial and were extrapolated after week 30. The mortality risks of NYHA functional class I were assumed to be the age- and sex-specific mortality risks of the US general population. The mortality risks for NYHA class II and III/IV were estimated using those for class I in conjunction with the relative mortality risks derived using patients with obstructive HCM from a large real-world registry. Health state utilities for each treatment were estimated from EXPLORER-HCM. Both LYs and QALYs were aggregated over a lifetime for each treatment arm, discounted at 3% annually, and compared between the 2 arms. Sensitivity analyses were conducted to evaluate the robustness of the model findings.

FINDINGS

Over a lifetime, treatment with mavacamten with or without BB or CCB monotherapy was associated with 3.67 incremental LYs compared with placebo with or without BB or CCB monotherapy (13.00 vs 9.33 LYs). Compared with individuals in the placebo group, patients in the mavacamten group were projected to spend 6.17 additional LYs in NYHA functional class I and 0.04 and 2.46 fewer LYs in NYHA functional classes II and III/IV, respectively. With utilities incorporated, mavacamten with or without BB or CCB monotherapy was associated with 4.17 additional QALYs compared with placebo with or without BB or CCB monotherapy (11.74 vs 7.57 QALYs). In the sensitivity analyses, incremental benefits ranged from 1.55 to 6.21 LYs and from 2.48 to 6.19 QALYs across the scenarios.

IMPLICATIONS

This model projected substantial net health benefits associated with mavacamten for symptomatic obstructive HCM owing to improved patient survival and quality of life. The projected QALY gain underscored the likely long-term clinical value of mavacamten in symptomatic obstructive HCM.

Sex-specific cardiac remodeling in early and advanced stages of hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most frequent genetic cardiac disease with a prevalence of 1:500 to 1:200. While most patients show obstructive HCM and a relatively stable clinical phenotype (stage II), a small group of patients progresses to end-stage HCM (stage IV) within a relatively brief period. Previous research has shown sex-differences in stage II HCM with more diastolic dysfunction in female than in male patients. Moreover, female patients more often show progression to heart failure. Here we investigated if differences in functional and structural properties of the heart may underlie sex-differences in disease progression from stage II to stage IV HCM. Cardiac tissue from stage II and IV patients was obtained during myectomy (n = 54) and heart transplantation (n = 10), respectively. Isometric force was measured in membrane-permeabilized cardiomyocytes to define active and passive myofilament force development. Titin isoform composition was assessed using gel electrophoresis, and the amount of fibrosis and capillary density were determined with histology. In accordance with disease stage-dependent adverse cardiac remodeling end-stage patients showed a thinner interventricular septal wall and larger left ventricular and atrial diameters compared to stage II patients. Cardiomyocyte contractile properties and fibrosis were comparable between stage II and IV, while capillary density was significantly lower in stage IV compared to stage II. Women showed more adverse cellular remodeling compared to men at stage II, evident from more compliant titin, more fibrosis and lower capillary density. However, the disease stage-dependent reduction in capillary density was largest in men. In conclusion, the more severe cellular remodeling in female compared to male stage II patients suggests a more advanced disease stage at the time of myectomy in women. Changes in cardiomyocyte contractile properties do not explain the progression of stage II to stage IV, while reduced capillary density may underlie disease progression to end-stage heart failure.

Prognostic value of the 12-lead surface electrocardiogram in sarcomeric hypertrophic cardiomyopathy: data from the REMY French register

Aims

To identify independent electrocardiogram (ECG) predictors of long-term clinical outcome based on standardized analysis of the surface ECG in a large multicentre cohort of patients with sarcomeric hypertrophic cardiomyopathy (HCM).

Methods and results

Retrospective observational study from the REMY French HCM clinical research observatory. Primary endpoint was a composite of all-cause mortality, major non-fatal arrhythmic events, hospitalization for heart failure (HF), and stroke. Secondary endpoints were components of the primary endpoint. Uni- and multivariable Cox proportional hazard regression analysis was performed to identify independent predictors. Among 994 patients with HCM, only 1.8% had a strictly normal baseline ECG. The most prevalent abnormalities were inverted T waves (63.7%), P-wave abnormalities (30.4%), and abnormal Q waves (25.5%). During a mean follow-up of 4.0 ± 2.0 years, a total of 272 major cardiovascular events occurred in 217 patients (21.8%): death or heart transplant in 98 (9.8%), major arrhythmic events in 40 (4.0%), HF hospitalization in 115 (11.6%), and stroke in 23 (2.3%). At multivariable analysis using ECG covariates, prolonged QTc interval, low QRS voltage, and PVCs of right bundle branch block pattern predicted worse outcome, but none remained independently associated with the primary endpoint after adjustment on main demographic and clinical variables. For secondary endpoints, abnormal Q waves independently predicted all-cause death [hazard ratio (HR) 2.35, 95% confidence interval (CI) 1.23–4.47; P = 0.009] and prolonged QTc the risk of HF hospitalization (HR 1.006, 95% CI 1.001–1.011; P = 0.024).

Conclusion

The 12-lead surface ECG has no independent value to predict the primary outcome measure in patients with HCM. The 12-lead surface ECG has been widely used as a screening tool in HCM but its prognostic value remains poorly known. The value of baseline surface ECG to predict long-term clinical outcomes was studied in a cohort of 994 patients with sarcomeric HCM. The surface ECG has no significant additional value to predict outcome in this patient population

Prevalence and Prognostic Significance of Right Ventricular Dysfunction in Patients With Hypertrophic Cardiomyopathy

Few data are available regarding the prevalence and clinical significance of right ventricular systolic dysfunction (RVSD) in hypertrophic cardiomyopathy (HC) patients. This study aimed to evaluate right ventricular (RV) systolic function by cardiovascular magnetic resonance and explore the prevalence and prognostic significance of RVSD in HC patients. A total of 226 patients with HC assessed by cardiovascular magnetic resonance were included in this retrospective study. RVSD was defined by RV ejection fraction (RVEF) ≤45% and was present in 26 (11.5%) patients. Association between RVSD, clinical characteristics, and outcomes were analyzed. RVEF was significantly lower in patients with RVSD than without RVSD (36.2 ± 7.0% vs 60.5 ± 7.4%, p < 0.001). There was a positive correlation between RVEF and left ventricular ejection fraction (r = 0.45; p < 0.001). During a mean follow-up of 30.5 ± 23.9 months, there were 22 (9.7 %) all-cause mortality, including 12 (5.3%) cardiovascular death. Kaplan-Meier analysis showed a significantly higher risk for cardiovascular mortality in patients with RVSD (p = 0.026), but no significant difference in all-cause mortality (p = 0.118) and heart failure related rehospitalization (p = 0.485). On multivariate Cox regression analysis, RVSD (hazard ratio 5.36; confidence interval 1.39 to 20.77; p = 0.015) and RVEF (hazard ratio 0.94; confidence interval 0.89 to 0.98; p = 0.011) were independent predictors of cardiovascular mortality. In conclusion, RVSD is a common phenotype and a strong independent predictor of cardiovascular mortality in HC patients.

Electrocardiogram phenotypes in hypertrophic cardiomyopathy caused by distinct mechanisms: apico-basal repolarization gradients vs. Purkinje-myocardial coupling abnormalities

AIMS

To identify key structural and electrophysiological features explaining distinct electrocardiogram (ECG) phenotypes in hypertrophic cardiomyopathy (HCM).

METHODS AND RESULTS

Human heart-torso anatomical models were constructed from cardiac magnetic resonance (CMR) images of HCM patients, representative of ECG phenotypes identified previously. High performance computing simulations using bidomain models were conducted to dissect key features explaining the ECG phenotypes with increased HCM Risk-SCD scores, namely Group 1A, characterized by normal QRS but inverted T waves laterally and coexistence of apical and septal hypertrophy; and Group 3 with marked QRS abnormalities (deep and wide S waves laterally) and septal hypertrophy. Hypertrophic cardiomyopathy abnormalities characterized from CMR, such as hypertrophy, tissue microstructure alterations, abnormal conduction system, and ionic remodelling, were selectively included to assess their influence on ECG morphology. Electrocardiogram abnormalities could not be explained by increased wall thickness nor by local conduction abnormalities associated with fibre disarray or fibrosis. Inverted T wave with normal QRS (Group 1A) was obtained with increased apico-basal repolarization gradient caused by ionic remodelling in septum and apex. Lateral QRS abnormalities (Group 3) were only recovered with abnormal Purkinje-myocardium coupling.

CONCLUSION

Two ECG-based HCM phenotypes are explained by distinct mechanisms: ionic remodelling and action potential prolongation in hypertrophied apical and septal areas lead to T wave inversion with normal QRS complexes, whereas abnormal Purkinje-myocardial coupling causes abnormal QRS morphology in V4-V6. These findings have potential implications for patients' management as they point towards different arrhythmia mechanisms in different phenotypes.

Comparison of Clinical Effects between Percutaneous Transluminal Septal Myocardial Ablation and Modified Morrow Septal Myectomy on Patients with Hypertrophic Cardiomyopathy

Background

Percutaneous transluminal septal myocardial ablation (PTSMA) and modified Morrow septal myectomy (MMSM) are two invasive strategies used to relieve obstruction in patients with hypertrophic cardiomyopathy (HCM). This study aimed to determine the clinical outcome of these two strategies.

Methods

From January 2011 to January 2015, 226 patients with HCM were treated, 68 by PTSMA and 158 by MMSM. Both ultrasonic cardiograms and heart functional class were recorded before, after operations and in the follow-up. Categorical variables were compared using Chi-square or Fisher's exact tests. Quantitative variables were compared using the paired samples t-test.

Results

Interventricular septal thickness was significantly reduced in both groups (21.27 ± 4.43 mm vs. 18.72 ± 4.13 mm for PTSMA, t = 3.469, P < 0.001, and 21.83 ± 5.03 mm vs. 16.57 ± 3.95 mm for MMSM, t = 10.349, P < 0.001, respectively). The left ventricular outflow tract (LVOT) pressure gradient (PG) significantly decreased after the operations in two groups (70.30 ± 44.79 mmHg vs. 39.78 ± 22.07 mmHg for PTSMA, t = 5.041, P < 0.001, and 74.58 ± 45.52 mmHg vs. 13.95 ± 9.94 mmHg for MMSM, t = 16.357, P < 0.001, respectively). Seven patients (10.29%) in the PTSMA group required a repeat operation in the follow-up. Eight (11.76%) patients were evaluated for New York Heart Association (NYHA) III/IV in the PTSMA group, which was significantly more than the five (3.16%) in the same NYHA classes for the MMSM group at follow-up. Less than 15% of patients in the PTSMA group and none of the patients in the MMSM group complained of chest pain during follow-up.

Conclusions

Both strategies can not only relieve LVOT PG but also improve heart function in patients with HCM. However, MMSM might provide a more reliable reduction in gradients compared to PTSMA.

Entresto therapy effectively protects heart and lung against transverse aortic constriction induced cardiopulmonary syndrome injury in rat

This study tested the hypothesis that entresto therapy effectively protected heart and lung against cardiopulmonary syndrome (CPS) caused by transverse aortic constriction (TAC) in rat. Adult-Male SD rats (n = 36) were equally categorized into group 1 [sham-operated control (SC)], group 2 [SC + enalapril (7 mg/kg/day) since day-28 after TAC induction], group 3 [SC + entresto (30 mg/kg/day) since day-14 after TAC induction], group 4 (TAC only), group 5 (TAC + enalapril) and group 6 (TAC + entresto) and euthanized at day 60 after TAC induction. By day 60, the left-ventricular (LV) ejection fraction was significantly lower in group 4 than in other groups and significantly lower in groups 5 and 6 than in groups 1 to 3, whereas the ratios of heart and lung weights to tibial-length as well as the right-ventricular-systolic blood pressure exhibited an opposite pattern among the groups (all P<0.001). The sarcomere-length (SL), LV fibrotic area, cardiomyocyte size, and lung injury score were highest in group 4, lowest in groups 1 to 3 and significantly lower in group 6 than in group 5 (all P<0.0001). The protein expressions of fibrotic (Smad3/TGF-β), apoptotic (mitochondrial-Bax/cleaved-caspase3/PARP) and DNA-damaged (γ-H2AX) markers in lung and LV myocardium as well as oxidative (NOX-1/NOX2/oxidized protein) in LV myocardium exhibited an identical pattern of SL (all P<0.0001). The protein expressions of pressure/volume overload (BNP/MHC-β) mitochondrial-damaged (cytosolic cytochrome-C) of LV myocardium exhibited an identical pattern of SL (all P<0.001). In conclusion, Entresto is non-inferior to enalapril for protecting the heart-lung against CPS.

Survival and prognostic factors in hypertrophic cardiomyopathy: a meta-analysis

Hypertrophic cardiomyopathy (HCM) is a clinically and genetically heterogeneous disorder but data on survival rates are still conflicting and have not so far been quantitatively reviewed. The aim of this study is to conduct a meta-analysis of cohort studies to assess pooled survival rates and prognostic factors for survival in patients with HCM. Nineteen studies were included representing 12,146 HCM patients. The pooled 1-, 3-, 5- and 10-year survival rates were 98.0%, 94.3%, 82.2% and 75.0%, respectively. Among patients with HCM, age, NYHA functional class, family history of sudden death (FHSD), syncope, atrial fibrillation, non-sustained ventricular tachycardia (nsVT), maximum left ventricular wall thickness and obstruction were significant prognostic factors for cardiovascular death. For sudden cardiac death, FHSD, nsVT, and obstruction showed significant predictive values. Moreover, estimation of population attributable risk (PAR) suggested that nsVT was the strongest predictor for cardiovascular death (13.02%, 95% CI 3.60–25.91%), while left ventricular outflow tract obstruction/mid-ventricular obstruction (LVO/MVO) was the strongest predictor for all-cause death and sudden cardiac death (10.09%, 95% CI 4.72–20.42% and 16.44%, 95% CI 7.45–31.55%, respectively). These risk factors may thus be useful for identifying HCM patients who might benefit from early diagnosis and therapeutic interventions.

Managing atrial fibrillation in the very elderly patient: challenges and solutions

Atrial fibrillation (AF) is the most common arrhythmia affecting elderly patients. Management and treatment of AF in this rapidly growing population of older patients involve a comprehensive assessment that includes comorbidities, functional, and social status. The cornerstone in therapy of AF is thromboembolic protection. Anticoagulation therapy has evolved, using conventional or newer medications. Percutaneous left atrial appendage closure is a new invasive procedure evolving as an alternative to systematic anticoagulation therapy. Rate or rhythm control leads to relief in symptoms, fewer hospitalizations, and an improvement in quality of life. Invasive methods, such as catheter ablation, are the new frontier of treatment in maintaining an even sinus rhythm in this particular population.