How common is hypertrophic cardiomyopathy… really?: Disease prevalence revisited 27 years after CARDIA

Unmasking Obstruction in Hypertrophic Cardiomyopathy With Postprandial Resting and Treadmill Stress Echocardiography

BACKGROUND

Latent left ventricular outflow tract obstruction (LVOTO) is an important cause of symptoms in patients with hypertrophic cardiomyopathy (HCM) but can be challenging to provoke.

OBJECTIVES AND METHODS

To examine the value of postprandial resting and stress echocardiography and utilization of invasive or enhanced drug therapies (surgical myectomy, alcohol septal ablation, disopyramide, and mavacamten) in patients with postprandial LVOTO. Consecutive HCM patients without LVOTO underwent routine and postprandial echocardiography at rest, with provocation (Valsalva and standing) and after symptom-limited treadmill stress.

RESULTS

Among 252 patients (mean age, 58 years, 39% women), postprandial LVOT gradients were higher compared with routine echocardiography at rest (median, 9.0 [0-38.0] vs 0 [0-14.0] mm Hg; P < .0001) and with provocation (18.5 [0-70.3] vs 1.5 [0-41.0] mm Hg; P < .0001). Postprandial exercise stress echocardiogram (PPXSE) gradients were higher in a subset of 44 patients who underwent both postprandial and fasting stress echocardiography (47.0 [5.3-81.0] vs 17.5 [0-46.0] mm Hg; P < .0001). In total, 49 (19.5%) patients achieved the ≥50 mm Hg threshold under routine conditions (rest/provocation); 90 (35.7%) additional patients achieved postprandial gradients ≥50 mm Hg (rest/provocation/exercise), 38 (15.1%) with PPXSE alone. A total of 71 patients were treated with 91 invasive or enhanced drug therapies, 32 (45.1%) of whom had gradients ≥50 mm Hg only after eating (rest/provocation) and 8 (11.3%) only with PPXSE, with symptom relief in the majority.

CONCLUSIONS

Postprandial echocardiography was useful at unmasking LVOTO in more than one-third of patients who did not have high gradients otherwise. Eating before echocardiography is a powerful provocative tool in the evaluation of patients with HCM.

Advancements in the Diagnosis and Treatment of Hypertrophic Cardiomyopathy: A Comprehensive Review

Hypertrophic cardiomyopathy (HCM) is characterized by excessive growth of myocardial tissue, most commonly due to genetic mutations in sarcomere proteins. This can lead to complications such as heart failure, mitral regurgitation, syncope, arrhythmias, sudden cardiac death, and myocardial ischemia. While we have come a long way in our understanding of the pathophysiology, genetics, and epidemiology of HCM, the past 10 years have seen significant advancements in diagnosis and treatment. As the body of evidence on hypertrophic cardiomyopathy continues to grow, a comprehensive review of the current literature is an invaluable resource in organizing this knowledge. By doing so, the vast progress that has been made thus far will be widely available to all experts in the field. This review provides a comprehensive analysis of the scientific literature, exploring both well-established and cutting-edge diagnostic and therapeutic options. It also presents a unique perspective by incorporating topics such as exercise testing, genetic testing, radiofrequency ablation, risk stratification, and symptomatic management in non-obstructive HCM. Lastly, this review highlights areas where current and future research is at the forefront of innovation in hypertrophic cardiomyopathy.

The syndrome of inferior non-infarctional Q-waves due to segmental basal left ventricular hypertrophy

Non-infarctional Q-waves in general are often recorded in the ECG, and are attributed to anatomical and electrical ECG axis shifts, presence of accessory pathways, pregnancy, HCM, and other HCM-like segmental LV myocardial hypertrophic states, that are currently not fully characterized, as to their nosological nature. The present focused review concerns in particular inferior Q-waves and their association with segmental basal anterior and/or septal LV hypertophies due to HCM, and other not yet fully characterized basal segmental LV hypertophies. Insights from the currently available literature on the topic are reviewed, and varying opinions about the nature of such hypertophic states are discussed, with some suggestions, for what is needed to be done, for their further pathlogenetic characterization.

Clinical course of adults with co-occurring hypertrophic cardiomyopathy and hypertension: A scoping review

Introduction

Hypertension affects approximately 50 % of patients with hypertrophic cardiomyopathy (HCM) but clinical course in adults with co-occurring HCM and hypertension is underexplored. Management may be challenging as routine anti-hypertensive medications may worsen obstructive HCM, the most common HCM phenotype. In this scoping review, we sought to synthesize the available literature related to clinical course and outcomes in adults with both conditions and to highlight knowledge gaps to inform future research directions.

Methods

We searched 5 electronic databases (PubMed, CINAHL, Scopus, Embase, Web of Science) to identify peer-reviewed articles, 2011-2023. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses-Scoping Review (PRISMA-ScR) guideline.

Results

Eleven articles met eligibility. Adults with both conditions were older and had higher rates of obesity and diabetes than adults with HCM alone. Results related to functional class and arrhythmia were equivocal in cross-sectional studies. Only 1 article investigated changes in medical therapy among adults with both conditions. Hypertension was a predictor of worse functional class, but was not associated with all-cause mortality, heart failure-related mortality, or sudden-death. No data was found that related to common hypertension-related outcomes, including renal disease progression, nor patient-reported outcomes, including quality of life.

Conclusions

Our results highlight areas for future research to improve understanding of co-occurring HCM and hypertension. These include a need for tailored approaches to medical management to optimize outcomes, evaluation of symptom burden and quality of life, and investigation of hypertension-related outcomes, like renal disease and ischemic stroke, to inform cardiovascular risk mitigation strategies.

Clinical to Population Prevalence of Hypertrophic Cardiomyopathy Phenotype: Insights From the National Echo Database Australia

BACKGROUND

There is a paucity of data describing the underlying prevalence of hypertrophic cardiomyopathy (HCM), a primary genetic disorder characterised by progressive left ventricular (LV) hypertrophy and sudden death, from both a clinical and a population perspective.

METHODS

We screened the echocardiographic reports of 155,668 men and 147,880 women within the multicentre National Echo Database Australia (NEDA) (2001-2019). End-diastolic wall thickness ≥15 mm anywhere in the left ventricle was identified as a characteristic of an HCM phenotype according to current guideline recommendations. Applying a septal-to-posterior wall thickness ratio >1.3 and LV outflow tract obstruction ≥30 mmHg (when documented), we further identified asymmetric septal hypertrophy and obstructive HCM (oHCM), respectively. The observed pattern of phenotypical HCM within the overall NEDA cohort (>650,000 cases) was then extrapolated to the ∼539,000 (5.7% of adult population) and ∼474,000 (4.8%) Australian men and women, respectively, who were investigated with echocardiography in 2021 on an age-specific basis.

RESULTS

Overall, 15,380 cases (mean age 71.1±14.6 years, 10,138 men [65.9%]) with the characteristic HCM phenotype within the NEDA cohort were identified. Of these 15,380 cases, 5,552 (36.1%) had asymmetric septal hypertrophy, and 2,276 of the 10,290 cases with LV outflow tract obstruction profiling data (22.1%) had obstructive HCM. A further 3,389 of 13,715 cases (24.7%) had evidence of LV systolic dysfunction (LV ejection fraction <55%). Within the entire NEDA cohort (including those without LV profiling), HCM was found in 10,138 of 342,161 men (2.96%; 95% confidence interval [CI] 2.91%-3.02%) and 5,242 of 308,539 women (1.70%; 95% CI 1.65%-1.75%). When extrapolated to the Australian population, we estimate that a minimum of 15,971 men and 8,057 women presented with echocardiographic features of phenotypical HCM in 2021. This translates into a minimum caseload/prevalence of ∼17 adult men (∼2.5 in those aged ≤50 years) and eight adult women (∼1 in those aged ≤50 years) per 10,000 population meeting phenotypical HCM criteria.

CONCLUSIONS

Using contemporary Australian echocardiographic and population data, we estimate that a minimum of 15,971 (17.5 cases/10,000) men and 8,057 women (8.2 cases/10,000) had echocardiographic evidence of phenotypical HCM in 2021. These disease burden data are particularly relevant as new treatment options are emerging.

Mouse Models of Cardiomyopathies Caused by Mutations in Troponin C

Cardiac muscle contraction is regulated via Ca2+ exchange with the hetero-trimeric troponin complex located on the thin filament. Binding of Ca2+ to cardiac troponin C, a Ca2+ sensing subunit within the troponin complex, results in a series of conformational re-arrangements among the thin filament components, leading to an increase in the formation of actomyosin cross-bridges and muscle contraction. Ultimately, a decline in intracellular Ca2+ leads to the dissociation of Ca2+ from troponin C, inhibiting cross-bridge cycling and initiating muscle relaxation. Therefore, troponin C plays a crucial role in the regulation of cardiac muscle contraction and relaxation. Naturally occurring and engineered mutations in troponin C can lead to altered interactions among components of the thin filament and to aberrant Ca2+ binding and exchange with the thin filament. Mutations in troponin C have been associated with various forms of cardiac disease, including hypertrophic, restrictive, dilated, and left ventricular noncompaction cardiomyopathies. Despite progress made to date, more information from human studies, biophysical characterizations, and animal models is required for a clearer understanding of disease drivers that lead to cardiomyopathies. The unique use of engineered cardiac troponin C with the L48Q mutation that had been thoroughly characterized and genetically introduced into mouse myocardium clearly demonstrates that Ca2+ sensitization in and of itself should not necessarily be considered a disease driver. This opens the door for small molecule and protein engineering strategies to help boost impaired systolic function. On the other hand, the engineered troponin C mutants (I61Q and D73N), genetically introduced into mouse myocardium, demonstrate that Ca2+ desensitization under basal conditions may be a driving factor for dilated cardiomyopathy. In addition to enhancing our knowledge of molecular mechanisms that trigger hypertrophy, dilation, morbidity, and mortality, these cardiomyopathy mouse models could be used to test novel treatment strategies for cardiovascular diseases. In this review, we will discuss (1) the various ways mutations in cardiac troponin C might lead to disease; (2) relevant data on mutations in cardiac troponin C linked to human disease, and (3) all currently existing mouse models containing cardiac troponin C mutations (disease-associated and engineered).

Imaging cardiac hypertrophy in hypertrophic cardiomyopathy and its differential diagnosis

PURPOSE OF REVIEW

The aim of this study was to review imaging of myocardial hypertrophy in hypertrophic cardiomyopathy (HCM) and its phenocopies. The introduction of cardiac myosin inhibitors in HCM has emphasized the need for careful evaluation of the underlying cause of myocardial hypertrophy.

RECENT FINDINGS

Advances in imaging of myocardial hypertrophy have focused on improving precision, diagnosis, and predicting prognosis. From improved assessment of myocardial mass and function, to assessing myocardial fibrosis without the use of gadolinium, imaging continues to be the primary tool in understanding myocardial hypertrophy and its downstream effects. Advances in differentiating athlete's heart from HCM are noted, and the increasing rate of diagnosis in cardiac amyloidosis using noninvasive approaches is especially highlighted due to the implications on treatment approach. Finally, recent data on Fabry disease are shared as well as differentiating other phenocopies from HCM.

SUMMARY

Imaging hypertrophy in HCM and ruling out other phenocopies is central to the care of patients with HCM. This space will continue to rapidly evolve, as disease-modifying therapies are under investigation and being advanced to the clinic.