MINNEAPOLIS — New treatment guidelines endorsed highly effective hypertrophic cardiomyopathy management strategies, saying those have altered clinical course and substantially lowered mortality and morbidity rates.
The report, authored by experts from the Hypertrophic Cardiomyopathy Center, Minneapolis Heart Institute Foundation in Minneapolis and colleagues, advised that HCM is a relatively common global heart disease, which often is inherited.
It has a complex phenotypic and genetic expression and natural history, affecting both genders and many races and cultures, according to the JACC State-of-the-Art Review. The articles noted that prevalence is 1:200-1:500 based on the disease phenotype with imaging.
While that would suggest that about 750,000 Americans have HCM, the authors pointed out, cross-sectional data indicates that only a fraction of patients are clinically diagnosed, which raises the possibility that the condition is under-recognized. Most clinicians only see small segments of the broad disease spectrum, they added.
New treatment advances emphasize the importance of optimal HCM diagnosis with echocardiography and cardiac magnetic resonance. The guidelines also encourage family screening with noninvasive imaging to identify relatives with the HCM phenotype and genetic analysis to pinpoint preclinical sarcomere gene carriers without left ventricular hypertrophy, but with the potential to transmit disease.
“Comprehensive initial patient evaluations are important for reliable diagnosis, accurate portrayal of HCM and family history, risk stratification, and distinguishing obstructive versus nonobstructive forms,” the guidelines added.
That is especially important, the authors noted, because HCM is treatable and consistent with normal longevity in many cases, so timely, accurate diagnosis is critical.
“Once considered a rare inherited cardiac disease, difficult to diagnose and without effective management options, HCM is now recognized as much more common with worldwide distribution, with a general population prevalence of 1:200-1:500, and effective treatment interventions that have significantly reduced disease-related mortality and morbidity,” according to the document. As a consequence, reliable identification and detailed clinical assessment of patients and family members, as well as a high index of diagnostic suspicion, have increased substantially in importance.
Especially important has been the development of modern cardiovascular imaging with echocardiography more than 50 years ago. It is essential for HCM, which has a varied morphologic presentation that can be difficult for clinicians, especially those less familiar with the disease, to manage, the authors noted.
The articles explained, “For example, the HCM phenotype encompasses patients with differing magnitude of left ventricular (LV) mass, eg, from mild LV wall thickness (≤15 mm) to massive hypertrophy ≥30 mm (arguably the most substantial of any cardiac disease), as well as gene carriers in whom LV hypertrophy is absent. Imaging markers also contribute to selection of patients for prevention of sudden death with implantable defibrillators.”
Adding to the complexity is the need to screen family members, as well as manage the care of the initial patient. “Identification of the HCM phenotype during cascade family screening relies initially on echocardiography or [cardiovascular magnetic resonance (CMR)] imaging but can be supplemented with genetic testing to more conclusively determine the affected status of preclinical phenotype-negative relatives,” the authors advised. “However, routine diagnostic echocardiographic imaging in very young (<10-12 years of age) family members can be fraught with uncertainty or false-positive diagnoses that create anxiety and may lead to unnecessary clinical recommendations, even though therapeutic interventions are seldom indicated for asymptomatic patients during the first decade.”
Another factor is that the “30-year single-gene (monogenic) causation hypothesis for HCM lacks robust evidence in many respects, for example, a firm genetic etiology can be identified in only a minority (ie. 30%) of clinically diagnosed patients. Alternatively, it is possible that the genesis of HCM may be multifactorial and involve nongenetic or environmental factors,” the article stated.
That’s why a consortium of experts was assembled to make recommendations based on current information about the complex disease.
“During the last 50 years, multidisciplinary imaging in HCM has evolved and achieved a high level of diagnostic sophistication,” the panel concluded. “Synergistic with echocardiography, CMR has over the last decade been an important part of that progress, and merits full utilization in the HCM clinical environment, ie, including during the initial comprehensive patient evaluation, as well as subsequently about every 3 to 5 years, as judged by the individual clinical circumstances.”
- Maron B, Desai M, Nishimura R, et al. Diagnosis and Evaluation of Hypertrophic Cardiomyopathy. J Am Coll Cardiol. 2022 Feb, 79 (4) 372–389.https://doi.org/10.1016/j.jacc.2021.12.002
