Nonobstructive & apical HCM · Decision guide
The treatment pathway depends on obstruction, symptoms and cavity size—not wall thickness alone.
Nonobstructive HCM lacks outflow obstruction; apical HCM describes thickening near the heart’s tip. Treatment targets the actual cause of symptoms. Routine outflow myectomy is not the default for either label.
Guidance allows expert-centre consideration for severe persistent symptoms, preserved pumping function and a very small ventricular cavity.
At 48 weeks, mavacamten did not significantly outperform placebo on the two primary outcomes in nonobstructive HCM.
Sources: Mavacamten in symptomatic nonobstructive hypertrophic cardiomyopathy: ODYSSEY-HCM
Symptom treatment, sudden-death risk assessment and family screening remain distinct parts of HCM care.
Sources: AHA/ACC HCM guidance (2024)
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Sources: AHA/ACC HCM guidance (2024)
Sources: Mavacamten in symptomatic nonobstructive hypertrophic cardiomyopathy: ODYSSEY-HCM · 2024 HCM guideline: official teaching slides
A small, stiff pumping chamber can cause symptoms without outflow obstruction. Exertional obstruction is a separate mechanism that may be missed on a resting scan. Cardiac MRI can clarify apical anatomy when ultrasound is inconclusive.
Apical thickening does not by itself establish a high outflow gradient. Demonstrated exertional obstruction leads to the latent-obstruction pathway.
Sources: AHA/ACC HCM guidance (2024) · Hypertrophic cardiomyopathy: diagnosis and treatment
| Finding | Treatment role | Important limit |
|---|---|---|
| Symptoms with preserved pumping function and no obstruction | Medicines may reduce breathlessness or chest discomfort and manage congestion | Relief of symptoms does not remove rhythm-risk and family-screening needs |
| Apical thickening and a very small chamber | Selected apical myectomy can create more useful cavity space | This is a specialised option for severe persistent symptoms, not routine surgery for apical HCM |
| Reduced pumping function or advanced heart failure | Heart-failure treatment and possible transplant assessment | Requires a different pathway from surgery directed at basal outflow obstruction |
Sources: 2024 HCM guideline: official teaching slides · AHA/ACC HCM guidance (2024)
The 2024 guideline allows consideration of apical myectomy for highly selected patients with severe breathlessness or angina despite maximal medical therapy, preserved ejection fraction and a small left-ventricular cavity. It is a limited recommendation for experienced surgeons at comprehensive HCM centres.
Apical myectomy aims to enlarge a small ventricular cavity. It differs from basal myectomy intended to relieve outflow obstruction, so published basal-myectomy outcomes do not automatically describe this operation.
Sources: 2024 HCM guideline: official teaching slides · Hypertrophic cardiomyopathy: diagnosis and treatment
In ODYSSEY-HCM, published in 2025, 580 adults with symptomatic nonobstructive HCM were assigned to mavacamten or placebo for 48 weeks. Neither primary measure—peak exercise oxygen uptake or patient-reported health status—improved significantly more with mavacamten. Falls in ejection fraction and treatment interruptions were more frequent with the drug.
The result applies to the studied drug, population and duration. Evidence from obstructive HCM cannot be transferred automatically to nonobstructive disease, and a clinical-trial treatment remains distinct from established care.
Sources: Mavacamten in symptomatic nonobstructive hypertrophic cardiomyopathy: ODYSSEY-HCM
Rhythm assessment, sudden-death risk review and family screening remain parts of HCM care even if symptoms improve. An apical aneurysm is a separate imaging finding relevant to risk assessment.
Sources: AHA/ACC HCM guidance (2024)
Explore each specialist’s clinical focus, current programme and the studies relevant to this treatment. The listed roles include cardiac surgeons and, where appropriate, interventional cardiologists.
Rochester, Minnesota · United States
cardiac surgeon
Joseph Dearani’s Mayo practice spans HCM, Ebstein anomaly, congenital surgery and complex reoperations. Mayo’s selected apical-myectomy research addresses a different problem from routine basal septal obstruction.
Sources: Mayo Clinic · HCM treatment options · Mayo · 67 patients with apical aneurysm repair
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