Heart failure & cardiomyopathiesCohort study
Natural History of Asymptomatic Phenotypically Mild Hypertrophic Cardiomyopathy (HCM)
- Prospective cohort study
- registry-based (Sarcomeric Human Cardiomyopathy Registry)
Authors' conclusion
Approximately 21% of patients with phenotypically mild HCM developed MACE over medium-term follow-up. Older age, symptoms development, and increasing LA diameter, LV hypertrophy, or LVOT gradient associated with MACE, particularly in instances of steeper rate of change.
Study context
- Population
- Patients with phenotypically mild HCM (disease duration <10 years or age ≤30 years, no previous major adverse cardiovascular events (MACE), NYHA class I, left ventricular (LV) maximal wall thickness (MWT) <25 mm)mean age 43 years, 31% women
- Participants
- 2,500 patients
- Outcome
- Incident MACE:
- AF
- MVA
- HF
- Stroke
- All-cause mortality
- Follow-up
- Mean 7 ± 6 years
Main finding
As reported in the abstract
Incident MACE · mean 7 ± 6 years
Developed MACE
534 (21%)
Atrial fibrillation (AF)
289
Malignant ventricular arrhythmia (MVA)
69
Heart failure (HF)
193
Observational data: associations, not effects.
Further findings
Predictors of MACE (Cox regression)
- Progression from NYHA class I to ≥ II (n = 585, 23%): times more likely to experience MACE
- 2.79 (95% CI: 2.30-3.39)
- Age at baseline, HR per 10-year increase
- 1.24 (95% CI: 1.17-1.32)
- BMI, HR per 5-kg/m² increase
- 1.10 (95% CI: 1.01-1.21)
- Left atrial (LA) diameter, HR per 5-mm increase
- 1.16 (95% CI: 1.09-1.25)
- LV MWT, HR per 5-mm increase
- 1.27 (95% CI: 1.10-1.46)
- LV outflow tract (LVOT) gradient, HR per 15-mm Hg increase
- 1.08 (95% CI: 1.05-1.12)
- LV late gadolinium enhancement presence: higher hazard of MACE
- 36% (95% CI: 5%-76%)
Remodeling trajectories (per 0.5 mm/year steeper increase)
- LA diameter increase → AF, HR
- 2.24 (95% CI: 1.69-2.97)
- LA diameter increase → HF, HR
- 2.22 (95% CI: 1.62-3.04)
- LV MWT increase → MVA, HR
- 1.92 (95% CI: 1.38-2.69)
- Higher sustained values and/or steeper increases in LA diameter, LV MWT or LVOT gradient associated with the highest MACE rates
Original publication
Natural History of Asymptomatic Phenotypically Mild HCM. J Am Coll Cardiol. Published 8 July 2026. doi:10.1016/j.jacc.2026.03.176
Summarised from the published abstract; every number is checked against it