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Progression from hypertrophic obstructive cardiomyopathy to typical dilated cardiomyopathy-like features in the end
Insights
Familial hypertrophic cardiomyopathy (HCM) can progress to a dilated cardiomyopathy (DCM)-like state due to intramural coronary artery stenosis and fibrosis. This highlights the importance of considering HCM in DCM diagnoses, especially with a family history.
Area of Science:
- Cardiology
- Pathology
- Genetics
Background:
- Familial hypertrophic cardiomyopathy (HCM) is a genetic heart condition.
- Some HCM patients can develop dilated cardiomyopathy (DCM)-like features.
- The progression from HCM to DCM is not fully understood.
Purpose of the Study:
- To present a case of a patient with familial obstructive HCM who developed end-stage DCM-like features.
- To investigate the pathological basis for the transition from HCM to DCM.
- To emphasize the diagnostic considerations for DCM in patients with a family history of HCM.
Main Methods:
- Case presentation of a 38-year-old male with familial HCM.
- Review of serial echocardiograms showing changes from asymmetric septal hypertrophy (ASH) and systolic anterior motion (SAM) to left ventricular (LV) dilatation and impaired contraction.
- Autopsy examination including heart weight, wall thickness measurements, and histological analysis of myocardial fibrosis, cellular disarray, and intramural coronary arteries.
Main Results:
- The patient exhibited typical HCM features (ASH, SAM) that evolved into DCM-like findings (LV dilatation, poor contraction) over six years.
- Autopsy revealed dilated LV hypertrophy, massive fibrosis (30% in ventricular septum), diffuse cellular disarray (18% in ventricular septum), and severe stenosis of intramural small arteries.
- Extramural coronary arteries were normal, implicating intramural vessel disease in the progression.
Conclusions:
- The transition from HCM to a DCM-like state can be attributed to chronic necrosis and fibrosis caused by severe intramural coronary artery stenosis.
- This case underscores that some patients clinically diagnosed with DCM may actually have underlying HCM, particularly those with a family history.
- Further research into the mechanisms of intramural coronary artery disease in HCM is warranted.
Abstract:
An autopsied patient who had shown typical dilated cardiomyopathy (DCM)-like feature in the end stage of familial obstructive hypertrophic cardiomyopathy (HCM) is presented. The patient, a 38-year-old male, had 2 sisters with HCM. Six years before death, the echocardiogram revealed marked asymmetric septal hypertrophy (ASH) with systolic anterior motion (SAM). The ventricular septum (VS) to left ventricular posterior wall (LVPW) ratio was 19 mm/10 mm and LVEDd was 47 mm. Subsequently, the signs and symptoms of congestive heart failure became progressively worse and DCM-like findings appeared insidiously. Two months before death, the echocardiogram revealed LV dilatation (LVEDd = 55 mm) with diffuse poor contraction, no ASH (VS/LVPW = 7 mm/9 mm) and no SAM. At autopsy, the heart weighed 480g and showed dilated LV hypertrophy with normal wall thickness (VS/LVPW = 9 mm/13 mm). Massive fibrosis (30% in the VS), diffuse disarray (18% in the VS) and severe narrowing of the intramural small arteries and arterioles were found in the middle and outer thirds of the VS and the anterior LV wall. The extramural coronary arteries were not stenosed. The insidious progression from HCM to typical DCM-like feature related to the chronic progression of necrosis and massive fibrosis, due to severe stenosis of the intramural coronary artery. The data indicate that patients diagnosed clinically as DCM may be HCM, especially in those with family history of HCM.