From the Guidelines
Idiopathic Hypertrophic Subaortic Stenosis (IHSS) is typically diagnosed at a median age of 8.9 years, with earlier onset in male individuals, those with a family history of sudden cardiac death, and pathogenic variants in MYH7/MYBPC3. The diagnosis of IHSS, also known as Hypertrophic Cardiomyopathy (HCM), can occur at any age, from infancy through late adulthood, but the median age of onset is reported to be around 8.9 years 1. This condition is often diagnosed during childhood and adolescence, with a disease rate of penetrance similar across the age range, and around 10% to 15% of first-degree relatives are found to have clinical HCM on echocardiographic screening throughout childhood and adolescence 1.
The age of diagnosis can vary depending on several factors, including gender, family history, and genetic mutations. For example, male individuals and those with a family history of sudden cardiac death tend to have an earlier onset of the condition 1. Additionally, pathogenic variants in MYH7/MYBPC3 have also been associated with an earlier age of diagnosis 1.
It is essential to note that the diagnosis of IHSS can be made at any age, and some patients may remain asymptomatic and be diagnosed incidentally during cardiac evaluations for other reasons or through family screening 1. The condition has an autosomal dominant inheritance pattern, with approximately 50% of cases having a familial basis, highlighting the importance of family screening and periodic evaluation of first-degree relatives 1.
Key points to consider in the diagnosis and management of IHSS include:
- The median age of onset is around 8.9 years, but the condition can be diagnosed at any age
- Earlier onset is associated with male individuals, family history of sudden cardiac death, and pathogenic variants in MYH7/MYBPC3
- Family screening and periodic evaluation of first-degree relatives are crucial due to the autosomal dominant inheritance pattern
- Echocardiographic screening can detect clinical HCM in 10% to 15% of first-degree relatives throughout childhood and adolescence 1
From the Research
Age of Diagnosis for Idiopathic Hypertrophic Subaortic Stenosis (IHSS)
The age at which IHSS is typically diagnosed can vary. According to the available studies:
- A study from 1978 2 found that the mean age of diagnosis for 36 young patients with IHSS was 11.3 years, with a range of 5 months to 20 years.
- Another study from 1986 3 discusses the importance of diagnosing hypertrophic cardiomyopathy (another term for IHSS) in adolescents, indicating that it can be diagnosed at this stage of life, but does not provide a specific age range.
- The studies from 1975 4, 5 and 1977 6 focus more on the diagnostic criteria, operative treatment, and postoperative results for IHSS, without specifically addressing the typical age of diagnosis.
Key Points
- IHSS can be diagnosed at any age, from infancy to adulthood.
- The condition may be difficult to diagnose, especially in younger patients or those with asymptomatic cases.
- Diagnostic techniques such as echocardiography can help identify IHSS by showing asymmetrical septal hypertrophy and other characteristic features.