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Familial hypertrophic cardiomyopathy: vectorcardiographic findings in echocardiographically unaffected relative
Insights
Electrocardiography can identify hypertrophic cardiomyopathy in relatives without echocardiographic evidence. Increased QRS anterior forces suggest genetic transmission, aiding early diagnosis in families with this heart condition.
Area of Science:
- Cardiology
- Genetics
- Diagnostic Imaging
Background:
- Familial hypertrophic cardiomyopathy (HCM) is a genetic heart disease.
- Early identification of affected individuals is crucial for management and genetic counseling.
- Diagnostic limitations exist for individuals without clear echocardiographic findings.
Purpose of the Study:
- To investigate electrocardiographic (ECG) and vectorcardiographic (VCG) features in first-degree relatives of HCM patients.
- To determine if ECG/VCG can identify affected individuals lacking echocardiographic evidence of HCM.
- To assess the utility of ECG/VCG in ascertaining genetic transmission of HCM.
Main Methods:
- Analysis of ECG and VCG (Frank system) in 9 affected members and 29 relatives across four families.
- Echocardiography used to define affected subjects (septal to free posterior wall thickness ratio > 1.3).
- Comparison of VCG data in young relatives without echocardiographic HCM (18 subjects) versus normal controls (38 subjects).
Main Results:
- Four relatives showed asymmetric septal hypertrophy (echocardiographic HCM).
- Among 25 relatives without echocardiographic HCM, 12 (10 under 20 years) had increased QRS anterior forces (Qz amplitude > 0.80 mV).
- Young relatives without echocardiographic HCM exhibited significantly greater Qz amplitude and Q/Rz ratio compared to controls.
Conclusions:
- ECG finding of abnormal anterior forces may help identify affected individuals in HCM families.
- This ECG pattern can aid in ascertaining genetic transmission of HCM.
- ECG may detect affected members who do not yet show echocardiographic evidence of HCM.
Abstract:
The electrocardiographic and vectorcardiographic (Frank system) features of the first degree relatives of subjects with documented familial hypertrophic cardiomyopathy were analysed. A total of nine affected members and 29 relatives were examined in four families. THe subjects were considered to be affected when the septal to free posterior wall thickness ratio exceeded 1.3 at M-mode echocardiography. Four relatives had asymmetric septal hypertrophy. Among 25 relatives without evidence of asymmetric septal hypertrophy, two over 20 years and 10 under 20 years of age showed increased voltage of QRS anterior forces (Qz amplitude greater than 0.80 mV) on the orthogonal electrocardiogram. The vectorcardiographic data of the relatives under 20 years of age without evidence of asymmetric septal hypertrophy (18 subjects) were compared with those of 38 normal control subjects of comparable age range. The young relatives without disproportionate septal hypertrophy had significantly greater Qz amplitude and Q/Rz ratio than the normal control subjects. In contrast, the echocardiographic data were not significantly different. We suggest that the electrocardiographic finding of abnormal anterior forces in one or more first degree relatives of subjects with documented hypertrophic cardiomyopathy may constitute a valuable aid in ascertaining the genetic transmission of the disease and in recognising affected members without echocardiographic evidence of hypertrophic cardiomyopathy.