Phenotypic differences between electrocardiographic and echocardiographic determination of hypertrophic...

Area of Science:

• Cardiovascular Genetics
• Molecular Cardiology
• Diagnostic Imaging

Background:

• Phenotypic variability in hypertrophic cardiomyopathy (HCM) includes electrocardiography (ECG) abnormalities in carriers without left ventricular hypertrophy (LVH) and normal ECGs in those with LVH.
• Understanding these ECG-echocardiography discrepancies is crucial in the molecular era of HCM diagnosis.

Purpose of the Study:

• To evaluate the diagnostic utility of ECG for identifying HCM carriers who do not yet exhibit LVH.
• To assess the prevalence of normal ECG patterns in HCM carriers with established LVH.
• To correlate ECG findings with the underlying genetic mutations in HCM.

Main Methods:

• A matched case-control study was conducted in Japanese university and general hospitals.
• ECG and echocardiographic data were analyzed from 173 genotyped individuals from families with known HCM-causing mutations.
• Subjects included 107 genetically affected carriers and 66 unaffected controls.

Main Results:

• ECG abnormalities were significantly more common in nonhypertrophic carriers (54.5%) than in noncarriers (13.6%).
• ST-T abnormalities demonstrated the highest accuracy for detecting nonhypertrophic carriers.
• Normal ECG patterns were observed in 10.8% of carriers with LVH. ECG sensitivity for detecting carriers with LVH varied by gene: 83% for cardiac myosin-binding protein C, 88% for cardiac troponin T, and 94% for cardiac troponin I mutations.

Conclusions:

• ECG possesses diagnostic value for identifying nonhypertrophic HCM carriers.
• The diagnostic performance of ECG in HCM varies depending on the specific gene mutation.
• These findings aid in interpreting ECG-echocardiography phenotypic differences in HCM from a molecular genetics perspective.