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QT-interval abnormalities in hypertrophic cardiomyopathy
A Dritsas1, E Sbarouni, D Gilligan
1Department of Medicine, Hammersmith Hospital, Royal Postgraduate Medical School, London, England.
Insights
Patients with hypertrophic cardiomyopathy (HCM) exhibit prolonged QTc intervals and increased QTc dispersion on ECGs. Left ventricular hypertrophy correlates with prolonged QTc, potentially indicating arrhythmia risk.
Area of Science:
- Cardiology
- Electrophysiology
- Genetics
Background:
- Hypertrophic cardiomyopathy (HCM) is a primary genetic heart muscle disease.
- Sudden cardiac death (SCD) is a significant concern in HCM patients.
- Electrocardiogram (ECG) abnormalities are common in HCM.
Purpose of the Study:
- To investigate differences in QTc interval and QTc dispersion between HCM patients and healthy controls.
- To explore the relationship between left ventricular hypertrophy and QTc parameters in HCM.
Main Methods:
- Surface ECGs were recorded in 24 HCM patients and 20 age/sex-matched controls.
- QT intervals were measured across all 12 leads, and corrected QT (QTc) was calculated.
- QTc dispersion was defined as the difference between maximal and minimal QTc intervals.
Main Results:
- Maximal QTc was significantly prolonged in HCM patients (465 ± 24 ms) versus controls (410 ± 20 ms).
- QTc dispersion was significantly greater in HCM patients (71 ± 21 ms) compared to controls (35 ± 11 ms).
- Maximal QTc showed a positive correlation with maximal left ventricular wall thickness (r = 0.48, p < 0.02) in HCM patients.
Conclusions:
- HCM patients demonstrate prolonged QTc intervals and increased QTc dispersion.
- The degree of left ventricular hypertrophy correlates with prolonged maximal QTc.
- These ECG findings may be associated with an increased risk of ventricular arrhythmias and SCD in HCM.
Abstract:
To examine whether QTc and QTc dispersion across the leads of a surface electrocardiogram (ECG) are different in patients with hypertrophic cardiomyopathy (HCM) compared with normal subjects, we measured QT and calculated QTc in all 12 leads of a surface ECG in 24 patients with HCM and in 20 age- and sex-matched normal control subjects. Maximal QTc was prolonged in HCM patients (465 +/- 24 ms) compared with controls (410 +/- 20 ms) (p < 0.001). QTc dispersion defined as the difference of maximum-minimum QTc was also greater in HCM patients (71 +/- 21 ms) compared with normals (35 +/- 11 ms) (p < 0.001). A correlation was found between the degree of left ventricular hypertrophy expressed by the maximal wall thickness and maximal QTc (r = 0.48, p < 0.02). However, QTc dispersion did not correlate with maximal wall thickness. Thus, patients with HCM show a prolonged QTc (> 440 ms) and increased QTc dispersion compared with normal subjects. In addition, the degree of left ventricular hypertrophy correlates with maximal QTc. The presence of a prolonged QT with increased regional dispersion may be associated with the occurrence of serious ventricular arrhythmia and sudden death in HCM.