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Defibrillation threshold testing in patients with hypertrophic cardiomyopathy
Brett D Roberts1, Robert E Hood, Magdi M Saba
1Department of Medicine, School of Medicine, University of Maryland, Baltimore, MD 21201, USA.
Pacing and Clinical Electrophysiology : PACE
|July 29, 2010
Summary
Patients with hypertrophic cardiomyopathy (HCM) have higher defibrillation thresholds (DFTs) requiring implantable cardioverter-defibrillators (ICDs). Higher DFTs increase with left ventricle wall thickness, necessitating careful DFT testing in HCM patients.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Implantable cardioverter-defibrillators (ICDs) are crucial for preventing sudden cardiac death in hypertrophic cardiomyopathy (HCM) patients.
- Defibrillation threshold (DFT) testing is vital to ensure effective ICD therapy.
- Hypothesis: HCM patients exhibit higher DFTs compared to those receiving ICDs for other conditions.
Purpose of the Study:
- To compare DFTs in patients with HCM versus those with other standard ICD indications.
- To investigate the relationship between DFT and left ventricular wall thickness in HCM patients.
Main Methods:
- Retrospective review of ICD implantation records (1996-2008).
- Inclusion of 23 HCM patients and 294 control patients with standard indications.
- Standardized DFT testing using step-down or binary search protocols with dual-coil leads.
Main Results:
- HCM patients had significantly higher average DFTs (13.9 J vs. 9.8 J, P=0.0004).
- A greater percentage of HCM patients (22%) had DFTs ≥ 20 J compared to controls (6%).
- Significant positive correlation found between DFT and left ventricle wall thickness in HCM patients (r=0.44, P=0.03).
Conclusions:
- HCM patients demonstrate elevated DFTs compared to other ICD recipients.
- Higher DFTs in HCM correlate with increased left ventricle wall thickness.
- Routine DFT testing is recommended for all HCM patients undergoing ICD implantation.
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