Risk Markers and Appropriate Implantable Defibrillator Therapy in Hypertrophic Cardiomyopathy
Peter Magnusson1,2, Fredrik Gadler1, Per Liv2
1Cardiology Research Unit, Department of Medicine, Karolinska Institutet, Karolinska University Hospital/Solna, Stockholm, Sweden.
Insights
Implantable cardioverter defibrillator (ICD) therapy effectively treats ventricular arrhythmias in hypertrophic cardiomyopathy (HCM). A history of atrial fibrillation (AF) or reduced ejection fraction (EF) <50% are key risk markers for appropriate ICD therapy in HCM patients.
Area of Science:
- Cardiology
- Electrophysiology
- Genetics
Background:
- Sudden cardiac death (SCD) risk stratification in hypertrophic cardiomyopathy (HCM) traditionally relies on specialized centers.
- Evaluating risk markers in unselected, nationwide HCM cohorts is crucial for broader clinical application.
Purpose of the Study:
- To identify and evaluate risk markers for appropriate implantable cardioverter defibrillator (ICD) therapy in a nationwide HCM cohort.
- To assess the effectiveness of ICD therapy in managing ventricular arrhythmias in HCM.
Main Methods:
- Utilized data from the Swedish ICD Registry and Patient Register, including retrieved medical records.
- Analyzed risk markers for ventricular arrhythmias leading to appropriate ICD therapy using Cox proportional hazard ratios (HR).
- Included 321 HCM patients with ICDs, followed for a mean of 5.4 years.
Main Results:
- Appropriate ICD therapy occurred in 24.0% of patients over a mean follow-up of 5.4 years.
- Ejection fraction (EF) <50% (HR 2.63) was significantly associated with appropriate ICD therapy.
- In primary prevention, atrial fibrillation (AF; HR 2.54) and EF <50% (HR 2.78) were prominent risk markers.
Conclusions:
- ICD therapy is effective in terminating ventricular arrhythmias in HCM.
- Atrial fibrillation (AF) history and reduced ejection fraction (EF <50%) should be considered in HCM risk stratification.
- Conventional risk markers have weaker associations compared to AF and reduced EF.
Background:
Risk stratification of sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) is mainly based on evaluations from patients at highly specialized centers.
Aim:
To evaluate risk markers for appropriate implantable cardioverter defibrillator (ICD) therapy in an unselected, nationwide cohort of HCM.
Methods:
Patients with an ICD due to HCM were identified from the Swedish ICD Registry since its start in 1995, merged with Patient Register data, and medical records were retrieved. Risk markers for ventricular arrhythmias leading to appropriate ICD therapy were analyzed using Cox proportional hazard ratio (HR).
Results:
Of 321 patients (70.1% males), at least one appropriate therapy occurred in 77 (24.0%) during a mean follow-up of 5.4 years (5.3% per year; primary prevention 4.5%, secondary prevention 7.0%). Cumulative incidences at 1 year, 3 years, and 5 years were 8.1%, 15.3%, and 21.3%, respectively. Cardioversion effectively restored rhythm in 52% of the first episode and antitachycardia pacing was sufficient in the remaining. For the whole cohort, ejection fraction (EF) <50% (HR 2.63; P < 0.001) was associated with appropriate ICD therapy. In primary prevention, patients with established risk markers experienced appropriate therapy; atrial fibrillation (AF; HR 2.54; P = 0.010), EF < 50% (HR 2.78; P = 0.004), and nonsustained ventricular tachycardia (HR 1.80; P = 0.109) had the highest HR, and wall thickness ≥ 30 mm, syncope, exercise blood pressure response, or family history of SCD had weaker associations.
Conclusion:
ICD therapy successfully terminates ventricular arrhythmias in HCM. In addition to conventional risk markers, a history of AF or EF < 50% may be considered in risk stratification.
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