What question did this study set out to answer?

This study aims to evaluate the prognosis and risk markers of sudden cardiac death in apical hypertrophic cardiomyopathy and compare long-term ICD therapy outcomes between apical and non-apical HCM.

May 20, 2026

Implantable Cardioverter-Defibrillator Therapy in Apical Hypertrophic Cardiomyopathy: Insights From a Multicenter Study

Q: What is the clinical evidence from this study?

Study design: Cohort. Population: Hypertrophic cardiomyopathy (n=96). Intervention: Implantable cardioverter-defibrillator (ICD) therapy in apical HCM vs. Non-apical HCM. Primary outcome: Total ICD therapy events (p=1.00).

Key Result

The incidence of total and appropriate implantable cardioverter-defibrillator therapies did not differ significantly between patients with apical and non-apical hypertrophic cardiomyopathy.

Key Points

This study aims to evaluate the prognosis and risk markers of sudden cardiac death in apical hypertrophic cardiomyopathy and compare long-term ICD therapy outcomes between apical and non-apical HCM.
Analyzed 96 patients with HCM who underwent ICD implantation at 3 hospitals in Korea.
Assessed risk markers recommended by 2024 AHA/ACC and 2023 ESC guidelines in apical HCM patients.
Evaluated long-term outcomes of ICD therapies between apical and non-apical HCM patients over an average follow-up of 6.03 years.
Of 15 patients (15.6%) with apical HCM, 7 (46.7%) experienced aborted cardiac arrest and/or documented ventricular fibrillation.
Total and appropriate ICD therapy events were 33.3% vs. 30.9% (p=1.00) and 13.3% vs. 19.8% (p=0.73) between apical and non-apical HCM, respectively.
Patients with apical HCM who received ICDs showed substantial risk markers at the index event, remaining at risk for recurrent arrhythmias.

Study Design

Type

Cohort (n=96)

Multicenter

Yes

Structured PICO

Does the apical HCM phenotype, compared to non-apical HCM, affect the rate of total or appropriate ICD therapy events in patients with HCM undergoing ICD implantation?

Population

n=96 patients with hypertrophic cardiomyopathy (HCM) who underwent implantable cardioverter-defibrillator (ICD) implantation at 3 tertiary care hospitals in Korea.

Intervention

Apical hypertrophic cardiomyopathy (apical HCM) phenotype

Comparator

Non-apical hypertrophic cardiomyopathy (non-apical HCM) phenotype

Outcome

Total and appropriate ICD therapy events over long-term follow-uphard clinical

Patients with apical HCM experience similar rates of appropriate ICD therapies compared to those with non-apical HCM, supporting the use of standard guideline-recommended risk markers for ICD implantation in this subgroup.

Main Result

Absolute Event Rate: 33.3% vs 30.9%

p-value: p=1.00

Limitations

Retrospective design subject to inherent limitations
Small sample size of patients with apical HCM and secondary prevention ICDs due to the rarity of this phenotype
No ICD therapy events occurred among patients with apical HCM who received an ICD for primary prevention, limiting statistical power
Lacks a comparison group of apical HCM patients without ICD implantation
CMR was not available in all patients, potentially underestimating the prevalence of late gadolinium enhancement
Long study period encompasses substantial evolution in ICD technology, programming strategies, and arrhythmia detection algorithms
Antiarrhythmic drug therapy was not systematically collected
Findings may not be generalizable to non-Asian populations

Abstract

Prognosis and risk markers of sudden cardiac death (SCD) remain incompletely defined in patients with apical hypertrophic cardiomyopathy (HCM). This study evaluated established SCD risk markers and compared long-term implantable cardioverter-defibrillator (ICD) therapy outcomes between apical and non-apical HCM. We analyzed 96 patients with HCM who underwent ICD implantation at 3 tertiary care hospitals in Korea. All SCD risk markers recommended by the 2024 American Heart Association (AHA)/American College of Cardiology (ACC) and 2023 European Society of Cardiology (ESC) guidelines were assessed in apical HCM patients who experienced aborted cardiac arrest (ACA) and/or documented ventricular fibrillation (VF). The long-term outcomes of ICD therapies between apical and non-apical HCM patients were evaluated. Of the 15 patients (15.6%) with apical HCM, 7 (46.7%) experienced ACA and/or documented VF. All 7 patients had at least one SCD risk marker as defined by the 2024 AHA/ACC or 2023 ESC guidelines. The most common markers were late gadolinium enhancement, unexplained syncope, non-sustained ventricular tachycardia, and left atrial enlargement. No significant differences were observed in total (33.3% 5/15 vs. 30.9% 25/81, p=1.00) or appropriate (13.3% 2/15 vs. 19.8% 16/81, p=0.73) ICD therapy events between patients with apical and non-apical HCM over a mean follow-up of 6.03±4.75 years. Patients with apical HCM who received ICDs for secondary prevention exhibited substantial risk markers at the index event and remained at risk for recurrent ventricular arrhythmias. These findings support risk-guided ICD implantation and careful long-term follow-up in patients with high-risk apical HCM.

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