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Implantable cardioverter-defibrillators in hypertrophic cardiomyopathy
A Pinheiro Vieira1, Pedro Pulido Adragão, Katya Res Santos
1Serviço de Cardiologia, Hospital Geral de Santo António, Porto, Portugal. pinheirovieira@sapo.pt
Insights
Hypertrophic cardiomyopathy patients with implantable cardioverter-defibrillators experienced appropriate therapies, particularly those with multiple risk factors. Non-sustained ventricular tachycardia predicted therapies in primary prevention cases, highlighting the importance of risk stratification for sudden cardiac death.
Area of Science:
- Cardiology
- Genetics
- Electrophysiology
Background:
- Hypertrophic cardiomyopathy (HCM) is an autosomal dominant genetic disorder posing a significant risk of sudden cardiac death, often in young, asymptomatic individuals.
- Effective risk stratification is crucial for guiding therapeutic strategies, including the use of implantable cardioverter-defibrillators (ICDs).
- ICDs are indicated for patients with a history of cardiac arrest or sustained ventricular tachycardia, and those with multiple non-invasive risk factors.
Purpose of the Study:
- To evaluate the incidence of appropriate therapies (anti-tachycardia pacing and defibrillation) delivered by ICDs in patients with HCM.
- To identify specific risk factors and their combinations that predict the occurrence of these therapies in HCM patients.
Main Methods:
- A cohort of 17 consecutive patients with HCM and implanted ICDs was retrospectively analyzed.
- Key risk factors assessed included prior cardiac arrest/ventricular tachycardia, family history of sudden cardiac death, genetic mutations, syncope, non-sustained ventricular tachycardia, hypotensive exercise response, and left ventricular hypertrophy.
- Appropriate ICD therapies and the predictive value of individual and combined risk factors for sudden cardiac death were determined.
Main Results:
- Over a mean follow-up of 40 months, 41% of patients received 293 appropriate ICD therapies.
- Patients receiving ICDs for secondary prevention (prior cardiac arrest/VT) had a higher incidence of appropriate therapies compared to primary prevention.
- The combination of risk factors demonstrated significant predictive value: two factors (33% positive predictive value) and three factors (100% positive predictive value).
Conclusions:
- A substantial proportion of high-risk HCM patients with ICDs experienced appropriate therapies, confirming the device's role in managing ventricular arrhythmias.
- Non-sustained ventricular tachycardia emerged as a key predictor for appropriate therapies in the primary prevention group.
- The presence of an increasing number of risk factors significantly enhances the prediction of arrhythmic events in HCM patients requiring ICD therapy.
Background:
Hypertrophic cardiomyopathy is a genetic disease inherited as an autosomal dominant trait associated with risk of sudden death. The majority of cases of sudden death occur in young adults with no or few symptoms, which underlines the importance of risk stratification as a basis for selecting a therapeutic strategy. Implantable cardioverter-defibrillators are indicated in patients resuscitated following cardiac arrest, and those with sustained ventricular tachycardia or two or more risk factors identified in non-invasive tests.
Aim:
The aim of this study was to determine the number of appropriate therapies (anti-tachycardia pacing and defibrillation) and the risk factors, or association of risk factors, that predict therapies in patients with hypertrophic cardiomyopathy and an implantable cardioverter-defibrillator.
Methods:
We studied 17 consecutive patients with hypertrophic cardiomyopathy and cardioverter-defibrillators implanted between December 1992 and June 2003. The following risk factors were analyzed: 1) previous cardiac arrest or sustained ventricular tachycardia; 2) family history of sudden cardiac death; 3) high-risk genetic mutations; 4) syncope; 5) non-sustained ventricular tachycardia; 6) hypotensive response to exercise; and 7) marked left ventricular hypertrophy. Appropriate therapies were determined and the predictive value of the different sudden death risk stratification parameters was analyzed.
Results:
During a mean follow-up of 40 +/- 29 months, 7 patients (41%) received a total of 293 appropriate therapies. Of the 9 patients with previous cardiac arrest or ventricular tachycardia, 4 received appropriate therapies. In the remaining 8 patients, with implantable cardioverter-defibrillators for primary prevention, 3 received appropriate therapies. Family history of sudden death was associated with a positive predictive value of 25% for appropriate therapies, 40% for syncope and 50% for non-sustained ventricular tachycardia. The presence of any two risk factors was associated with a positive predictive value of 33% and the presence of three factors with 100%.
Conclusion:
In this group of patients, considered to be at high risk for sudden cardiac death, a considerable percentage had ventricular tachycardias that were correctly identified and treated by the implantable cardioverter-defibrillator. The percentage of patients with appropriate therapies was slightly higher in the group who had a cardioverter-defibrillator for secondary prevention of sudden death (aborted sudden death or sustained ventricular tachycardia). In patients with an implantable cardioverter-defibrillator for primary prevention, non-sustained ventricular tachycardia was the risk factor with the highest predictive value. An association of risk factors was also predictive of arrhythmic events.
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