From the Specialist Literature
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Understanding Arrhythmogenic Cardiomyopathy (ACM)
Arrhythmogenic cardiomyopathy (ACM), previously referred to as arrhythmogenic right ventricular dysplasia, significantly elevates the risk of sudden cardiac death, particularly among younger individuals and athletes. The focus is shifting from a phenotype-centered approach to a genotype-oriented perspective on this condition. This change is crucial for diagnostics and therapeutic strategies.
Evolution in Terminology and Diagnosis
Over the past two decades, awareness has grown that ACM is not limited to the right ventricle; forms can also affect both ventricles. The term “arrhythmogenic cardiomyopathy” is now preferred to reflect this broader scope. According to a review by Dr. Alessio Gasperetti and colleagues from Johns Hopkins University, the terminology is still in transition.
Signs and Symptoms of ACM
It’s essential to recognize that unclassified presyncope may indicate ACM. Although there have been attempts to broaden diagnostic definitions, a lack of scientific consensus remains on the criteria. ACM presents with a variety of genetic and acquired phenotypes, with causal genetic variants found in 50-60% of cases.
The hallmark of ACM involves fibrotic and/or fibrolipomatous remodeling of the myocardium and often manifests during endurance sports. Subtle indicators such as unexplained presyncope, T-wave inversions in right-sided ECG leads, or palpitations may also be present. Whenever a young individual displays these symptoms without typical cardiovascular risk factors, ACM should be considered.
Five Pillars in Managing ACM
Successful management of ACM relies on five key strategies:
- Stratification of Arrhythmia Risk: Assessing the risk for arrhythmias based on genetic testing and clinical presentation.
- Shock and Arrhythmia Management: Implementing strategies for managing cardiac shocks and arrhythmias effectively.
- Prevention of Disease Progression: Identifying and mitigating factors that could worsen the condition.
- Regular Monitoring: Continuous evaluation through ECGs and imaging techniques like echocardiography and MRI.
- Patient Education and Lifestyle Modifications: Informing patients and guiding them towards a healthier lifestyle to reduce risks.
The Role of Genetics
Genetic research identifies variants in desmosomal protein-coding genes as primary culprits in ACM. Researchers suggest that individuals with variations in the same gene exhibit similar arrhythmia event rates, regardless of clinical phenotype. This emphasizes the importance of genotype over phenotype in assessing the likelihood of arrhythmic episodes.
A variety of genes have been implicated in ACM, such as:
- Plakophilin-2 (PKP2): Most commonly associated with right ventricular forms and linked to arrhythmias during physical activity.
- Desmoplakin (DSP): Often presents with biventricular or left ventricular involvement and frequent myocarditis episodes.
- Filamin C (FLNC): Typically associated with left ventricular ACM.
Given these genetic links, studies have explored specific risk calculators for arrhythmias based on these variants. For instance, individuals with established ventricular arrhythmias are recommended to receive an implantable cardioverter-defibrillator (ICD) as per current guidelines.
Future Directions in Sports Recommendations
As ACM is a progressive condition, regular evaluations of arrhythmic risk are essential. Ongoing surveillance through annual ECGs and periodic echocardiography could lead to more tailored recommendations for physical activity.
The European Society of Cardiology (ESC) acknowledges the role of arrhythmias as crucial diagnostic markers but asserts that a clear morphologic or functional definition must be established before classifying ACM as a standalone subtype. Their guidelines emphasize defining the phenotype as the first diagnostic step, while ideally integrating etiology for final diagnosis and treatment planning.
Conclusion
ACM represents a complex interplay of genetic and environmental factors, necessitating a dynamic approach to diagnosis and treatment. As the understanding of its genetic basis expands, so too will the implications for risk management and lifestyle recommendations for affected individuals. With continued research and awareness, the ultimate aim remains to reduce the incidence of life-threatening arrhythmias and improve the quality of life for those living with ACM.
References
Gasperetti A et al. Eur Heart J 2026; doi: 10.1093/eurheartj/ehag297
