Inherited arrhythmia syndromes are an important cause of sudden cardiac death in young people. Although the individual conditions in this group have unique features and management strategies, an awareness of shared clinical red flags along with family screening can help prevent sudden cardiac death.
- Early identification of patients at risk of inherited arrhythmia syndromes (IAS) is a crucial step in reducing sudden cardiac death in our community.
- Electrocardiographic signatures of IAS are dynamic, and provocation testing should be considered when clinical suspicion of an IAS is high.
- Understanding of the genetic basis of IAS continues to evolve, and patients’ genetic testing results should be reassessed periodically.
- Lifestyle modifications are key to reducing arrhythmic events in patients with IAS.
- Care for patients and families with IAS is optimally provided by a multidisciplinary genetic heart disease team.
The inherited arrhythmia syndromes (IAS) are traditionally grouped together on the basis of their shared pathophysiology of cardiac ion channel disruption and common clinical endpoint of malignant ventricular arrhythmia. These conditions exhibit a broad spectrum of disease, from incidental diagnosis in an asymptomatic individual to sudden cardiac death (SCD). Indeed, up to 40% of SCD victims under 35 years of age have no cause identified on autopsy, and primary cardiac arrhythmia is presumed to be the culprit.1 Key challenges for clinicians include the identification of at-risk patients, accurate risk stratification and timely management aimed at preventing SCD events. Rapidly evolving knowledge of the genetic basis of these conditions continues to provide insights into their unique clinical features, which can be used to improve diagnosis and optimise therapeutic strategies.
This review aims to provide busy clinicians with practical information that can help them care for patients or families at risk of an IAS. We will highlight the clinical situations where IAS should be considered and discuss the principles of diagnosis, utility of genetic testing and importance of risk stratification in optimising management and preventing SCD events. Finally, we will provide a brief update on the specific features of three of the more common IAS.
Although IAS are rare, the diverse presentations of patients with, or at risk of, a primary inherited arrhythmia requires clinicians to be aware of the ‘red flags’ that should prompt further assessment. Clinical situations where IAS should be considered are summarised in Box 1.
In individuals presenting with possible IAS symptoms, such as syncope, a detailed history is of great importance. For example, understanding the circumstances in which a syncopal event occurred allows the clinician to identify features that may favour a diagnosis of cardiac arrhythmia over a simple vasovagal event. Syncope during exercise should always raise suspicion of a cardiac cause. Certain triggers, such as swimming, emotional stimulus or a loud noise, can even provide a clue towards a specific IAS (see below). Individuals who have experienced recurrent syncopal events or those with a history of seizures but normal results on neurological assessment or whose condition is refractory to therapy should undergo detailed cardiac investigation.
Enquiring about a family history of IAS or SCD is also key, and where elicited should heighten suspicion and guide investigations. A family history of SCD or known IAS is clearly concerning, but clinicians should also seek a more obscure family history that might indicate a risk of IAS. This includes any deaths due to sudden infant death syndrome, unexplained motor vehicle accidents or near- drowning (particularly in the young), or seizures, especially if refractory to therapy.