Original ArticleSymptoms and Signs Associated with Syncope in Young People with Primary Cardiac Arrhythmias
Introduction
Whilst reflex syncope, orthostatic hypotension and primary seizure disorders are relatively common in the general population, cardiac syncope is rare. Studies examining symptomatic presentation of syncope have mostly included older patients and/or have been dominated by orthostatic or neurocardiogenic syncope [1], [2]. Although syncope is common in the young [3], events due to cardiac arrhythmias have important prognostic implications, and are often the first evidence of a life threatening arrhythmic condition [4], [5], [6], [7], [8], [9], [10]. Prompt recognition of cardiac events is important, as appropriate intervention can significantly reduce mortality and morbidity [11], [12], [13], [14], [15]. We have previously reported that misdiagnosis as seizure disorder is common in LQTS, resulting in inappropriate treatments and potentially preventable deaths of family members in some cases [16]. It is often reported that symptoms are useful in differentiating cardiac from non-cardiac syncope. Our observations from clinical practice suggested that this may not be correct. We aimed to describe the symptoms and signs associated with syncopal episodes in a series of patients with subsequently diagnosed cardiac channelopathies. In particular, we wanted to capture these aspects of the history as they were originally reported before the final diagnosis was known to the patients or their attending clinicians.
Section snippets
Methods
Patients were identified from the New Zealand Cardiac Inherited Disease Registry. This registry enables confidential storage of clinical and genetic information for the purposes of clinical management and research into inherited cardiac disease. Ethical approval for the registry has been obtained from the regional ethics committee.
Between 2000 and 2005, 84 families underwent molecular diagnostic screening through the Cardiac Inherited Disease Registry. A member of each family underwent genetic
Results
Thirty-five consecutive unrelated probands were identified as gene-positive cases (Fig. 1). Diagnoses were LQT1 in 18 (with mutations in KCNQ1) and LQT2 in 10 (with mutations in HERG). Seven had mutations in the cardiac sodium channel gene (SCN5A); presenting as LQT3 in 3, Brugada Syndrome in 3 and Progressive Cardiac Conduction Disorder in 1. There were 24 females (69%) and 11 males (31%). Median age at presentation was 13.4 years (1 day to 54.2 years). Probands self-identified their ethnicity
Discussion
Syncope is a common diagnosis with a lifetime cumulative incidence in the general population of 35% and a bimodal age distribution. The peak prevalence in the young is around the age of 15 years [19], with a second spike in the elderly. Syncope is more frequent in women than men [19], [20], [21].
There are several causes for non-traumatic transient loss of consciousness, including syncope and seizures. Whilst syncope is relatively common in the young population [3], cardiac syncope is rare.
Conclusions
In our series of unrelated patients with genetically confirmed cardiac channelopathies, symptoms both preceding and following syncope were common. Peri-syncopal symptoms are unlikely to be as helpful in distinguishing cardiac from non-cardiac events as is often thought. The presence of dizziness prior to, and drowsiness following, syncope may be falsely reassuring. Seizure-like activity and urinary incontinence are common in those with cardiac syncope and these features alone should not be used
Acknowledgements
The CIDG inherited heart disease registry was established with funds from the Lion Foundation. Genetic testing was supported by Cure Kids, and the Green Lane Research and Educational Fund. The coordinator position (Jackie Crawford) was financed by a non-directive grant from Medtronic Ltd. We are grateful to Felicity Roberts for the preparation of this manuscript.
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