Abstracts

Rationale: The long QT-syndrome (LQTS) is an inherited cardiac channelopathy and is characterized by ventricular arrhythmias that may lead to syncope and sudden cardiac death. Due to similarities in clinical presentation, syncope in LQTS patients has often been erroneously classified as epileptic seizures. However, many of the cardiac ion channels that have been associated with LQTS are also expressed in the brain, and there is emerging evidence that cardiac channelopathies can cause not only cardiac arrhythmias and syncopes, but also genuine epilepsy. We aimed to describe possible electroencephalographic (EEG) alterations in patients with a genotyped diagnosis of LQTS-1 or LQTS-2. Methods: LQTS patients with a genotyped diagnosis of LQTS-1 or LQTS-2 were recruited prospectively from the Department of Cardiology, Oslo University Hospital-Rikshospitalet between May 2015 and May 2016.  We also included healthy controls. In all patients and controls a 1hr 64-channel awake EEG was performed and analyzed by visual assessment. The EEGs were considered to be abnormal if there were signs of ictal or interictal epileptiform discharges or slow wave activity. A chi-square test was conducted to evaluate whether a statistically significant difference between patients and controls was present. Results: 35 (median age: 42 (15-56) patients with LQTS were included; fifteen with LQTS-1 (11 females, 4 males, median age: 40 (15-55)) and 20 with LQTS-2 (13 females, 7 males, median age: 45 (21-56)). Twenty-one healthy controls were also studied (15 females, 5 males, median age: 39 (22-59)). Among LQTS-1 patients fronto-central theta activity was found in 53% (8/15). In the LQTS-2 group abnormalities were found in 60% (12/20). Of these 40% (8/20) showed bilateral and 30% (6/20) showed fronto-central theta activity. Only 5% (1/20) had epileptiform, generalized activity. EEGs were abnormal in 33% (7/21) of the healthy controls.Analyzing both LQT1 and LQT2 as a one group, abnormalities were found in 57% (20/35) opposed to 33% (7/21) abnormalities found in the healthy controls (p ≤ 0.001).  Conclusions: LQTS patients had increased frequency of EEG abnormalities compared to healthy controls. This indicates that LQTS is not only a cardiac, but a cardio-cerebral channelopathy. This should be taken into account when evaluating patients with LQTS and episodes of loss of consciousness.  Funding: Oslo University Hospital, Oslo-NorwayStavanger University Hospital, Stavanger-Norway