Abstracts

Rationale: Alterations in the cardiovascular system have been associated with epilepsy. These include seizure-associated ventricular repolarization abnormalities. In this retrospective case-control study we sought to examine seizure-associated ventricular repolarization abnormalities occurring in children and explore clinical factors that may be associated with altered ventricular repolarization.Methods: Children admitted to the Texas Children’s Hospital Pediatric Intensive Care Unit (PICU) between 2/1/2011 and 2/28/2013 were recruited into the study. The inclusion criteria were as follows: 1) primary admission diagnosis of seizure or status epilepticus, 2) age between 1 month and 21 years, and 3) 12-lead EKG within 24 hours of admission. The exclusion criteria were as follows: 1) use of vasoactive agents, 2) history of heart disease, 3) history of a known channelopathy, or 3) family history of channelopathy. Seizure patients were categorized as children with or without epilepsy. Age-matched control patients (n=31) had no history of seizures or epilepsy. A pediatric cardiologist blinded to the clinical history interpreted the EKG tracings. The primary outcomes were ventricular repolarization abnormalities, represented by ST segment changes, abnormal T wave morphology, and QRS axis deviation. The QT/RR relationship and short-term variability (STV) of the corrected QT interval (QTc) were used as markers of ventricular repolarization stability. STV = (∑|QTcn+1 - QTcn|)/(N x √2). |QTcn+1 - QTcn| is the absolute difference between the 2 successive beats and N is number of heartbeats. Continuous variables were analyzed using ANOVA with post hoc Tuckey. Categorical variables were analyzed using Fisher exact test. Simple linear regression was used for QT/RR relationship. Clinical factors that may contribute to EKG abnormalities were analyzed using Student t test or Fisher exact test.Results: There were 4681 PICU admissions, of which 317 children were eligible, 59 met inclusion criteria. 28 children presented with seizure for the first time and constituted the non-epileptic group while the epileptic group had 31 children. Compared with the control group, the seizure patients were more likely to have ST segment changes, abnormal T wave and QRS axis with relative risk of 3.55, 6.67, and 6.83 respectively (p < 0.05). The epileptic group also exhibited impaired QT/RR relationship (r2 = 0.6 vs. r2 = 0.87, epileptic vs. control, p < 0.0001) and increased STV (10.07 ± 1.20 vs. 6.55 ± 0.76, epileptic vs. control, p < 0.05). The diagnosis of epilepsy was the only clinical factor associated with EKG abnormalities (p < 0.05).Conclusions: Our study demonstrates seizure-associated ventricular repolarization abnormalities and instability in children, especially in those with epilepsy. Our findings also suggest that the post-ictal period may be most vulnerable to the development of ventricular arrhythmias. These ventricular alterations provide insights into early arrhythmogenic cardiac remodeling and support cardiac surveillance of children with epilepsy.