Cardiac electrical instability in newly diagnosed/chronic epilepsy tracked by Holter and ECG patch

Abstract

ObjectiveWe hypothesized that cardiac electrical instability and abnormal autonomic tone result from cumulative cardiac injury sustained in recurrent seizures. We tested this hypothesis by comparing T-wave alternans (TWA) and heart rate variability (HRV), both established markers of sudden cardiac death (SCD) risk, in patients with chronic as compared to newly diagnosed epilepsy.MethodsIn this prospective, observational cohort study, patients (newly diagnosed epilepsy, n = 6, age 41.8 ± 6.8 years; chronic epilepsy, n = 6, age 40.2 ± 5.6 years [p = 0.85]) were monitored either with Holter recorder alone or simultaneously with 14-day Zio XT extended continuous ECG patch monitor. TWA was assessed by Food and Drug Administration–cleared Modified Moving Average analysis; HRV was calculated by rMSSD.ResultsTWA levels in chronic epilepsy were significantly higher than in newly diagnosed epilepsy (62 ± 5.4 vs 35 ± 1.3 μV, p < 0.002); the latter did not differ from healthy control adults. In all patients with chronic epilepsy, TWA exceeded the established ≥47-μV TWA cutpoint and rMSSD HRV was inversely related to TWA levels. Patients with chronic epilepsy exhibited elevated TWA levels equivalently on Holter and ECG patch recordings (p = 0.38) with a high correlation (r2 = 0.99, p < 0.01) across 24 hours.ConclusionBased on the limited number of patients studied, it appears that chronic epilepsy, the common use of sodium channel antagonists, or other factors are associated with higher TWA levels and simultaneously with lower rMSSD HRV, which is suggestive of autonomic dysfunction or higher sympathetic tone. The ECG patch monitor used has equivalent accuracy to Holter monitoring for TWA and HRV and permits longer-term ECG sampling.

Identifying patients with epilepsy at high risk of cardiac death: signs, risk factors and initial management of high risk of cardiac death

“…Furthermore, TWA levels appear to depend on the duration of epilepsy, again supporting the notion of acquired cardiac damage. People with chronic epilepsy displayed higher TWA levels than those with newly diagnosed epilepsy, and TWA levels of adults with newly diagnosed epilepsy did not differ from healthy controls [104]. Importantly, PWE had reduced TWA levels and increased HRV upon vagus nerve stimulation (VNS), suggesting that VNS can considerably reverse or compensate epilepsy‐related cardiac dysfunction [102, 103].…”

Prevention of sudden unexpected death in epilepsy: current status and future perspectives

“…Ventricular tachycardias, in turn, are facilitated by abnormalities of cardiac repolarization (e.g. prolonged QT intervals, increased QT dispersion, increased T wave alternans) which are commonly found in people with chronic epilepsy [73,74]. Valid ECG predictors for an increased SUDEP risk, however, were not convincingly reported to date [62,75].…”

Epileptic heart: A clinical syndromic approach

“…The available clinical evidence suggests that recurring seizures impose an imprint on myocardial structural integrity and electrical function that can be detected by the standard electrocardiogram (EKG) and more recently by multiday EKG patches 41,42 39 .…”

“…TWA levels in patients with chronic epilepsy are in the abnormal range, indicating elevated risk for cardiovascular mortality and SCD, and the levels are similar in magnitude to those reported in post‐myocardial infarction patients with significant risk for ventricular tachycardia (Figure 3). 41,50,52–54 Pang et al 41 demonstrated that TWA is present in the severely abnormal range in patients with chronic but not newly diagnosed epilepsy. TWA can be measured on ambulatory EKG monitors, 54 EKG patches, 41 and exercise tolerance testing (ETT) equipment by modified moving average analysis 50,55 …”