A case of inappropriate implantable cardioverter defibrillator shock due to epileptic seizures: A possible limitation of the Wavelet discrimination algorithm

In the present report, we describe the case of a 63-year-old man who received an inappropriate implantable cardioverter defibrillator (ICD) shock due to an epileptic seizure. He experienced an acute myocardial infarction 12 months previously, and his left ventricular (LV) ejection fraction was markedly reduced (21.1%) due to the presence of advanced LV remodeling and an LV aneurysm. An implantable cardioverter-defibrillator (ICD, Medtronic Protecta XT VR) was implanted for the primary prevention of sudden cardiac death. After the implantation, ICD shock data were transmitted via a remote monitoring system. Although many episodes of tachycardia due to atrial fibrillation (AF) were detected, inappropriate discharge was avoided by the use of the Wavelet™ morphology discrimination algorithm (Medtronic Inc., MN, USA). However, an ICD shock was inappropriately delivered for AF tachycardia accompanied by frequent noise detected in the intracardiac electrocardiogram. A detailed analysis showed that the observed noise was derived from the myopotential induced by an epileptic seizure, which overlapped with the QRS wave. This resulted in inappropriate ICD shock delivery that could not be avoided with the use of Wavelet algorithm. To eliminate the involvement of the myopotential derived from an epileptic seizure, the nominal direction of the intracardiac electrocardiogram was changed. This adjustment prevented inappropriate ICD shock delivery during subsequent epileptic seizures. Here, we describe for the first time a case of inappropriate ICD shock delivery induced by an epileptic seizure, suggesting a possible limitation of the Wavelet discrimination algorithm.