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  • br Case report A year old man with a history

    2019-05-23


    Case report A 63-year-old man with a history of longstanding atrial fibrillation (AF) was admitted to our hospital with anterior acute myocardial infarction (AMI). Emergency cardiac catheterization revealed chronic total occlusion of the distal right coronary artery, total occlusion of the proximal left anterior descending coronary artery (LAD) (culprit lesion), and severe stenosis of the mid left circumflex artery (LCX). He was successfully treated with percutaneous coronary intervention (PCI) of the proximal LAD 9h after the onset. The left ventriculography (LVG) revealed a mild LV systolic dysfunction with a LV ejection fraction (LVEF) of 41.1%. An additional PCI at the mid LCX was performed, involving drug-eluting stents, at 2 weeks after the onset. After 12 months of the onset, he developed chronic Tunicamycin failure classified as NYHA class II. Although cardiac catheterization did not indicate restenosis of the implanted stents, a markedly reduced LVEF (21.1%) was noted, possibly due to the presence of advanced LV remodeling and an LV aneurysm. As indicated in the Japanese Circulation Society Guidelines for ICD implantation (class IIa indication) [9], the patient underwent an ICD implantation (Protecta XT VR, Medtronic Inc.) for the primary prevention of sudden cardiac death. Device programming for ventricular fibrillation (VF) therapy was set only for zone 1; >188 beat per min; number of intervals to detect (NID), 30/40; Rx#1, antitachycardia pacing (ATP) during charging; and Rx#2-#6, Defibrillation 35J. Prior to discharge from the hospital, the patient׳s ICD was also connected to a remote monitoring system. Two months after ICD implantation, the ICD shock data were transmitted by the remote monitoring system. The transmitted EGMs showed that an increase in the ventricular rate had been recognized as VF, and consequently, an ICD shock was delivered after ATP during charging. To allow for further analysis, the patient was asked to visit the hospital for a follow-up examination after 3 days. The device interrogation data showed a number of tachycardia events (Fig. 1). The Wavelet revealed higher matching scores for most tachycardia EGMs, recognized as SVT (Fig. 2), and thereby avoided inappropriate ICD shocks. Most notably, a low amplitude and relatively periodic wave pattern was detected on the EGMs recorded between Can-RV coil EGMs immediately before the ICD shock delivery. However, dna mutant wave pattern was not detected on the EGMs recorded between the RV tip and RV ring (RV tip-RV ring) (Fig. 3A). In addition, no lead damages were detected. Further detailed analysis showed that the frequency of this wave pattern was lower than that of his instrinsic ventricular rhythm. When this wave pattern was not overlapped with the QRS wave, the matching score was high (match, >70%; Fig. 3B, 4, and 7). However, when this wave pattern was overlapped with the QRS wave, the matching score was low (Fig. 3B, 1–3, 5, 6, and 8). Overall, since the matching score in 6 of the 8 beats did not reach the programmable match threshold, an ICD shock was delivered. His wife had witnessed his epileptic seizures, accompanied by convulsions and syncope just 1min before the delivery of the ICD shock. Furthermore, the patient himself did not feel any pain after ICD shock delivery.
    Discussion Inappropriate ICD shock delivery remains a significant clinical issue. Although the most common cause for inappropriate ICD shock is known to be SVT, the Wavelet algorithm used with a single-chamber ICD appears to be effective for avoiding inappropriate ICD shock caused by SVT [10]. These findings were confirmed in the present case, as the use of the Wavelet algorithm prevented a number of potential inappropriate ICD shocks by SVTs. Inappropriate ICD shock is also associated with oversensing of myopotential. Babuty et al. reported the occurrence of inappropriate ICD shock due to the oversensing of diaphragmatic myopotential, with integrated bipolar sensing during deep breathing or the Valsalva maneuver, in the absence of lead damages or electrical interference [11]. The incidence of inappropriate detections due to the oversensing of diaphragmatic myopotential was reported to be 8.6%, whereas that of inappropriate ICD shocks was 3% [12]. Notably, these were reported before the development of the Wavelet algorithm for ICD.