[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-0-en-105":3,"doc-seo-455423-105":59,"doc-detail-455423-en":131},{"code":4,"msg":5,"data":6},0,"success",[7,13,18,23,28,33,38,43,48,51,55],{"id":8,"doc_module":4,"doc_module_name":9,"category_name":10,"show_sort_weight":11,"slug":12},1,"Document","Story & Novel",90,"story-novel",{"id":14,"doc_module":4,"doc_module_name":9,"category_name":15,"show_sort_weight":16,"slug":17},2,"Literature",80,"literature",{"id":19,"doc_module":4,"doc_module_name":9,"category_name":20,"show_sort_weight":21,"slug":22},4,"Exam",70,"exam",{"id":24,"doc_module":4,"doc_module_name":9,"category_name":25,"show_sort_weight":26,"slug":27},5,"Comic",60,"comic",{"id":29,"doc_module":4,"doc_module_name":9,"category_name":30,"show_sort_weight":31,"slug":32},6,"Technology",50,"technology",{"id":34,"doc_module":4,"doc_module_name":9,"category_name":35,"show_sort_weight":36,"slug":37},7,"Healthcare",40,"healthcare",{"id":39,"doc_module":4,"doc_module_name":9,"category_name":40,"show_sort_weight":41,"slug":42},8,"Research & Report",30,"research-report",{"id":44,"doc_module":4,"doc_module_name":9,"category_name":45,"show_sort_weight":46,"slug":47},9,"Religion & Spirituality",20,"religion-spirituality",{"id":46,"doc_module":4,"doc_module_name":9,"category_name":49,"show_sort_weight":46,"slug":50},"World Cup","world-cup",{"id":52,"doc_module":4,"doc_module_name":9,"category_name":53,"show_sort_weight":52,"slug":54},10,"Lifestyle","lifestyle",{"id":56,"doc_module":4,"doc_module_name":9,"category_name":57,"show_sort_weight":24,"slug":58},19,"General","general",{"code":4,"msg":60,"data":61},"ok",{"site_id":62,"language":63,"slug":64,"title":65,"keywords":66,"description":67,"schema_data":68,"social_meta":124,"head_meta":126,"extra_data":128,"updated_unix":130},105,"en","a-case-of-vf-misclassification-corrected-by-vf-therapy-assurance-implications-for-icd-programming","A Case of VF Misclassification Corrected by VF Therapy Assurance: Implications for ICD Programming","","A 58-year-old woman with malignant lymphoma treatment developed ventricular fibrillation (VF) and received a dual-lead ICD for secondary prevention. The initial VF programming led to misclassification of atrial fibrillation (AF) as VF, though ATP coincidentally terminated the episode; prevention of inappropriate therapy required reducing the VF termination criterion. Later, VF shock initially failed due to undersensing as signal amplitude progressively declined, but ventricular fibrillation therapy assurance (VFTA) detected sustained low-amplitude VF and delivered an effective additional shock. After AF ablation and β-blocker initiation, programming adjustments improved VF detection sensitivity and returned criteria while keeping VFTA active, with no recurrence reported.",{"@graph":69,"@context":123},[70,84,106],{"@type":71,"itemListElement":72},"BreadcrumbList",[73,77,79,82],{"item":74,"name":75,"@type":76,"position":8},"https://docshare.wps.com","Home","ListItem",{"item":78,"name":9,"@type":76,"position":14},"https://docshare.wps.com/document/",{"item":80,"name":35,"@type":76,"position":81},"https://docshare.wps.com/document/healthcare/",3,{"item":83,"name":65,"@type":76,"position":19},"https://docshare.wps.com/document/a-case-of-vf-misclassification-corrected-by-vf-therapy-assurance-implications-for-icd-programming/455423/",{"url":83,"name":65,"@type":85,"image":86,"author":91,"headline":65,"publisher":94,"fileFormat":97,"inLanguage":63,"description":67,"dateModified":98,"datePublished":99,"encodingFormat":97,"isAccessibleForFree":100,"interactionStatistic":101},"DigitalDocument",{"url":87,"@type":88,"width":89,"height":90},"https://docshare.wps.com/thumbnails/a-case-of-vf-misclassification-corrected-by-vf-therapy-assurance-implications-for-icd-programming/455423.png","ImageObject",300,407,{"name":92,"@type":93},"moss~","Person",{"url":74,"name":95,"@type":96},"DocShare","Organization","application/pdf","2026-10-31","2026-09-30",true,{"@type":102,"interactionType":103,"userInteractionCount":105},"InteractionCounter",{"@type":104},"ViewAction",13,{"@type":107,"mainEntity":108},"FAQPage",[109,115,119],{"name":110,"@type":111,"acceptedAnswer":112},"How did AF get misclassified as VF in the initial ICD episode?","Question",{"text":113,"@type":114},"AF was misclassified as VF because termination criteria and detection behavior allowed the event to be treated as a VF episode until the applied ATP coincidentally ended it.","Answer",{"name":116,"@type":111,"acceptedAnswer":117},"Why did the first VF shock fail during the later VF recurrence?",{"text":118,"@type":114},"During VF, the RV signal amplitude gradually decreased; after an unsuccessful first shock, undersensing led to the ongoing episode being interpreted as terminated based on three consecutive ventricular sensed markers.",{"name":120,"@type":111,"acceptedAnswer":121},"What role did ventricular fibrillation therapy assurance (VFTA) play in the successful outcome?",{"text":122,"@type":114},"VFTA detected sustained VF despite low-amplitude undersensing and triggered an additional shock, restoring sinus rhythm after the initial failure.","https://schema.org",{"og:url":83,"og:type":125,"og:title":65,"og:site_name":95,"og:description":67},"article",{"robots":127,"canonical":83},"index,follow",{"doc_id":129,"site_id":62},455423,1790816645,{"code":4,"msg":5,"data":132},{"doc_id":129,"user_id":133,"nickname":92,"user_avatar":134,"doc_module":4,"category_id":34,"category_name":35,"doc_title":65,"doc_description":67,"doc_content":135,"file_id":136,"file_url":137,"file_type":138,"file_size":139,"view_count":105,"is_deleted":4,"is_public":8,"is_downloadable":8,"audit_status":8,"page_count":24,"language":140,"language_code":63,"site_id":62,"html_lang":63,"table_of_contents":141,"faqs":142,"seo_title":143,"seo_description":67,"update_tm":144,"read_time":105,"preview_page_count":4},962090895452,"https://ap-avatar.wpscdn.com/davatar_a8503ba1806abce46bf441b54a3ca4cd","Journal of Arrhythmia  \nA Case of VF Misclassification Corrected by VF Therapy Assurance: Implications for ICD Programming  \nNaoki Matsumoto1  | Kenji Shimeno1  | Masanori Matsuo1  | Yukio Abe1  | Daiju Fukuda2  \n1Department of Cardiology, Osaka City General Hospital, Osaka, Japan | 2Department of Cardiovascular Medicine, Osaka Metropolitan University Graduate School of Medicine, Osaka, Japan  \nCorrespondence: Kenji Shimeno ([vtvf200@yahoo.co.jp](vtvf200@yahoo.co.jp))  \nReceived: 13 June 2025 | Revised: 13 November 2025 | Accepted: 21 December 2025  \nKeywords: implantable cardioverter defibrillator | ventricular fibrillation | ventricular fibrillation therapy assurance  \n1 | Case Presentation  \nA 58-year-old female with a family history of sudden cardiac death experienced ventricular fibrillation (VF) during malignant lymphoma treatment. She was diagnosed with idiopathic VF and underwent implantation of an implantable cardioverterdefibrillator (ICD) (Gallant DR, Abbott, Sylmar, CA) for secondary prevention, along with an atrial lead (Tendril STS 2088TC, Abbott, Sylmar, CA) and a ventricular lead (Durata 7122Q, Abbott, Sylmar, CA) . The right ventricular (RV) amplitude at implantation was 6.5 mV and remained stable, ranging from 5–7 mV thereafter (Supplemental Figure S1A) . The tachycardia detection and therapy settings were as follows: The VF zone was set at ≥222 bpm with a Number of Intervals to Detect (NID) of 30, while the ventricular tachycardia (VT) zone was set at ≥171 bpm with an NID of 30 as a monitor zone. Termination criteria were set at 5 consecutive Ventricular Sensed (VS) markers, and postshock redetection was set at 6 VF (F) markers, with the sensitivity for VF detection at 0.5 mV. She later experienced atrial fibrillation (AF), which was misclassified as VF (Figure 1A) . During shock charging, anti-tachycardia pacing (ATP) was delivered (Figure 1B), which incidentally terminated the episode. As ATP was applied before accumulating 5 VS markers (Figure 1A), the event would have continued to be classified as VF if the termination criterion had remained unchanged. To prevent inappropriate future therapy, the termination criterion was reduced to 3 VS markers. No other therapy settings were modified. She subsequently underwent catheter ablation for AF. Despite the procedure, AF control remained poor, and there was a trend toward worsening heart failure (Supplemental Figures S1B and S2) . Under these circumstances, she experienced VF. An appropriate  \nICD shock for VF was delivered but failed to terminate the arrhythmia. During VF, a gradual reduction in signal amplitude was observed, which further decreased after the unsuccessful first shock (Supplemental Figure S3), leading to misclassification of the ongoing VF episode as terminated based on 3 consecutive VS markers. However, ventricular fibrillation therapy assurance (VFTA) detected sustained VF and triggered an additional shock that successfully restored sinus rhythm (Figure 2) . Afterward, a β-blocker was initiated, resulting in satisfactory control of both AF and VF. Given the importance of preventing undersensing observed during this VF episode, the VF detection sensitivity was changed from 0.5 mV to 0.3 mV, and the termination criterion was returned to 5 consecutive VS markers. No other therapy parameters were modified, and the VFTA function was kept activated. She continues to be followed as an outpatient, with no recurrence of AF or VF observed to date.  \n2 | Discussion  \nVFTA is a feature available in Gallant (Abbott, Sylmar, CA) and Entrant ICDs (Abbott, Sylmar, CA), designed to address undersensing in polymorphic VT and VF. As VF progresses, RV amplitude may decrease [1], causing signal fluctuations that lead to misclassification. VFTA utilizes a discrimination channel to monitor potentials between the device and the RV coil. When the amplitude falls within 0.3–0.6 mV, VS2 markers are assigned. VFTA is triggered when continuous VS2 markers (Low-Amplitude ","cbCaiqoPTB9X24Jl","https://ap.wps.com/l/cbCaiqoPTB9X24Jl","pdf",1893351,"English","# Case Presentation\n## Discussion","[{\"question\":\"How did AF get misclassified as VF in the initial ICD episode?\",\"answer\":\"AF was misclassified as VF because termination criteria and detection behavior allowed the event to be treated as a VF episode until the applied ATP coincidentally ended it.\"},{\"question\":\"Why did the first VF shock fail during the later VF recurrence?\",\"answer\":\"During VF, the RV signal amplitude gradually decreased; after an unsuccessful first shock, undersensing led to the ongoing episode being interpreted as terminated based on three consecutive ventricular sensed markers.\"},{\"question\":\"What role did ventricular fibrillation therapy assurance (VFTA) play in the successful outcome?\",\"answer\":\"VFTA detected sustained VF despite low-amplitude undersensing and triggered an additional shock, restoring sinus rhythm after the initial failure.\"}]","A Case of VF Misclassification Corrected by VF Therapy Assurance: Implications for ICD Programming | PDF",1790742841]