Reel Syndrome in Subcutaneous Implantable Cardioverter-Defibrillator Causing Lead Dislodgement and Inappropriate Shock: Successful Rescue with Intermuscular Two-Incision Technique and Serratus Anterior Plane Block

Background: Reel syndrome, rotation of the generator on its transverse axis with coiling of the lead, is a rare cause of cardiac implantable electronic device failure. While described for transvenous systems, it is exceptionally rare in subcutaneous ICDs (S-ICD). Case presentation: A 63-year-old woman with dilated cardiomyopathy and S-ICD implanted in 2022 for secondary prevention in a standard subcutaneous pocket presented with a shock during exertion. Remote monitoring (LATITUDE) had not been activated. Device interrogation showed an inappropriate 80J shock due to myopotential oversensing after caudal retraction of the lead. Chest X-ray documented Reel syndrome with proximal coiling around the can and distal tip retracted to the subcostal region, >10 cm from the manubrio-sternal junction, with horizontalization of the shock coil, incompatible with effective defibrillation. Management: The system was explanted and a new S-ICD re-implanted using the intermuscular two-incision technique in the virtual space between serratus anterior and latissimus dorsi. The procedure was performed under ultrasound-guided serratus anterior plane block combined with parasternal block. The generator was anchored to the fascia with non-absorbable sutures. Defibrillation test was effective at 40J. Remote monitoring was activated. Conclusion: To our knowledge, this is one of the few documented cases of Reel syndrome in S-ICD with both radiographic and stored electrogram evidence of inappropriate 80J shock, rescued with intermuscular two-incision technique under ultrasound-guided serratus anterior plane block. Intermuscular fixation with non-absorbable sutures, combined with regional anesthesia and systematic remote monitoring, ensures device stability and maintains continuous defibrillation protection.