Wide QRS Complex Tachycardia in a Patient With Acute Myocarditis Temporarily Protected With a Wearable Cardioverter-Defibrillator.

A wearable cardioverter-defibrillator (WCD) provides noninvasive and temporary protection against sudden cardiac death (SCD) in patients at transient risk of ventricular arrhythmias, including myocarditis. We report the case of a 68-year-old man with recurrent wide QRS complex tachycardia (WCT) and myocarditis confirmed by cardiac magnetic resonance imaging, who was discharged with a WCD following in-hospital stabilization. During the one-month follow-up, the device detected 200 WCT episodes, lasting up to 50 seconds and reaching rates of 150 beats per minute, despite clinical improvement and recovery of left ventricular ejection fraction (from 47% to 52%). An electrophysiological study revealed orthodromic atrioventricular reentrant tachycardia mediated by a retrogradely conducting accessory pathway (AP), reproducing the WCT morphology recorded by the WCD. Radiofrequency ablation of AP successfully eliminated the arrhythmia. This case highlights the diagnostic value of prolonged electrocardiographic monitoring with WCD beyond protection from malignant arrhythmia, enabling timely intervention and avoidance of unnecessary implantable cardioverter-defibrillator implantation.