Background: Implantable cardioverter-defibrillators (ICDs) reduce mortality in patients at risk for sudden cardiac death. However, clinical trials report higher rates of appropriate ICD therapies in implanted patients than untreated patient mortality rates would predict.
Objective: This study sought to describe a newly recognized form of ventricular proarrhythmia related to the mechanical presence of the ICD.
Methods: Four ICD patients were referred for management of recurrent ventricular tachycardia (VT) refractory to medications and catheter ablation. All were treated with lead extraction and followed prospectively for arrhythmia recurrence.
Results: Two patients received ICDs for primary prevention because of a family history of sudden death and nonischemic cardiomyopathy, respectively. Episodes of VT with ICD therapies began 2 months and 1 year after implantation, and continued for 3 months and 5 years, respectively, until referral. Two secondary prevention ICD patients with ischemic cardiomyopathy developed incessant VT within 1 day and 3 days after implantation with multiple ICD shocks. VT was not suppressed by antiarrhythmic drugs, and catheter ablation failed in 2 patients. In all patients, spontaneous VT's had a QRS morphology similar to the paced morphology from the ICD leads, raising suspicion of lead-related proarrhythmia. After lead extraction, primary prevention ICD patients remained free of VT during follow-up periods of 17 and 21 months, and VT storm was controlled in the secondary prevention patients.
Conclusions: ICD leads can cause uncontrollable VT until the lead is extracted, suggesting a mechanical effect. In contrast to transient ectopy that occurs early after implantation, this proarrhythmia can be chronic. Recognition is important because lead extraction is curative and can prevent unnecessary ICD shocks, antiarrhythmic medications, and catheter ablation.