ICD storm

Teaching topics from the New England Journal of Medicine - Vol. 357, No. 26, December 27, 2007

ICDs: Not a Cure for VT or VF
Patients with a history of myocardial infarction who survive a spontaneous episode of ventricular arrhythmia are at high risk for subsequent sudden death from recurrent ventricular tachycardia or ventricular fibrillation. Implantable cardioverter-defibrillators (ICDs) decrease mortality and have, therefore, become the mainstay of treatment. However, ICDs are not a cure for ventricular arrhythmias. Defibrillator discharges (shocks) for treatment of recurrent arrhythmias are painful, and syncope may occur before delivery of therapy.

Catheter-Based Mapping and Ablation Techniques
Catheter-based mapping and ablation techniques represent nonpharmacologic methods for the treatment of ventricular tachycardia. The most common indication for radiofrequency ablation is ventricular tachycardia refractory to drug therapy in patients with coronary artery disease that results in frequent shocks from an ICD. However, only 5 to 10% of patients with coronary artery disease show sufficient hemodynamic stability to allow identification of target sites with catheter-based mapping during an episode of ventricular tachycardia. This limitation thus sharply constrains the clinical application of catheter ablation.

Q: What is an 『ICD storm?』
A: An 『ICD storm』 is the term used to describe repeated ICD (implantable cardioverter-defibrillator) shocks delivered within a short time interval. These events occur in 10 to 25% of patients with implantable cardioverter-defibrillators. Clinically significant anxiety and depression as a result of recurrent ICD shocks may occur in more than 50% of patients.