Implantable cardioverter-defibrillators in patients with long QT syndrome: a multicentre study

Abstract

Background: Implantable cardioverter-defibrillator (ICD) therapy has been proven effective in the prevention of sudden cardiac death, but data on outcomes of ICD therapy in the young and otherwise healthy patients with long QT syndrome (LQTS) are limited.

Aim: We sought to collect data on appropriate and inappropriate ICD discharges, risk factors, and ICD-related complications.

Methods: All LQTS patients implanted with an ICD in 14 centres were investigated. Demographic, clinical, and ICD therapy data were collected.

Results: The study included 67 patients (88% female). Median age at ICD implantation was 31 years (12-77 years). ICD indication was based on resuscitated cardiac arrest in 46 patients, syncope in 18 patients, and malignant family history in three patients. During a median follow-up of 48 months, 39 (58%) patients received one or more ICD therapies. Time to first appropriate discharge was up to 55 months. Inappropriate therapies were triggered by fast sinus rhythm, atrial fibrillation, and T-wave oversensing. No predictors of inappropriate shocks were identified. Risk factors for appropriate ICD therapy were: (1) recurrent syncope despite b-blocker treatment before ICD implantation, (2) pacemaker therapy before ICD implantation, (3) single-chamber ICD, and (4) noncompliance to b-blockers. In 38 (57%) patients, at least one complication occurred.

Conclusions: ICD therapy is effective in nearly half the patient population; however, the rates of early and late complica-tions are high. Although the number of unnecessary ICD shocks and reimplantation procedures may be lowered by modern programming and increased longevity of newer ICD generators, other adverse events are less likely to be reduced.

Keywords: ICD outcome; device recalls; implantable cardioverter-defibrillator; lead dysfunction; long QT syndrome; risk factors.