Introduction: Implantable cardioverter defibrillators (ICDs) are increasingly being used in high‐risk long QT syndrome (LQTS) patients, but there are limited data regarding clinical experience with this therapeutic modality. The aim of this study is to describe the clinical characteristics of 125 LQTS patients treated with ICDs compared with LQTS patients having similar risk indications who were not treated with ICDs.

Methods and Results: Among 125 LQTS patients with ICDs, there were 54 cardiac arrest survivors, 19 patients who had ICDs implanted due to recurrent syncope despite beta‐blocker therapy, and 52 patients with ICDs implanted due to other reasons, including syncope and LQTS‐related sudden death in a close family member. Patients with cardiac arrest and those with recurrent syncope despite beta‐blocker therapy (n = 73) were compared to 161 LQTS patients who had similar indications (89 cardiac arrest and 72 recurrent syncope despite beta‐blocker therapy) but did not receive ICDs. Total mortality was the endpoint of the analysis. There was 1 (1.3%) death in 73 ICD patients followed an average of 3 years, whereas there were 26 deaths (16%) in non‐ICD patients during mean 8‐year follow‐up (P = 0.07 from log rank test from Kaplan‐Meier curves).

Conclusion: ICDs provide an important therapeutic option to prevent sudden arrhythmic death in high‐risk LQTS patients. A long‐term prospective study is needed to determine the benefit of this therapeutic modality in LQTS patients. (J Cardiovasc Electrophysiol, Vol. 14, pp. 337‐341, April 2003)