Frequency of and outcomes associated with nonadherence to guideline-based recommendations for an implantable cardioverter-defibrillator in patients with congenital long QT syndrome

Background: Guideline-directed device therapy for long QT syndrome (LQTS) has evolved during the years, and indications for an implantable cardioverter-defibrillator (ICD) vary between professional cardiac societies. Objective: We aimed to identify the subset of patients with LQTS who satisfied a class I or class II 2022 European Society of Cardiology guideline-based recommendation for an ICD and to determine the outcomes of those patients who received an ICD compared with those treated without an ICD. Methods: Retrospective analysis was conducted of 2861 patients with LQT1, LQT2, or LQT3 to identify patients meeting contemporary recommendations for guideline-directed device therapy. Basic demographics, clinical characteristics, and frequency/type of breakthrough cardiac events (BCEs) were extracted, and outcomes/complications were compared between patients treated with an ICD and those treated without one. Results: Of the 290 patients (approximately 10%) who met a guideline-based recommendation, 53 (18%) satisfied a class I/level B indication for an ICD; 56 (19%), a class I/level C indication; 19 (7%), a class IIa/level C indication; and 162 (56%), a class IIb/level B indication. However, most patients (156/290 [54%]) did not receive an ICD. Of those who received an ICD, 55 of 134 (41%) experienced ≥1 appropriate ventricular fibrillation–terminating ICD therapy, whereas ICD-related complications occurred in 13 patients (10%). Of those who were treated without an ICD, only 6 of 156 patients (4%) had nonlethal BCEs, which was significantly lower compared with the ICD group (P < .001). Conclusion: With >1200 years of combined follow-up, the experience and evidence from our 2 LQTS specialty centers suggest that many patients who satisfy a recommendation for an ICD based on the latest 2022 European Society of Cardiology guidelines may not need one. This is particularly true when the indication stemmed from a BCE while receiving beta blocker therapy or in asymptomatic patients with an increased 1-2-3-LQTS-Risk score.