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Treating the long-QT syndrome in the era of implantable defibrillators.

We live in an era of defensive medicine. Implantable cardioverter defibrillators (ICDs) increasingly are used to treat patients with congenital long-QT syndrome (LQTS), although not always with compelling indications.1 In different series, some patients underwent ICD implantation without ever receiving β-blockers,1–3 others never had symptoms1,4 and a few did not even have LQTS to begin with.5 A few studies probably boosted the use of ICDs in LQTS: (1) In a case-control study2 comparing ICD therapy with conservative management in high-risk patients with LQTS, ICDs were associated with decreased 3-year mortality (1.3% versus 16%, P =0.07). However, as explained elsewhere,6 the mortality reduction associated with the ICD was probably overestimated in that study, because 26% of conservatively managed patients did not receive β-blockers after the cardiac arrest, and some died shortly thereafter, probably due to sequelae of the cardiac arrest. (2) Several studies3,4,7,8 showed that high proportions (22% to 60%) of ICD-treated patients with LQTS receive appropriate ICD shocks within 2 to 5 years (Table). These impressive rates of life-saving therapy probably convinced many physicians that ICDs may be the treatment of choice for LQTS; however, these high rates of “life-saving therapy” (higher than the expected mortality in LQTS)9 could be related in part to the definition of “appropriate ICD therapy.” In these studies, appropriate ICD therapy was defined as an “ICD shock that terminated a ventricular tachyarrhythmia,” regardless of its duration and whether or not it caused symptoms. As appreciated from the Table, only 2 of the studies reported the parameters used for detection of ventricular arrhythmias. One can calculate that ICD shocks in these studies were probably delivered within 10 to 12 seconds from arrhythmia onset (Table). This is consequential, because torsade de pointes often terminates spontaneously (Figure). It is …