Beinart, Roy

Background Sex‐specific risk management may improve outcomes in congenital long QT syndrome (LQTS). We recently developed a prediction score for cardiac events (CEs) and life‐threatening events (LTEs) in postadolescent women with LQTS. In the present study, we aimed to develop personalized risk estimates for the burden of CEs and LTEs in male adolescents with potassium channel‐mediated LQTS. Methods and Results The prognostic model was derived from the LQTS Registry headquartered in Rochester, NY, comprising 611 LQT1 or LQT2 male adolescents from age 10 through 20 years, using the following variables: genotype/mutation location, QTc‐specific thresholds, history of syncope, and β‐blocker therapy. Anderson‐Gill modeling was performed for the end point of CE burden (total number of syncope, aborted cardiac arrest, and appropriate defibrillator shocks). The applicability of the CE prediction model was tested for the end point of the first LTE (excluding syncope and adding sudden cardiac death) using Cox modeling. A total of 270 CEs occurred during follow‐up. The genotype–phenotype risk prediction model identified low‐, intermediate‐, and high‐risk groups, comprising 74%, 14%, and 12% of the study population, respectively. Compared with the low‐risk group, high‐risk male subjects experienced a pronounced 5.2‐fold increased risk of recurrent CEs ( P <0.001), whereas intermediate‐risk patients had a 2.1‐fold ( P =0.004) increased risk . At age 20 years, the low‐, intermediate‐, and high‐risk adolescent male patients had on average 0.3, 0.6, and 1.4 CEs per person, respectively. Corresponding 10‐year adjusted probabilities for a first LTE were 2%, 6%, and 8%. Conclusions Personalized genotype–phenotype risk estimates can be used to guide sex‐specific management in male adolescents with potassium channel‐mediated LQTS.

AbstractAimsIntraoperative defibrillation testing (DT) during implant or replacement of implantable cardioverter-defibrillators (ICDs) has been a matter of debate for many years. This debate was put to rest by the Simple and Nordic ICD trials, and the practice of testing during new implantations has essentially been almost abandoned. Old registries demonstrated an increased incidence of significant findings in DT during replacements. The aim of the present study was to evaluate frequency of significant findings and safety of DT in subjects undergoing device replacement.Methods and resultsA prospective observational multi-centre study included consecutive patients undergoing ICD generator replacement. The primary outcome was a failure to terminate induced ventricular fibrillation (VF) with a single shock 10 J below the maximal capacity of the device. Secondary outcomes included complications of DT. Patients were followed-up at 1- and 6-months post-procedure. A total of 92 patients were eligible, and consented to the study, of which 84 underwent DT during battery replacement. The median age was 68 years and 79.8% were males. Induction of VF was successful in 84 patients as was a successful conversion on the first attempt in all. There were no procedure-related complications. During follow up one patient had two appropriate ICD shock events. In four patients, ICD programming was changed. None suffered inappropriate shock. There was no evidence of lead malfunction. Two deaths occurred, none of which was related to arrhythmia.ConclusionThe present study found DT was not associated with complications in patients undergoing ICD generator replacement but produced no clinically important information.