Collins, Kathryn K.

Implantable cardioverter-defibrillator (ICD) therapy in children and congenital heart disease (CHD) patients is hampered by poor long-term lead survival. Lead extraction is technically difficult and carries substantial morbidity. Manufacturers developed distinct strategies for this issue: thinner lead bodies or a Gore ePTFE coil coating. Both design changes were thought to improve ease of lead removal, but have not been directly compared in children or adults. The purpose of this study was to assess thin and ePTFE-coated ICD lead survival in pediatric and CHD pts. Methods: The Pediatric Lead Extractability and Survival Evaluation (PLEASE) Study began as a Phase IV multicenter open-label prospective study [ NCT00335036 ], facilitated by the Pediatric & Congenital EP Society. Initially designed as a randomized study, it changed to a parallel assignment registry when 1 lead had an advisory due to high incidence of failure, prompting concern about continued clinical equipoise. Pediatric and CHD pts who underwent ICD lead implant from 2005-2010 were eligible. The end date was NCDR ICD Registry v2.0 release (includes pediatric & lead data). 23 centers participated; each site obtained IRB approval. De-identified data was sent to the PI center for verification and statistical analyses. Results: A total of 982 ICD pts (357 VVI, 558 DDD, 67 CRT-D) entered the PLEASE study, incl. 423 pts (43%) with CHD. Mean age at implant = 18.3 ± 9.9 yrs. Thin (< 7Fr) ICD leads accounted for 51%, 23% were ePTFE-coated, 26% neither thin nor coated. There were 113 ICD lead failures (11.5%) at a mean lead-age of 2.2 ± 1.7 yrs, causing shocks in 55 pts. Failure occurred in 21% of thin leads vs 3.5% of ePTFE leads (p<0.01). Extraction was performed on 142 (14.5%) leads overall; 21% of thin leads (incl. extraction of 29 functioning leads due to recall) vs. 4.4% of ePTFE leads (p<0.01). There were 7 major extraction complications (4.9%), but no procedural mortality. Among thin leads, 90/270 (33.3%) of recalled leads failed vs 15/229 (6.6%) non-recalled thin leads. Conclusions: This Phase IV study demonstrates that ICD leads in children and CHD pts have suboptimal performance overall. Thinner leads were much more likely to fail and/or be extracted compared with ePTFE leads, chiefly driven by one lead type.

Background: Genetic variants in calsequestrin-2 ( CASQ2 ) cause an autosomal recessive form of catecholaminergic polymorphic ventricular tachycardia (CPVT), although isolated reports have identified arrhythmic phenotypes among heterozygotes. Improved insight into the inheritance patterns, arrhythmic risks, and molecular mechanisms of CASQ2 -CPVT was sought through an international multicenter collaboration. Methods: Genotype-phenotype segregation in CASQ2 -CPVT families was assessed, and the impact of genotype on arrhythmic risk was evaluated using Cox regression models. Putative dominant CASQ2 missense variants and the established recessive CASQ2-p.R33Q variant were evaluated using oligomerization assays and their locations mapped to a recent CASQ2 filament structure. Results: A total of 112 individuals, including 36 CPVT probands (24 homozygotes/compound heterozygotes and 12 heterozygotes) and 76 family members possessing at least 1 presumed pathogenic CASQ2 variant, were identified. Among CASQ2 homozygotes and compound heterozygotes, clinical penetrance was 97.1% and 26 of 34 (76.5%) individuals had experienced a potentially fatal arrhythmic event with a median age of onset of 7 years (95% CI, 6–11). Fifty-one of 66 CASQ2 heterozygous family members had undergone clinical evaluation, and 17 of 51 (33.3%) met diagnostic criteria for CPVT. Relative to CASQ2 heterozygotes, CASQ2 homozygote/compound heterozygote genotype status in probands was associated with a 3.2-fold (95% CI, 1.3–8.0; P =0.013) increased hazard of a composite of cardiac syncope, aborted cardiac arrest, and sudden cardiac death, but a 38.8-fold (95% CI, 5.6–269.1; P <0.001) increased hazard in genotype-positive family members. In vitro turbidity assays revealed that p.R33Q and all 6 candidate dominant CASQ2 missense variants evaluated exhibited filamentation defects, but only p.R33Q convincingly failed to dimerize. Structural analysis revealed that 3 of these 6 putative dominant negative missense variants localized to an electronegative pocket considered critical for back-to-back binding of dimers. Conclusions: This international multicenter study of CASQ2 -CPVT redefines its heritability and confirms that pathogenic heterozygous CASQ2 variants may manifest with a CPVT phenotype, indicating a need to clinically screen these individuals. A dominant mode of inheritance appears intrinsic to certain missense variants because of their location and function within the CASQ2 filament structure.

AbstractBackgroundAxillary implant location is an alternative implant location in patients for cardiac implantable electronic devices (CIEDs) for the purposes of improved cosmetic outcome. The impact from the patient's perspective is unknown. The purpose of this study was to compare scar perception scores and quality of life (QOL) in pediatric patients with axillary CIED implant location versus the standard infraclavicular approach.MethodsThis is a multicenter prospective study conducted at eight pediatric centers and it includes patients aged from 8 to 18 years with a CIED. Patients with prior sternotomy were excluded. Scar perception and QOL outcomes were compared between the infraclavicular and axillary implant locations.ResultsA total of 141 patients (83 implantable cardioverter defibrillator [ICD]/58 pacemakers) were included, 55 with an axillary device and 86 with an infraclavicular device. Patients with an ICD in the axillary position had better perception of scar appearance and consciousness. Patients in the axillary group reported, on average, a total Pediatric QOL Inventory score that was 6 (1, 11) units higher than the infraclavicular group, after adjusting for sex and race (P = 0.02).ConclusionsQOL is significantly improved in axillary in comparison to the infraclavicular CIED position, regardless of device type. Scar perception is improved in patients with ICD in the axillary position.