Atrial Standstill in the Pediatric Population: A Multi-Institution Collaboration.

BACKGROUND: Atrial standstill (AS) is a rare condition characterized by absence of electrical activity within the atria. Studies to date have been limited. OBJECTIVES: The authors sought to describe the clinical characteristics, genetics, and outcomes of patients with AS. METHODS: This was a retrospective multicenter study of patients <18 years at AS diagnosis, defined as absence of atrial activity documented during an electrophysiology study, device placement, or noninvasive rhythm tracings and confirmed by echocardiogram. Patients with acquired disorders were excluded. Clinical details and genetic variants were recorded and analyzed. RESULTS: Twenty patients were diagnosed at a median age of 6.6 years (IQR: 2.9-10.8 years). Arrhythmias included 16 (80%) with atrial/supraventricular arrhythmias and 8 (40%) with ventricular tachycardia, including 4 with cardiac arrests. A type 1 Brugada pattern was documented in 4. Pacemakers were implanted in 18 (90%). Although atrial leads were attempted in 15, only 4 achieved pacing at implantation. During a median follow-up of 6.9 years (IQR: 1.2-13.3 years), 7 (35%) had thromboembolic events. Of these, none had atrial pacing, 6 were not on anticoagulation, and 1 was on aspirin. Genetic testing identified SCN5A variants in 13 patients (65%). Analyses suggest SCN5A loss-of-function may be one mechanism driving AS. Ventricular arrhythmias and cardiac arrest were more commonly seen in patients with biallelic SCN5A variants. CONCLUSIONS: AS may be associated with loss-of-function SCN5A variants. Patients demonstrate atrial and ventricular arrhythmias, and may present challenges during device placement. Patients without the capacity for atrial pacing are at risk for thromboembolic events and warrant anticoagulation.

Utility of incomplete right bundle branch block as an isolated ECG finding in children undergoing initial cardiac evaluation.

OBJECTIVE: This study evaluates the ability of experienced pediatric electrophysiologists (EPs) to reliably classify incomplete right bundle branch block (IRBBB) and assesses its clinical utility as an isolated ECG finding in a group of healthy outpatient children without prior cardiac evaluation. DESIGN: We performed a retrospective analysis of all electrocardiographic and echocardiographic records at Boston Children's Hospital between January 1, 2005, and December 31, 2014. Echocardiographic diagnoses were identified if registered between the date of the index electrocardiogram and the ensuing year. A selected subset of 473 ECGs was subsequently reanalyzed in a blinded manner by six pediatric EPs to determine the consistency with which the finding of IRBBB could be assigned. RESULTS: Of the 331 278 ECGs registered in the BCH database, 32 127 (9.7%) met inclusion criteria and were analyzed for the prevalence of isolated right bundle conduction disturbance findings. The mean age was 12.1 ± 4.0 years, and the population was 49% male. Of the 32 127 ECGs, 72.5% were coded normal, 3.0% were coded IRBBB, and 0.5% were coded complete right bundle branch block (CRBBB). A total of 7.3% of patients coded as normal had an ensuing echocardiogram, compared to 12.5% coded IRBBB. Echo findings were recorded in 0.1% of normal and 0.2% of IRBBB. Patients with ASD-secundum type were no more likely to have isolated IRBBB on previous ECG than the general population (2.5% vs 3.0%). Analysis of inter-reader variability in ECG findings and conduction disturbance identification was high (range of IRBBB prevalence 1-20% among readers). Reinterpretation of ECGs using explicit diagnostic criteria did not demonstrate consistent discrimination of IRBBB and Normal ECGs. CONCLUSIONS: IRBBB is not uncommon in a healthy school age population and is observed to have high inter-reader variability. It was associated with increased use of echocardiographic exam but was not associated with increased rate of echocardiographic findings when compared with rates for normal ECGs.

Time dependence of risks and benefits in pediatric primary prevention implantable cardioverter-defibrillator therapy.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) used to prevent sudden cardiac arrest in children not only provide appropriate therapy in 25% of patients but also result in a significant incidence of inappropriate shocks and other device complications. ICDs placed for secondary prevention have higher rates of appropriate therapy than those placed for primary prevention. Pediatric patients with primary prevention ICDs were studied to determine time-dependent incidence of appropriate use and adverse events. METHODS AND RESULTS: A total of 140 patients aged <21 years (median age, 15 years) at first ICD implantation at Boston Children's Hospital (2000-2009) in whom devices were placed for primary prevention were retrospectively identified. Demographics and times to first appropriate shock; adverse events (including inappropriate shock, lead failure, reintervention, and complication); generator replacement and follow-up were noted. During mean follow-up of 4 years, appropriate shock occurred in 19% patients and first adverse event (excluding death/transplant) occurred in 36%. Risk of death or transplant was ≈1% per year and was not related to receiving appropriate therapy. Conditional survival analysis showed rates of appropriate therapy and adverse events decrease soon after implantation, but adverse events are more frequent than appropriate therapy throughout follow-up. CONCLUSIONS: Primary prevention ICDs were associated with appropriate therapy in 19% and adverse event in 36% in this cohort. The incidence of both first appropriate therapy and device-related adverse events decreased during longer periods of follow-up after implantation. This suggests that indications for continued device therapy in pediatric primary prevention ICD patients might be reconsidered after a period of nonuse.

Absolute vs relative improvements in congenital diaphragmatic hernia survival: what happened to "hidden mortality".

PURPOSE: The aim of this study is to determine if there has been a true, absolute, or apparent relative increase in congenital diaphragmatic hernia (CDH) survival for the last 2 decades. METHOD: All neonatal Bochdalek CDH patients admitted to an Ontario pediatric surgical hospital during the period when significant improvements in CDH survival was reported (from January 1, 1992, to December 31, 1999) were analyzed. Patient characteristics were assessed for CDH population homogeneity and differences between institutional and vital statistics-based population survival outcomes. SAS 9.1 (SAS Institute, Cary, NC) was used for analysis. RESULT: Of 198 cohorts, demographic parameters including birth weight, gestational age, Apgar scores, sex, and associated congenital anomalies did not change significantly. Preoperative survival was 149 (75.2%) of 198, whereas postoperative survival was 133 (89.3%) of 149, and overall institutional survival was 133 (67.2%) of 198. Comparison of institution and population-based mortality (n = 65 vs 96) during the period yielded 32% of CDH deaths unaccounted for by institutions. Yearly analysis of hidden mortality consistently showed a significantly lower mortality in institution-based reporting than population. CONCLUSION: A hidden mortality exists for institutionally reported CDH survival rates. Careful interpretation of research findings and more comprehensive population-based tools are needed for reliable counseling and evaluation of current and future treatments.

Misuse of baseline comparison tests and subgroup analyses in surgical trials.

It is unclear whether the misuse of statistical tests that compare patients' baseline characteristics and subgroup analyses in randomized controlled trials can be extrapolated to the surgical literature. We did an observational study evaluating the current use of baseline comparability tests and subgroup analyses in surgical randomized controlled trials. Published surgical randomized controlled trials in four medical journals were identified. We also identified randomized controlled trials in the Journal of Bone and Joint Surgery (American and British volumes). We identified 72 randomized controlled trials, with a mean of 10 +/- 8 baseline variables. Of 166 significance tests, 17 (10%) were significant. Twenty-seven (38%) trials included 54 subgroup analyses with a minimum of one and maximum of 23 subgroup analyses per study. Inappropriate emphasis on subgroup analyses occurred frequently. Forty-nine (91%) analyses were performed post hoc without prior hypotheses. Investigators reported differences between subgroups in 31 (57%) of the analyses, all of which were featured in the summary or conclusion. These inferences may be misleading, making their application to clinical practice unwarranted.

Management of suspected common bile duct stones in children: role of selective intraoperative cholangiogram and endoscopic retrograde cholangiopancreatography.

BACKGROUND: Evidence for diagnostic accuracy and clinical efficacy of intraoperative cholangiogram (IOC) and endoscopic retrograde cholangiopancreatography (ERCP) in the management of common bile duct (CBD) stones in children is sparse and unclear. METHODS: Retrospective analysis of 202 children who underwent laparoscopic cholecystectomy (LC) between 1996 and 2002 was performed. Forty-eight children had suspected CBD stones on clinical, biochemical, and radiologic grounds. Two clinical pathways, LC followed by ERCP (L-->E) versus ERCP followed by LC (E-->L) were compared. RESULTS: From the cohort of 202 patients, 154 did not have suspected CBD stones. Of the 48 patients that did have suspected stones, 2 management pathways were followed: (1) ERCP first: 14 of 48 patients (including 1 failed examination). Three yielded positive findings on ERCP. Ten had negative findings on ERCP, 3 of which went on to have a subsequent IOC. All 3 had negative IOC examination findings. (2) LC +/- IOC first: 34 of 48 patients. Twenty-eight had negative findings on IOC and had no further investigations. Three patients had positive IOC examination findings and went on to have postoperative ERCP. Two of these 3 patients were positive for CBD stones. The remaining 3 of 34 patients had LC with no IOC followed by ERCP. Only 1 of 3 patients yielded a positive examination finding on ERCP. Therefore, of the 168 patients that did not have IOC, only 1 stone (0.6%) would have been missed using the selective criteria. Of those that did meet the criteria for IOC, only 2 of 31 (6.5%) had positive examination findings. There were no adverse effects of a retained or passed stone during our study, nor where there complications in those who had a concomitant sphincterotomy (12 of 20 ERCP patients, mean follow-up of 4.2 years). IOC and ERCP findings correlated in all 6 of the patients in which both procedures were performed. CONCLUSIONS: Selective IOC with LC is an acceptable and safe initial approach in suspected CBD. Most CBD stones in children pass spontaneously. Endoscopic sphincterotomy appears to be safe with no long-term sequelae.