Changes in Provider Prescribing Behavior for Infants with Single Ventricle Physiology After Evidence-Based Publications.

BACKGROUND: The impact of published evidence on clinical practice has been understudied in pediatric cardiology. OBJECTIVE: We sought to assess changes in prescribing behavior for angiotensin-converting enzyme inhibitor (ACEI) and digoxin at discharge after initial palliation of infants with single ventricle (SV) physiology following the publication of two large studies: The Pediatric Heart Network Infant Single Ventricle (PHN-ISV) trial showing no benefit with routine ACEI use and the National Pediatric Cardiology Quality Improvement Collaborative (NPC-QIC) analysis showing an association between digoxin and survival. METHODS: ICD-9-10 codes identified SV infants from the Pediatric Health Information System (1/2004 to 1/2018) and charge codes identified medications at discharge. Generalized estimating equations implementing segmented logistic regressions modeled medication use, before and after (with a 3-month washout period) the relevant publication (ACEI 7/1/2010; digoxin 4/1/2016). A subgroup analysis was performed for hypoplastic left heart syndrome (HLHS). RESULTS: ACEI use (37 centers, n = 4700) at discharge did not change over time during the pre-publication period. After publication of the PHN-ISV trial, ACEI use decreased (OR: 0.61, CI 0.44-0.84, p = 0.003). Digoxin use (43 centers, n = 4778) decreased by 1% monthly before publication. After the NPC-QIC publication, digoxin use increased (OR: 2.07, CI 1.05-4.08, p = 0.04) with an ongoing increase of 9% per month. Results were similar for the HLHS subgroup. CONCLUSIONS: Prescribing behavior changed congruently after the publication of evidence-based studies, with decreased ACEI use and increased digoxin use at discharge following initial palliation of SV infants. Our findings suggest scientific findings were rapidly implemented into clinical practice.

Whole Exome Sequencing and Heterologous Cellular Electrophysiology Studies Elucidate a Novel Loss-of-Function Mutation in the CACNA1A-Encoded Neuronal P/Q-Type Calcium Channel in a Child With Congenital Hypotonia and Developmental Delay.

BACKGROUND: A 4-year-old boy born at 37 weeks' gestation with intrauterine growth retardation presented with developmental delay with pronounced language and gross motor delay, axial hypotonia, and dynamic hypertonia of the extremities. Investigations including the Minnesota Newborn Screen, thyroid stimulating hormone/thyroxin, and inborn errors of metabolism screening were negative. Cerebral magnetic resonance imaging and spectroscopy were normal. Genetic testing was negative for coagulopathy, Smith-Lemli-Opitz, fragile X, and Prader-Willi/Angelman syndromes. Whole genome array analysis was unremarkable. METHODS: Whole exome sequencing was performed through a commercial testing laboratory to elucidate the underlying etiology for the child's presentation. A de novo mutation was hypothesized. In attempt to establish pathogenicity of our candidate variant, cellular electrophysiologic functional analysis of the putative de novo mutation was performed using patch-clamp technology. RESULTS: Whole exome sequencing revealed a p.P1353L variant in the CACNA1A gene, which encodes for the α1-subunit of the brain-specific P/Q-type calcium channel (CaV2.1). This presynaptic high-voltage-gated channel couples neuronal excitation to the vesicular release of neurotransmitter and is implicated in several neurologic disorders. DNA Sanger sequencing confirmed that the de novo mutation was absent in both parents and present in the child only. Electrophysiologic analysis of P1353L-CACNA1A demonstrated near complete loss of function, with a 95% reduction in peak current density. CONCLUSIONS: Whole exome sequencing coupled with cellular electrophysiologic functional analysis of a de novoCACNA1A missense mutation has elucidated the probable underlying pathophysiologic mechanism responsible for the child's phenotype. Genetic testing of CACNA1A in patients with congenital hypotonia and developmental delay may be warranted.