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Background-Targeted postmortem genetic testing of the 4 major channelopathy-susceptibility genes (KCNQ1, KCNH2, SCN5A, and RYR2) have yielded putative pathogenic mutations in ≤30% of autopsy-negative sudden unexplained death in the young (SUDY) cases with highest yields derived from the subset of exertion-related SUDY. Here, we evaluate the role of whole-exome sequencing in exertion-related SUDY cases. Methods and Results-From 1998 to 2010, 32 cases of exertion-related SUDY were referred by Medical Examiners for a cardiac channel molecular autopsy. A mutational analysis of the major long-QT syndrome-susceptibility genes (KCNQ1, KCNH2, and SCN5A) and catecholaminergic polymorphic ventricular tachycardia-susceptibility gene (RYR2) identified a putative pathogenic mutation in 11 cases. Whole-exome sequencing was performed on the remaining 21 targeted genenegative SUDY cases. After whole-exome sequencing, a gene-specific surveillance of all genes (N=100) implicated in sudden death was performed to identify putative pathogenic mutation(s). Three of these 21 decedents had a clinically actionable, pathogenic mutation (CALM2-F90L, CALM2-N98S, and PKP2-N634fs). Of the 18 remaining cases, 7 hosted at least 1 variant of unknown significance with a minor allele frequency <1:20 000. The overall yield of pathogenic mutations was higher among decedents aged 1 to 10 years (10/11, 91%) than those aged 11 to 19 years (4/21, 19%, P=0.0001). Conclusions-Molecular screening in this clinical scenario is appropriate with a pathogenic mutation detection rate of 44% using direct DNA sequencing followed by whole-exome sequencing. Only 5 of the 100 interrogated sudden death genes hosted actionable pathogenic mutations for more than one third of these exertion-related, autopsy-negative SUDY cases.

BackgroundStenosis of the venous connections and conduits is a well‐known late complication of the Fontan procedure. Currently, data on the outcomes of percutaneous intervention for the treatment of extra‐ or intracardiac conduits and lateral tunnel baffles obstruction are limited. In an attempt to better define the nature and severity of the stenosis and the results of catheter interventional management, we reviewed Fontan patients with obstructed extra‐ or intracardiac conduits and lateral tunnel baffles.MethodsRetrospective review of all Fontan patients who had cardiac catheterization from January 2002 to October 2018 was performed. Hemodynamic and angiographic data that assessed extra‐ or intracardiac conduit, or lateral tunnel baffle obstruction/stenosis were evaluated.ResultsTwenty patients underwent catheter intervention because of conduit stenosis, including calcified homografts, stenotic Gore‐Tex conduits and obstructed lateral tunnels. Six other patients had Fontan obstruction but were referred for surgical revision. After stenting, there was a significant reduction in the connection gradient [2.0 mm Hg (IQR 2; 3) vs 0 mm Hg (IQR 0; 1), P < .0001]. Fontan conduit/connection diameter increased [10.5 mm (IQR 9; 12) vs 18 mm (IQR 14.9; 18); P < .0001] and New York Heart Association class [III (IQR II; III) vs I (IQR II; III); P = .03) with stent placement.ConclusionsWe demonstrated the hemodynamics and angiographic subtypes of conduit stenosis in patients after Fontan, We showed that calcified homografts, stenotic Gore‐Tex conduits and lateral tunnels pathways can be safely and effectively stented to eliminate obstruction. Percutaneous stenting is associated with a decrease in connection gradients and improvement in functional capacity.