Histopathology of the Conduction System in Long QT Syndrome.

While much is known about the channelopathy disorder Long QT Syndrome (LQTS), the histopathological findings and their implications on the disease have remained largely unexplored to date. In this review, we discuss the background of LQTS and highlight the importance of histological findings in the absence of genetic markers or when genetic testing is unavailable. Three pediatric cases of LQTS were identified, evaluated histologically, and compared to two adult cases. Histological examination of three pediatric LQTS patients demonstrated fibrotic alterations to the cardiac conduction system with markedly decreased conductive tissue density and volume. Both adult cases revealed fibrosis with similar reductions in tissue volume. When diagnostic methods such as genetic testing are unavailable, histopathology offers clinicians an alternative tool for postmortem diagnosis of LQTS when considered alongside clinical presentation. Confirmation of diagnosis in a proband can prevent the death of relatives in hereditary LQTS.