Systemic-Pulmonary Collaterals in KCNT1-Related Disorders: Precise Nomenclature and Management

Pathogenic variants in KCNT1, a gene encoding a sodium-activated potassium channel, are classically associated with severe early-onset epileptic encephalopathies. Emerging evidence indicates that some individuals with KCNT1-related disorders also develop systemic-to-pulmonary vascular anomalies, often initially misidentified as major aortopulmonary collateral arteries (MAPCAs) due to radiographic similarities with congenital heart disease. Unlike true MAPCAs, these vessels arise in the absence of structural cardiac defects and appear to result from abnormal angiogenesis driven by dysregulated KCNT1-mediated signaling. Misclassification may lead to inappropriate interventions or management strategies. Here, a multidisciplinary expert working group reviewed published cases, institutional experience, and imaging findings to develop an expert opinion for nomenclature, diagnosis, and management of these vascular anomalies. We recommend adopting the term systemic-pulmonary collaterals (SPCs) to accurately describe these angiogenic vessels. Risk-based screening, judicious catheter-based embolization when physiologically indicated, and careful avoidance of standard pulmonary vasodilators are emphasized. This statement aims to improve clinical recognition, precision in terminology, and safe management of vascular complications in patients with KCNT1-related disorders.