Exercise Collapse Associated With Sickle Cell Trait: Diagnosis, Treatment, Prevention, Current Controversies, and Gaps in the Literature

Sickle cell trait (SCT) is often benign but can be associated with occasional hemoglobin sickling, particularly in the setting of physical exertion. Screening for SCT, while controversial, reduces exertional events and death. Exertional sickling (ES) is the presumed and hypothesized etiology of collapse and death in athletes, where sickling, microvascular occlusion, and muscle necrosis result in ischemia, hyperkalemia, arrhythmia, and fulminant rhabdomyolysis. Due to the lack of clarity surrounding ES, the term exercise collapse associated with SCT (ECAST) was developed to describe individuals with SCT who suffer from an exertional collapse. Certain environmental and physical conditions may increase the likelihood of ECAST, but prompt recognition and treatment may reduce morbidity and mortality. This narrative review identifies current evidence regarding ECAST and discusses treatment, prevention, recent controversies, and gaps in the literature, highlighting that knowledge of SCT among athletes, warfighters, and their supervisors remains inadequate.