Fatal Water Intoxication and Cardiac Arrest in Runners During Marathons: Prevention and Treatment Based on Validated Clinical Paradigms
As marathons have become more popular, literature has focused on potential adverse outcomes including cerebral edema and sudden cardiac arrest during these endurance running events. The author of this study proposes a link between cerebral edema caused by hyponatremia and cardiac arrest caused by atherosclerosis, suggesting a simple solution to target high-risk populations engaging in marathon running. Exercise-associated hyponatremia was initially thought to be attributable to excessive free-water intake during sporting events and led to the “drink to thirst” campaign. Further studies have found that skeletal muscle breakdown, known as rhabdomyolysis, during sporting events causes secretion of vasopressin, compounding the development of hyponatremia in endurance athletes. Because of osmotic shifts, severe hyponatremia can cause cerebral edema that is essential to recognize and treat with hypertonic saline to avoid neurological injury.
Although the rate of cardiac arrest during marathon running is relatively low at 0.2 per 100,000 running hours, the average age of cardiac arrest patients was 42 years old and atherosclerotic heart disease was the most common cause. The biochemical cascade in the setting of extreme physical exertion of a marathon event creates an ideal situation for atherosclerotic plaque rupture in vulnerable middle-aged men. Prerace aspirin has been proposed to provide antithrombotic protection and is concordant with recommendations from the American Heart Association, which endorses primary prophylaxis for high-risk subgroups.
The author proposes that middle-aged men engaging in marathon running are at higher risk for both cerebral edema owing to hyponatremia and cardiac arrest caused by underlying atherosclerosis. To avoid preventable deaths in susceptible marathon runners, the author’s recommendation is to take a low-dose aspirin before the race and to drink to thirst during the race. Future studies are needed to investigate these recommendations to determine efficacy.
(Am J Med. 2015 April; Epub) AJ Siegel.
Prepared by Matthew Stewart, MD, FAWM, University of Utah Emergency Medicine Global Health Fellow, Salt Lake City, UT, USA.