A decade of Paris marathon data puts a number on cardiac arrest risk. Most survive.

With the spring marathon season underway, a decade of data out of Paris offers one of the more precise pictures available of how often endurance runners actually suffer sudden cardiac arrest — and what happens to them afterward. The answer, published in the cardiology journal Europace: the event is rare, disproportionately affects men, and, when it does happen, most runners survive with their brain function intact [s1].

What the registry covers

Researchers analyzed the Paris Sudden Death Expertise Centre Registry, which tracked cardiac arrest cases at the city's half marathon, full marathon, and 20-kilometer race events from 2011 through 2024, excluding 2020 [s1]. Across roughly 1.2 million total participants over that period, the registry identified 17 cases of sports-related sudden cardiac arrest [s1].

The numbers

The crude incidence worked out to 16.9 cases per million participants among men and 5.7 per million among women [s1] — men account for 88% of the cases identified [s1]. The study's authors also looked at where in a race arrest tended to strike, finding that it was overrepresented in the final kilometers specifically in the shorter races [s1]. Pace data showed men accelerated at roughly twice the rate women did in that late stage, which the researchers suggest may point to a behavioral or physiological factor — pushing harder in a final sprint — contributing to the sex gap in risk, though the study stops short of establishing that as a confirmed mechanism [s1].

Despite extensive medical workups, researchers could not identify an underlying cause in 47.1% of the cases — a reminder that "unexplained" is a common, not unusual, outcome even with modern cardiac investigation [s1].

The outcome that matters most to runners

The figure most relevant to anyone lacing up for a spring marathon is survival: 88% of the runners who suffered a cardiac arrest during these races — 15 of 17 — survived to hospital discharge, and of those survivors, all but one recovered with the best possible neurological outcome on the standard scale used to measure it [s1]. That high survival rate is generally attributed in the endurance-sports medicine literature to the density of trained bystanders, on-course medical staff, and rapid defibrillator access at major organized road races — conditions that don't apply to a solo run on a quiet street, though this study did not compare outcomes between race and non-race settings.

What this does and doesn't mean for a runner

Sudden cardiac arrest during a race remains, by this data, a very low-probability event — on the order of 1 in 60,000 for men and roughly 1 in 175,000 for women, based on the incidence rates reported [s1]. The study does not attempt to weigh that risk against the well-documented cardiovascular benefits of regular endurance training, and it is not designed to tell any individual runner whether their personal risk is elevated; the near-half of cases with no identifiable cause underscores that current screening cannot catch everything. What the ten years of Paris data does offer is a rare, large-sample answer to a question that's usually addressed with anecdote: arrest is uncommon, it skews heavily toward men accelerating late in shorter races, and when it happens at an organized event with medical support in place, most runners walk away from it intact.