BY Morten Busch
A new Danish study investigated young people who died suddenly from heart attacks and concluded that twice as many men as women die from sudden cardiac arrest. It also concludes that men die much more frequently after physical activity, whereas women die more often in their sleep.
Heart attacks are often unexpected among people 1–35 years old but are a frequent cause of death in this age group, accounting for 7% of the deaths. Danish researchers recently investigated the deaths of 8756 young people in the past decade to see whether young women and men differ in death rates from sudden cardiac arrest.
“The pattern was extremely clear for each age group we investigated. Twice as many men as women die from sudden cardiac arrest,” explains Jacob Tfelt-Hansen, a cardiologist at the Heart Center of Rigshospitalet in Copenhagen, Clinical Research Associate Professor at the Department of Clinical Medicine of the University of Copenhagen and a main author of the study.
6–7 times more men die during physical activity
The study is the first to investigate the gender differences among people 1–35 years old who die suddenly from a heart attack. Although it has previously been shown that twice as many men as women die from sudden cardiac arrest has been observed previously, it is still surprising that this pattern is so clear in this young population group.
“This is surprising because we assume that about the same number of men and women inherit the same heart diseases from their parents. It is also therefore reasonable to believe that the same number of men and women would die from sudden cardiac arrest. However, this is not true. Some unknown factor therefore protects women from having heart attacks. We do not yet know what this is, but since this pattern is repeated among young people, examining this further would be extremely interesting,” explains Bo Gregers Winkel, the first author of the article and a cardiologist at the Heart Center of Rigshospitalet.
The study determined the circumstances under which the men and women die, and this provides a reason why more men die from sudden cardiac arrest. The researchers found that 6–7 times more men than women died after physical activity, including sports.
“One of our theories is that men and women have the same level of heart disease, but men have more difficulty in taking care of themselves and determining their limits. This may explain why so many men die after strenuous physical activity. In contrast, more women die from heart attacks while sleeping. This hardly results from them being more physically inactive, and the explanation is unclear.”
Psychosocial factors could be important
Denmark’s unique global position enabled the study. Denmark has population-based registries that enable statistics on disease and the causes of death, showing the reasons and trends. Another unique factor makes studies of sudden death much more precise in Denmark.
“When a person dies unexpectedly in Denmark, the law mandates a thorough forensic autopsy. This means that death certificates and autopsy reports reveal the precise location where a person died and the reasons. We can thus also better explain these tragic and incomprehensible deaths of young people,” explains Jacob Tfelt-Hansen.
It is still too early to determine whether the considerable differences between men and women can be explained by disease expressivity or by an unknown factor that protects women. The researchers hope that physiological studies of animals may determine whether the differences result from the differences in physiology between women and men, such as oestrogen or testosterone concentrations, or whether gender-based psychosocial factors may be important.
“Gender differences in sudden cardiac death in the young – a nationwide study” has been published in BMC Cardiovascular Disorders. In 2014, the Novo Nordisk Foundation awarded a grant to Jacob Tfelt-Hansen for the project Risk Factors for Sudden Cardiac Death During Acute Myocardial Infarction (MI-RISK).