Sports-related sudden cardiac deaths: Why do men have it worse?
When it comes to sports-related* sudden cardiac death (SCD) rates, men appear to have it worse than women, according to data presented at EHRA 2022.
There is a striking difference between males and females in terms of SCD incidence, noted Dr Moniek Cox from the University Medical Center Groningen, the Netherlands. "Across 13 studies on SCD, men are way overrepresented, yielding a ratio of 7:1 – even up to 32:1.”
Women’s participation in sports has markedly evolved over the years. The 2-percent female participation rate in the Paris Olympic Games in 1900 rose to 48 percent during the 2020 Tokyo Olympic Games.
But back in the day, sports was a male-dominated scene. “[At the time,] women’s femininity and fragility were taken into account,” noted Cox. Furthermore, SCD rates rise as men age. Whereas for women, the rate remains consistent across all age intervals**. [Circ Arrhythm Electrophysiol 2013;6:1185-1191] “[These] might explain why more men die during sports compared with women.”
Hormones. One of the things that could explain for the difference in SCD incidence between men and women is hormones. “[For one,] the testosterone binding to androgen receptors directly promotes hypertrophy, whereas oestrogen protects against hypertrophy,” explained Cox. “[Moreover,] studies have shown that testosterone has a QT shortening effect, whereas oestrogen has a QT prolonging effect.”
Hormones may also influence RV remodelling and the development of arrhythmogenic cardiomyopathy. “Looking at the electrocardiograms of athletes, males have much more right ventricular dimensions that fulfil the ARVC*** diagnostic criteria than females do,” added Cox.
Coronary artery disease. More men die from coronary artery disease than women. In one study, there were twice as many male athletes with coronary plaques compared with their sedentary counterparts (44 percent vs 22 percent; p=0.009). This difference was not present in females. [Circulation 2017;136:126-137]
Autonomic tone. In the presence of underlying cardiac disease, vagal tone is much higher in women. “Vagal activation is more often activated [in women]. When looking at studies done in men during exercise, they had much higher adrenalin concentrations than females,” said Cox.
Blood pressure. In a study on asymptomatic triathletes, fibrosis was detected in males but not in females (17 percent vs 0 percent; p<0.05). [JACC Cardiovasc Imaging 2018;11:1260-1270] “This fibrosis was associated with higher blood pressure during peak exercise and with longer training or racing distances,” said Cox. “In general, men had higher blood pressure during exercise than women. The fibrosis, which was thought to be inflammation-related, might be a substrate for ventricular tachycardias.”
Taken together, these factors may explain for the higher incidence of sports-related SCDs in men than in women. “It appears that in men, you have to look more for structural abnormalities, whereas in women, arrhythmic diseases are the most common causes of SCDs,” said Cox.