A new study of young athletes shows a possible link between sleep-disordered breathing and sudden cardiac death.
Sudden cardiac death, also known as sudden arrhythmia death syndrome (SADS), is when someone dies suddenly following a cardiac arrest and no obvious cause can be found.
It is estimated that more than 5,000 people die of sudden cardiac death in Ireland each year. While the majority of these deaths occur from late middle age onwards as a result of coronary heart disease, a small percentage of these deaths occur in people under the age of 40 years. These deaths have gained national attention, particularly in the sports world, following the deaths of a number of athletes.
Now, a new study of university rugby players has shown they are more likely to suffer sleep-disordered breathing (SDB) than an average middle-aged man. SDB is characterised by abnormal respiratory patterns or pauses in breathing during sleep, ranging from snoring to sleep apnea.
The study, published in ERJ Open Research, showed that the athletes who experience this problem are also more likely to have low levels of oxygen in their blood and higher pulse rates during the night, suggesting that athletes with SDB may be at risk of heart abnormalities.
According to researchers, this could indicate that SDB is a factor in the phenomenon of seemingly healthy young athletes dying from a sudden and unexplained heart attack.
If untreated, patients with SDB-related conditions face an increased risk of developing chronic diseases such as cardiovascular disease, heart failure and type 2 diabetes.
Yoshitaka Iso is a cardiologist and associate professor at Showa University Research Institute for Sport and Exercise Sciences in Japan. Iso said we tend to assume that young, competitive athletes will not experience conditions such as SDB, which are more common in people with a higher BMI and inactive lifestyles.
“But more research is needed to determine what may be contributing to sudden cardiac death in athletes, and SDB is a good candidate for this as it can affect the heart’s normal functions.”
Higher than expected
In the study, a special device was used to monitor overnight changes in the athletes’ breathing rhythm, heartbeats and heart rate, blood oxygen levels, the number of times they woke up, and how long they were awake for.
The data showed that more than 40pc of athletes met the criteria for SDB. Those athletes had higher average heart rates and lower levels of oxygen in their blood than athletes who did not have SDB.
Iso said that not only was this rate higher than expected for athletes, but it’s higher than the levels of SDB reported among middle-aged men from the general population of the US and Europe.
“Although none of the athletes in this study were found to have serious conditions yet, likely due to their young ages, we do not know how their conditions may worsen in the future due to associated cardiovascular consequences.”
While a link between SDB and abnormal heart functions could point to more ways to screen for warning signs against SADS, it is still too early to conclude SDB as a definite factor. The researchers said that additional large studies are necessary to confirm their results and to determine the underlying mechanisms that lead to SDB.
They also noted that a limitation of the study was that the SDB assessment was only performed on a single night.