There is a relationship between sudden cardiac death and sport. However it is important to emphasise that sport is good for the heart. Sport reduces the risk of high blood pressure, it improves cholesterol levels and generally, it reduces the risk of someone dying from a cardiac problem. Indeed people who play sport on a regular basis live an average of six years more than people who don’t play any sport at all.
However, if an individual that plays sport harbours a condition that’s capable of causing sudden cardiac death – such as hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy or a blocked artery – then sport is three times more likely to kill that individual. So there’s a bit of an irony, sport promotes longevity of life and reduces the risk of death from a cardiac problem but increases the risk of sudden death in an individual who already has a cardiac condition.
I don’t believe that sport per se actually causes a cardiac problem that will pre-dispose to sudden death.