The medical profession don't really know what causes a sudden cardiac arrest. There is a common misconception that it is definately linked to heart defects, but it is not mostly the case. SCA's are an 'electrical' problem, where as heart attacks are ' plumbing' issues.
SCA's can be infections or nerve problems, so best not to lump them all together. I was fit, normal blood pressure, cholestrol and BP ( was told my heart was strong after tests 6 weeks before) until just before. I got lucky. I get to see great football still.There has been an increase in defib units, but more are needed and a national database, easily accessable, of where they are.