Further testing also revealed that Letang, 26, has had a very small hole in the wall of his heart since birth. This small defect in the wall is present in all individuals before birth but seals shut in most people. It is possible that the hole in the heart led to the stroke.
The hole is between the two atria - not a hole leading into the thorax like it sounds. It is normal in everyone to have a hole called the foramen ovale - which shunts blood past the lungs due to blood being oxygenated by the mother while in the womb - its actually quite common that this does not fully close (into a fossa ovalis) in people after birth - but it is pretty uncommon that this would not be found in a high performance athlete by now.