Oh yes it can! There are many documented cases of patients who have had mild to moderate untreated dental infections that lead to serious, and even fatal heart complications. Our mouths are very dirty places and also very vascular and provide great access for bacteria into the blood stream. However, cause of death listed as Cardiopulmonary, does not mean that there was heart damage, it just means that the heart and lungs failed, causing death. The abcessed tooth may be unrelated.