 CORONARY ARTERY DISEASE AND THE BENEFIT OF BYPASSES Despite considerable advances in medicine, cardiovascular diseases remain the number one cause of death globally. In industrialized countries, coronary artery disease CAD is the leading cause of death, consequence of myocardial infarction MI. Artificial - or natural - bypasses exert a protective effect by providing an alternative source of blood flow to a myocardial territory potentially affected by an acute coronary occlusion. Coronary collaterals represent pre-existing inter-arterial anastomoses and as such are the natural counter-part of surgically created bypasses. In patients with chronic CAD, sufficient coronary collaterals have been shown to confer a significant benefits in terms of overall mortality and cardiovascular events. 