Arteriogenesis – Therapeutic Stimulation of the Coronary Collateral Circulation

The coronary arteries have been regarded as end-arteries for a long time. Functionally, they are end-arteries in most cases indeed. However, there are interconnecting collateral channels between the large epicardial arteries which are sufficient to prevent myocardial ischemia during an acute vessel occlusion in about 1/4 to 1/3 of patients [1]. There are even very impressive rare examples of patients with left main artery occlusions who never had a myocardial infarction and who have very mild symptoms [2]. Despite such anecdotes which clearly illustrate the importance of the collateral circulation in human in some extreme situations, the overall relevance of collaterals is still not very clear. Even a very recent large study failed to show a clear clinical benefit of collaterals [3]. However, this study had some limitations and pooling the results of all currently available data on this topic clearly shows an association between the degree of collateralization and survival [4]. This meta-analysis included a total of 12 studies enrolling 6529 patients. Patients with a well developed collateral network had a 36% reduced mortality risk. One potential mechanism is the protective effect of the collateral circulation on the repolarization during an acute occlusion of a main coronary artery which usually puts the patient at risk for dangerous ventricular arrhythmias [5].