[Antioxidative treatment in myocardial reperfusion ischemia]

Perfusion-induced myocardial ischaemia is observed in several situations: chronic coronary insufficiency, unstable angina, myocardial infarction, and during coronary angioplasty or bypass surgery. Oxygen-derived free radicals are liberated in large quantities during myocardial reperfusion ischaemia. Though very toxic in experimental studies, the responsibility of these free radicals in myocardial injury remains to be demonstrated clinically. Oxidant stress, characterised by an imbalance between the free radical attack and insufficient cellular defense seems partially responsible for reperfusion arrhythmias and post-ischemic stunning. On the other hand, its role is less evident in prolonged myocardial ischaemia causing irreversible myocardial lesions such as infarction. Antioxidant therapy is under evaluation in clinical trials. There are several options: some prevent the formation of free radicals by inhibiting the biochemical reactions which may produce them or by limiting the intervention of the neutrophils--the "fulcrum" of free radicals formations. Other antioxidant therapies inactivate free radicals as they are formed by promoting their degradation or their neutralisation. Experimental data is profuse and discordant. The models are very different. The first clinical trials are under way using either specific antioxidant molecules or molecules having other beneficial effects: in the latter case, the benefit of the antioxidant action is more difficult to demonstrate. Antioxidant therapy could play a role in surgical myocardial protection, especially of transplant organs, in very early forms of ischaemia. It could also prevent the pejorative hemodynamic consequences of myocardial stunning of the border zones of infarction, so enabling patients to survive a difficult period. The results of on-going studies should clarify the role of antioxidant therapy in reperfusion-induced myocardial ischaemia.