Is there a role for remote ischemic conditioning in preventing 5-fluorouracil-induced coronary vasospasm?

Cardiac ischemia associated with chemotherapy has been linked to several anti-neoplastic agents and is multifactorial in etiology. Coronary artery vasospasm is one of the most commonly reported effects of cancer therapy that can lead to myocardial ischemia or infarction. The chemotherapy agent 5-fluorouracil (5-FU) or its oral pro-drug capecitabine can result in coronary vascular endothelial dysfunction causing coronary artery spasm, and possibly coronary thrombosis. These drugs have also been shown to be associated with myocardial infarction, malignant ventricular arrhythmias, heart failure, cardiogenic shock, and sudden death. The proposed mechanisms underlying cardiotoxicity induced by 5-FU are vascular endothelial damage followed by thrombus formation, ischemia secondary to coronary artery vasospasm, direct toxicity on myocardium, and thrombogenicity. There remains a pressing need to discover novel and effective therapies that can prevent or ameliorate 5-FU associated cardiotoxicity. To this point, promising overlap has been observed between proposed remote ischemic conditioning (RIC) cardioprotective mechanisms and 5FU-associated cardiotoxic cellular pathways. RIC, in which transient episodes of limb ischemia and reperfusion (induced by inflations and deflations of a pneumatic cuff placed on the upper arm or thigh), confer both cardioprotective and vasculoprotective effects, and may therefore prevent 5-FU coronary artery spasm/cardiotoxicity. In this review, we will be discussing the following potentially therapeutic aspects of RIC in ameliorating 5-FU associated cardiotoxicity: sequential phases of 5-FU cardiotoxicity as possible targets for dual windows of cardioprotection characteristic of RIC; protective effects of RIC on endothelial function and microvasculature in relation to 5-FU induced endothelial dysfunction/microvascular dysfunction; reduction in platelet activation by RIC in the context of 5-FU induced thrombogenicity; and the utility of improvement in mitochondrial function conferred by RIC in 5-FU induced cellular toxicity secondary to mitochondrial dysfunction.