Remote Ischemic Preconditioning to Prevent Contrast Nephropathy

Contrast-medium induced nephropathy (CIN) is a frequent and devastating complication of coronary angiography, occurring in 10-50% of cases. As would be expected, the incidence of CIN is much higher in patients with underlying renal dysfunction. Multiple trials have found CIN to be an independent predictor of prolonged hospitalization and both 30 day and 1 year mortality in patients with coronary artery disease. Intravenous contrast dye is felt to cause renal ischemia as the mechanism of injury. Unfortunately, despite the significant morbidity and mortality with CIN, there are few therapeutic interventions to reduce the risk with the exception of hydration and high dose statin therapy. Recently, remote ischemic preconditioning (RIPC), a process of inducing transient arm ischemia by inflating a blood pressure cuff to 200 mmHg for 3 repetitive 5 minute cycles, leads to a systemic cytoprotective response and ultimately reduces ischemic renal injury, myocardial injury, and even cerebral injury following coronary bypass grafting. While there is significant data supporting the role of RIPC in reducing systemic ischemic injury in surgical patients, there is only one small trial studying RIPC in patient's undergoing coronary angiography. The investigators hypothesize that RIPC will reduce the incidence of contrast-induced nephropathy in patients with baseline renal dysfunction undergoing coronary angiography for stable or unstable coronary artery disease.