The BRICK study is a prospective, double-blind, sham-controlled, randomized clinical trial in patients with non-ST elevation myocardial infarction and unstable angina undergoing coronary angiography and/or percutaneous coronary intervention who are at high risk for acute kidney injury. The study will investigate the effects of remote ischemic preconditioning before cardiac catheterization on rate of acute kidney injury and novel biomarkers of renal injury/protection within 48hrs of coronary angiography and/or percutaneous coronary intervention.