The aim of this study was to evaluate the risk of performing cardiac catheterization or intraaortic balloon pump placement in patients with transesophageal echocardiographically detected atherosclerotic aortic debris. Cardiac catheterization was performed in 70 patients with atherosclerotic aortic debris (in 11 via the brachial approach and in 59 via the femoral approach) and in 71 control patients. An embolic event occurred in 10 (17%) of 59 patients with atherosclerotic aortic debris after femoral catheterization compared to 2 (3%) of 71 control patients without atherosclerotic aortic debris (p = 0.01). None of the 11 patients with atherosclerotic aortic debris who underwent brachial catheterization had an embolic event. An intraaortic balloon pump was placed in 10 patients with atherosclerotic aortic debris and in 12 control patients. An embolic event related to placement of the intraaortic balloon pump occurred in 5 (50%) of 10 patients with atherosclerotic aortic debris; no control patient had an embolic event (p = 0.02). Patients with mobile atherosclerotic aortic debris were at the highest risk for catheter-related embolism. The strongest clinical predictors of atherosclerotic aortic debris were advanced age and peripheral vascular disease. Transesophageal echocardiographic recognition of atherosclerotic aortic debris identifies patients at high risk of stroke or peripheral embolism after cardiac catheterization or intraaortic balloon pump placement. If the aortic debris is mobile, the risk is particularly high. When atherosclerotic aortic debris is detected, especially if the debris is mobile, substituting brachial for femoral catheterization and avoiding placement of an intraaortic balloon pump may reduce the risk of embolism.