Thinking outside the "box"-the ultrasound contrast controversy.

On October 10, 2007, the U.S. Food and Drug Administration (FDA) announced a new "black box" warning for the perflutren-containing ultrasound contrast agents, contraindicating their use in patients with acute coronary syndromes, acute myocardial infarction, and worsening or clinically unstable heart failure. These warnings ignore the proven efficacy of ultrasound contrast agents, the previously established safety of these compounds, the potential risks of alternative procedures, and the likely confounding effect of pseudocomplication. We suggest that the FDA Medical Imaging Division convene a panel of cardiologists experienced in a variety of imaging modalities to fully assess the adverse events that have been attributed to these agents and that any future FDA warnings acknowledge the possible influence of pseudocomplication, the proven efficacy of the modality in question for early and accurate diagnosis of cardiovascular disease, and the known and theoretical risks of alternative testing that may be necessary.