At the core of the medical profession is the collaborative decision-making process between physician and patient, where clinical evidence and best practice guidelines are applied to optimize outcomes for the individual patient. This process has long been shielded from public view. Decisions on the use of cardiovascular procedures are of particular interest, in part because of wide practice variation (1). New information technologies, electronic health records, and large administrative databases now permit outside observation of clinical decision making. With observation comes the potential for regulation. Governments, payers, professional organizations, and patients all wish to influence the use of medical procedures, either to decrease costs or to increase quality. These stakeholders have increasing access to clinical information. Billing and clinical registry data are widely available. Patients can access their electronic health record online and post reviews of their physicians to social media. Use of “big data” to understand, quantify, and regulate clinical decision making is inevitable.