Screening for carotid artery disease before cardiac surgery: Is current clinical practice evidence based?

Background: There is no clear consensus as to the correct screening procedure to identify patients undergoing cardiac surgery and who are at greatest risk of stroke because of the presence of significant carotid artery stenosis. Such screening is important because some patients benefit from combined carotid and cardiac surgery and, regardless of this, the information gained puts the cardiac surgeon in a position to provide an accurate assessment of surgical risk. Our objective was to examine current clinical practice of carotid artery investigation prior to urgent cardiac surgery and to review this illustrative practice in the context of the world literature. Hypothesis: The study aimed to establish that current typical practice for screening cardiac surgical patients for carotid artery disease is illogical according to the evidence in the world literature. Methods: The study consisted of a retrospective assessment of all patients undergoing urgent cardiac surgery and a Medline-derived literature review, and included all patients undergoing urgent cardiac surgery at a tertiary cardiothoracic center between January 1 and December 31, 1997. Results: Of 529 patients undergoing urgent cardiac surgery, 44 (8%) were screened preoperatively by duplex Doppler ultrasonography for carotid disease. The indications for screening were asymptomatic carotid bruit in 24 patients, history of stroke or transient ischemic attack (TIA) in 12 patients, and neither stroke, TIA, or bruit in 7 patients. The tests were requested either by the attending cardiologists or by the cardiac surgeon to whom they were referred. One patient had already been diagnosed as having carotid artery disease in the past. Thirteen patients underwent additional carotid investigations. Eleven patients were demonstrated to have internal carotid artery stenosis ≥ 60% and 3 patients underwent combined cardiac and carotid surgery. Review of the literature revealed the following groups to be at increased risk of future stroke unrelated to surgery, and of postoperative stroke: those with a history of stroke or TIA, those with carotid bruits, and, of importance, all patients with significant carotid stenosis. Recent data suggest that symptomatic patients and the elderly are at greatest risk. Conclusions: Only 8% of patients undergoing urgent cardiac surgery in a 1-year period were screened for carotid artery disease. We suggest that screening should definitely be performed in all patients with a history of stroke or TIA, all patients with a bruit, and all patients aged > 65 years. The literature suggests, however, that significant reductions in stroke rate could be achieved by screening the whole cardiac surgical population, although there is a paucity of data that are specifically pertinent to this patient subgroup. Further data are therefore required for the construction of a scientifically valid and medicolegally sound policy.