Routine preoperative CT: Ready to roll or a step too far?

The incidence of stroke after coronary artery bypass grafting (CABG) is around 1.3% in the Society of Thoracic Surgeons database but carries a mortality of almost 20%. The stroke rate is even higher with aortic valve replacements with the Determining Neurologic Outcomes from Valve Operations (DeNOVO) study reporting stroke rates as high as 17%. It is also likely that variations in the definition of stroke lead to underreporting of this event. There is thus, no denying that stroke remains the Achilles heel of cardiac surgery and efforts must be made to mitigate its occurrence. The case by Osorio–Jaramillo published in this issue of the journal reignites the discussion on the value of computerized tomographic (CT) imaging as a routine preoperative investigation before cardiac surgery. The identification of a mass on the ascending aorta led to a revision in operative strategy whereby along with the initially planned CABG, concomitant supracoronary replacement of the ascending aorta was also performed. It is likely that in the absence of modification of surgical strategy this unexpected mass in the ascending aorta may have led to a perioperative stroke with serious adverse outcomes. Atheromatous disease of the aorta not only increases the risk of perioperative stroke but also impacts upon long term mortality. The stroke rate has been shown to be quadrupled in presence of atheroma in the proximal aorta. Prevention of these adverse outcomes thus hinges on the identification of the atheromatous aorta. While this has been attempted intra‐operatively by manual palpation of the aorta the reliability with manual palpation is low with the additional risk of plaque embolization. Trans‐ esophageal‐echocardiography (TEE) has also been used to detect atherosclerotic aorta but has limited access to the ascending aorta and arch and the sensitivity is only marginally better than manual palpation. Epi‐aortic ultrasound is significantly better than both manual palpation and TEE and is recommended for identification of atheromatous plaques (Class IIa, level of evidence C) The downside of Epi‐aortic ultrasound is it is operator dependent and more importantly the information is available only after a sternotomy has been performed. Preoperative planning and a considered discussion with the patient is thus not possible. Multidetector computed tomography (MDCT) is being used increasingly to diagnose the atheromatous aorta and its superior spatial resolution coupled with 3D reconstruction capabilities makes it an attractive option in the preoperative setting. Preoperative CT has been used in the past predominantly in the re‐operative setting. Studies comparing patients undergoing reoperative surgery have reported a reduction in stroke rates in patients undergoing preoperative CT scans. Apart from stroke, there was also a reduction in sternotomy‐related injury, complication rates and this resulted in improved perioperative outcomes. There are contradictory findings with regard to the effect of preoperative CT scans on mortality with some studies suggesting improved outcomes while others suggest an increase of mortality in these patients. While the findings of all these studies may be influenced by several factors and are open to questioning one fact remains indisputable that most studies report a change in either surgical access, the strategy of cannulation, or even operability. While the indication for a preoperative CT in re‐operative surgery is essential to assess the anatomical orientation of structures and