Background: Current Practice Guidelines recommend screening for coronary artery diseases (CAD) in the setting of elective heart valve surgeries if patients are aged over 40 years or have coronary risk factors. While conventional coronary angiography is regarded as the gold standard method, computed tomography (CT) has emerged as an alternative imaging modality to evaluate of CAD; however, there have been only few studies that evaluated the feasibility of CT in this setting.
Methods: Out of 6,104 consecutive adult patients undergoing elective heart valve operations between 2001 and 2015, we identified 3,949 patients aged >40 years or who had coronary risk factors after the exclusion of patients who had infective endocarditis or pre-existing CAD. Of these, 3,205 patients (81.2%) underwent CT coronary angiography (n=1420; CT group) or conventional coronary angiography (n=1785; CAG group) for CAD screening. Perioperative outcomes were compared between these two groups after adjustments with propensity score based on 30 baseline variables.
Results: Overall, the CT group patients showed lower cardiovascular risk profiles compared with the CAG group. In the CT group, 200 patients (14.0%) underwent additional CAG due to positive findings on the CT evaluations. Detection rate of significant coronary stenosis (50% or more) was lower in CT group (5.1% vs 10.3%, p<0.001). Proportion of patients receiving concomitant coronary bypass grafting (CABG) was 3.0% in the CT group while 4.6% in the CAG group (p=0.015). There was higher incidence of low cardiac output syndrome in CT group (2.3% vs. 1.1%, p=0.007). There was no significant difference in the early mortality (30-day or in-hospital) rate between the two groups (1.8% vs. 1.5%, p=0.495) as was in the rate of postoperative acute kidney injury (post-AKI, 6.3% vs. 6.9% defined by RIFLE classification, p=0.443). Propensity score matching yielded 588 pairs of patients that were well balanced for all baseline covariates. In the matched cohort, the outcomes did not change: lower detection rate of significant coronary stenosis, lower rate of concomitant CABG, more events of low cardiac output syndrome, similar risks of early death, and similar rate of post-AKI. In the CT group (n=1479), patients who had CAG after CT experienced higher incidence of post-AKI than who only had CT (11.4% vs. 5.4%, OR, 2.24; 95% CI, 1.33-3.65; p=0.002).
Conclusions: Although CT coronary angiography showed an equivalent feasibility in terms of mortality and post-AKI, detecting significant coronary diseases and finding CABG candidates were inferior to conventional coronary angiography in patients scheduled for elective heart valve operations.