Utility of carotid intimal medial thickness as a screening tool for evaluation of coronary artery disease in pre-transplant end stage renal disease

Background: Coronary artery disease (CAD) is associated with a higher incidence of allograft failure and mortality in patients wit end-stage renal disease (ESRD) following renal transplant. Aim: To evaluate the efficacy of using carotid intimal medial thickness (CIMT) to predict the presence of CAD in patients with ESRD, using coronary angiography (CAG) as the gold standard. Materials and Methods: This prospective study enrolled consecutive patients with ESRD who underwent CAG as a part of pretransplant evaluation to rule out the presence of atherosclerotic CAD. An operator who was blinded with respect to the results of the CAG, measured carotid IMT in all patients prior to CAG and recorded it on videotape. Two independent observers blinded to the results of CAG measured carotid IMT offline to validate its predictive accuracy as a noninvasive test in predicting the presence or absence of CAD. Measurement of carotid IMT was done on USG B mode 7.5 MHZ probe [HP 5500 andover, Massachusetts]. Student's t-test was used for inter-group comparisons. Pearson correlation coefficient test was used to assess the relation between CAD and various risk factors and carotid IMT. Linear regression analysis was applied to identify independent factors determining presence of CAD. A P value < 0.05 was considered statistically significant. Results: Mean CIMT was significantly higher in those with CAD as compared to those without [0.80 +/- 0.06 vs. 0.70 +/- 0.06 mm, P< 0.0001). Patients with CIMT> 0.75 mm were older and had more incidence of diabetes (78% vs. 47%; P=0.001). Only 4/53 (7%) of patients with CIMT< 0.75 mm had CAD, vs. 38/52 (73%) in those with CIMT >0.75 mm. The sensitivity and specificity of using CIMT > 0.75 as a predictor of CAD was 90.47% and 73% and its positive and negative predictive values were 0.73 and 0.92. On multivariate analysis, only CIMT was a significant predictor of CAD. Conclusion: Carotid IMT can be used to predict CAD in patients with ESRD. In the absence of other risk factors, patients with IMT < 0.75 mm may not need a pretransplant CAG.