Use of multidetector computed tomography after mildly abnormal myocardial perfusion stress testing in a large single-specialty cardiology practice

Background Data are limited on using 64-slice multidetector computed tomography (MDCT) as a gatekeeper to cardiac catheterization in patients with mild abnormalities on myocardial perfusion stress imaging (MPI). Objective We compared the rate of invasive coronary angiography (ICA) within 6 months after finding mildly abnormal MPI results before and after implementing 64-slice MDCT. Methods This retrospective cohort study included patients referred for follow-up based on a mildly abnormal MPI. Pre- and post-MDCT cohorts were matched according to age, sex, prior history of coronary artery disease (CAD), and presence of clinical symptoms (chest pain or exertional dyspnea or both). Case matching resulted in 154 patients in each cohort. The primary endpoint was the rate of ICA. Results From the clinical evaluation or MDCT results, 87 patients were referred for ICA, 60 (39%) in the pre-MDCT cohort and 27 (18%) in the post-MDCT cohort. Among those referred for ICA, 22 (14%) in the pre-MDCT cohort and 17 (11%) in the post-MDCT cohort underwent revascularization. Given the similar rate of revascularizations in both cohorts, we estimate that patients in the post-MDCT cohort were 86% less likely to receive ICA compared with patients in the pre-MDCT cohort (odds ratio = 0.14; 95% confidence interval, 0.06–0.33). During 6 months of follow-up, no clinical events were observed in either cohort for patients not referred to ICA. Conclusion For patients with mildly abnormal MPI followed by clinical evaluation, MDCT examination was associated with a significant reduction in rate of referral to ICA.