Efficiency assessment of a two-stage diagnostic strategy combining CT angiography and fractional flow reserve derived from coronary CT angiography for the detection of myocardial ischemia: a simulation study

Abstract

The importance of a diagnostic strategy combining coronary computed tomography angiography (CCTA) with fractional flow reserve derived from CCTA (FFRCT) for detecting myocardial ischemia is increasing. However, sensitivity and specificity alone may be insufficient to understand the efficiency characteristics of a diagnostic strategy combining CCTA and FFRCT (DSCCF). Our study aimed to evaluate the overall efficiency of DSCCF in detecting myocardial ischemia and compare it with other diagnostic strategies to determine whether evaluation by DSCCF is currently appropriate. This simulation study included 1000 patients with stable chest pain and suspected myocardial ischemia. Using a decision tree analysis, assuming a diagnostic strategy of adding FFRCT to CCTA-positive patients, we calculated the following efficiency parameters of DSCCF: (1) true positive (TP), false positive (FP), net false negative (FN), and net true negative (TN) test results; (2) net sensitivity; (3) net specificity; (4) positive predictive value; (5) negative predictive value; (6) post-test probability; (7) diagnostic accuracy; (8) diagnostic odds ratio; and (9) number needed to diagnose. We also calculated the efficiency parameters of other diagnostic strategies and compared them with those of DSCCF. In the basic setting, regarding efficiency parameters (1), the number of TPs, FPs, net FNs, and net TNs were 254, 69, 46, and 631, respectively. Efficiency parameters (2)–(9) were 0.85 (95% confidence interval [CI], 0.80–0.89), 0.90 (95% CI 0.88–0.92), 0.79 (95% CI 0.74–0.83), 0.93 (95% CI 0.91–0.95), 0.07 (95% CI 0.05–0.09), 0.89 (95% CI 0.86–0.90), 50.50 (95% CI 33.83–75.37), and 1.34 (95% CI 1.24–1.48), respectively. Compared with other diagnostic strategies, DSCCF had good efficiency parameters. Moreover, the sensitivity analysis did not reveal any evidence to contradict the findings in the basic setting. This study demonstrated the diagnostic ability characteristics of DSCCF by assessing various efficiency parameters. Compared with other diagnostic strategies, DSCCF had good efficiency. In terms of efficiency, evaluation using DSCCF for detecting myocardial ischemia appears to be appropriate.