We evaluated and compared efficiencies of five non-invasive diagnostic imaging modalities for the detection of myocardial ischemia in patients with stable angina. In addition, we conducted a sensitivity analysis to account for the variation in PTP due to differences in patient background factors. Our study findings that may be useful to patients were as follows:
Among the five types of modality in basic settings (PTP: 50%),
・The maximum and minimum probability of a positive result and ischemia was 87% (CMRI) and 75% (SE), respectively.
・The maximum and minimum probability of a negative result and no ischemia was 89% (PET) and 71% (SE), respectively.
・Despite a negative result, the minimum and maximum probability of ischemia, i.e., the probability of missing detection was 11% (PET) and 29% (SE), respectively.
・PET generated the best TP, NPV, and least FN among the five imaging modalities.
・CMR generated the best DA, PPV, TN, and least FP among the five imaging modalities.
・FFRCT produced more false-positive cases than PET, CMR, and SPECT.
・SE was inferior to all modalities.
In addition, the following information may be useful to physicians who order the examinations:
In the sensitivity analysis,
・PET generated the highest TP, NPV, and lowest FN in all PTPs.
・The TPs and FNs of FFRCT were almost similar to those of PET.
・The NPVs of FFRCT were almost similar to those of CMR.
PET is considered best for patients or physicians who focus on an accurate detection and less missed diagnoses of CAD. However, it has slightly higher FPs than CMR. This can be attributed to the relatively lower specificity, compared to that of CMR. The DA and NND of PET and CMR were almost similar in basic settings. However, the number of FP in PET was about 20 cases more than that in CMR. PET may be slightly inferior to CMR, in terms of its role as a gatekeeper for CAG or revascularization. In contrast, CMR is considered best if it focuses on higher DA, PPV, and less FP. The TPs and FNs of FFRCT are almost similar to PET. Thus, FFRCT should be added to CCTA when the results of CCTA are equivocal. However, the number of FPs in FFRCT was the highest among the five modalities due to the lowest specificity of FFRCT (Fig. 2-b and Table 2). The FP and FN results can lead to an inaccurate diagnosis. In addition to unnecessary psychological distress, FP test results in patients with no disease can increase their medical risk due to additional examinations [24]. Moreover, FN test results can cause late diagnosis or misdiagnosis [24].
Among non-invasive diagnostic imaging modalities, researchers have primarily conducted studies to evaluate the efficiency of detecting myocardial ischemia in stable angina by economic analysis, such as cost-effectiveness analysis, cost-benefit analysis, and cost-benefit analysis [25-27]. However, an interpretation of the indicators of efficiency obtained from the results, such as cost-effectiveness ratio and cost-utility ratio requires a certain degree of specialized knowledge. Therefore, patients might find it difficult to understand these indicators, despite being presented directly with the information. This is the first study that used currently available evidences to assess the efficiency of each modality to detect myocardial ischemia by simulation. Therefore, we could elucidate the number of TP, FN, FP, and TN per 1,000 patients as efficiencies. In addition, by comparing them, we could elucidate the difference in efficiency as a specific index. Similarly, the efficiency of indices, such as PPV, NPV, DA, and post-test probability were also elucidated and compared with each other. The aforementioned calculations require setting the PTP. However, we were able to assess efficiencies at different PTPs using sensitivity analyses. Besides, physicians might easily understand the indicators using NND than standard diagnostic accuracy expressions, such as sensitivity and specificity [16]. Thus, it is conceivable that our results would help patients to understand the ability of each examination and undergo the appropriate one. Apart from sensitivity and specificity, the aforementioned indices would be needed not only by patients but also by physicians who order the examinations during busy practices. Furthermore, physicians can determine the degree of an inaccurate CAD diagnosis by the percentage and number of people. Therefore, our findings might contribute to reviewing diagnostic strategies and improving the workflow for diagnosis in patients with suspected CAD. The primary purpose of using non-invasive imaging modalities was to select patients who were likely to benefit from invasive coronary angiography and revascularization [1,28,29]. Therefore, the importance of non-invasive imaging is increasing [1]. Each imaging modality has a good ability to detect CAD. Moreover, they contribute to the reduction of unnecessary revascularization and optimization of the diagnosis and treatment costs. However, physicians should refer to the various economic evaluations while considering the efficiencies of each examination, based on diagnostic costs.