Clinical usefulness of the 16-slice computed tomography coronary angiography for evaluation of early phase intracoronary stent patency

Abstract

Coronary artery stenting is currently treatment of choice for management of coronary artery disease. Stent restenosis is the most important problem during follow up. Conventional coronary angiography is the gold standart for assessment of intracoronary stent patency. It is an invasive method and even though rare, has some significant risks. For this reason, noninvasive imaging methods are necessary to evaluate stent potency. Noninvasive methods such as the exercise test, myocardial perfusion scintigraphy and stress echocardiography could not reach enough diagnostic accuracy. Multislice computed tomography (MSCT) has been under investigation for stent restenosis detection. Aim of this study is to investigate usefulness of the 16-slice CT for evaluation of stent potency in patients with suspicion of stent restenosis. Thirty six patients were included in the study and 16-slice CT and conventional coronary angiographies were performed in all patients. The results of 16-slice CT and conventional coronary angiography were compared. Sufficient or good quality imaging with 16-slice CT angiography was obtained in 69% of all patients. Sixteen-slice CT angiography detected 42/49 (86%) stents and gave the correct localization for all of the detected stents. Stent lumen could be assessed in 30 (61%) stents and according to the results of luminal assessment, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy of 16-slice MSCT were calculated as 33%, 95%, 75%, 77% and 77%, respectively. According to these results, the diagnostic performance of 16-slice CT angiography for detection of stent restenosis was relatively low. However, the assessment of relatively small number of stents because of insufficient heart rate control did not allow reliable and precise evaluation. Our results showed that diagnostic capacity of 16 slice CT angiography for detection of coronary stent restenosis is limited.

Keywords

• Conventional coronary angiography
• Coronary artery disease
• Intracoronary stent
• Multislice computed tomography
• Stent patency
• Stent restenosis

References

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8. In our study, 23 patients (64%) with heart rates higher than 70 beats/min received the intravenous premedication. However, unlike many other studies, there was no upper heart rate limit established as a criterion for exclusion. In our study, the mean heart rate at the beginning of the scan was 73 ± 9 beats / minute. This heart rate is quite high compared to the other studies. Nowadays, more and more widely used 64 and higher slice CT scanners with high gantry rotation speeds and capacity of taking more slice allow to obtain higher quality images in patients with high heart rates. In a meta-analysis of 15 studies, 1175 intracoronary stent were assessed with the 16 and 64-slice CT scanners, and the average sensitivity and specificity were reported as 84% and 91%, respectively (Hamon et al., 2008). In our study, 33% sensitivity of 16-slice CT angiography is below the sensitivities of other studies but 95% specificity level is comparable to other studies. However, only nine restenotic stents were assessed within 30 stents. The evaluation of 16-slice CT angiography in intracoronary stent restenosis detection with only 9 stents is not reliable enough to draw conclusions. For this reason, the low number of the total and restenotic stents assessed is one of the limitations of our study.

9. The patients included in this study underwent 16-slice CT angiography and conventional coronary angiography with the clinical indications. This study was not planned in randomized, prospective design. The potential bias caused by results of 16-slice CT and conventional coronary angiography performed with clinical indications are another limitation of the study. In conclusion; the 16-slice CT angiography seems unlikely to take place of conventional coronary angiography in the evaluation of stent restenosis in clinical practice according to the data obtained from this study. It is difficult to reach a reliable conclusion about performance of 16-slice CT angiography in assessment of stent restenosis because of the low number of stents and low restenosis rate. More comprehensive studies including higher number of stents and high restenosis rate are needed.