In this study, we verified the real-world application of our scoring protocol to patients with carotid stenosis. In our patient population, a majority (93.3%) of the treatment options were chosen by the protocol. Among those in whom the scores were equal and those who should have undergo CEA according to the protocol, patients tended to choose CAS over CEA. Seven patients who would have benefitted from CEA (based on the protocol) actually underwent CAS. We suspect that it is unnecessary to determine which treatment arm is better than the other between CAS and CEA. We believe that no future efforts should be made to choose one or the other. Instead, we should identify which treatment option is more appropriately tailored to each patient. The consideration of both CEA and CAS simultaneously (with respect to each patient) is expected to improve clinical outcomes overall.
Our protocol was developed using clinically relevant preoperative factors (with regard to risk/benefit) that had been identified in several previous articles [13]. Among the 192 articles that we found on PubMed and Medline, 28 were selected as references and they all met the following criteria: 1) single or multiple randomized clinical trials; 2) review articles in journals with high impact factors (≥ 6); or 3) well-designed case-control studies including a large number of patients. We made a general outline for our protocol based on these studies. We then specified the exact indicative values for each factor suitable for our institution. For example, we gave one point for moderate calcification around the carotid stenosis with a concentric circumference of 90–270 degrees with maximal thickness of calcified plaque ≥ 3 mm as favorable for CEA. We also gave one point for lesion length ≥ 30 mm as favorable for CEA [14–20]. However, those factors are not contraindications to perform CAS. Although we gave these points in favor of CEA, we expected patients to prefer CAS by choice. This method allowed us to assess the real-world application of our protocol.
Among the seven violation cases, all patients declined to undergo CEA. These patients preferred CAS because it is minimally invasive, produces less of a scar, and does not require general anesthesia. It is certainly possible that emotions and indirect outside influences affected patients’ decision to undergo CAS over what was recommended by the medical evidence. These same factors may have also influenced patients’ decisions when the scores were equal between CEA and CAS. Among the 37 patients with equal scores on the protocol, 28 (75.7%) underwent CAS. We preferred CAS to CEA in emergent situations, such as acute ischemic stroke. We performed CAS in 11 patients in emergent situations.
Based on previous large trials [4–11], the American guidelines recommended CEA as the initial treatment option in patients with symptomatic severe stenosis in 2014 [12]. However, CAS has become an option based on several new recommendations if the periprocedural stroke or death rate is < 6%. This recommendation allows patients to be treated with CAS if there is no available vascular surgeon to perform CEA. In addition, CAS is equivalent to CEA in young patients. The clinical outcomes from our series cannot be directly compared with those of previous studies due to the purpose and the design of this study. However, our study does provide evidence that protocol-based decision making is safe and produces comparable outcomes to those from previous trials and recommendations [4–12]. Although our sample size was very small, there was no permanent neurological deficits or deaths in our series. This suggests that our scoring protocol could be applicable to the real-world clinical setting. The thirty-day mortality (0%), major stroke (0%), minor stroke (3.1%) and myocardial infarction (0%) rates were similar or better in our series than those from previous large trials. Our clinical outcomes were also comparable between both treatment options. The 12-month outcomes of the 105 consecutive patients in this study might be sufficient to recommend our protocol for determining the appropriate treatment of carotid stenosis.
We have considered additional factors for modification of our protocol. First, atrial fibrillation with anticoagulation may belong to the category of “favorable CEA,” because dual antiplatelet therapy for CAS may increase the bleeding risk. In addition, acute ischemic stroke requiring mechanical thrombectomy combined with large artery occlusions due to severe carotid stenosis may belong to the category of “favorable CAS,” given its emergent nature. Furthermore, the string sign requires more precise indicative values. We may give one point to CEA if the length of the string sign is ≥ 2 cm. Otherwise, both treatment options are applicable. We did not experience restenosis after CAS in this present study. However, if we had, it would likely belong the category of “favorable CAS.” Finally, we should have included an indication to choose CEA or CAS if absolute CAS and absolute CEA are pitted against each other. We recognize that our small sample size is a limitation of this study. Still, we suspect that it is sufficient to show the tendency of real-world practice with application of our protocol and the shift toward CAS and minimally invasive treatment.