The reality of the treatment for acute aortic dissection in a megacity

Epidemiological studies using big data of medical fields are in full bloom. In the field of cardiovascular surgery, big data reports on acute aortic dissection include the International Registry of Acute Aortic Dissections (IRAD) and the German registry for acute aortic dissection type A (GERAADA), which reaffirmed the fact that they were naturally overlooked in daily clinical practice. This will give us an overall picture of the treatment system, including not only surgery but also disease prevention, transportation, initial treatment and rehabilitation. As a result, it is expected that medical care for acute aortic dissection will be greatly improved. This issue features a report by Yamasaki et al. [1] analysing data from the Tokyo acute aortic super-network. This report is noteworthy in that it collects data in a single megacity, unlike the IRAD [2], an international study and the GERAADA [3], a national study in Germany.

This Tokyo acute aortic super-network covers the night-time population of 13 million people in Tokyo and functions to provide safe and rapid treatment for acute aortic diseases including acute aortic dissection. In this study, data of >2000 people registered in the 3 years from 2015 have been analysed. These results may be influenced not only by racial and cultural differences but also by differences in medical systems and health insurance systems, which may lead to differences from the results reported by the IRAD and the GERAADA. In particular, it was also shown that the frequency of intestinal ischaemia, which was a risk factor both before and after surgery, was significantly lower than that of the GERAADA. However, this could be a difference in the definition of intestinal ischaemia. Preoperative cerebral ischaemia was only 3.9% in this study, and the rate was much lower than those reported in the IRAD and the GERAADA.

It is known that the number of cardiovascular surgery facilities in Japan is overwhelmingly larger than that in other developed countries. In fact, this Tokyo acute aortic super-network also includes 12 core hospitals and 27 support hospitals, and it is possible that this decentralization led to a reduction in transportation time. To excuse as a Japanese surgeon, there is only one attending surgeon in many of these facilities, but the number of surgical experiences per the attending surgeon is not so small [4]. As an evidence of this, the surgical results of acute aortic dissection reported in this report were 8.9%, which is extremely good. The average time from onset to initial treatment was only 47 min, and the average time from onset to the start of surgery was about 4 h. It is extremely excellent as a medical transport in a huge and crowded city, and this rapid transport seems to be linked to good results. In fact, according to the GERRADA data, the average time from onset to the start of surgery was 10 h, of which the average time for survivors was 8 h [3]. In cardiovascular surgery, it is known that centralization enhances the experience value of the entire facility and improves surgical results, but from this report, the decentralized cardiovascular surgery system unique to Japan might lead the fine results.

Male sex, use of percutaneous circulatory assist devices (PCADs) and cardiopulmonary arrest, shock, myocardial ischaemia and intestinal ischaemia were found as preoperative risk factors for 30-day mortality in this report. Cardiac tamponade, cerebral ischaemia and intestinal ischaemia were found as postoperative risk factors for 30-day mortality. Among them, myocardial ischaemia, cerebral ischaemia and intestinal ischaemia have been known as the risk factors for a long time, and the novel ones are preoperative PCADs and postoperative cardiac tamponade. It is possible to start IABP or ECMO in an emergency outpatient department if the haemodynamics of the patient are unstable and a correct diagnosis cannot be made before starting the treatment. It is not difficult to imagine that the surgical results will be inferior in such an unstable preoperative condition. It should be noted that 3/4 of the patients with the preoperative PCADs could be saved.

The postoperative cardiac tamponade in this study was defined as causing cardiogenic shock due to cardiac tamponade due to postoperative bleeding, despite the placement of a drainage tube. Bleeding after acute aortic dissection often depends on bleeding tendency, but bleeding from the anastomotic site of artificial blood vessels with fragile tissue is still a major issue as a surgical procedure. It seems to suggest that coagulation factors need to be supplemented by appropriate blood transfusion [5], as well as the need to improve the anastomosis method to secure the haemostasis. In Japan, cryoprecipitate and fibrinogen cannot be easily used for the repair of acute aortic dissection at this moment and it might have influenced the bleeding.

As stated above, this database of acute aortic dissection in Tokyo indicated several new information. I believe that the report can lead to construct better system for supporting the patients with acute aortic dissection not only in Tokyo but also in any city all over the world. I heartily congratulate their efforts and accomplishments. Further reports are expected.

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