Vascular Disease
Will the Advanced Aging Society Produce Brand New Insight on Aortic Dissection?
2023 Volume 87 Issue 9 Pages 1162-1163
Details
2023 Volume 87 Issue 9 Pages 1162-1163
Because acute aortic dissection (AAD) is a life-threatening emergency associated with high mortality and morbidity, attempts have been made to understand the actual situation on the global scale, mainly using the Stanford Classification. It is well known that type A has a higher frequency and mortality rate than type B.1
Article p 1155
In Japan, various nationwide registries have been investigating the real clinical picture of AAD.2,3 Because of its distinct nature, in which out-of-hospital deaths are relatively common, determining the incidence of acute type A aortic dissection (AAAD) is particularly challenging. In fact, the out-of-hospital death rates reported by several authors are as high as almost 50%, and cardiac tamponade leading to sudden death is a common scenario according to autopsy data from the Tokyo-to Medical Examiner Office.4–6 Reasons for the aforementioned challenging situations are, of course, multifactorial, but peculiarities of the Japanese sociomedical environment may be involved. Japan has a geographically smaller size, a quality emergency medical system, universal health insurance system and highest availability of computed tomography (CT) at not only aortic centers but also community medical facilities. In fact, Eagle et al documented that the apparent incidence of AAD is probably related to heightened clinical awareness of the condition as well as an exponential increase in the availability and use of CT in emergency departments.7 In other words, especially in Japan, the diagnosis and treatment of this aortic emergency is not centralized, making it difficult to ascertain the total number of patients.
Second, it is often difficult to distinguish between acute and chronic dissection on imaging, so the possibility of overestimating the incidence of acute cases cannot be ruled out. As the author of the present study states in the limitation section,1 it is necessary to consider the significance of the study in light of the fact that the handling of prehospital death was a major limitation.
In this issue of the Journal, Higo and colleagues1 document much that is known, including the higher incidence of AAAD in Japan than in other Western countries, but new perspectives are included: (1) incident cases with AAAD had female predominance with unique background data, and (2) the older the patients, the higher incidence of AAD.
Sex-based AAD outcomes have been reported by several multicenter registries, including the International Registry of Acute Aortic Dissection (IRAD) and the German Registry for AAAD.8–10 These international registries showed that both type A and type B AAD have a higher frequency in males.10,11 In general, the interval from symptom onset to diagnosis >24 h occurs more often in women, because of the lower incidence of abrupt chest pain at onset and higher incidence of coma on arrival, compared with men. A higher proportion of patients undergoing medical therapy and/or isolated ascending aortic replacement for AAAD have been also reported among female cases, because a higher incidence of intramural hematoma has been reported. Against this background, the result from this study (i.e., more females in type A and more males in type B) is interesting and makes this study unique. Furthermore, the proportion of diabetes mellitus (DM) was extremely high: in 25% of patients with type A dissection.7,12,13 In general, DM is a major cardiovascular risk factor and epidemiological studies have highlighted an inverse association between the presence of DM and the incidence of aortic dissection. These findings suggest there may be other factors underlying the data, such as advanced age, that are not found in other Western countries.
The crude incidence rate of AAD shown in this study is also impressive. Various Japanese studies in the cardiovascular field have reported that the average age of patients requiring emergency surgery for type A dissection is late 60s.3,14 JRAD, a multicenter study in the field of surgery, also reported a mean age of onset of AAAD of ≈67 years, even though 20% of octogenarians were included and 25% of patients were treated medically.3 According to Western reports, AAD occurs less frequently in women than in men but women are significantly older than men at the onset of AAD (AAD occurs on average 6 or 7 years later in women; 50% of women with AAD are aged ≥70 years).7 If this tendency would be applicable for Asia, then it is reasonable to support the mean age of ≈75 years old in AAAD patients presented by this study. In addition, it has also been reported that aortic dissection is more common during the morning commute to work, and that the patient population differs between weekdays and weekends, which is represented as a weekend effect.7,15 As the authors state in the limitation section, the possibility that the incidence of male patients is underestimated cannot be eliminated because Shiga prefecture is located adjacent to a major city. Given that, it may explain the age of AAAD patients being 75 years old and the fact that it was particularly common among women.
In any case, few studies have described the incidence of aortic dissection in patients over 85 years of age, and a new relationship between aging and aortic dissection has been described. Such data may be valuable because Japan has an advanced aging population with a predominance of women that has never been experienced in Western countries. Because epidemiological data of AAD remain insufficient owing to the lack of a comprehensive, global, prospective population, further investigation organized by the Shiga Stroke and Heart Attack Registry (SSHR) is strongly warranted.
The authors have no conflicts of interest regarding this study.
