In recent years, the surgical outcome of acute type A aortic dissection has improved, but various complications occur after surgery, and it remains a fatal disease. In the present age of the aging society, there are increasing opportunities to experience acute type A aortic dissection cases in the elderly. In particular, Japan is one of the world’s longest-lived countries, and it is thought that there are many opportunities to encounter such situations.
There are many reports of surgical outcomes in elderly patients for acute type A aortic dissection. The surgical mortality rate was 3.7–35% [2–4, 9, 10, 15–18]. Regarding the surgical procedure for acute type A aortic dissection, TAR has been reported to have a higher mortality and morbidity than ascending or hemiarch replacement [19], while it has been reported that CPB, aortic clamp and circulatory arrest times were longer, there is no difference in mortality and morbidity between hemiarch replacement and TAR [20]. There are reports that all surgical procedures for acute type A aortic dissection in elderly patients were ascending or hemiarch replacement [2, 9], and nearly 90% were ascending or hemiarch replacement [3, 10, 17, 19]. In other words, there are many reports that elderly patients avoid TAR as a surgical procedure for acute type A aortic dissection. We have strategy that we have selected the ascending or hemiarch replacement as the surgical procedure for acute type A aortic dissection in patients over 80 years old regardless of the primary entry site. Then, there is a problem that if the primary entry cannot be resected, does it affect the prognosis? Non- resection of the primary entry was a predictor of survival and distal aortic events [21]. It has been reported that aggressive primary entry resection enhances the false lumen thrombosis and reduces aortic reoperation [22]. On the other hand, there is also a report that aortic events do not change even if the entry is not resected by careful follow-up [23]. In our study, the entry resection rate in the elderly group was 87%, and all patients in the elderly selected ascending or hemiarch replacement as the surgical procedure. Elderly patients did not differ in entry resection rate and long-term aortic events compared to non-elderly patients. Descending aorta replacement, TEVAR and rupture of the descending aorta as late aortic events occurred in 2 cases in the elderly group and 8 cases in the non-elderly group (Table 3). Of these, both of the 2 cases in the elderly group were able to undergo entry resection and 5 cases in the non-elderly group were able to undergo entry resection. Therefore, even if the entry can be resected, if there is a reentry in the residual aorta, aortic remodeling may proceed, and careful follow-up is required. In addition, in our multivariate analysis of postoperative hospital mortality, advanced age and longer CPB time were risk factors. CPB time can be shortened by selecting ascending or hemiarch replacement for the elderly. From the above, selecting ascending or hemiarch replacement without sticking to the entry resection and shortening the operation time may contribute to the surgical outcomes in the elderly with acute type A aortic dissection.
The location of the primary entry tear in patients with acute type A aortic dissection significantly influences early outcomes, short and long-term survival of patients [24]. In general, the intimal tear is frequently found in segments exposed to the greatest shear stress, namely the right lateral wall (opposite the main pulmonary artery) of the ascending aorta or in the proximal segment of the descending aorta [25]. In our study, primary entry was likely to occur in the ascending aorta and DeBakey type Ⅱ dissection was likely to occur in elderly patients. There are other reports like this [3, 4]. Elderly patients may be more likely to be stressed by the ascending aorta due to the prognosis of arteriosclerosis. Therefore, the primary entry is common in the ascending aorta in the elderly patients.
Next, we would like to discuss the indication for surgery and postoperative course in the elderly. Although the general condition before surgery affects the surgical outcome, advanced age alone should not be considered as a contraindication to acute type A aortic dissection repair [2, 3, 6]. The age 80 years or older was the risk factor for hospital mortality in operation for acute type A aortic dissection [4]. Hata and colleagues described [9] that the elderly patient after surgery had complications such as cerebral damage, depression, pneumonia, or renal failure and ultimately became bedridden, causing the family significant mental, physical, and economic stress. Aoyama and colleagues described [19] that patients of acute type A aortic dissection aged 80 years or older were compared in the surgical treatment group and in the conservative treatment group, the home discharge rate was significantly higher for the conservative treatment group (52.8% conservative treatment group, 42.8% surgical treatment group, p < 0.01). Furthermore, the hospital length of stay and ICU length of stay were significantly longer in the surgical treatment group, and the medical expenses were also significantly higher in the surgical treatment group than in the conservative treatment group. In our study, the ADL status at discharge was significantly worse in the elderly, also, the home discharge rate was 41.9% in the elderly group, which was significantly lower than 63.6% in the non-elderly group. In addition, of the 12 patients who were transferred to the rehabilitation hospital after surgery in the elderly group, 4 died, and all died of pneumonia or heart failure within one year after surgery. In addition, when comparing the surgical treatment group and the conservative treatment group of the elderly, there was no difference in 5-year survival between the two groups. In the elderly, even if life can be saved, it may lead to a decrease in quality of life and may not benefit from surgical treatment in long-term prognosis.
Based on the above, surgical indication for elderly patients with acute type A aortic dissection should be carefully considered. Elderly patients are apt to fall into irreversible physical deterioration after surgery, and may progress to dementia, or be bedridden at worst. In such a situation, the burden and stress on the family will increase. Post intensive care syndrome (PICS) [26, 27] should be fully considered. It is necessary to work together for postoperative rehabilitation as a united team of cardiac surgery in order to be discharged home as much as possible.
In our study, postoperative stroke was found to be more frequent in both the elderly group and the non-elderly group. Four out of 8 cases of postoperative stroke in the elderly had persistent CNS malperfusion before surgery. And 14 out of 39 cases of postoperative stroke in the non-elderly had persistent CNS malperfusion before surgery. Therefore, the cases with postoperative stroke may include cases in which stroke has occurred before surgery. On the other hand, postoperative stroke is a major risk factor affecting hospital mortality, as shown by our study. Stroke was the most common cause of postoperative death in both elderly and non-elderly patients. Stroke reduction is the most important factor to improving surgical results. The effectiveness of axillary artery cannulation has been reported to prevent strokes after aortic arch replacement [28–30]. To reduce postoperative neurological damage, we are currently trying to actively introduce and improve cannulation from the right axillary artery in the CPB.
Limitations
The present study is limited due to its retrospective, single-center design. It is hard to say a clear conclusion because of the small numbers of cases, there was no difference in hospital death and long-term survival between the surgical treatment group and the conservative treatment group of the elderly. In the future, as the number of cases increase, it may be possible to obtain results that the hospital death is significantly reduced in the surgical treatment group. Therefore, the superiority of surgical treatment for acute type A aortic dissection may increase even in the elderly. Although not in this study, we have recently been collecting data to assess pre and postoperative ADL using the Barthel index. It may help predict postoperative outcomes in the elderly.