Coronary artery involvement is a lethal complication, with high mortality rates (19.5-33%) (3–5). However, one of the most difficult aspects of ACI is a correct preoperative diagnosis and its evaluation. Firstly, the main symptom of ATAAD “masks” that of coronary ischemia (6), and secondly, there is no definitive diagnostic examination.
CK-MB is prevalently used as an absolute quantitative value, helpful in diagnosing myocardial infarction. Since the etiology of the ACI due to ATAAD is different from that of ordinary CAD, the ACI does not necessarily lead to myocardiac necrosis at the same speed. However, it was unknown that how many patients with ACI had a CK-MB elevation and the true impact of CK-MB elevation on the surgical outcome of ATAAD with ACI.
The present study showed that about 62% of patients with ACI had an increase in CK-MB. Moreover, the MI group had significantly higher mortality than the NMI group. As time is an essential factor when considering CK-MB, it should be noted that this study dealt with the data when surgery was performed about 4 hours after the onset. If it took more time to operate, the proportion of patients with a CK-MB elevation would increase, and as a result, the mortality was also expected to increase. Then, what kind of management should be done so as not to raise CK-MB?
Previous reports showed that time to operation was a predictive factor for patients with ATAAD (7, 8). However, in patients with ACI, time management to prevent CK-MB from rising is important. PCI would be able to revascularize fastest, and there is a possibility that it can prevent CK-MB elevation. However, as mentioned at the beginning, it is not easy to diagnose ACI preoperatively. Moreover, it would be difficult for both cardiologists and cardiac surgeons to treat every emergency case in actual clinical practice. On the other hand, although it would take more time than PCI, additional CABG can be performed safely only by cardiac surgeons, which is more practical. As for the timing of CABG, we performed CABG after aortic repair. We prioritized achieving cardiac arrest over revascularization of the coronary arteries because the progression of myocardial ischemia can be delayed by circulatory arrest. After all, it reduces myocardial oxygen demand by more than 90%.However, there is a situation where PCI first management is superior. In the most severe ACI cases, sudden occlusion of the coronary artery may result in death in tens of minutes. This study included only one case of such acute occlusion of the left main trunk (Figure1). In this case, preoperative PCI played an important role as a bridge to operation. Although the patient was in hemodynamically severe condition even after the PCI, he underwent operation successfully. He survived five years follow-up. Presumably, other similar cases have occurred. However, they died before reaching the hospital. Future studies are needed for better management.
According to the International Registry of Acute Aortic Dissection study, the number of organs with malperfusion is also an independent predictor of outcome; the more organs suffering malperfusion, the worse the prognosis. In this study, there was no significant difference in the rate of other organ’s ischemia between the MI group and the NMI group. However, the CK value tended to be higher in the MI group because there were more patients with other artery involvement in the MI group. In particular, Mesenteric malperfusion has been reported to be an independent prognostic factor for ATAAD (9). Since there were few cases of mesenteric malperfusion with ACI in this study, it was not known how mesenteric malperfusion affects the prognosis in patients with ACI. More research is necessary.
Our report described a retrospective and observational single-center non-randomized study. Secondary, the sample volume was small. However, ATAAD with ACI was rare, and the sample volume was not large even in past reports. Finaly we had no control group of patients with ACI not receiving CABG, or undertaking PCI only without CABG. Further studies are required to clarify the best treatment for life-saving patients.