The impact of CK-MB elevation in patients with acute type A aortic dissection with coronary artery involvement

Acute type A aortic dissection (ATAAD) is lethal and requires emergency intervention. Although recently, the treatment of ATAAD has provided better outcomes than before, acute coronary artery involvement (ACI) is an independent predictor of mortality [1].

Although there were many articles about ACI, the definition of ACI differs because there were no criteria for diagnosis. It was reported that ACI did not necessarily cause myocardial ischemia because the degree of impairment varied from case to case. There was no paper focusing on the actual impact of myocardial damage on patients with ACI. Therefore, in this study, we retrospectively analyzed the surgical outcomes of ACI with or without myocardial damage.

Baseline patient characteristics are shown in Table 1. The average CK-MB was 226.5 IU/L in the MI group and 13.5 IU/L in the NMI group. No significant difference was observed in most, but only heart failure was significantly more in the MI group.

Operative data are shown in Table 2. There was no significant difference in the involved artery between the right coronary artery and the left coronary artery. All patients with simultaneous right and left coronary artery involvement were observed in the MI group.

Total operative time was 209 ± 84 min in the MI group and 207 ± 40 min in the NMI group. Circulatory arrest time was 25 ± 5 vs. 25 ± 4 min, and the cardiopulmonary bypass time was 152 ± 27 vs. 150 ± 28 min, respectively.

Table 3 shows the mortality and major complications. The mortality was significantly higher in the MI group than in the NMI group ( 69% vs. 13% p = 0.03). The mean ICU stay days were 4 ± 5 days in the MI group and 3 ± 3 days in the NMI group. There was no significant difference in other complications.

Previously, the mortality of ATAAD with ACI was reported to be between 19.5 and 33% [2‐4]. However, one of the most challenging aspects of ACI is a correct preoperative diagnosis and evaluation. Firstly, the main symptom of ATAAD “masks” that of coronary ischemia [5], and secondly, there is no definitive diagnostic examination.

As a diagnostic material for acute myocardial infarction, CK-MB is prevalently used. Since the etiology of the ACI due to ATAAD is different from that of ordinary coronary artery disesase, the ACI does not necessarily lead to myocardial necrosis at the same speed. However, it was unknown 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 h 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 be higher. Previous reports showed that time to operation was a predictive factor for patients with ATAAD [6, 7]. 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.

Since it is not easy to diagnose ACI preoperatively, it would be difficult for cardiologists and cardiac surgeons to treat every emergency case practically. 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 feasible. 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 (Fig. 1). Preoperative PCI played an important role as a bridge to operation in this case. Although the patient was in hemodynamically severe condition even after the PCI, he underwent the operation successfully. He survived five years of follow-up. In the real world, the degree of ACI, the transportation time to the surgical facility, and the medical level of the initial medical institution would vary for each patient. Therefore, it is a future research subject to clarify what kind of treatment is the best for each patient’s severity.

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. Finally, 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.

Sixty-two percent of patients with ACI increased CK-MB in an average of 4 h from onset to surgery. The mortality of patients with CK-MB elevation was significantly higher than those without CK-MB elevation. It is important to treat patients with ATAAD complicated with ACI before they have an increase in CK-MB.