Approval for this study was granted by the Institutional Ethics Research Board (Protocol #K-2020019). Individual patient consent was not required due to the retrospective nature of the cohort study. The patient flow diagram is shown in Figure 1. A total of 211 consecutive patients were diagnosed with aortic dissection at the General Hospital of the Northern Theater Command from January 2021 to July 2024. Of these, 15 patients were diagnosed with type B aortic dissection, and 10 patients with non-A-non-B aortic dissection via thoracic and abdominal aortic CTA. Eight patients declined surgical treatment, and 3 patients died before surgery due to dissection rupture. Additionally, 7 patients underwent median sternotomy for other cardiovascular diseases. Ultimately, 168 patients were included in the study cohort and were divided into two groups: 66 patients in the early myocardial reperfusion group (EMR group) and 102 patients in the cardioplegic arrest group (CA group). Inclusion criteria included age between 18 and 80 years old, confirmed diagnosis of TAAD via thoracic and abdominal aortic CTA, and a preoperative cardiac ultrasound examination confirming the condition of the aortic valve and the absence of pericardial tamponade. Exclusion criteria were failure to meet the inclusion criteria, a history of two or more cardiac surgeries, unstable hemodynamic conditions, the need for median thoracotomy surgery, the presence of cancer, and incomplete clinical data.

The surgical approach and cardiopulmonary bypass (CPB) strategy utilized for all patients followed the upper hemisternotomy technique for TAAD, with corresponding enhancements implemented. All patients underwent tracheal intubation and general anesthesia, with brain protection provided by ice caps during surgery. Continuous monitoring included bilateral radial artery pressure, dorsalis pedis artery pressure, cerebral oxygen saturation, nasopharyngeal temperature, and rectal temperature.

The surgical procedure involved a sternotomy from the suprasternal fossa to the center of the fourth intercostal space, followed by a horizontal cut of the right half of the sternum at the fourth intercostal space. The innominate vein, brachiocephalic artery, left common carotid artery, and left subclavian artery were individually isolated. After systemic heparinization, the surgeon selected the appropriate arterial cannulation site based on the extent of the dissection and performed direct right atrial cannulation for venous access. CPB was established through arterial and venous cannulation, with a left heart drainage tube placed at the root of the right upper pulmonary vein.

For patients in the CA group, after establishing CPB, the nasopharyngeal temperature was gradually reduced to 32°C. The aorta was clamped, and the ascending aorta was transected. Cardiac arrest was induced by direct perfusion through the coronary sinus. Procedures such as aortic valve reconstruction, aortic valve replacement, and Bentall surgery were performed as needed based on the involvement of the AD.

The left common carotid artery and left subclavian artery were clamped using Hem-o-lock clips, and the aortic arch was excised. A frozen elephant trunk (FET) was inserted into the descending aorta, and LBP was initiated using a 16Fr cannula with an occlusion balloon (Longlaifu, Changzhou, China) inserted through the distal artery of the 4-branch prosthetic graft (Hemashield Platinum Double Velour Vascular Graft; MAQUET, La Ciotat, France), providing blood flow recovery to the lower body at a rate of 25 ml/kg·min. Once the distal aorta incorporating the stent graft was securely attached to the distal end of the 4-branch prosthetic graft, LBP was initiated via the perfusion limb of the 4-branch prosthetic graft. A four-branch prosthetic graft was anastomosed with the FET and distal aorta, and then sequentially anastomosed with the left common carotid artery, proximal aortic stump, left subclavian artery, and brachiocephalic artery. After completing the anastomosis of the left common carotid artery, CPB gradually returned to normal flow, and rewarming was initiated.

In the EMR group, after the establishment of CPB and cardiac arrest, the aortic root was addressed based on the extent of aortic dissection involvement. Once the 4-branch prosthetic graft was anastomosed to the proximal ascending aorta, a perfusion tube was inserted into the graft, the distal end was clamped, and selective myocardial perfusion was initiated. Warm blood (at a flow rate of 250–400 ml and maintained at a temperature of approximately 32°C) was used to achieve early cardiac resuscitation. The perfusion flow rate was adjusted based on electrocardiogram (ECG) monitoring of ST-segment changes and perfusion pressure, which was maintained at approximately 150 mmHg using a myocardial protection perfusion device with built-in pressure monitoring. Effective left ventricular drainage was ensured during selective myocardial perfusion, with the drainage volume closely matching the perfusion flow rate to prevent ventricular distension. Following this, the aortic arch was excised, and the FET was inserted. The remaining steps of the procedure were identical to those performed in the CA group.

This study utilized SPSS Statistics 27.0 (IBM Corporation, Chicago, USA) and R version 4.4.1 (R Foundation for Statistical Computing, Vienna, Austria) for data analysis. Categorical variables were presented as counts and percentages (%), and group comparisons were conducted using either the chi-square test or Fisher's exact test. Continuous variables following a normal distribution were expressed as mean ± standard deviation, while those not following a normal distribution were presented as median and interquartile range, with group comparisons performed using t-tests or Mann-Whitney U-tests. We utilized the standardized mean difference (SMD) to evaluate the balance between groups. An SMD value of less than 0.1 indicates that the baseline characteristics between the two groups are well balanced. A generalized linear model was used to analyze the repeated measurement data, as they did not follow a normal distribution in this study. A P-value of less than 0.05 was considered statistically significant. GraphPad Prism 10 (GraphPad Software Inc., San Diego, CA, USA) was used for generating graphical illustrations.

No significant differences were observed between the two groups regarding age, sex, weight, time of onset, hypertension, smoke, drink and Marfan's disease. The comparisons were as follows: age [49.27 ± 12.33 years (EMR group) vs. 52.04 ± 11.58 years (CA group)], sex [78.8% male (EMR group) vs. 67.6% male (CA group)], weight [80.00 kg (70.00, 95.00) (EMR group) vs. 79.00 kg (67.50, 90.00) (CA group)], time of onset [70.00 h (28.75, 160.75) (EMR group) vs. 48.50 h (22.75, 106.50) (CA group)], smoke [45.5% (EMR group) vs. 39.2% (CA group)], drink [27.3% (EMR group) vs. 23.5% (CA group)], hypertension prevalence [62.1% (EMR group) vs. 70.6% (CA group)], coronary heart disease prevalence [7.6% (EMR group) vs. 9.8% (CA group)] and Marfan's disease prevalence [7.6% (EMR group) vs. 5.9% (CA group)]. In the EMR group, no patients had diabetes and a history of cerebrovascular accidents (CVA), while in the CA group, 4 patients (3.9%) had a history of CVA and 5 patients (4.9%) had a history of CVA. There were 5 patients (7.6%) EMR group had cerebral malperfusion, 1 patient (1.5%) had renal malperfusion and 2 patients (3.0%) had limb malperfusion in EMR group at the time of admission. And 5 patients (4.9%) had cerebral malperfusion, 1 patient (1.0%) had visceral malperfusion, 7 patient (6.9%) had renal malperfusion and 7 patients (6.9%) had limb malperfusion at the time of admission in CA group. The preoperative characteristics of patients are detailed in Table 1.

Table 2 presents the surgical procedures and intraoperative data of the patients, showing no significant differences between the two groups except for the time of cardioplegic arrest [45.00 (36.00, 73.00) (EMR group) minutes vs. 85.00 (71.00, 101.25) (CA group) minutes]. The CPB time was comparable between the EMR group and the CA group [157.00 (135.75, 190.50) minutes vs. 162.00 (137.00, 198.25) minutes], as were the cross-clamp time [92.00 (78.00, 112.75) vs. 92.00 (80.00, 106.00) minutes] and circulatory arrest time [6.00 (5.00, 7.00) minutes vs. 6.00 (5.00, 7.00) minutes]. Additionally, both groups primarily utilized bilateral selective antegrade cerebral perfusion as their brain perfusion strategy (95.5% vs. 97.1%).

The early postoperative outcomes between the EMR group and CA group are presented in Table 3. The ventilation time [23.08 (18.21, 66.74) hours vs. 48.58 (19.18, 122.97) hours], ICU stay time [58.80 (21.20, 126.68) hours vs. 84.86 (41.12, 168.81) hours], and hospitalization time [13.00 (10.00, 16.00) days vs. 15.00 (11.75, 19.00) days] were significantly shorter in the EMR group compared to the CA group (P < 0.05). There was no significant difference in hospital costs [22.59 (20.67, 25.12) ¥ vs. 23.16 (21.18, 28.18) ¥], first-day chest tube drainage [245.00 (150.00, 352.50) ml vs. 250.00 (167.50, 332.50) ml], left ventricular ejection fraction [58.00 (56.50, 59.00) % vs. 58.00 (56.00, 59.00) %] and blood transfusion (83.3% vs. 89.2%). The units of red blood cell transfusion were significantly lower in the EMR group compared with the CA group [2.00 (0.00, 3.85) ml vs. 3.25 (0.75, 6.00) U]. The postoperative adverse events between the two groups had no significant difference, except for the rate of CRRT treatment, where the EMR group had significantly fewer patients requiring postoperative CRRT (10.6% vs. 23.5%).

Ten patients died during hospitalization. In the EMR group, two patients died of multiple organ failure. In the CA group, two patients died of multiple organ failure, three patients died of circulatory dysfunction, and three patients died of malignant arrhythmia.

The trend of laboratory outcomes in patients before and after surgery is shown in Tables 4, 5 and Figure 2. There was a significant difference in TNT levels between the two groups of patients 1 week after surgery [47.00 (29.00, 184.75) ng/L vs. 89.00 (41.50, 243.00) ng/L, P = 0.009]. However, there were no significant differences in other laboratory results (P > 0.05). In addition, there was no significant difference in the group comparison of all the above laboratory outcomes, but significant differences were observed in the intra-group comparison (P < 0.05).

This study has several limitations. First, it is a retrospective, single-center analysis with a small sample size, introducing a risk of bias. Second, due to individual differences among patients and preoperative comorbidities, achieving randomization was challenging, potentially leading to selection and observational biases. However, due to our current dataset's constraints, this study lacks adjustment for relevant baseline and operative covariates and our study does not incorporate multivariate analysis to adjust for potential confounding variable. Third, the study only compared perioperative surgical outcomes and lacked mid-term and long-term follow-up data. Finally, our study only used TNT as an indicator to measure the severity of myocardial injury and lacked other biomarkers. Additionally, the young age of patients included in the cohort and their very low prevalence of malperfusion suggest that there could be confounders introducing bias in this analysis. However, we believe that these results are particularly relevant and applicable to younger patient populations. In the future, we plan to conduct a prospective randomized controlled trial with a larger sample size, multicenter, long-term follow-up and to examine multiple markers of myocardial injury postoperatively to evaluate the safety and feasibility of this surgical technique over the long term.