NORCAAD : the nordic consortium for acute type A aortic dissection

Background

ATAAD is a lethal condition, and emergency surgery is warranted for almost all patients. Despite advances in surgical techniques, as well as medical and anesthetic management, surgery for ATAAD continues to carry a high risk of major complications and early mortality. The optimal approaches to organizational, surgical, and medical management of ATAAD remain subjects of ongoing debate. The overall aim of this work was to investigate differences in management of ATAAD, as well as factors associated with short- and long-term adverse outcomes, with the goal of improving clinical decision-making and optimizing the management of ATAAD.

Methods and results

Study I - Type A aortic dissection repair in patients with prior cardiac surgery. All patients who underwent surgery for ATAAD between 2005 and 2014 identified from the NORCAAD database were included in the study. Patients who had undergone PCS (n=40) were compared with those who had not undergone PCS (n=1119). The primary outcome measure was 30-day mortality, and the secondary outcome measure was a composite outcome of early major complications: 30-day mortality, perioperative stroke, postoperative cardiac arrest, or de novo dialysis. Patients with PCS had higher 30-day mortality (30% vs 17.8%, p=0.049) and a higher prevalence of major complications (52.5% vs 35.7%, p=0.030). However, PCS was not an independent predictor for 30-day mortality (OR 0.78; 95% CI 0.30-2.07, p=0.624) or major complications (OR 1.07, 95% CI 0.45-2.55, p=0.879).

Study II - Improving outcomes of surgery for acute type A aortic dissection. All patients (n=204) who underwent surgery for ATAAD between 2015 and 2020 at Karolinska University Hospital were included. Patients were divided into two groups: recent (n=102) and earlier (n=102). Uni- and multivariable statistical analysis were performed to identify predictors of early mortality. A significantly lower 30-day mortality was observed in the recent group (recent: 3.9% vs earlier: 14.6%, p=0.014). There was no statistically significant difference in early mortality between high- and low-volume surgeons. Biological composite graft, concomitant coronary artery bypass grafting (CABG), intraoperative adverse event, preoperative lactate, non-normal left ventricular ejection fraction (LVEF) and dissection of any arch vessel were identified as independent predictors of 30-day mortality.

Study III - Late aortic reinterventions after surgery for acute type A aortic dissection. All patients (n=225) who underwent surgery for ATAAD at least a decade earlier (2005-2013) at Karolinska University Hospital were included. Information regarding the indication for and type of reintervention(s) were obtained from local databases and medical records. Measurements of aortic diameters were obtained from serial computed tomography (CT) scans. A Fine- Gray multivariable model, treating death and contraindication to reintervention as competing risks, was used to investigate factors associated with reintervention. The median follow-up was 10.3 years (5.0-13.4). A total of 37 patients underwent at least one aortic reintervention. Aortic root diameter >45 mm and no root replacement at index repair, bicuspid aortic valve (BAV), and age were associated with proximal reintervention. Failure to completely resect the primary tear and connective tissue disease (CTD) were associated with distal aortic reintervention. Event-free survival at 1, 5, 10 and 15 years was 82% (77-87), 72% (65-77), 48% (41-54) and 33% (26-40), respectively.

Study IV - Management of acute type A aortic dissection in the Nordic countries. A questionnaire with 32 questions regarding strategies for pre-, peri- and postoperative management of ATAAD was sent to participating centers in NORCAAD2. Of the 17 centers that received the questionnaire, 12 centers (71%) responded. Regarding the primary site of arterial cannulation, seven centers (58%) used femoral artery cannulation. Nine centers (75%) used cerebral perfusion in most cases requiring hypothermic circulatory arrest (HCA). Five centers (42%) reported that total arch replacements and valve-sparing root replacements were never performed. The number of annual ATAAD cases ranged from 5-50, and the number of surgeons performing ATAAD repairs ranged from 3 to 8. Regarding postoperative surveillance, 42% of centers had unlimited follow-up time, 25% followed patients for 10 years and 33% followed patients for 5 years. All centers reported that they used a CT scan interval of 6-12 months.

Conclusions

Patients with PCS had a higher prevalence of major complications. However, PCS itself was not independently associated with adverse events. Previous cardiac surgery should not deter emergency surgery.

Early outcomes after surgery for ATAAD improved in the most recent era. Possibly, having fewer surgeons performing more procedures, adopting a relatively conservative surgical approach, and ensuring adequate cerebral protection may have contributed to the improvement.

With sufficient follow-up, event-free survival following ATAAD repair appears to be substantially compromised. Potentially, aortic root replacement in patients with moderate aortic root dilatation and ensuring complete resection of the primary tear may reduce the need for future aortic reinterventions.

NORCAAD2 comprises low-, medium- and high-volume centers, each employing different strategies for cannulation, cerebral protection, extent of aortic resection, surgical techniques, and postoperative surveillance. These variations make NORCAAD2 an excellent opportunity to study these contested topics in a large patient population.

List of scientific papers

I. Bjurbom M, Olsson C, Geirsson A, Gudbjartsson T, Gunn J, Hansson E, Hjortdal V, Jeppsson A, Mennander A, Ede J, Zindovic I, Ahlsson A, Wickbom A, Dalén M. Type A aortic dissection repair in patients with prior cardiac surgery. Ann Thorac Surg 2023;115:591-9.
https://doi.org/10.1016/j.athoracsur.2022.05.033

II. Bjurbom M, Dalén M, Franco-Cereceda A, Olsson C. Improving outcomes of surgery for acute type A aortic dissection. Scand Cardiovasc J 2023 Dec;57(1):2210275
https://doi.org/10.1080/14017431.2023.2210275

III. Bjurbom M, Ma K, Dalen M, Franco-Cereceda A, Olsson C. Late aortic reinterventions after surgery for acute type A aortic dissection. Ann Thorac Surg [Submitted]

IV. Bjurbom M, Franco-Cereceda A, Olsson C. Management of acute type A aortic dissection in the Nordic countries. Scand Cardiovasc J [Submitted]