Acute type A aortic dissection (ATAAD) remains one of the most lethal cardiovascular emergencies, with mortality rising rapidly without surgical intervention. Even with timely operative repair, postoperative complications such as death, stroke, and organ dysfunction significantly influence patient prognosis. In this Article in Press published in BMC Cardiovascular Disorders, Li and colleagues investigate a clinically relevant but underexplored variable: cardiopulmonary bypass (CPB) weaning time, defined as the interval from aortic cross-clamp release to complete discontinuation of CPB .
The study retrospectively analyzed 475 patients with ATAAD who underwent total arch replacement combined with stented elephant trunk implantation between June 2015 and June 2024. As shown in the flow diagram (Figure 1, page 13), 641 consecutive patients were screened, with exclusions for ECMO/IABP support, preoperative renal failure, organ malperfusion, coma or new stroke, and incomplete data . The final cohort reflects a substantial, high-acuity surgical population treated at a specialized center.
The investigators hypothesized that CPB weaning time could serve as a measurable and objective indicator of intraoperative physiologic stress and myocardial recovery. Unlike the loosely defined concept of “difficult weaning,” CPB weaning time offers a quantifiable metric. Prolonged weaning may reflect myocardial injury, vasoplegia, impaired cardiac function, or hemodynamic instability during separation from mechanical support.
Key Findings
Among the 475 patients, 58 (12.2%) experienced in-hospital mortality. As detailed in Tables 1 and 2 (pages 16–17), patients who died had significantly longer operative times, CPB durations, and notably prolonged CPB weaning times (median 91 minutes vs 64 minutes in survivors, p<0.001) .
In univariate analysis (Table 3, page 17), CPB weaning time was associated with postoperative death (OR 1.06 per minute increase, p<0.001), renal failure, and stroke. However, after multivariable adjustment, CPB weaning time remained independently associated only with in-hospital death (OR 1.05, 95% CI 1.02–1.07, p<0.001) and stroke (OR 1.02, 95% CI 1.00–1.04, p=0.016) .
Receiver operating characteristic (ROC) curve analysis (Figure 3, page 15) demonstrated strong predictive value for mortality, with an area under the curve (AUC) of 0.844. The optimal cutoff value identified using the Youden index was 90 minutes . Patients with CPB weaning times ≥90 minutes had a dramatically increased adjusted risk of death (OR 7.35, p<0.001) .
Importantly, survival analysis using Kaplan–Meier curves and a 1-month landmark (Figure 4, page 15) revealed that prolonged CPB weaning time significantly reduced short-term survival but did not significantly impact mid-term survival . This suggests that CPB weaning time is primarily a marker of early postoperative vulnerability rather than long-term structural disease progression.
Subgroup Insights
Subgroup analyses (Figure 2, page 14) demonstrated that the association between CPB weaning time and in-hospital mortality remained consistent across age, sex, coronary heart disease (CHD), and cannulation strategies . However, the relationship between CPB weaning time and stroke appeared modified by sex, CHD history, CABG performance, and arterial cannulation approach.
The authors note that axillary artery cannulation, which provides antegrade cerebral perfusion, may reduce stroke risk compared to femoral cannulation. Thus, more dominant cerebral perfusion strategies may attenuate the independent impact of prolonged CPB weaning on neurologic outcomes.
Clinical Implications
CPB weaning time represents a practical, immediately available intraoperative variable. Unlike composite or subjective definitions of difficult weaning, it provides objective data that can inform early postoperative risk stratification. A 90-minute threshold may serve as a red flag, prompting intensified monitoring, hemodynamic optimization, and proactive organ support.
The findings reinforce the concept that early mortality in ATAAD is influenced not only by anatomical severity and comorbidities but also by intraoperative physiologic resilience. Myocardial protection strategies, coronary assessment, and proactive planning for CABG may indirectly influence CPB weaning time and outcomes.
Interestingly, despite its strong association with short-term mortality, CPB weaning time did not significantly affect mid-term survival. As discussed by the authors, long-term outcomes in ATAAD are more strongly driven by comorbid conditions and anatomical factors rather than perioperative hemodynamics.
Limitations
This study is retrospective and single-center, introducing potential selection bias. Exclusion of patients with missing follow-up data may further limit generalizability. Additionally, the lack of detailed cause-of-death data and incomplete imaging variables restricts deeper mechanistic interpretation. The findings may not apply to other CPB-dependent procedures beyond ATAAD repair .
Conclusion
This study establishes CPB weaning time as an independent predictor of in-hospital death and postoperative stroke in patients undergoing total arch replacement for acute type A aortic dissection. A weaning time exceeding 90 minutes identifies patients at significantly increased risk of early mortality. While not predictive of mid-term survival, CPB weaning time provides a valuable intraoperative marker of early postoperative vulnerability and may enhance risk stratification in complex aortic surgery.
