Can routine laboratory tests flag patients at greater risk of major bleeding after acute type A aortic dissection repair? A retrospective study from Lund, Sweden, found that a longer preoperative activated partial thromboplastin time (APTT) was associated with postoperative massive bleeding. The finding is relevant to perfusion and blood-management teams, but it remains a risk signal requiring validation rather than a stand-alone treatment trigger.
Study Design and Population
Norén and colleagues reviewed patients undergoing acute type A aortic dissection repair at Skåne University Hospital between January 2005 and May 2023. Of 498 surgical patients, 20 who died during the index operation and four with incomplete outcome data were excluded. The analysis included 474 patients who survived the operation; 87 (18.4%) subsequently met the study’s definition of massive bleeding.
The investigators assessed routine preoperative coagulation tests and other clinical variables. The multivariable analysis used 364 complete cases. This was a single-center observational cohort, not a trial of a bleeding-prevention strategy.
How Massive Bleeding Was Defined
Patients met the BART-based composite outcome if they had at least one of the following:
- Chest-tube drainage exceeding 1,500 mL during any eight-hour period.
- Reoperation for bleeding or cardiac tamponade within 24 hours.
- More than 10 units of red blood cells transfused within 24 hours after surgery.
- Death from hemorrhage within 30 days.
These components could overlap. The endpoint therefore captures several different manifestations of severe bleeding and treatment burden, rather than a single measured blood-loss threshold.
Key Findings
| Measure | Massive bleeding | No massive bleeding |
|---|---|---|
| Patients | 87 | 387 |
| Median preoperative APTT | 33 seconds | 29 seconds |
| Median platelet count | 172 × 10⁹/L | 187 × 10⁹/L |
| Median cardiopulmonary bypass time | 221 minutes | 170 minutes |
| 30-day mortality, as reported | 20.7% | 5.7% |
| 90-day mortality, as reported | 24.1% | 6.5% |
Selected results from the source study. Mortality data were missing for a small number of patients; percentages are reproduced as reported. Group differences do not establish causation.
APTT remained associated with bleeding after adjustment
An APTT above 34.5 seconds was associated with higher adjusted odds of massive bleeding: odds ratio 2.95 (95% confidence interval 1.60–5.47). In the continuous-variable analysis, the odds ratio was 1.04 per additional second (95% CI 1.01–1.07). These are odds ratios, not estimates of an individual patient’s absolute risk.
The threshold was selected from this dataset using receiver-operating-characteristic analysis and Youden’s index. APTT alone had an area under the curve of 0.624, indicating limited discrimination. It should not be presented as a validated cutoff that reliably separates patients who will bleed from those who will not.
Other associated factors
Preoperative creatinine above 82.5 µmol/L was associated with massive bleeding in a separate threshold-based model (adjusted OR 2.16; 95% CI 1.15–4.06). Hypertension and longer CPB time were also associated with the outcome. Each additional 10 minutes of CPB had an adjusted OR of 1.09 (95% CI 1.05–1.13).
Although platelet counts were lower in the bleeding group, platelet count was not independently significant in the adjusted analyses. Fibrinogen and D-dimer data were frequently missing, limiting what can be inferred about their predictive value.
What This Means for Perfusion Teams
The study reinforces the importance of understanding the patient’s coagulation status before bypass and communicating that information within the surgical, anesthesia, perfusion, and transfusion team. In aortic dissection, pre-existing coagulation disturbances coexist with the additional hemostatic stresses of complex surgery and CPB.
However, the association with CPB duration is not evidence that reducing bypass time by a fixed amount will produce a corresponding reduction in bleeding. Longer bypass may also reflect procedural complexity or illness severity. Moreover, CPB duration is an intraoperative variable, so the adjusted model is not a purely preoperative prediction tool.
Likewise, this study did not test whether giving procoagulant therapy earlier to patients above the APTT threshold improves outcomes. The results support further investigation of risk assessment, not automatic transfusion or drug treatment based on APTT alone.
Limitations and Evidence Assessment
The retrospective, single-center design leaves the findings vulnerable to residual confounding and limits generalizability. Excluding intraoperative deaths means the results apply to patients who survived the initial procedure and may omit some of the most severe presentations.
The 18-year study period also spans changes in surgical practice and hemostatic management. The authors report that the APTT and creatinine associations persisted after adjustment for treatment era, but this does not eliminate all effects of changing care. Missing laboratory data and incomplete information about the timing of preoperative antiplatelet therapy add uncertainty.
Finally, the thresholds were derived and assessed in the same cohort, without external validation. APTT reference ranges and assay characteristics may also differ between laboratories. The most defensible interpretation is that preoperative APTT may contribute to a broader bleeding-risk assessment, pending prospective validation and studies showing that its use improves care.
Source and Attribution
This original IPA educational summary is based on the open-access study by Norén and colleagues, published under the Creative Commons Attribution 4.0 license. Selected results are summarized and presentation has been adapted. The cover is a conceptual medical illustration, not an anatomical teaching diagram.
Original Article
Norén E, Ede J, Larsson M, Nozohoor S, Sjögren J, Teurneau-Hermansson K. Preoperative levels of biomarkers of coagulation to predict massive bleeding after surgical repair for acute type A aortic dissection: a retrospective cohort study. Journal of Cardiothoracic Surgery. 2026;21:762. doi:10.1186/s13019-026-04692-8.
