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Mortality and Clinical Outcomes of Type B Aortic Dissection Versus Intramural Haematoma: A Systematic Review and
Byeng Hun Jeon1, Tae Hong Yoon2, Jun Woo Cho3
1Department of Thoracic and Cardiovascular Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
Objective:
To compare mortality and clinical outcomes between type B intramural haematoma (IMH) and type B aortic dissection, given the absence of synthesised comparative evidence between these two entities.
Data Sources:
PubMed, Embase, and Cochrane Library.
Review Methods:
A systematic search was conducted from inception to October 2025, in accordance with the PRISMA guidelines (PROSPERO; CRD420251158538). Observational cohort studies directly comparing type B IMH with type B aortic dissection were eligible. Risk of bias was assessed using the ROBINS-I tool, and certainty of evidence was evaluated using GRADE. The outcomes included early and overall mortality and malperfusion. Time to event analyses were performed using Cox models and restricted mean survival time based on reconstructed data from Kaplan-Meier curves.
Results:
Nine studies comprising 2 529 patients (2 031 aortic dissection and 498 IMH) were included. Patients with IMH were older than those with aortic dissection (mean difference [MD] +6.65 years, 95% confidence interval [CI] 3.87 - 9.42). Overall mortality did not differ between IMH and aortic dissection (risk ratio [RR] 0.74, 95% CI 0.37 - 1.51; GRADE: very low), consistent with pooled survival analysis (hazard ratio [HR] 0.98, 95% CI 0.54 - 1.79) and the meta-analytic HR (0.87, 95% CI 0.32 - 2.42). Similarly, restricted mean survival time analyses across multiple time horizons showed no significant differences in survival. Malperfusion occurred less frequently in IMH than in aortic dissection (RR 0.27, 95% CI 0.12 - 0.63; GRADE: low), whereas no significant differences were observed in aortic related mortality and aortic rupture.
Conclusion:
Malperfusion occurred less frequently in type B IMH, but no significant difference in mortality or survival outcomes was observed between type B IMH and aortic dissection. The certainty of evidence is low to very low. Further studies involving contemporary cohorts and adequate follow up durations are required to clarify the prognostic implications of these findings.
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