Should Type B intramural hematoma be treated like Type B aortic dissection? A narrative review

Type B aortic dissection (TBAD) and Type B intramural hematoma (IMH) are 2 pathologies that fall within acute aortic syndromes. Complication risk in TBAD is determined by false lumen hemodynamics, whereas IMH progression is driven more by morphologic factors. However, it is still debated as to how these high-risk features, in the absence of complications, should affect their management. To synthesize current evidence and evaluate whether TBAD-analogous treatment protocols are most appropriate for Type B IMH, a narrative review was conducted of guidelines, retrospective cohorts, registries, and studies assessing optimal medical therapy and thoracic endovascular aortic repair (TEVAR). The focus was on high-risk features, intervention timing, and guideline discordance. IMH demonstrates greater early-phase instability. Optimal medical therapy, for low-risk cases, and TEVAR, for complicated pathology, are effective for both IMH and TBAD. However, high-risk IMH assessment and course pose greater variability. There are low-quality evidence and reports for early prophylactic TEVAR in high-risk IMH and TBAD. Surveillance recommendations are similar but supported by weaker IMH evidence. Despite overlapping initial medical management strategies in low-risk cases, Type B IMH requires a management approach that is not fully analogous to TBAD. Its unique risk factors and unpredictable course require individualized decision making rather than protocolized care at the current state of evidence. Harmonized risk criteria, optimized intervention timing, and concrete prospective studies are needed to strengthen IMH-specific management.