Surgery compared with medical treatment in patients with type A aortic intramural hematoma: a systematic review and meta-analysis

Introduction

Acute aortic syndrome is a life-threatening condition encompassing classic aortic dissection, intramural hematoma (IMH), and penetrating aortic ulcer (1-4). Accounting for approximately 5–25% of cases, IMH involves a medial-layer aortic hematoma without an intimal disruption or a flowing false lumen (1-4). Compared with the Western population, the reported proportion of IMH in the Asian population is relatively higher (1-11).

IMH is categorized as type A and type B, based on the presence or absence of ascending aortic or arch involvement (1-4). Type A IMH carries a high risk of progression to dissection, rupture, or cardiac tamponade, contributing to substantial morbidity and mortality (1-4). Timely diagnosis and management are therefore critical.

Principles for IMH management is originally stemmed from the treatment protocols of aortic dissection. Contemporary guidelines predominantly advocate urgent surgical intervention, intending to eliminate diseased segments and prevent lethal complications (1-4). However, surgery is also associated with multiple complications (such as infection, spinal cord ischemia, neurologic complications, etc.), leading to adverse outcomes (5-26). A growing number of studies, primarily from Asian cohorts, suggest that a subset of patients with “uncomplicated” type A IMH may be managed successfully with initial medical treatment (MT) focusing on strict blood pressure and heart rate control, followed by close clinical and imaging surveillance (5,7-10,13,15,17,19-26).

However, no consensus has been reached regarding the management for type A IMH, primarily because available evidence is confined to small-scale observational studies (5-26), and previous syntheses have seldom accounted for the nuanced realities of clinical decision-making and treatment pathways (27-30). Therefore, we conducted this systematic review and meta-analysis to compare the outcomes of surgery vs. MT in patients with type A IMH. We present this article in accordance with the PRISMA reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1104/rc) (31).

Methods

This study was registered at PROSPERO (ID: CRD420261286005). A systematic literature search was carried out independently by S.Q.L. and S.W. across PubMed, the Cochrane Library, EMBASE, and ClinicalTrials.gov to retrieve English-language studies published prior to Nov 16, 2025, that compared early surgery (ES) vs. initial MT for type A IMH. The core search strategy is detailed in Table S1. Reference lists of identified articles were manually screened for potentially qualifying reports.

Eligibility criteria involved: (I) population: type A IMH patients. (II) Intervention: ES group. (III) Control: initial MT group. (IV) Outcomes: all-cause death and/or aortic-related death. In-hospital mortality was defined as the primary outcome, while all-cause death and aortic-related death during follow-up were regarded as the secondary outcomes. (V) Strategy: prospective or retrospective, single-center or multi-center, randomized controlled trials or observational studies. Studies were excluded if they: (I) lacked relevant data; (II) included less than 5 patients in either the ES group or the Initial MT group; and (III) reported overlapping or duplicated data (the one with the latest or most complete data was included).

Two independent reviewers (S.Q.L. and S.W.) extracted all data and assessed study quality. Any disagreements were settled by consensus or adjudication by a third reviewer (Y.M.Y.). The Risk Of Bias In Non-randomized Studies of Interventions (ROBINS-I; version 2) tool was utilized for quality assessment, which evaluates bias due to confounding, classification of interventions, selection of participants, deviation from intended interventions, missing data, measurement of outcomes, and selection of reported results. Overall risk of bias was classified as low, moderate, serious, or critical (32).

Statistical analysis

Binary random-effects models were utilized to calculate pooled relative risks (RRs) with 95% confidence intervals (CIs). Based on the Cochrane Q test and I² statistic, heterogeneity across studies was classified as low (I²=26–50%), moderate (I²=51–75%), or high (I²=76–100%), respectively. During index hospitalization and follow-up, a portion of the patients in the initial MT group were converted to timely surgery (CS). The initial MT group could be divided into three subgroups: patients receiving initial MT but CS during hospitalization (CS group), patients declining doctor-recommended surgery (DS group), and patients receiving pure MT (pure MT group) (shown in Figure 1). In order to evaluate the prognostic differences between different management strategies, we conducted further analysis in different subgroup combinations. According to whether undergoing surgery ultimately, patients could be classified into the ES + CS group and the pure MT group. When excluding patients declining DS, patients could be divided into the ES group and the initial MT excluding those declining DS group (initial MT-DS group) (shown in Figure 1). To evaluate the stability of the meta-analytic findings, a sensitivity analysis was carried out by omitting studies one by one and re-pooling the effect sizes from the remainder. Subgroup analyses were stratified by sample size, population characteristics, publication year, and effect measure. Begg’s funnel plot and Egger’s test were employed to detect potential publication bias. Review Manager 5.3 (The Cochrane Collaboration, 2014, Copenhagen, Denmark) and Stata 12.0 (StataCorp LP, College Station, TX, USA) were used for analysis.

Figure 1 Different grouping of patients with type A aortic IMH according to their management strategy. CS, converted to timely surgery; DS, declining surgery; ES, early surgery; IMH, intramural hematoma; MT, medical treatment.

Results

As shown in Figure 2 of the literature retrieval procedure, 22 studies with a total of 1,831 patients were incorporated in our meta-analysis (5-26). Table 1 summarizes the baseline characteristics for each eligible study. All studies were observational in design. Six studies were conducted in Western countries, whereas the remaining sixteen involved Asian populations. Across all participants, 848 underwent ES, and 983 received MT initially. The indications for ES were displayed in Table S2. Follow-up durations ranged from 3 to 120 months. ROBINS-I assessment indicated that the majority of the studies had moderate risk of bias, while eight studies carried serious risk of bias.

Figure 2 Flow diagram of the literature retrieval process.

ES vs. initial MT

Figure 3 summarizes the quantitative synthesis results. For the primary outcome, the ES group showed a trend toward lower in-hospital mortality over the initial MT group, but the difference has not reached statistical significance (RR: 0.74; 95% CI: 0.50–1.10; P=0.14).

Figure 3 Primary and secondary endpoints for the ES group vs. the initial MT group. CI, confidence interval; ES, early surgery; MH, Mantel-Haenszel; MT, medical treatment.

Regarding the secondary outcomes (Figure 3), ES conferred a remarkable benefit over initial MT in decreasing all-cause mortality during follow-up (RR: 0.56; 95% CI: 0.37–0.83; P=0.004). But the two strategies yielded similar risk of aortic-related death (RR: 0.85; 95% CI: 0.34–2.09; P=0.72). Heterogeneity across studies was low (P>0.05; I²<50%).

ES vs. CS

In patients receiving initial MT but CS later (indications for conversion were summarized in Table S2), the incidence of in-hospital death was comparable to that in patients undergoing ES (ES vs. CS: RR: 0.85; 95% CI: 0.44–1.64; P=0.63) (Figure 4). In addition, there was a significantly decreased all-cause mortality during follow-up in the CS group compared with the ES group (ES vs. CS: RR: 3.80; 95% CI: 1.12–12.84; P=0.03). Heterogeneity between studies was low (P>0.05; I²<50%).

Figure 4 Outcomes in patients undergoing ES compared with those receiving initial MT but CS. CI, confidence interval; CS, converted to timely surgery; ES, early surgery; MH, Mantel-Haenszel; MT, medical treatment.

ES or CS vs. pure MT

We undertook an analysis according to different groupings for surgical treatment and MT. The in-hospital mortality (RR: 0.59; 95% CI: 0.36–0.94; P=0.03) and all-cause mortality (RR: 0.50; 95% CI: 0.25–1.00; P=0.05) were relatively lower in patients undergoing ES or CS, compared with pure MT (Figure 5). The risk of aortic-related death was comparable between the ES + CS group and the pure MT group (RR: 0.67; 95% CI: 0.23–2.00; P=0.48). Low heterogeneity was noted (P>0.05; I²<50%).

Figure 5 Outcomes in patients undergoing ES or CS compared with those receiving pure MT. CI, confidence interval; CS, converted to timely surgery; ES, early surgery; MH, Mantel-Haenszel; MT, medical treatment.

ES vs. initial MT-DS

As we removed patients declining DS from the initial MT group, the risk of in-hospital death was comparable between the ES group and the initial MT-DS group (RR: 1.04; 95% CI: 0.49–2.17; P=0.93) (Figure 6). They are existed low heterogeneity (P=0.43; I²=0%).

Figure 6 Outcomes in the ES group compared with the initial MT excluding those declining surgery group. CI, confidence interval; DS, declining surgery; ES, early surgery; MH, Mantel-Haenszel; MT, medical treatment.

Sensitivity and subgroup analysis

As displayed in Figure S1, sensitivity analysis by sequential removal of each study has not altered the pooled RR for the primary outcome remarkably. As summarized in Table 2, subgroup analyses stratified by sample size, population characteristics, publication year, and effect measure all yielded findings that aligned with the main analysis. Publication bias for the primary outcome was not remarkable according to Begg’s funnel plot (P>0.99) and Egger’s test (t=0.66; P=0.51) (Figure 7).

Figure 7 Begg’s funnel plot assessing potential publication bias concerning the primary endpoints across studies comparing ES with initial MT. Horizontal line means magnitude of the effect. ES, early surgery; logRR, natural logarithm of relative risk; MT, medical treatment; SE, standard error.

Discussion

In our pooled analysis of 1,831 type A IMH patients, the ES group displayed a trend toward lower in-hospital mortality over the Initial MT group, but the difference has not reached statistical significance. Meanwhile, a remarkably reduced risk of all-cause death during follow-up could be observed in the ES group. Patients receiving initial MT but CS later had a comparable in-hospital mortality and significantly reduced all-cause mortality during follow-up compared with ES. Compared with pure MT, ES and CS still displayed superiority in decreasing the risk of in-hospital death and all-cause death. However, when excluding patients declining DS from the initial MT group, the risk of in-hospital death was comparable between the ES group and the initial MT-DS group.

The management strategy for type A IMH was primarily derived from that for aortic dissection. However, type A IMH might represent a more heterogeneous disease spectrum than classic type A aortic dissection (1-4). Unlike classic dissection, IMH involves a hematoma within the aortic media without an identifiable intimal tear. This pathophysiological distinction may explain the various prognoses of patients with IMH, ranging from regression to progression into dissection and eventually rupture (1-4). The dynamic nature of IMH supports an individualized surveillance-based strategy rather than a one-size-fits-all surgical approach.

The principal finding of our study—a non-significant trend toward lower in-hospital mortality and a significant reduction in long-term all-cause mortality in patients undergoing ES—aligns with current guideline recommendations (1-4). This substantial risk reduction might be attributed to the pathophysiological rationale for surgery. Type A IMH involves the ascending aorta, where wall stress and structural vulnerability converge to heighten rupture risk and malperfusion (1-4). The ascending aorta in type A IMH represents a high-risk anatomical milieu in which progression to rupture or catastrophic aortic events can occur despite initial stability (1-4). Operative repair removes the diseased aortic segment, potentially mitigating risks of rupture, tamponade, malperfusion, and progression to dissection (11,28,33,34). The relative reduction in in-hospital mortality underscores the effectiveness of early surgical intervention in preventing the most immediate life-threatening complications of type A IMH. The significant reduction in all-cause death further reinforces the long-term benefit of surgery.

For patients with type A IMH, the optimal timing for surgical intervention remains controversial. In the IMH cohort, a subset of patients might evolve to require urgent surgery due to progression or complications (5,7-9,15-21,23,24,26). In our study, patients who initially received MT but subsequently converted to surgery demonstrated similar in-hospital mortality but remarkably reduced long-term all-cause mortality compared with those who underwent ES. Compared with pure MT, ES and CS still exhibit advantages in reducing in-hospital mortality and all-cause mortality. This finding suggests that “timely” surgical intervention—whether urgent or delayed—may be the critical determinant of survival. This finding has important implications for clinical practice. On one hand, it supports the staged “wait-and-see” strategy with aggressive surveillance and timely intervention in selected patients initially managed medically (1-4). Initial MT and conversion to surgery may improve aorta tissue stabilization and allow time for diagnostic reassessment, comorbidity optimization, and clearance of antithrombotic agents (1-4,21,28). These steps may help improve outcomes and could be reserved for stable patients. On the other hand, it indicates that delayed surgery might not be inferior to urgent surgery in patients with type A IMH. The key factor may not be the timing of surgery per se (urgent vs. delayed), but rather the avoidance of a sentinel event before surgery is performed (1-4,21,28). This underscores the importance of meticulous monitoring protocols in medically managed patients, including frequent clinical assessments and serial imaging studies. It implies that outcomes comparable to ES can be achieved if patients are monitored with extreme vigilance and timely escalation to surgery when indicated. This practice demands a highly organized multidisciplinary team and immediate access to a cardiovascular surgical center. Rapid reassessment protocols, standardized imaging intervals, and clearly defined conversion criteria are essential components of a safe “wait-and-see” strategy (1-4). However, it must be emphasized that in our study, the conversion group is inherently subject to immortal time bias because patients must survive from presentation until the time of conversion to surgery, whereas the ES group undergoes intervention urgently. This bias likely favors the conversion group and substantially limits the validity of comparisons with ES. This bias precludes causal inferences about the optimal timing of surgery, and the findings should be interpreted with substantial caution. Our data could not robustly support a “wait-and-see” strategy, but only suggest that this approach might lead to acceptable outcomes. High-quality prospective studies with time-to-event analyses accounting for immortal time bias are needed.

When we excluded patients who declined DS from the initial MT group, the mortality difference between the ES group and the initial MT-DS group became nonsignificant (RR: 1.04). Compared with those not advised for surgery, patients recommended for surgery by doctors tended to have poorer baseline status and more complications (35). Those who declined surgery appeared to carry a worse prognosis. When excluding these high-risk patients from the initial MT group, the initial MT-DS group demonstrated an in-hospital mortality comparable to the ES group. This shift might highlight that initial MT could be acceptable in managing selected patients without high-risk features. However, it must be pointed out that only four studies in Asian populations reported data on patients declining DS, which might introduce selection bias. Consequently, conclusions regarding the efficacy and safety of primary MT should be interpreted with caution.

Several meta-analyses have previously explored the outcomes of type A IMH patients receiving different treatment strategies (21,28,30). Tian et al. have undertaken a single-arm study to evaluate the efficacy and safety of surgery in patients with type A IMH (28). The pooled results suggested that the mortality of patients undergoing surgery was acceptable, but there existed significant discrepancies between Asian and Western patients. Chow et al. (21) and Sá et al. (30) have undertaken meta-analyses of studies comparing ES and initial medical management. Their results consistently demonstrated that ES is associated with lower mortality. Our study has confirmed the relative advantages of ES in patients with type A IMH. In addition, our study provides several novel and clinically important contributions that distinguish it from previous work. First, we have carried out an updated literature search of relevant studies and incorporated recent large-scale studies [e.g., Akita 2024 (10), Jung 2026 (24), Kim 2025 (11), Liu 2025 (25), Naito 2025 (26)] that were not included in earlier meta-analyses. These newer studies add substantial patient numbers and contemporary data. Second, we have undertaken head-to-head comparisons between ES and CS, and between ES + CS vs. pure MT, which offer a more detailed understanding of treatment pathways. In addition, we specifically analyzed outcomes in patients who declined DS (DS group) and those who were initially managed medically without a recommendation for surgery (initial MT-DS group). This analysis revealed that when patients who refused recommended surgery (a high-risk subgroup) were excluded, the in-hospital mortality between ES and initial MT became comparable. This nuanced finding has important implications for risk stratification. Theses analysis might shed some light on future well-designed studies exploring management strategies for type A IMH.

There exist controversies across regions regarding the management of IMH. Western centers typically advocate urgent surgery for type A IMH (6,11,12,14,16,18), whereas some Asian centers report acceptable outcomes with initial medical management and delayed surgery (5,7-10,13,15,17,19-26). Traditionally viewed as a precursor of aortic dissection, IMH is thought to arise from ruptured vasa vasorum in the aortic media, causing aortic wall infarction and potential secondary tears (1-3). In Western guidelines, aortic dissection with thrombosed false lumen and ulcer-like projection (ULP)-type dissection were also regarded as IMH (1-3). However, some Asian societies regard IMH as a pathology distinct from aortic dissection, warranting tailored treatment (4). Data on successful MT for type A IMH predominantly come from Asian populations, whose outcomes have been reported to be better than those in Western populations (5-26). Our study likewise indicated a relatively lower mortality in the Asian subgroup compared with the Western subgroup. In our study, initial MT followed by necessary CS was more likely to be adopted in Asian centers, while Western centers have generally favored upfront surgery. These discrepancies might reflect genetic, ethnic, or environmental factors, as well as regionally varying practice patterns influenced by surgeon volume, institutional protocols, access to expedited imaging, availability of aortic centers, and multidisciplinary collaboration (1-4). The favorable outcomes of MT in Eastern cohorts might be attributed to timely detection of mild cases, rigorous diagnostic criteria, and close computed tomography (CT) follow-up throughout the course (4). Accordingly, our overall findings should therefore be interpreted in the context of this regional skew. Nonetheless, the current evidence remains limited and subject to confounding and bias. Well-designed, multicenter studies are essential to clarify management approaches for type A IMH.

According to the most recent European Society of Cardiology (3) and American College of Cardiology/American Heart Association (2) guidelines, urgent surgery is recommended for type A IMH (class I), albeit with relatively low levels of evidence (level C and level B). On the other hand, for a subset of uncomplicated type A IMH individuals who have elevated surgical risk and no high-risk imaging characteristics, a “wait-and-see” approach of medical management might be adopted (class IIb, level C) (1-3). Complicated IMH is characterized by persistent/recurrent pain, difficult blood pressure control, hematoma thickness >10 mm, maximum aortic diameter >45–50 mm, progression to aortic dissection, focal intimal disruption with ULP, pericardial effusion at admission, recurrent pleural effusion, and organ malperfusion (1-3). Due to the lack of high-quality clinical studies, the level of evidence was relatively low. Meta-analysis synthesizing results from multiple studies could shed some light on this issue. Our meta-analysis aligns with current guidelines that advocate urgent repair for complicated type A IMH and support a selective approach for uncomplicated disease. But timely escalation to surgery should be reserved for patients who demonstrate progression or instability on MT. Outcomes in type A IMH might depend less on the binary choice of “surgery vs. MT” and more on the dynamic treatment trajectory and timing of escalation. Patients who remain stable under MT without high-risk features may continue MT and avoid surgery. Those who develop progression can undergo surgery at the time of detection, ideally before catastrophic events occur. This “wait-and-see” approach requires frequent reassessment and dynamic risk stratification. The key clinical question is not whether to operate or not, but rather how to identify patients at high risk of progression and how to monitor them effectively to enable timely conversion. This appeals for reasonable surveillance protocols and explicit objective criteria for conversion. Future research should pay more attention to developing validated risk stratification tools and practical clinical management pathways for type A IMH. Establishing optimal clinical strategies for type A IMH calls for further properly-conducted, multicenter, randomized controlled trials.

Limitations

This meta-analysis has some shortcomings warranting attention. Firstly, randomized controlled studies for type A IMH were lacking. All included studies were observational, which precludes causal inference and leaves residual confounding. Baseline imbalance might bias crude comparisons. Patients undergoing ES might have higher-risk clinical and imaging profiles compared with those selected for initial MT. However, our results showed that patients undergoing ES actually have a lower mortality. It should be recognized that the potential higher risk in the ES group would bias results toward the null, thereby underestimating the true benefit of ES on outcomes. Secondly, the lack of patient-level data prevented us from adjusting for key baseline characteristics or performing analyses based on specific imaging risk features. Meanwhile, the limited availability of adjusted effect estimates precluded a fully adjusted meta-analysis. Therefore, our pooled estimates should be interpreted as associations rather than causal effects. Future studies should prioritize rigorous adjustment for confounders using propensity score matching, and ideally conduct randomized controlled trials in a carefully selected population. Binary pooling of all-cause mortality across studies with follow-up durations ranging from 3 to 120 months does not adequately capture the time-dependent nature of outcomes. However, the lack of time-dependent estimates and the inaccessibility of raw individual patient data make it difficult to conduct further time-to-event analyses. Thirdly, heterogeneity in patient populations, follow-up durations, and outcome definitions may influence the robustness of pooled estimates. Although statistical heterogeneity was low (I²<50%), this does not indicate low clinical heterogeneity. The included studies varied substantially in institutional protocols, imaging criteria, clinical practice patterns, and treatment eras. These clinical differences may influence pooled estimates more than statistical heterogeneity suggests. Although we have conducted subgroup analyses, residual confounding remains plausible. Finally, definitions of “ES” and protocols for “MT” were not uniform across studies. The expertise of doctors in surgery techniques further complicates the analysis. Surgeon-dependent technical variations introduced further complexity. The applicability of our results to broader clinical settings might be constrained.

Conclusions

For type A IMH, ES was associated with non-significantly lower in-hospital mortality and remarkably reduced all-cause mortality during follow-up compared with initial MT. Conversion from initial MT to timely surgery yielded non-inferior outcomes compared to ES, indicating that a “wait-and-see” approach might also yield acceptable outcomes in selected patients with type A IMH. Excluding patients who refused DS from the Initial MT group resulted in a comparable in-hospital mortality in Asian patients. These findings reinforce current guideline recommendations favoring surgical repair for most patients with type A IMH while acknowledging that initial medical management may be a feasible alternative in carefully selected patients, provided that close surveillance and prompt intervention are ensured. But the optimal timing of surgery remains unresolved. It must be pointed out that this conclusion is tempered by the exploratory nature of analyses and the limited event numbers. Given the substantial risk of confounding by indication, these findings should be interpreted as associations requiring confirmation in well-designed prospective studies with rigorous adjustment for baseline risk factors. Further high-quality randomized controlled trials are required to establish the optimal management approach for this population.

Acknowledgments

The authors wish to thank all investigators participating in this study. The abstract of the manuscript has been accepted to be presented as a poster in European Society of Cardiology Congress 2026.

During the preparation of this work, the authors used DeepSeek in order to improve language only. After using this tool/service, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

Footnote

Reporting Checklist: The authors have completed the PRISMA reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1104/rc

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1104/prf

Funding: This work was supported by a grant from the Noncommunicable Chronic Diseases-National Science and Technology Major Project (No. 2023ZD0515000).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2026-1104/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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