Non-A non-B aortic dissection: a systematic review and meta-analysis

OBJECTIVES: Non-A non-B aortic dissections are rare, and little is known about their natural history, indications for surgery and operative results. We aim to examine the literature to summarize what is known of the natural history of non-A non-B dissections and evaluate the outcomes of the therapeutic options available. METHODS: An extensive literature search was performed using MEDLINE to find all published studies that report data on the natural history and outcomes of patients with non-A non-B aortic dissection. Data on patients treated with medical therapy were extracted to characterize the natural history. Primary end points included 30-day mortality, stroke and retrograde type A dissection. RESULTS: Of the 423 studies found, 14 articles (433 patients) fulfilled the inclusion criteria for quantitative analysis. The proportion of medically treated patients ranged from 5 to 54% with a pooled rate of 36% (50/138). The 30-day mortality of patients treated with medical therapy was 14% (7/50). The overall estimated proportion of 30-day mortality for patients who underwent intervention was 3.6% [95% confidence interval (CI) 1.7-5.6%], retrograde type A dissection was 2.6% (95% CI 0.8-4.4%) and stroke was 2.8% (95% CI 1.0-4.5%). CONCLUSIONS: Despite the likelihood of reporting and selection bias, patients with non-A non-B dissection often have a complicated course requiring some form of intervention. The 30-day mortality of patients treated with medical therapy seems higher than surgical or endovascular therapy. Ideally, further large prospective studies are necessary to confirm our suggestion that early intervention may be indicated in non-A non-B dissections.