DOES ZONE 2 OR ZONE 3 PRODUCE BETTER OUTCOMES FOR TOTAL AORTIC REPLACEMENT WITH THE FROZEN ELEPHANT TRUNK TECHNIQUE? A METANALYSIS

Backgroung: Frozen elephant trunk (FET) technique is a treatment for various pathologies of the thoracic aorta. The distal aortic anastomosis may be made at various points along the aortic arch, most often zone 3 but it is hypothesized that zone 2 may be safer. This meta-analysis aimed to compare short-term mortality and incidence of various adverse effects for FET procedures which used aortic zone 2 or aortic zone 3 as a starting point. Methods: Pubmed, Medline, and Embase were searched on the 6th March 2024 producing 253 results. Abstracts and then full texts were screened to identify 4 studies which met all criteria. Our protocol was registered in PROSPERO on the 25th May 2024 with registration number CRD42024550403. Data were extracted via custom computer code and analyzed with Revman. Results: Acute kidney injury (AKI) was significantly less likely to occur in procedures using zone 2 (RR: 0.66; p=0.003). Choice of zone 2 or zone 3 confers no statistically significant effects on risk of bleeding events (RR: 0.53; p=0.42); parapesis (RR: 0.97; p=0.96); paraplegia (RR: 0.52; p=0.25); 30-day mortality (RR: 0.48; p=0.31); stroke (RR: 0.51; p=0.10). Conclusions: AKI appears to be less likely in when distal anastomosis is made in zone 2. Otherwise, carrying out a distal anastomosis in aortic zone 2 or aortic zone 3 may be equally safe in terms of the outcomes analyzed. With neither option appearing to any statistically significant effect on short-term mortality, or incidence of stroke, paraplegia, or parapesaris.