Clamp-on versus open distal anastomosis in acute type a aortic dissection: a systematic review and meta-analysis

Background The clamp-on technique for acute type A aortic dissection (ATAAD) repair has gained traction as an alternative to open distal anastomosis (ODA), but procedure-specific evidence comparing these strategies remains limited. This study aimed to compare surgical safety, postoperative morbidity, and organ protection between the clamp-on technique and conventional ODA. Methods PubMed, Embase, and Cochrane Library were systematically searched through May 2026 for studies comparing clamp-on versus ODA in adults with ATAAD. Random-effects models with Mantel-Haenszel weighting were used to estimate pooled risk ratios (RRs) for binary endpoints. Confidence intervals were adjusted using the Hartung-Knapp-Sidik-Jonkman (HKSJ) method, and 95% prediction intervals were calculated. Results Nine observational studies (2,032 patients) were included, of which eight contributed crude event data to the quantitative synthesis, whereas the propensity-matched IRAD analysis (Pupovac et al.) was addressed narratively because its event counts derive from multiply imputed matched cohorts of varying size (94–101 pairs). No significant differences were observed between groups in hospital mortality (RR 1.26; 95% CI 0.83 to 1.92) or postoperative stroke (RR 0.98; 95% CI 0.41 to 2.35). Risks did not differ significantly for distal reoperation (RR 1.41; 95% CI 0.34 to 5.80) or new-onset dialysis (RR 0.78; 95% CI 0.42 to 1.45). The clamp-on strategy was associated with a non-significant trend toward lower acute kidney injury (RR 0.76; 95% CI 0.52 to 1.11; three studies) and sepsis (RR 0.64; 95% CI 0.33 to 1.26; three studies). Conclusions In patients undergoing surgical repair for acute type A aortic dissection, clamp-on repair and open distal anastomosis showed no detectable difference in hospital mortality or stroke, although confidence intervals remain compatible with clinically important benefit or harm in either direction. The association of clamp-on with lower acute kidney injury and sepsis did not remain statistically significant with Hartung-Knapp-Sidik-Jonkman-adjusted confidence intervals and should be regarded as hypothesis-generating. Given the very low certainty of evidence and inherent selection biases, these findings support a patient-tailored approach over a standardized strategy and underscore the need for prospective multicenter registries.