Clamp On vs Off. Impact of distal anastomotic technique during ascending aortic replacement in acute type A aortic dissection: IRAD insights

Objectives: Most ascending aortic replacements for acute type A aortic dissection (ATAAD) are performed utilizing hypothermic circulatory arrest with an 'open' distal anastomosis ('hemiarch'), whereas some are completed without ever removing the aortic cross-clamp. We sought to determine the impact of distal anastomotic technique in ascending aortic replacement for ATAAD repair. Methods: All patients in the IRAD Interventional Cohort database who underwent ATAAD repair between 2010 and 2020 were identified (n = 2559). Data for distal anastomotic technique was available in 2031 patients who underwent ascending aortic replacement, divided into 2 groups, based on whether they underwent hypothermic circulatory arrest (Clamp Off, n = 1900 {93.5%}) or not (Clamp On, n = 131, 6.5%}). We then propensity-matched 101 pairs of patients and analyzed operative data and short- and mid-term outcomes. Results: In-hospital mortality for the unmatched population was 13.1% (266 deaths), not statistically different between matched groups (Clamp Off, 11.0% vs Clamp On, 5.1% p = 0.22). There were no statistically significant differences observed in three-year post-discharge survival curves between matched cohorts (Clamp Off, 89.5% vs Clamp On, 90.4%; stratified log-rank p value = 0.46). Major perioperative complications (renal failure requiring dialysis, reoperation for bleeding, respiratory insufficiency) were not significantly different between groups, notably including stroke (Clamp Off, 10.2% vs Clamp On, 5.8%, p = 0.32). Conclusions: In this propensity-matched cohort, postoperative mortality, major morbidity, and mid-term survival were comparable between open distal anastomosis and clamp-on strategies in selected patients undergoing ascending aortic replacement for ATAAD.