Use of extracorporeal bypass is associated with improved outcomes in open thoracic and thoracoabdominal aortic aneurysm repair

Objective: There is no consensus on the use or benefit of extracorporeal circulation (EC) during aneurysm repair of the descending thoracic aorta (DTA) or thoracoabdominal aorta (TAA). We evaluated the role of EC during DTA or TAA aneurysm repair using U.S. Medicare data. Methods: Medicare (2004-2007) patients undergoing open repair of nonruptured DTA or TAA aneurysm were identified by International Classification of Diseases, Ninth Revision code. Specific exclusions included ascending aortic or arch repairs, concomitant cardiac procedures, and procedures employing deep hypothermic circulatory arrest. The impact of EC (code 3961) on early and late outcomes was analyzed using univariate analysis and multivariable regression. Survival was assessed using Kaplan-Meier analysis and Cox proportional hazards regression models. Results: There were 4230 patients who had repair of intact DTA or TAA aneurysms, 2433 (57%) of which employed EC. Differences in baseline clinical features of EC and non-EC patients showed that patients undergoing aortic reconstruction with EC were older (73 +/- 1 years vs 72 +/- 1 years; P = .002), were more likely to be female (53% vs 47%; P < .001), and had more hypertension (56% vs 53%; P = .02); they had less chronic obstructive pulmonary disease (28% vs 34%; P < .0001), peripheral vascular disease (5.7% vs 11.3%; P < .001), and chronic kidney disease (7.7% vs 5.5%; P = .003). The 30-day mortality (9.7% for EC vs 12.2%; P = .02) and any major complication (49% for EC vs 58%; P < .001) were significantly reduced with EC use. EC use was associated with a shorter length of stay (13.5 +/- 13 days vs 17.2 +/- 18 days; P < .01) and lower total hospital charges ($151,000 +/- 140,000 vs $180,000 +/- 190,000; P < .01) compared with non-EC patients. EC patients were more likely to be discharged home instead of to an extended care facility (67% vs 56%; P < .01). Multivariable regression modeling to adjust for baseline clinical differences showed EC to independently reduce the risk of operative mortality (odds ratio [OR], 0.80; 95% confidence interval [CI], 0.65-0.97; P = .02), any complication (OR, 0.67; 95% CI, 0.59-0.76; P < .01), pulmonary complications (OR, 0.68; 95% CI, 0.59-0.79; P < .01), and acute renal failure (OR, 0.52; 95% CI, 0.44-0.61; P < .01). Long-term survival was higher (log-rank, P < .01) in EC patients at 1 year (81% +/- 0.8% vs 73% +/- 1%) and 5 years (67% +/- 1% vs 52% +/- 1%). Risk-adjusted Cox proportional hazards regression also showed that EC was independently associated with improved long-term survival (hazard ratio, 0.69; 95% CI, 0.63-0.74; P < .01). Conclusions: Although important clinical variables such as DTA or TAA aneurysm extent and spinal cord ischemic complications cannot be assessed with the Medicare database, EC use during open DTA and TAA aneurysm repair is associated with improved late survival and a significant reduction in operative mortality, morbidity, and procedural costs. These data indicate that EC should be a more widely applied adjunct in open DTA or TAA aneurysm repair.