Early and mid-term outcomes of surgery of the ascending aorta/arch: is there a relationship with caseload?

Abstract

The relationship between caseload and early outcome remains a subject for debate in cardiac surgery. Surgery of the thoracic aorta is an area of specialist expertise within the adult cardiac surgical field. There is, however, a conflict between the concentration of expertise and the provision of effective emergency cover. This study evaluates the early and mid-term outcomes of patients undergoing surgery of the ascending aorta/aortic arch in a single institution and compares the results of a single higher volume surgeon with lower volume operators. From March 1992 till August 2003, 296 procedures were carried out on 291 patients (aged 17-80, median 62) who underwent operations for replacement of the ascending aorta/aortic arch. One hundred and thirty procedures were carried out by the higher volume surgeon and 160 by one of the six lower volume surgeons (range 10-57). Emergency operation was performed in 138 (47%) patients. One or more other associated cardiac procedures were carried out in 65 patients (22%). The overall early mortality was 37 (12.5%). After adjustment for baseline differences, era and surgical risk/complexity, the risk of in-hospital death was lower in the higher volume group, but not significantly so. For survival to 3 years the overall risk of death was significantly lower for patients in the higher volume group (hazard ratio 0.72; 95% CI 0.54-0.95) Apart from post-operative renal failure no other significant differences between the two groups were observed. Elective surgery of the ascending aorta/arch was associated with low mortality. Outcomes after emergency surgery conformed to contemporary expectations. Only limited differences were identified both with respect to the case profile and early clinical outcomes. Better outcomes in the mid-term in the higher volume group persisted despite adjustment for differences in caseload and are worthy of further study. We believe that these data support our hypothesis that dissemination of appropriate techniques among a group of surgeons represents the most practical method of service provision.