Nonruptured abdominal aortic aneurysm: six-year follow-up results from the multicenter prospective Canadian aneurysm study. Canadian Society for Vascular Surgery Aneurysm Study Group

Abstract

Purpose: Based on the prospective analysis of data on 680 patients undergoing surgery for nonruptured abdominal aortic aneurysm (AAA) and recorded in the Canadian Society for Vascular Surgery Aneurysm Registry, this study determines the late survival rate by comparison to an age- and sex-matched population, the causes of late death, the effect of heart-related death on late survival, and the prognostic variables that are associated with late survival.

Methods: To identify the variables that were associated with survival, statistical methods included Kaplan-Meier analysis and Cox regression analysis. The Canadian Society for Vascular Surgery Aneurysm Registry provided ongoing current follow-up of patients.

Results: The survival rate was 94.6% at 1 month, 90.7% at 1 year, 87.1% at 2 years, 81.0% at 3 years, 74.0% at 4 years, 67.7% at 5 years, and 60.2% at 6 years. The late survival rate of patients with AAA is significantly less than the age- and sex-matched normal population (60.2% versus 79.2%). In the AAA group, heart-related causes of late death (44.4% versus 34.1%) and cerebrovascular causes (8.3% versus 5.8%) were more frequent. The calculated 5-year heart-related mortality rate is 14.3%. This is higher than the heart-related mortality rate for the age- and sex-matched population, which is 6.4%. Hence, the risk of heart-related death for patients who have undergone AAA repair is increased by 1.6% per year. Vascular complications from aortic aneurysm repair or recurrent aneurysmal disease were an uncommon cause of late death: ruptured thoracic aneurysm, 1.5%; ruptured aortic false aneurysm, 1.5%; and aortoenteric fistula, 0%. This incidence appears to be less than reported in earlier series. By Cox regression analysis, the variables that were significant predictors of a lower late survival rate were increased age, preoperative electrocardiogram indicating a previous myocardial infarction, and elevated serum creatinine levels.

Conclusions: Because cardiac complications accounted for 68.8% (22/32) of the 4.7% in-hospital mortality rate (i.e., a heart-related mortality rate of 3.2%), it seems reasonable to develop a strategy to reduce the cardiac operative risk by identifying and treating patients at high risk before operation. However, it is doubtful that a preoperative program that screens and treats all patients can be cost-effective in preventing late heart-related deaths.