Growth rate of abdominal aortic aneurysms. Ultrasounds study and clinical outcome

Background. The standard treatment for abdominal aortic aneurysms (AAA) >55 mm is actually represented by surgical repair mainly or by endovascular repair, in selected cases; conversely the debate is still ope for those ranging 40-55 mm. These last and smaller aneurysms are usually followed-up by ultrasounds (US), in order to detect too fast expansions and to prevent sudden ruptures. Aim of this study is to present the results of the US follow-up of a series of asymptomatic AAAs and the correlation between expansion rate and associated risk factors. Methods. All patients evaluated for an AAA between March 1991 and December 2000 were included and, according to the maximum diameters of the infrarenal aorta, were divided into 3 groups: A (26-29 mm), B (30-39 mm) and C (>39 mm). Groups A and B underwent US follow up at 6-month intervals, while group C underwent a complete preoperative evaluation. Results. The mean follow up was 36′24 months for the entire series (225 AAA); the mean expansion rate was 1 mm/year for group A, <1.5 mm/year for group B for the first 5 years with a sharp increase (5 mm/year) in the following 2 years and 3 mm/year for group C up to 5 years. Among the associated risk factors, hypertension and smoking have confirmed their main role, independent from the initial diameter (p<0.01). Eight ruptures (3.8%) occurred in patients unsuitable for surgery or who refused it and in 7 cases they were letal. The range between diagnosis and death (19-61 months) and the maximum size (38-93 mm) were absolutely unpredictable. The remaining 40 deaths were related to vascular diseases (MI and stroke - 29.8%) or concurrent neoplasms (29.8%) mainly. The surgical treatment was carried out as elective repair on 45 patients (mortality rate 2.2%) and in emergency in 2 cases, both dead, with a mean interval from diagnosis to surgery of 28′17 months. Conclusions. Our results agree with the literature data concerning the dilatative trend and the risk factors and, according to these, elective repair in patients with AAA ranging 45-55 mm should be considered.