Surveillance imaging modality does not affect detection rate of asymptomatic secondary interventions following EVAR

Literature reports that surveillance imaging following endovascular aortic aneurysm repair (EVAR) gives rise to asymptomatic secondary interventions (SI) in 1.4-9% of cases. This retrospective study aimed to evaluate whether the modality of surveillance imaging influences the detection rate of asymptomatic SI.

Two EVAR surveillance protocols were compared at the same vascular centre. Protocol I, performed from January 2003 to December 2006, consisted of colour duplex ultrasound scan (CDU) plus CT angiography (CTA) 1 month after procedure and every 6 months thereafter. Protocol II, performed from January 2007 to June 2010, consisted of CDU plus CTA 1 month after operation and CDU plus plain abdominal films (XR) every 6 months thereafter. In the second protocol, CTA was carried out only during follow-up in specific conditions. The term 'asymptomatic SI' was used when the necessity for SI was detected by imaging alone on an elective basis, prior to development of any symptoms.

Enrolment included 376 and 341 consecutive patients with a mean follow-up of 1148 days (range 1-3204 days) and 942 days (range1-1512 days) in Protocols I and II, respectively (p < 0.001). Freedom rates from aneurysmal rupture, freedom from SI and detection rate for asymptomatic SI at 3 years were 98.3% and 98.7% (p = 0.456), 82% and 83.5%(p = 0.876) and 8.8% (n = 33/376) and 8.5%(n = 25/341) (p = 0.49) in Protocols I and II, respectively. Estimated comparison of the costs, radiation exposure and contrast used at 3 years in Protocol I versus Protocol II showed that Protocol II allowed for a three-, four- and six fold reduction in overall costs, radiation exposure and contrast used, respectively (p < 0.0001).

The detection rate of asymptomatic SI following EVAR is not affected by the type of surveillance imaging. A surveillance schedule based primarily on CDU and XR appears to be justified.