Prognosis

The natural course involves slow and steady growth. With progressive aneurysm enlargement, the risk of AAA rupture increases.[3]​ Most patients with rupture will not survive to reach the operating theatre. Given the morbidity and mortality associated with surgical intervention, repair is typically deferred until the theoretical risk of rupture exceeds the estimated risk of operative mortality. 

The majority of patients undergoing open repair remain without significant graft-related complications during the remainder of their lives (0.4% to 2.3% incidence of late graft-related complications).​[193] Five-year survival rates after intact aneurysm repair average 60% to 75%. Those undergoing endovascular aneurysm repair (EVAR) are more likely to have a delayed complication and require re-intervention, and late survival may be worse in patients undergoing EVAR for intact AAA.[194][195][196]​​​ Other risk factors for poor outcome include skeletal muscle mass; there is a significant link between low skeletal muscle mass and morbidity following AAA repair.[197] In older patients there is an early deterioration in postoperative quality of life, with a delay to mental health recovery of about 4-6 weeks, and to physical health recovery of 1-3 months, regardless of operative technique. However, quality of life does return to baseline and is maintained in the long term, supporting surgical intervention for AAA in older patients.[198]​ ​​

More info: Elective repair outcomes

Data regarding the comparative safety and efficacy of EVAR and open repair differ depending on the outcome of interest. Evidence to date suggests that:

  • Short-term all-cause postoperative mortality (≤30 days) is lower for endovascular than open repair

  • Aneurysm-related mortality (≥3 years post repair) is higher after EVAR than open repair

  • Operative, perioperative, and postoperative mortality (≤30 days) is greater among women than men for both open repair and EVAR[199][200]​

  • Overall rates of re-intervention are more common following EVAR than open repair.[195][196]​

Six-month postoperative mortality appears to be lower among patients with AAA who undergo EVAR than those who have open surgery, but this is primarily attributable to lower 30-day operative mortality.[201] Pooled analysis of data from four high-quality randomised trials (that enrolled patients with AAA diameter >5 cm) found that short-term mortality (30-day or in-hospital mortality) was significantly lower among those randomised to EVAR than among those who underwent open repair (1.4% vs. 4.2%, odds ratio [OR] 0.33, 95% CI 0.20 to 0.55; P <0.0001).[202] The early benefit of EVAR is diminished with follow-up, although long-term to very long-term outcomes of EVAR are comparable to those of open repair.[201][202][203][204]​​​​ Open repair was significantly associated with lower all-cause mortality than EVAR, after more than 8 years of follow-up, in the UK endovascular aneurysm repair trial 1 (46% vs. 53%, P=0.048).[122] One meta-analysis identified a survival curve crossover point at 1.8 years post repair, whereafter patients undergoing EVAR had lower survival compared with those undergoing open repair.[194]

The same trend is seen in aneurysm-related mortality. One meta-analysis found 3-year aneurysm-related mortality to be significantly higher following EVAR repair than after open repair (pooled hazard ratio [HR] 5.16, 95% CI 1.49 to 17.89; P=0.010).[201] Data from the UK endovascular aneurysm repair trial 1 indicate that, after more than 8 years of follow-up, aneurysm-related mortality is greater among EVAR patients than open repair patients (5% vs. 1%, P=0.0064).[122] Aneurysm rupture was more common in patients after EVAR than open repair (5.4% vs. 1.4%, P <0.001) in a large cohort study with 8 years of follow-up.[205] Extenuating factors have been proposed to account for the worse late-phase mortality reported in EVAR patients compared with those who undergo open repair. One systematic review concluded that long-term postoperative survival in patients undergoing EVAR had improved in trials published after 2005, and attributed this to a possible improvement in EVAR techniques and perioperative care.[206]

Perioperative and short-term mortality is higher among women than among men.[199][200]​ During elective AAA repair, operative mortality among women exceeds that of men for both open (7.0% vs. 5.2%) and endovascular approaches (2.1% vs. 1.3%).[207] In the UK, women undergoing elective AAA repair were found to have increased short-term mortality compared with men for open repair (30-day mortality: OR 1.39; 95% CI 1.25 to 1.56) and EVAR (30-day mortality: OR 1.57; 95% CI 1.23 to 2.00), despite having fewer preoperative cardiovascular risk factors.[208] Female sex was an independent risk factor for all-cause mortality among women who had an open repair at 1 year (crude cumulative all-cause mortality 15.9% vs. 12.1%, P <0.001) and at 5 years (22.2% vs. 19.6%, P <0.001).[208] Long-term all-cause survival did not differ significantly between women and men in the EVAR group (P=0.356). One review concluded that the morphological criteria for diagnosing aneurysms and offering EVAR did not take sex-related variations in aortic size into account: women are less likely to be offered intervention because they have smaller aortas.[209]

Overall rates of re-intervention are higher with EVAR than with open surgery; however, rates have been reported heterogeneously in clinical trials.[195][196][201][202]​​​​​ In pooled analysis of individual-patient data, re-intervention was reported in 65.8% of EVAR patients with type I endoleak (79 of 120) and 22.8% of EVAR patients with type II endoleak (99 of 435) over 5 years of follow-up.[201] Observational data suggest that interventions related to the management of aneurysm or its complications are more common following EVAR than open surgery (18.8% vs. 3.7%, P <0.001) over 8 years of follow-up.[205]

Meta-analysis found no significant difference between EVAR and open surgery in the incidence of myocardial death (OR 1.14, 95% CI 0.86 to 1.52; P=0.36), fatal stroke (OR 0.81, 95% CI 0.42 to 1.55; P=0.52), or non-fatal stroke (OR 0.81, 95% CI 0.50 to 1.31; P=0.39).[202] Patients with moderate renal dysfunction or cardiovascular disease do not appear to derive an early survival benefit (to 6 months) from EVAR, while those with peripheral arterial disease may benefit from open repair.[201] In another meta-analysis, long-term survival following elective AAA repair (EVAR or open) was worst among patients with end-stage renal disease (HR 3.15, 95% CI 2.45 to 4.04) and COPD requiring supplementary oxygen (HR 3.05, 95% CI 1.93 to 4.80).[210]

Low-quality evidence from four small randomised controlled trials suggests that elective open repair performed retroperitoneally can reduce blood loss and hospital stay compared with a transperitoneal approach.[211]​ However, there was no difference in mortality between retroperitoneal and transperitoneal elective open AAA repair (very low-quality evidence). Moreover, the retroperitoneal approach may increase the risk of haematoma, chronic wound pain, and abdominal wall hernia compared with transperitoneal.[211]

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