Meta-analysis: Mortality Rates Eventually Converge for EVAR, Surgical AAA Repair

The early and intermediate-term survival advantage that accompanies endovascular abdominal aortic aneurysm repair (EVAR) compared with open surgery eventually dissipates over the long-term, according to a meta-analysis published in the October 2012 issue of JACC: Cardiovascular Interventions. The findings also show higher reintervention rates among EVAR-treated patients.

Researchers led by George D. Dangas, MD, PhD, of Mount Sinai Medical Center (New York, NY), pooled data from 10 studies with results from 6 randomized, controlled trials including a total of 2,899 AAA patients who received EVAR (n = 1,470) or open surgery (n = 1,429). The papers were published between 2004 and 2011.

Baseline characteristics were similar between the EVAR and open surgery groups, with low overall rates of crossover (below 4%) and immediate conversion (below 1%). Length of hospitalization in the EVAR group (3-6 days) was shorter compared with the open surgery group (7-12 days; P < 0.05), as was ICU stay (3-24 hours vs. 23-96 hours; P < 0.05). In addition, there were no differences in cerebrovascular, cardiac, or renal complications.

At 30 days, all-cause mortality was lower for EVAR compared with open surgery, with the difference becoming much smaller at intermediate follow-up (up to 2 years postprocedure), and disappearing at long-term follow-up (at least 3 years postprocedure; table 1).

Table 1. All-Cause Mortality at Varying Follow-up Times

A similar pattern was shown with AAA-related mortality, which was lower with EVAR at intermediate follow-up (RR 0.46; 95% CI 0.28-0.74), but similar to open repair at long-term follow-up (RR 1.57; 95% CI 0.20-12.35). Reinterventions related to the original AAA repair were higher with EVAR at both intermediate (RR 1.48; 95% CI 1.06-2.08) and long-term (RR 2.53; 95% CI 1.58-4.05) follow-up.

“In patients randomized to open or endovascular AAA repair, all-cause perioperative mortality, as well as AAA-related mortality at short- and intermediate-term follow-up are lower in patients undergoing endovascular stent-graft placement,” the authors conclude. “This was associated with greater reintervention in the endovascular group noted at intermediate follow-up. Long-term survival appears to converge between the 2 groups.”

They point out that the results should not be generalized to all AAA patients, since an important patient-selection criterion for the trials in the meta-analysis was a low or intermediate surgical risk. “Excluding high-risk patients should have altered mortality outcomes and complication rates in both treatment groups,” Dr. Dangas and colleagues write. On the other hand, they add, “The requirement for aortic anatomy amenable to either open or endovascular repair can also potentially improve outcomes in both treatment arms, as mortality rates were generally lower in the randomized trials than in retrospective cohort studies.”

At the same time, endovascular devices, EVAR technique, and hospital systems have continued to improve, making comparison to contemporary practice difficult.

Comorbidities ‘Likely Responsible’ for Convergence

In an e-mail communication with TCTMD, Dr. Dangas noted that “the main message is that EVAR is able to provide AAA repair with lower morbidity and mortality that extend not only in the immediate perioperative period but also to a much longer intermediate follow-up duration.  In brief, it tackles AAA-related mortality quite nicely,” he said, adding that the existence of other comorbidities in this patient cohort are “likely responsible” for the comparable late clinical outcomes.

In a telephone interview with TCTMD, Robert M. Bersin, MD, of Swedish Medical Center (Seattle, WA), noted that while the mortality rates for the 2 treatments do converge over time, “you have to keep in mind that these were patients who were felt, by definition, to be equally managed [by either EVAR or surgery] in the randomized trials. That’s the vast minority of patients who are treated. So what about the rest of the universe that’s not in clinical trials? How do they fare?”

Dr. Bersin pointed to a 2008 study in the New England Journal of Medicine (Shimmerhorn ML, et al. NEJM. 2008;358:464-474) demonstrating a durable survival advantage with EVAR in a large Medicare population. “It makes the point that in general use, the mortality difference and all the morbidity indicators are far greater in actual use than in the trials,” Dr. Bersin said. “So the early advantage that was observed with endografting in the randomized trials was only bigger in the actual Medicare population.”

EVAR Still First Option?

Dr. Bersin acknowledged that EVAR is slightly more costly compared with surgery over the long term due to surveillance imaging and the need for reinterventions, but he maintains the difference is small.

According to Dr. Dangas, endovascular repair should remain the first option, “provided that the preoperative imaging (CT angiogram) can support the ability to achieve a perfect seal of the aneurysm with the stent graft and the patient has adequate support for the required follow-up.” He added that he supports further study to “focus on the findings of follow-up CT angiograms and duplex ultrasound imaging after EVAR in order to better understand the reasons for repeat procedures and the best way to tackle them and achieve the most durable results in the minority of patients with endoleaks after EVAR.”

According to Dr. Bersin, the study may be viewed as an argument favoring open repair by a minority in the surgical community. “Nevertheless, my interpretation would be that it isn’t very surprising that the early advantage would regress toward equality over the years in patients who are good operative candidates. But that’s the minority of treatments,” he said adding that good alternatives are lacking for patients not suited for surgery, who represent “the majority of patients we treat today with endografts.”

Note: Dr. Dangas is a faculty member of the Cardiovascular Research Foundation, which owns and operates TCTMD.

Source:

Dangas G, O’Connor D, Firwana B, et al. Open versus endovascular stent graft repair of abdominal aortic aneurysms: A meta-analysis of randomized trials. J Am Coll Cardiol Intv. 2012;5:1071-1080.

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