INDIANAPOLIS – Contrary to conventional wisdom, endovascular aneurysm repair (EVAR) provides outcomes superior to those achieved with open surgical repair of abdominal aortic aneurysm in patients with chronic renal insufficiency, a large study indicates.
"EVAR should be the first-line therapy in the patient with chronic renal insufficiency when the patient has the appropriate anatomy. However, in patients with severe renal impairment, a higher threshold should be applied for repair because the risks of both open repair and EVAR are significantly higher," Dr. Bao-Ngoc H. Nguyen declared at the annual meeting of the American Surgical Association.
"Chronic renal failure is quite prevalent in patients with abdominal aortic aneurysm: up to 30%. It is quite worrisome because any further decline in renal function in these patients could push them toward dialysis. More than that, postoperative renal failure is a predictor for early and late mortality," noted Dr. Nguyen of George Washington University, Washington.
She presented a retrospective study in patients with abdominal aortic aneurysm and chronic kidney disease. The aim, she explained, was to answer a key question: "Which one of these two treatment modalities is the lesser of two evils?"
For answers, Dr. Nguyen and coinvestigators turned to the American College of Surgeons National Quality Improvement Program (NSQIP) database for 2005-2010. They identified 3,523 patients with moderate chronic renal insufficiency, defined as an estimated glomerular filtration rate (eGFR) of 30-60 mL/minute, who underwent EVAR for abdominal aortic aneurysm and 1,117 treated via open surgical repair. Another 363 EVAR patients had severe chronic renal insufficiency, with an eGFR of less than 30 mL/minute, as did 139 patients who underwent open repair. Vascular surgeons performed all procedures in this study.
Patients with moderate renal insufficiency who underwent EVAR had markedly lower 30-day rates of mortality, pulmonary complications, cardiovascular events, and postoperative renal dysfunction, including acute kidney injury, than did those who had open surgical repair. One or more adverse events occurred in 6% of the EVAR group, compared with 24.1% of open repair patients. In a multivariate analysis controlled for preoperative differences in the patient groups, those undergoing open repair had an adjusted 4.1-fold greater risk of mortality as well as a 2.2-fold increased risk of cardiovascular events, a 4.2-fold increased risk of renal deterioration including a 5.2-fold greater risk of dialysis, and additional hazards.
In contrast, among the much smaller population of patients with baseline severe chronic renal insufficiency, there was no significant difference between the two treatment groups in terms of 30-day mortality, postoperative renal deterioration, or cardiovascular complications, although pulmonary complications were an adjusted fivefold more likely in the open surgery than among EVAR patients. Of note, rates of all adverse outcomes were markedly higher in both groups than in those with moderate chronic renal insufficiency, such that one or more adverse events occurred in 16.9% of EVAR patients and 42.5% of the open repair patients with severe chronic renal insufficiency.
Discussant Dr. Michael Watkins commented that this study has one glaring shortcoming resulting from a limitation of the NSQIP database.
While NSQIP contains only validated data entered by unbiased, well-trained professionals and NSQIP is "far superior" to the various administrative databases commonly used in evaluating outcomes, it doesn’t include key details about patients’ presenting anatomy, observed Dr. Watkins, director of the vascular research laboratory at Massachusetts General Hospital, Boston.
"Was the anatomy really similar in the two groups, or were patients who underwent open repair not candidates for EVAR?" he asked.
Dr. Nguyen conceded that this constitutes a major study limitation, adding that she agrees with Dr. Watkins that anatomy should be the first and foremost factor considered in deciding upon the surgical approach in abdominal aortic aneurysm repair.
She reported having no financial conflicts.