CHICAGO – Proximal abdominal aortic aneurysm repair can be achieved with a low perioperative mortality of about 3%, although renal dysfunction remains an Achilles’ heel, according to a 27-year review involving 245 patients.
In all, 60% of patients had postoperative acute kidney injury (AKI), 28% had persistent AKI at discharge, and 1.6% were discharged on hemodialysis. Persistent AKI at discharge was also associated with reduced long-term survival, Dr. Loay Kabbani said at the annual meeting of the Midwestern Vascular Surgical Society.
AKI stage was based on the Risk, Injury, Failure, Loss, and End-stage (RIFLE) kidney disease/Acute Kidney Injury Network (AKIN) classification system, with a change in serum creatinine of more than 0.3 mg/dL considered positive for injury. This is a much more sensitive criterion than what was used in previous studies, but is the new standard for reporting renal injury.
"This data should assist in establishing a benchmark for endovascular repair of these complex aneurysms," said Dr. Kabbani, a vascular surgeon at Henry Ford Hospital in Detroit.
The investigators identified 245 patients who underwent proximal AAA repair between 1986 and February 2013 at Henry Ford Hospital for juxtarenal (127), suprarenal (68), or type IV thoracoabdominal AAAs (50). The average aneurysm size was 6.4 cm (range, 3.1-14 cm), and mean preoperative estimated glomerular filtration rate was 62 mL/min per 1.73 m2 (range, 14-166 mL/min per 1.73 m2).
Most patients were male (69%), white (88.5%), and hypertensive (84%); 55% had chronic kidney disease based on a preoperative estimated glomerular filtration rate below 60 mL/min per 1.73 m2. Their average age was 71 years.
For most patients, the approach was retroperitoneal (48%) or thoracoabdominal (30%); the clamp was placed supraceliac (58%); and tube grafts were used (64%).
In-hospital mortality was 2.9% (7 patients) and 30-day mortality 3.3% (8 patients), Dr. Kabbani said.
Postoperative complications were AKI in 144 patients (60%), major pulmonary complications in 55 (22%), myocardial infarction in 9 (4%), return to the operating room for postoperative bleeding in 7 (3%), neurologic complications in 7 (3%), and bowel ischemia in 5 (2%).
Specifically, postoperative AKI was stage 1 (mild) in 35%, stage 2 (moderate) in 15%, and stage 3 (severe) in 10%, improving to 12%, 4%, and 3%, respectively, at discharge.
Though preoperative comorbidities were similar between patients with juxtarenal, suprarenal, and type IV aneurysms, postoperative complications increased significantly as the aneurysm extended more proximally (31% vs. 50% vs. 72%; P < .0001), Dr. Kabbani said.
Rates of AKI at discharge also followed the same pattern (18.2% vs. 35.4% vs. 43.8%; P less than .0012).
After a median follow-up of 54 months, the 5-year survival estimate was 70% and 10-year survival 43% based on a review of electronic medical records and the Social Security Death Index.
Cox regression analyses revealed no difference in long-term survival based on aneurysm type, but significantly worse survival based on increased aneurysm size (hazard ratio, 1.1; P = .01), preoperative chronic obstructive pulmonary disease (HR, 1.8; P = .002), congestive heart failure (HR, 3.5; P less than .001), history of stroke (HR, 1.9; P = .04), and persistent stage 2 (HR, 5.29; P = .001) and stage 3 AKI at discharge (HR, 2.71; P = .014), he said.
During a discussion of the results, Dr. Kabbani said the hospital usually uses mannitol (12.5-25 g) for renal protection and cold renal perfusion in select patients, although the latter did not jump out as a risk factor for CKI. The data were not broken down to see whether use of renal bypass during surgery affected outcomes for specific AAA types. Some attendees countered that renal protection should be used for all patients undergoing proximal AAA repair.
Dr. Kabbani reported having no financial disclosures.