Each year, nearly 40,000 Americans undergo elective surgery to repair an abdominal aortic aneurysm with the goal of preventing a life-threatening rupture of this potentially dangerous cardiovascular condition. A new study from researchers at Beth Israel Deaconess Medical Center (BIDMC) compared open surgical repair with a catheter-based procedure and found that the less invasive endovascular aortic repair has clear benefits for most patients, providing both a safer operation and a quicker recovery. The study was published July 22 in The New England Journal of Medicine.
An abdominal aortic aneurysm (AAA) occurs when a portion of the aorta, the main blood vessel carrying blood from the heart to the lower part of the body, becomes enlarged and bulges out, weakening the wall of the aorta. Doctors recommend repair of aneurysms that pose risk of life-threatening rupture, typically those five centimeters in diameter or larger or that are fast-growing. The repair can be done through an open abdominal incision or by using a less invasive, endovascular procedure to place a stent inside the artery using a catheter fed through the femoral artery in the groin.
"Abdominal aortic aneurysm is common, especially among men over the age of 65 who have ever smoked and among individuals with a family history of the condition," said lead author Marc Schermerhorn, MD, Chief of Vascular Surgery at BIDMC and Associate Professor of Surgery at Harvard Medical School. "Endovascular aortic repair (EVAR) for AAA began in 1991, and over the years we've seen the number of endovascular cases steadily increase, making repair available to those who might not be healthy enough to undergo an open procedure."
As surgeons gained experience with EVAR, there was a growing need to evaluate long-term outcomes to be sure EVAR was durable. The researchers examined national Medicare data from 2001-2008 involving nearly 80,000 patients who had undergone elective repair of AAA. Half of the patients had open procedures, and half had EVAR.
"We found that endovascular repair was markedly superior to open repair for the first 30 days, that it continued to be superior for the next 60 days, and the benefits endured for at least three years," said Schermerhorn. "Our research also suggests that the EVAR outcomes have been improving over time."
"The fact that EVAR outcomes have been improving over time is particularly important," said senior author Bruce Landon, MD, a member of the Division of General Medicine and Primary Care at BIDMC and Professor of Health Care Policy and Medicine at Harvard Medical School. "Our findings suggest that even as sicker patients have undergone EVAR, the short- and long-term outcomes have continued to improve, and the results seem durable."
"When we compared the data between groups, we saw an early survival benefit for EVAR patients," Schermerhorn added. "In the 30 days after surgery or the time of hospitalization if longer than 30 days, the EVAR mortality rate was 1.6 percent compared with 5.2 percent for open procedures."
The patients in the EVAR cohort also had lower rates of perioperative medical and surgical complications like pneumonia and had shorter hospital stays, with an average 3.5 days spent in the hospital, compared with 9.8 days for the open repair group. EVAR patients were also more likely to go home after surgery, rather than to a rehabilitation center or a nursing home.
The researchers found that the survival advantage of EVAR over open repair decreased over time; after eight years, survival rates for the two groups were virtually even. They also found that interventions for surgical incision complications were more common after open repair. Interventions related to the management of the aneurysm or its complications were more common after EVAR, but most of these were minor procedures that could also be performed with a minimally invasive procedure.
"Importantly, aneurysm rupture occurred in 5.4 percent of EVAR patients who survived for eight years versus 1.4 percent of patients who received open repair," said Schermerhorn. "The importance of this key finding is that we need to focus our efforts at minimizing this risk after EVAR. Patients need to come back for follow-up after endovascular surgery and undergo these additional interventions, if needed, to prevent late rupture."
The results of this large, eight-year study extend the findings of earlier studies.
"Results from smaller randomized trials of selected patients treated at institutions in the United Kingdom, the Netherlands and the United States Veterans Affairs system were reproduced broadly here in the US Medicare population," said Landon. "But, these new results represent a much larger study population and double the years of follow up."
The study results, together with prior analyses from the research team, also suggest that surgeons are appropriately selecting which patients will benefit most from EVAR, particularly older and sicker patients who may not have been treated in the past.
"AAA rupture is still a common cause of death. Because there are typically no warning signs, heightened awareness among patients and physicians is needed," said Schermerhorn. "AAA can be diagnosed with a simple ultrasound and can now often be treated with an effective, durable, minimally invasive approach."
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