SAN FRANCISCO – The introduction of endovascular aneurysm repair, or EVAR, has improved outcomes for the repair of intact and ruptured aortic abdominal aneurysms, particularly among those aged 80 years and older, based on a review of more than 400,000 Medicare beneficiaries.
Among patients in this age group, there was an increase in the number of intact abdominal aortic aneurysm (AAA) repairs, coupled with declines in rupture deaths. In those younger than 75 years, intact repair rates decreased about 10%. Those aged 75-79 years had an increase of about 10%. However, those aged 80 years and older had a more dramatic increase of more than 50%. In addition, operative mortality for intact repair has decreased over time for all age groups, although the decline becomes greater with increasing age.
"The greatest benefit [of EVAR] has been seen in those over 80, who had the largest increase in intact repair rates, the largest decline in intact repair mortality, and the largest decline in rupture deaths," Dr. Marc L. Schermerhorn said at the annual meeting of the American Surgical Association.
The researchers used a 100% sample of Medicare data between 1995 and 2008. They identified patients with intact AAAs undergoing repair – by either EVAR or open surgical repair – as well as patients with ruptured AAAs (with and without repair). They determined the 30-day or in-hospital mortality, then standardized the rates (per 100,000 beneficiaries), adjusting for changes in age, sex, and population size over time.
They identified 338,278 intact repairs and 69,653 ruptures (with 47,524 repairs). EVAR use rapidly increased after Food and Drug Administration approval of the procedure in 1999; as of 2008, EVAR was used for 77% of all intact aneurysm repairs.
"There was a more delayed response but an increase nonetheless in the use of EVAR for ruptured aneurysms, to the point where [in 2008] 31% of all ruptured aneurysms are treated with EVAR," said Dr. Schermerhorn. During this time period, the average age of those undergoing repair increased from 73.7 to 75.5 years.
Operative mortality during open intact repair remained steady, at roughly 5%. EVAR mortality dropped from about 2% in 1995 to 1.4% in 2008. The total operative mortality for intact repair (open and EVAR) fell from roughly 5% to 2.4%, despite the fact that there were more repairs in 2008 and the average age of these patients increased.
"As we increase our utilization of EVAR, this is driving down the total mortality of intact aneurysm repair, so that it’s half of what it was at the beginning of that time period," said Dr. Schermerhorn, chief of vascular and endovascular surgery at Beth Israel Deaconess Medical Center in Boston.
The researchers also found that the annual number of ruptures decreased from 6,535 in 1995 to 3,298 in 2008. The greatest decrease in ruptures (repaired or not) was seen in older patients – those 75 years and older – but there was also a decline among patients younger than 75 years. The mortality with open rupture repair remained largely unchanged during the time period (approximately 45%). However, EVAR rupture repair declined from about 45% to 28%. The rate of all rupture repairs also has decreased from about 45% to 36%.
"Rather than suggesting that we’re simply taking the hemodynamically stable patients for EVAR, the best evidence to say that there’s actually a true reduction in mortality is the fact that for the first time in 3 decades, the overall mortality for ruptured aneurysm repair is now well below 40%," Dr. Schermerhorn said. The mortality for all ruptures (repaired or not) has gone down the most dramatically in those aged 80 years and older, although there were declines in the other age groups as well.
Invited discussant Dr. Philip B. Paty noted that reduced rates of intact aneurysm repair and rupture in patients aged 65-74 years may be attributed to a change in the natural history or a decline in the incidence of aneurysms.
"Did you evaluate the age-specific incidence of comorbidities or medical risk over the period of study to see if we are, in fact, dealing with different patient populations? Alternatively, is it possible that repair in recent years was deferred until a larger sac size was present?" he asked.
"We did look at comorbidities over time, and there have been increases in all of the various comorbidities that you would typically associate with aortic aneurysm patients. Coronary artery disease, peripheral arterial disease, hypertension, and [heart failure] all increased. We did not have access to data about rates of cigarette smoking or medication," Dr. Schermerhorn said.