EVAR Feasible for Mycotic Aortic Aneurysm, but Risk of Infection High

Endovascular treatment for the rare, life-threatening condition of mycotic aortic aneurysm (MAA) is feasible and durable in most patients, according to a study published online November 5, 2014, ahead of print in Circulation. However, the investigators say infections are not uncommon and are often lethal, warranting long-term antibiotic therapy.

MAA “is a misnomer for infection (usually bacterial) which degrades the aortic wall with subsequent aneurysm development,” according to Anders Wanhainen, MD, PhD, of Uppsala University (Uppsala, Sweden), and colleagues. They estimate the incidence to be about 0.65% to 2% of all aortic aneurysms in Western countries, with higher rates reported in East Asia. In addition, MAA carries very poor prognosis—not only do the aneurysms have a tendency to grow rapidly and to rupture, but patients often have severe comorbidities such as immunodeficiency and coexisting sepsis, they say.

Methods
The investigators retrospectively reviewed 123 patients with 130 MAAs treated with endovascular aneurysm repair (EVAR) at 16 European centers in 8 countries from 1999 to 2013. Mean patient age was 69 years, 71% were men, 47% presented with immunodeficiency, and 38% presented with rupture. Mean follow-up was 35 weeks.
Aneurysms most often presented in the infrarenal aorta (48.5%), and as such, 54.6% of patients underwent infrarenal EVAR. Patients were prescribed long-term antibiotic therapy for a mean duration of 30 weeks, and 67% were treated with multiple antibiotics.


Most Fatal Infections Seen in First 90 Days

In all, 91% of patients survived to 1 month, with survival waning after 12 months (76%), 60 months (55%), and 120 months (41%). A total of 33 patients (27%) developed an infection-related complication (recurrent sepsis, graft infection, aortoenteric fistula, or occurrence of a new MAA in the same or at a different location). Among them, 23 patients (70%) died: 30% within the first 30 days after EVAR, 52% within 90 days, and 82% within 1 year. In 9 of the 23 patients who died, a fatal recurrent infection-related event occurred after discontinuation of antibiotics (mean time 31 weeks, range 10-52).

Cumulative incidence of infection-related death (with death of other causes as the competing risk) was 16.4% at 1 year, 21.7% at 5 years, and 21.7% at 10 years.

Cox regression analysis showed that all-cause mortality over the long term was associated with both age and non-Salmonella positive blood culture and inversely associated with a negative culture (table 1).

 Table 1. Predictors of All-Cause Mortality

Moreover, 5-year survival in patients with non-Salmonella positive blood culture was 41%, with half of deaths related to infection. In the subgroup of 15 patients with Salmonella positive blood cultures, 5-year survival was 90%, with 4 of 6 deaths occurring within 90 days. Five-year survival in patients with immunodeficiency was 40% (64% of such deaths being infection related).

Among the 6 patients who were converted to open repair for reasons including graft infection, aortoenteric fistula, type I endoleak, or recurrent MAA, 2 survived. Thirteen patients (11%) required repeat endovascular treatment, resulting in cumulative incidences of 13.4% at 1 year, 16.6% at 5 years, and 16.6% at 10 years.

Duration, Choice of Antibiotic Up for Debate

Because of the rarity of MAA, “the disease is difficult to study…, [and] therefore large-scale multicenter collaborations are necessary,” Dr. Wanhainen and colleagues write.

As most reports of open repair in patients with MAA “show a much worse outcome,” they say, EVAR appears to be a durable treatment option for patients unsuitable for major open surgery.

While it is clear that MAA patients who undergo EVAR must receive long-term antibiotics postprocedure, the authors report, the duration and choice are “an important matter for debate.” Since most infections occur within the first year, especially within the first 6 weeks, “this suggests that long-term [antibiotic] therapy, for at least 6-12 months and possibly for life, is a prerequisite for successful endovascular treatment of MAA,” they argue.

In MAA patients with non-Salmonella positive blood cultures who are at higher risk for death, Dr. Wanhainen and colleagues suggest that EVAR “could be considered a palliative treatment option…, or a bridge to later elective radical open surgery, once the patient has recovered from the initial emergency.”

Prospective Data Needed

In an editorial accompanying the study, Robert J. Hinchliffe, MD, of St. George’s Vascular Institute (London, England), and Janet T. Powell, MD, PhD, of Imperial College (London, England), argue for the importance of registries for rare diseases.

“The label mycotic aneurysm is misleading, since mycoses or fungal infections of the aorta are much rarer still. The management of bacterial infections of the aorta has always been considered difficult, largely because they frequently herald aortic rupture and the outcomes of traditional surgery have been poor,” they explain, adding that these patients have traditionally been surgically managed with “disappointing” results.

The current study and the registry it created are “important [steps] forward in improving patient management,” Drs. Hinchliffe and Powell observe, although they express caution regarding the traditional drawbacks of retrospective analyses. While the registry “demonstrates the feasibility of the endovascular approach…, prospective data will be needed to progress the management of bacterial aneurysms,” they write, as a prospective analysis could possibly include data on the duration of preoperative antibiotics, imaging follow-up outcomes, and how missing data were handled.

 


Sources:
1. Sörelius K, Mani K, Björck M, et al. Endovascular treatment of mycotic aortic aneurysms: a European multicenter study. Circulation. 2014;Epub ahead of print.

2. Hinchliffe RJ, Powell JT. The value of registries for rare diseases: bacterial or mycotic aortic aneurysm [editorial]. Circulation. 2014;Epub ahead of print.

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Disclosures
  • Drs. Wanhainen, Hinchliffe, and Powell report no relevant conflicts of interest.

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