Graft Infection After TEVAR or EVAR a Rare But Serious Complication

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While rare, endograft infection is increasing in frequency after endovascular abdominal aortic aneurysm repair (EVAR) or thoracic endovascular aneurysm repair (TEVAR), carrying with it a high risk of morbidity and mortality. Surgical excision continues to be the standard of care, notes a single-center study appearing online July 8, 2013, ahead of print in the Journal of Vascular Surgery, but medical management with IV antibiotics may be preferred in certain patients.

Researchers led by Edward Y. Woo, MD, of the Hospital of the University of Pennsylvania (HUP; Philadelphia, PA), performed a retrospective review at their institution of all patients treated for abdominal or thoracic endograft infection following previous EVAR or TEVAR over a 10.5-year period (January 2000-July 2011).

A total of 18 patients were treated for endograft infection over the length of the study, 3 before 2006, and 15 between 2006 and 2011. After excluding the 9 patients who were transferred from an outside institution for management of infections, the endograft infection rate (0.6%) remained constant before and after 2006. During this time, though, there was a significant increase in transfers to HUP for management of infected endografts.

The majority of patients were male (83%), with a mean age of 69.1 years. Roughly two-thirds of cases (67%) involved abdominal endografts, and over half (61%) presented with infection within the first 3 months after endograft placement, with a median time to presentation of 90 days.

Different Devices All Equally to Blame

Abdominal infections were seen with the following devices:

• Zenith (n = 5; Cook Medical, Bloomington, IN)
• Excluder (n = 3; WL Gore, Flagstaff, AZ)
• AneuRx (n = 2; Medtronic, Minneapolis, MN)
• Talent (n = 2; Medtronic)

Thoracic infections were seen with the Tag device (n = 3; WL Gore) and the Talent thoracic endograft (n = 1). There were no significant differences among devices in terms of infection rates.

Over two-thirds of patients (72%) presented with sepsis, while over half (56%) presented with aortic fistula. Eleven percent presented with aortic rupture. In the majority of patients (67%), a potential source of infection was identified in proximity to the timing of endograft infection. In particular, 3 were implanted in an infected field, 4 had interval procedures within 4 months of presentation of the graft infection, and 6 had interval infections leading to potential bacteremia.

Group A Strep Most Common Bacterium

Lab evaluation was performed in all patients, showing a white blood cell count at time of presentation of 12.7 ± 6.2. Blood and graft cultures were obtained when possible and were positive in 83% and 70% of cases, respectively. The most common blood isolate was group A strep (n = 4). However, most graft cultures were polymicrobial (n = 7). Methicillin resistant S. aureus (n = 4) and E. coli (n = 1) were also cultured in isolation

Surgical total endograft explantation was the most common treatment, used in 10 patients. Reconstruction was performed with axillofemoral bypass (n = 5), in situ homograft (n = 4), or rifampin grafts (n = 1) in the remaining patients. In addition, medical management without endograft explantation was used in 8 patients who were too high risk for endograft excision, refused open surgery, or had minimal evidence of graft contamination. All patients were maintained on culture specific lifelong antibiotics as determined by infectious disease prior to discharge. These included Augmentin (n = 4), Levaquin (n = 3), and Bactrim (n = 4).

Mean ICU and hospital stays were 1.82 and 21.8 days, respectively. Postoperative complications were infrequent in the absence of aortoenteric or aortobronchial fistulas. Thirty-day mortality was 28%, with an aneurysm-related mortality of 39% at a median follow-up of 24.7 months. There were no infectious recurrences among survivors.

TEVAR Mortality Higher

TEVAR was associated with higher mortality compared with EVAR (83% vs. 17%; P = 0.03), as was aortic fistula compared with no fistula (60% vs. 13%; P = 0.04). In addition, medical management and surgical explant achieved similar mortality rates of 0 and 25%, respectively (P = 0.39).

According to the authors, while endograft infection after EVAR or TEVAR is rare, with a frequency of 0.05% to slightly over 4%, “the overall numbers may be increasing as we noted a significant increase in transfers to our institution for management of infected endografts after 2006.”

They point out that most of the endograft infections in the study occurred during the first 3 months “and may indicate that the graft is particularly susceptible to bacterial seeding during this time.”

Furthermore, they say, the study results “are highly suggestive that patients with thoracic and abdominal endografts may require lifetime suppressive antibiotics prior to any invasive procedures, such as is common practice with prosthetic heart valves.”

Surgery Remains Gold Standard

Regardless, Dr. Woo and colleagues point out, the gold standard for treatment of endograft infection remains surgery: either total surgical endograft excision with arterial reconstruction or, in the case of fistulae, enteric or airway repair with flap coverage. That is not to say, however, that medical management is not appropriate for some.

“Nonoperative management of abdominal endograft infection is reserved for patients deemed too high-risk for explant or for patients with more indolent presentations and low level infections such as a bacteremia associated with a concomitant infection without evidence of significant gross graft contamination,” the authors advise.

For some patients, though, such as those with thoracic aortic infections, surgical excision should remain standard therapy.  “As these infections are so rapidly progressive, we cannot at this time consider thoracic patients candidates for medical therapy alone,” the authors note. “In general, the degree of infection and clinical presentation affect the treatment decision. In patients with gross contamination of the graft and/or an aortoenteric fistula, explantation is strongly recommended as medical management would [be] unlikely [to] resolve these issues.”

 

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Source:
Murphy EH, Szeto WY, Herdrich BJ, et al. The management of endograft infections following endovascular thoracic and abdominal aneurysm. J Vasc Surg. 2013;Epub ahead of print.

 

 

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