Semi-Conservative Treatment Versus Radical Surgery in Abdominal Aortic Graft and Endograft Infections

OBJECTIVE

Abdominal aortic graft and endograft infections (AGIs) are rare complications following aortic surgery. Radical surgery (RS) with resection of the infected graft and reconstruction with extra-anatomical bypass or in situ reconstruction is the preferred therapy. For patients unfit for RS, a semi-conservative (SC), graft preserving strategy is possible. This paper aimed to compare survival and infection outcomes between RS and SC treatment for AGI in a nationwide cohort.

METHODS

Patients with abdominal AGI related surgery in Sweden between January 1995 and May 2017 were identified. The Management of Aortic Graft Infection Collaboration (MAGIC) criteria were used for the definition of AGI. Multivariable regression was performed to identify factors associated with mortality.

RESULTS

One hundred and sixty-nine patients with surgically treated abdominal AGI were identified, comprising 43 SC (14 endografts; 53% with a graft enteric fistula [GEF] in total) and 126 RS (26 endografts; 50% with a GEF in total). The SC cohort was older and had a higher frequency of cardiac comorbidities. There was a non-significant trend towards lower Kaplan-Meier estimated five year survival for SC vs. RS (30.2% vs. 48.4%; p = .066). A non-significant trend was identified towards worse Kaplan-Meier estimated five year survival for SC patients with a GEF vs. without a GEF (21.7% vs. 40.1%; p = .097). There were significantly more recurrent graft infections comparing SC with RS (45.4% vs. 19.3%; p < .001). In a Cox regression model adjusting for confounders, there was no difference in five year survival comparing SC vs. RS (HR 1.0, 95% CI 0.6 - 1.5).

CONCLUSION

In this national AGI cohort, there was no mortality difference comparing SC and RS for AGI when adjusting for comorbidities. Presence of GEF probably negatively impacts survival outcomes of SC patients. Rates of recurrent infection remain high for SC treated patients.

Risk Factors for Abdominal Compartment Syndrome After Endovascular Repair for Ruptured Abdominal Aortic Aneurysm: A Case Control Study

OBJECTIVE

Ruptured abdominal aortic aneurysms (rAAA) are treated by endovascular aneurysm repair (rEVAR) increasingly often. Despite rEVAR being a minimally invasive method, abdominal compartment syndrome (ACS) remains a significant post-operative threat. The aim of this study was to investigate risk factors for ACS after rEVAR, including aortic morphological features.

METHODS

The Swedish vascular registry (Swedvasc) was assessed for ACS after rEVAR in the period 2008 - 2015. All patients identified were compared with controls (i.e., patients who did not develop ACS after rEVAR), matched by centre and repair date. Case records were reviewed, and radiology images analysed in a core laboratory. Comparisons were performed with respect to physiological and radiological risk factors.

RESULTS

The study population consisted of 40 patients with ACS and 68 controls. Pre-operatively, patients with ACS had a lower blood pressure (BP) than controls (median 70 mmHg vs. 97 mmHg; p < .001). Intra-operatively, they had aortic balloon occlusion more often (55.0% vs. 10.3%; p < .001) and received more transfusions than controls (median nine units of packed red blood cells [pRBC] vs. two units; p < .001). Ninety-seven per cent of those who developed ACS had a pre-operative BP < 70 mmHg, aortic balloon occlusion, or received more than five pRBC unit transfusions. Treatment outside the instructions for use did not differ between patients and controls (57.5% vs. 54.4%; p = .84), and neither did the pre-operative patency of the inferior mesenteric artery (57.1% vs. 63.9%; p = .52) nor the number of visible lumbar arteries on pre-operative imaging (2 vs. 4; p = .014). In multivariable logistic regression, the number of intra-operative transfusions were predictive of ACS (p < .001), while pre-operative hypotension (p = .32) and aortic balloon occlusion (p = .018) were not.

CONCLUSION

ACS after rEVAR is mainly associated with physiological factors and is unlikely to develop without the presence of a pre-operative BP < 70 mmHg, the need for an aortic occlusion balloon, or more than five intra-operative pRBC unit transfusions. Treatment outside the IFU or any other morphological factor were not associated with a risk of ACS.

Prevalence and natural history of and risk factors for subaneurysmal aorta among 65-year-old men

Background: The aims of this study were to determine the prevalence of screening-detected subaneurysmal aorta (SAA), i.e. an aortic diameter of 2.5-2.9 cm, its associated risk factors, and natural history among 65-year-old men. Methods: A total of 14,620 men had their abdominal aortas screened with ultrasound and completed a health questionnaire containing information on smoking habits and medical history. They were categorized based on the aortic diameter: normal aorta (<2.5 cm; n = 14,129), SAA (2.5-2.9 cm; n = 258), and abdominal aortic aneurysm (AAA) (≥3.0 cm; n = 233). The SAA-group was rescanned after 5 years. Associated risk factors were analyzed. Results: The SAA-prevalence was 1.9% (95% confidence interval 1.7%-2.1%), with 57.0% (50.7%-63.3%) expanding to ≥3.0 cm within 5 years. Frequency of smoking, coronary artery disease, hypertension, hyperlipidemia, and claudication were significantly higher in those with SAA and AAA compared to those with normal aortic diameter. Current smoking was the strongest risk factor for SAA (odds ratio [OR] 2.8; P < 0.001) and even stronger for AAA (OR 3.6; P < 0.001). Men with SAA expanding to AAA within 5 years presented pronounced similarities to AAA at baseline. Conclusions: Men with SAA and AAA presented marked similarities in the risk factor profile. Smoking was the strongest risk factor with an incremental association with disease severity, and disease progression. This indicates that SAA and AAA may have the same pathophysiological origin and that SAA should be considered as an early stage of aneurysm formation. Further research on the cost-effectiveness and potential benefits of surveillance as well as smoking cessation and secondary cardiovascular prevention in this subgroup is warranted.

Outcome of the Swedish Nationwide Abdominal Aortic Aneurysm Screening Program

Background:

A general abdominal aortic aneurysm (AAA) screening program, targeting 65-year-old men, has gradually been introduced in Sweden since 2006 and reached nationwide coverage in 2015. The aim of this study was to determine the outcome of this program.

Methods:

Data on the number of invited and examined men, screening-detected AAAs, AAAs operated on, and surgical outcome were retrieved from all 21 Swedish counties for the years 2006 through 2014. AAA-specific mortality data were retrieved from the Swedish Cause of Death Registry. A linear regression analysis was used to estimate the effect on AAA-specific mortality among all men ≥65 years of age for the observed time period. The long-term effects were projected by using a validated Markov model.

Results:

Of 302 957 men aged 65 years invited, 84% attended. The prevalence of screening-detected AAA was 1.5%. After a mean of 4.5 years, 29% of patients with AAA had been operated on, with a 30-day mortality rate of 0.9% (1.3% after open repair and 0.3% after endovascular repair, P <0.001). The introduction of screening was associated with a significant reduction in AAA-specific mortality (mean, 4.0% per year of screening, P =0.020). The number needed to screen and the number needed to operate on to prevent 1 premature death were 667 and 1.5, respectively. With a total population of 9.5 million, the Swedish national AAA-screening program was predicted to annually prevent 90 premature deaths from AAA and to gain 577 quality-adjusted life-years. The incremental cost-efficiency ratio was estimated to be €7770 per quality-adjusted life-years.

Conclusions:

Screening 65-year-old men for AAA is an effective preventive health measure and is highly cost-effective in a contemporary setting. These findings confirm the results from earlier randomized controlled trials and model studies in a large population-based setting of the importance for future healthcare decision making.

Low prevalence of abdominal aortic aneurysm among 65-year-old Swedish men indicates a change in the epidemiology of the disease

BACKGROUND

Screening elderly men with ultrasound is an established method to reduce mortality from ruptured abdominal aortic aneurysm (AAA; Evidence Level 1a). Such programs are being implemented and generally consist of a single scan at 65 years of age. We report the results from screening 65-year-old men for AAA in middle Sweden.

METHODS AND RESULTS

All 65-year-old men (n=26,256), identified through the National Population Registry, were invited to an ultrasound examination. An AAA was defined as a maximum infrarenal aortic diameter of ≥30 mm. In total, 22 187 (85%) accepted, and 373 AAAs were detected (1.7%; 95% confidence interval, 1.5 to 1.9). With 127 previously known AAAs (repaired/under surveillance) included, the total prevalence of the disease in the population was 2.2% (95% confidence interval, 2.0 to 2.4). Self-reported smoking (odds ratio, 3.4; P<0.001), coronary artery disease (odds ratio, 2.0; P<0.001), and hypertension (odds ratio, 1.6; P=0.001) were independently associated with AAA in a multivariate logistic regression model. Thirteen percent of the entire population reported to be current smokers, one third of the frequency reported in the 1980s. The observed low prevalence of AAA was explained mainly by this change in smoking habits.

CONCLUSIONS

On the basis of the observed reduced exposure to risk factors, lower-than-expected prevalence of AAA among 65-year-old men, unchanged AAA repair rate, and significantly improved longevity of the elderly population, the current generally agreed-on AAA screening model can be questioned. Important issues to address are the threshold diameter for follow-up, the possible need for rescreening at a higher age, and selective screening among smokers.