The natural history of abdominal aortic aneurysms and their risk of rupture

The UK Small Aneurysm Trial has shown that ultrasound surveillance is a safe management option for patients with small abdominal aortic aneurysms (4.0 to 5.5 cm in diameter), with an annual rupture rate of only 1%. We investigated baseline risk factors associated with aneurysm rupture in the 1090 trial patients and an additional 1167 patients enrolled in the UK Small Aneurysm Study. In this cohort of 2257 patients there were 103 cases of aneurysm rupture. After 3 years the annual rate of rupture was 2.2% (95% CI 1.7 to 2.8). The risk of rupture was independently and significantly associated with female sex (p < 0.001), larger initial aneurysm diameter (p < 0.001), current smoking (p = 0.01) and higher mean blood pressure (p = 0.01). Age, body mass index, serum cholesterol concentration and ankle/brachial pressure index were not associated with an increased risk of aneurysm rupture. The most surprising finding was that women had a 3-fold higher risk of aneurysm rupture than men. Effective control of blood pressure and cessation of smoking are two simple measures that are likely to diminish the risk of aneurysm rupture and improve the cardiovascular health of patients with abdominal aortic aneurysm.     

Abdominal aortic aneurysm in the interval 5.0-5.5 cm, art or evidence?

The risk of rupture for aneurysms 5-5.5 cm in diameter has not been specifically studied. Two large randomised trials, the United Kingdom Small Aneurysm Trial and the Aneurysm Detection And Management Study Trial concluded that immediate surgical repair did not offer any benefit compared to surveillance and surgical repair if the aneurysm reached 5.5 cm or became symptomatic. Despite these findings many indications today suggest that a lower threshold should be used in patients with higher risk for rupture e.g. women or low risk of mortality in connection with AAA repair such as patients in the lower range of ages.     

Wall stress analysis in small asymptomatic, symptomatic and ruptured abdominal aortic aneurysms.

OBJECTIVES: To evaluate the potential of wall stress analysis for the identification of abdominal aortic aneurysm (AAA) at elevated risk of rupture in spite of small diameter. MATERIALS AND METHODS: Thirty patients with small AAA, 10 asymptomatic, 10 symptomatic and 10 ruptured, were included. Demographic data and results from physical examinations were recorded in a retrospective fashion. After CT-evaluation and the creation of a patient specific 3D model, wall stress was calculated using the finite element method. RESULTS: No differences were observed in diameter between asymptomatic, symptomatic or ruptured aneurysms (5.1+/-0.2 cm vs. 5.1+/-0.2 cm vs. 5.3+/-0.2 cm respectively; p=0.57). Peak aortic wall stress at maximal systolic blood pressure is significantly higher in ruptured than asymptomatic aneurysms (51.7+/-2.4 N/cm(2) vs. 39.7+/-3.3 N/cm(2) respectively; p=0.04). Wall stress analysis at uniform blood pressure, performed to correct for higher blood pressure in the symptomatic and rupture group did not result in significant differences in peak wall stress (asymptomatic 31.7+/-2.3 N/cm(2); symptomatic 30.5+/-1.3 N/cm(2); rupture 36.7+/-4.0 N/cm(2); p=0.26). CONCLUSIONS: Wall stress analysis at maximal systolic blood pressure is a promising technique to detect aneurysms at elevated aneurysm rupture risk. Since no significant differences were found at uniform blood pressure, the need for adequate blood pressure control in aneurysm patients is reiterated.     

Should abdominal aortic aneurysm be managed differently in women?

Although abdominal aortic aneurysm (AAA) is 4 to 6 times more common in men than in women, more than a third of all AAA deaths occur in women. In several reports from the UK Small Aneurysm Trial group, the rupture rate for women was 3-4 times that seen in men. A joint council of several vascular societies responded to these observations with the recommendation that AAA should be repaired earlier in women, at 4.5 cm to 5.0 cm rather than the 5.5 cm established in randomized trials for men. However, this recommendation does not appear to reflect a full consideration of the evidence. For example, population-based studies have reported mortality following AAA repair to be 40-60% higher in women than in men. Also, in the UK Small Aneurysm Trial itself, there was no trend toward a benefit from early repair in women. The totality of evidence available at present provides no good reason to alter for women the 5.5 cm threshold for elective repair established for men by the small AAA trials.     

Aneurysm enlargement following endovascular aneurysm repair: AneuRx clinical trial

OBJECTIVE: The purpose of this study was to determine the incidence and significance of aneurysm enlargement, with or without treatment, in relation to the primary end points of rupture, surgical conversion, aneurysm-related death, and survival following endovascular repair. METHOD: Aneurysm (AAA) size changes and clinical outcome of all patients treated from 1997 through 1998 during the Phase II AneuRx multicenter clinical trial of endovascular AAA repair were reviewed. Aneurysm dimensions and the presence or absence of endoleak were determined by an independent core laboratory, with enlargement or shrinkage defined as a diameter change of 5 mm or more compared with baseline. RESULTS: Among 383 patients (89% men, 11% women, age 73 +/- 9 years), with a mean device implant time of 36 +/- 11 months (median = 39 months), aneurysm diameter decreased from 5.7 +/- 1.0 at baseline to 5.2 +/- 1.0 at 3 years (P =.0001). A total of 46 patients (12%) experienced AAA enlargement, 199 patients (52%) had no change in AAA diameter, and 138 patients (36%) had a decrease in AAA diameter of 5 mm or more. Significant risk factors for enlargement included age (enlargement patients were 4 years older on average than patients with aneurysms that decreased in size; P =.002) and the presence of an endoleak (P <.001). Among patients with endoleak at any time, 17% had aneurysm enlargement, whereas only 2% of patients without endoleak had aneurysm enlargement (P <.001). Patients with enlargement were more likely to undergo secondary endovascular procedures and surgical conversions (P <.001). Twenty patients (43%) with enlargement underwent treatment, and 26 patients were untreated. There were two deaths following elective surgical conversion and one death in a patient with untreated enlargement and a type I endoleak. Three aneurysms ruptured: one with enlargement, one with no change, and one with a decrease in aneurysm size; all three aneurysms were larger than 6.5 cm. Kaplan-Meier analysis showed that freedom from rupture at 3 years was 98% with enlargement, 99% with no change, and 99% with decrease in AAA size (log-rank test, not significant). Freedom from AAA death at 3 years was 93% in patients with enlargement, 99% in no increase, and 99% in decrease (P =.005). Survival at 3 years was 86% with increase, 82% with no change, and 93% with decrease (P =.02). CONCLUSIONS: Aneurysm enlargement following endovascular repair was not associated with an increased risk of aneurysm rupture or decrease in patient survival during a 3-year observation period. Aneurysm size rather than enlargement may be a more meaningful predictor of rupture. Close follow-up and a high re-intervention rate (43%) may account for the low risk of rupture in patients with enlargement. The long-term significance of aneurysm enlargement following endovascular repair remains to be determined.     

Aneurysm rupture after endovascular repair using the AneuRx stent graft

OBJECTIVE: The purpose of this study was to determine the cause and frequency of aneurysm rupture after endovascular aneurysm repair. METHODS: We reviewed each patient who sustained aneurysm rupture among all patients enrolled for endovascular aortic aneurysm repair in phases I, II, and III of the US AneuRx Multicenter Clinical Trial from June 1996 through October 1999. RESULTS: A total of 1067 patients were enrolled for endovascular aneurysm repair. The AneuRx stent graft was successfully implanted in 1046 patients (98%). Endovascular repair was unsuccessful in 21 patients (2%); 13 patients (1%) were converted to open aneurysm repair. Among these, two patients (0.2%) sustained aneurysm rupture due to procedure-related instrumentation and underwent open surgical conversion. Aneurysm rupture has occurred in seven patients (0.7%) 3 weeks to 24 months (mean, 16 months) after successful endovascular repair. Four patients survived open surgical repair, and three patients died within 30 days. Overall rupture-related mortality was 0.5% and included late deaths after rupture. Before rupture, two patients had endoleak and aneurysm enlargement, and five patients had no endoleak and no aneurysm enlargement. After aneurysm rupture all seven patients had evidence suggesting that there was poor fixation of the stent graft at the proximal distal, or iliac junction fixation sites. The two patients with endoleak declined recommended open surgical or endovascular repair, which could have prevented aneurysm rupture. In retrospect, the five patients without endoleak could potentially have avoided rupture with better patient selection, better stent graft positioning, or reinforcement of fixation points with stent graft extenders. The probability of no aneurysm rupture for all patients undergoing endovascular repair is 0.996 +/- 0.002 at 1 year and 0.974 +/- 0.011 at 2 years by life table analysis with the longest follow-up of 41 months. CONCLUSION: The early risk of aneurysm rupture after endovascular aneurysm repair is low. However, the possibility of rupture persists even in patients with no endoleak after the procedure. Therefore, all patients treated with endovascular aneurysm repair should continue to be monitored after the procedure. Patients with evidence suggesting insecure stent graft fixation should undergo further endovascular treatment or open surgical repair.     

An evaluation of new methods of expressing aortic aneurysm size: relationship to rupture.

The diameter of aortic aneurysms were standardized to measures of patient size and normal aortic size in an effort to define indexes that might be more predictive of aneurysm rupture than raw aneurysm diameter alone. Normal aortic diameters were measured in 100 patients undergoing abdominal CT scans for other reasons, and an average infrarenal aortic diameter of 2.10 +/- 0.05 cm was observed. Normal aortic diameter was dependent on both age and sex, ranging from 1.71 +/- 0.06 cm in women below age 40 years to 2.85 +/- 0.04 cm in men above age 70 years. Overall, 11 (5.1%) of the ruptures occurred in aneurysms less than 5 cm in diameter, and four (1.9%) occurred in aneurysms less than 4.0 cm in diameter. When the CT scans of 100 patients undergoing elective aneurysm resection were compared with those of 36 patients with ruptured aneurysms, no threshold diameter value accurately discriminated between the two groups. However, standardization of the aneurysm diameter to the transverse diameter of the third lumbar vertebral body as an index of patient body size produced an accurate predictor of rupture when a threshold ratio of 1.0 was used. No aneurysm ruptured below this ratio, but 29% of elective aneurysms were smaller than the vertebral body diameter. Receiver operating characteristic curve analysis confirmed the superiority of the aneurysm to vertebral body diameter ratio as a discriminator of ruptured aneurysms. It appears that aneurysm diameter alone is not sufficiently predictive of rupture to be used as the sole indication for elective resection.     

Palliation of Abdominal Aortic Aneurysms in the Endovascular Era

ObjectivesTo establish outcome of patients with abdominal aortic aneurysm (AAA) deemed unfit for repair.DesignRetrospective non-randomised study.Materials and methodsIdentification of males with >5.5 cm or females with >5.0 cm AAA turned down for elective repair between 01/01/2006–24/07/2009 from a prospective database. Comorbidities, reasons for non-intervention, aneurysm size, survival, use of CPEX (cardio-pulmonary exercise) testing and cause of death were analysed. Although well-established at the time, patients unfit for open operation were not considered for endovascular repair.ResultsSeventy two patients were unsuitable for AAA repair. Aneurysm size ranged from 5.3 cm to 12 cm. Functional status, comorbidity and patient preference determined decision to palliate. Sixty percent of patients were alive at study close. Aneurysm rupture was cause of death in 46%. CPEX testing was performed in 54%, whose mortality was 28%, vs. 54% in the non-CPEX group (P < 0.05).Median survival of patients with 5.1–6.0 cm AAA was 44 months and 11% died of rupture. Between 6.1 and 7.0 cm median survival was 26 months and 20% died of rupture. However, with >7 cm aneurysms, survival was 6 months and 43% ruptured.ConclusionUnder half the deaths in our comorbid cohort were due to rupture. However, decision to palliate may be revisited as risk-benefit ratio changes with aneurysm expansion.     

Patency of Infrarenal Aortic Side Branches Determines Early Aneurysm Sac Behavior after Endovascular Repair

In this study we sought to determine whether initial abdominal aortic aneurysm (AAA) sac anatomy, morphology, and side branch patency influence changes in aneurysm size and development of endoleak following endovascular repair. A blinded, retrospective review of preintervention CT scans and angiograms was conducted on 70 consecutive patients treated for infrarenal AAA (mean size 6.0 +/- 0.8 cm) by AneuRx stent-graft exclusion. Initial AAA diameter and side branch (inferior mesenteric artery [IMA], lumbar artery pair) patency, AAA clot/sac diameter ratio, wall thrombus and calcification distributions, attachment site anatomy, endograft size, and other clinical parameters were correlated with postoperative persistent side branch patency, presence of type II endoleak, and change in AAA diameter (increase/decrease ? 5 mm) using contingency table analyses. Patients underwent CT scanning and/or color duplex imaging at 1 month and at 3 (with endoleak) or 6 (without) month intervals postoperatively with 50 patients followed beyond 6 months (mean follow-up 11 +/- 7 months). The majority of patients possessed patent side branches prior to intervention (lumbar [n = 60, 86%], IMA [n = 45, 64%]). Development of type II endoleak or persistence of side branches could not be predicted (p > 0.05) from preoperative AAA side branch patency or any of the other initial anatomic AAA variables. On serial post-repair CT or duplex cans, 42% (19/45) of IMAs and 27% (16/60) of lumbar artery pairs remained patent. For patients followed beyond 6 months, type II endoleaks persisted in half (13/25) of the patients with patent side branches with roughly equal proportions fed by IMA and lumbar sources. Persistent side branches or presence of type II endoleak was associated with AAA expansion or the failure of aneurysm size diminution after endografting (p <0.01). Aneurysm sac regression was most likely in the absence of endoleak and patent side branches. We conclude that persistent side branch patency not only fuels development of type II endoleak but also influences early aneurysm sac behavior after endovascular repair. Optimal anatomic patient selection for endografting may not be possible on the basis of our initial experience, since preoperative AAA variables did not predict persistence of side branches or type II endoleaks.     

Influence of sex on expansion rate of abdominal aortic aneurysms

BACKGROUND: The UK Small Aneurysm Trial suggested that female sex is an independent risk factor for rupture of abdominal aortic aneurysm (AAA). This study assessed the effect of sex on the growth rate of AAA. METHODS: Between January 1985 and August 2005 all patients who were referred to the Royal Infirmary of Edinburgh with an AAA who were not considered for early aneurysm repair were assessed by serial abdominal ultrasonography. Maximum anteroposterior and transverse diameters of the AAAs were measured. RESULTS: A total of 1255 patients (824 men and 431 women) were followed up for a median of 30 (range 6-185) months. A median of six examinations (range 2-37) was performed for each patient. Median diameter on initial examination was 41 (range 25-83) mm. Median growth rate overall was 2.79 (range - 4.80-37.02) mm per year. Median growth rate of AAA was significantly greater in women than men (3.67 (range - 1.2-37.02) versus 2.03 (range - 4.80-21.00) mm per year; P < 0.01). Weighted linear regression analysis revealed that large initial anteroposterior AAA diameter and female sex were significant predictors of faster aneurysm growth rate (P < 0.001 and P = 0.006 respectively). CONCLUSION: The growth rate of AAA was significantly greater in women than in men. This may have implications for the frequency of follow-up and timing of repair of AAA in women.     

The natural history of abdominal aortic aneurysms

This study examines the rate of expansion of abdominal aortic aneurysms and the risk of rupture in relation to their size. To assess these variables, we conducted a prospective study of 300 consecutive patients who presented over a 6-year interval with abdominal aortic aneurysms (AAA) that were initially managed nonoperatively. The mean age of the patients was 70.4 years, and 211 (70%) were men. The mean initial aneurysm diameter was 4.1 cm. Among the 208 patients who underwent more than one ultrasound or computed tomographic (CT) scan, the diameter of the aneurysm increased by a median of 0.3 cm per year. The 6-year cumulative incidence of rupture was 1% and 2% among patients with aneurysms less than 4.0 cm and 4.0 to 4.9 cm in diameter, respectively (p greater than 0.05). In comparison, the 6-year cumulative incidence of rupture was 20% among patients with aneurysms greater than 5.0 cm in diameter (p less than 0.004). We conclude that (1) abdominal aortic aneurysms expand at a median rate of 0.3 cm per year; and (2) the risk of rupture of abdominal aortic aneurysms less than 5.0 cm is substantially lower than the risk of rupture of aneurysms 5.0 cm or more in diameter.     

Abdominal aortic aneurysms following orthotopic heart transplantation

The purpose of these authors' study was to analyze their center's experience with orthotopic heart transplantation (OHT) and abdominal aortic aneurysms (AAA) with particular attention to corticosteroid dosing, hemodynamic parameters, and aneurysm growth rate. A retrospective review of all patients (453) who underwent OHT at their university-affiliated medical center over an 18-year period (1981-1999) was undertaken. Nine (2%) patients who developed AAAs were identified and aneurysm growth was correlated with corticosteroid immunosuppression and hemodynamic parameters. The mean age of OHT patients was 44.5 +/-15 years and the majority were males (371 males, 82%). Median follow-up was 5.7 years. Ischemic cardiomyopathy (IC) was the most common indication for transplantation (45.5% of patients). All AAA patients were male (p=0.157), with a mean age of 58.4 +/-4.8 years (p=0.001), and had undergone OHT for IC (p=0.001). Mean arterial blood pressure and ejection fraction in the AAA patients had increased from pretransplant values of 107 mm Hg and 14.3 +/-5.7% to 142 mm Hg (p=0.017) and 54.1 +/-14.1% (p<0.001), respectively, before aneurysm repair. Mean aneurysm diameter at the time of repair was 6.0 +/-0.8 cm, and the average growth rate was 1.2 +/-0.4 cm/year in the 4 patients in whom it could be measured. Aneurysm repair was performed urgently in 2 patients and electively in 7 patients with 1 early postoperative death (11%). The extent of corticosteroid immunosuppression, corticosteroid pulses, and total corticosteroid dosing did not correlate with the rate of aneurysm growth. Improved hemodynamics and progressive posttransplant hypertension may contribute to aneurysm formation and growth in this group of patients.     

Selective management of abdominal aortic aneurysms smaller than 5.0 cm in a prospective sizing program with gender-specific analysis

PURPOSE: We present extended follow-up findings of the Kingston prospective sizing program for patients with abdominal aortic aneurysm (AAA) smaller than 5.0 cm in diameter, with gender-specific analysis. METHODS: From 1976 to 2001, 895 patients (688 men, 207 women) with AAA smaller than 5.0 cm were entered, regardless of fitness, in a prospective sizing program in which computed tomography scans were obtained every 6 months. Operations were performed in fit patients with an increase in AAA size to 5 cm (n = 190), AAA expansion greater than 0.5 cm in 6 months (n = 27), or for other reasons (n = 33). Follow-up continued until AAA rupture, surgery, death, or removal from the program. RESULTS: No AAA smaller than 5.0 cm ruptured during prospective follow-up. There was a statistically significant increase in expansion rate relative to size at entry, with the highest mean expansion rate of 0.52 cm/y for AAA 4.5 to 4.9 cm in diameter. There was no significant difference in AAA expansion rate between men and women. The frequency of surgery was inversely related to age at entry, but was positively related to AAA size at entry, with patients with AAA 4.5 to 4.9 cm at entry 6.8 times more likely (95% confidence interval, 4.3-10.7) to undergo surgery than those with AAA 3.0 to 3.4 cm at entry. Women were older than men at entry, and age at entry in those undergoing surgery was significantly greater in women. CONCLUSIONS: The study confirms the results of the United Kingdom Small Aneurysm Trial and the Aneurysm Detection and Management Study, that is, that risk for rupture is extremely unlikely with AAA smaller than 5.0 cm, which enables safe follow-up surveillance programs in both men and women with AAA smaller than 5.0 cm.     

Abdominal aortic aneurysm: epidemiology,screening and work-up for repair

Abdominal aortic aneurysm (AAA) is a dilatation of the infra-renal abdominal aorta to greater than 3 cm. Population screening is offered to men in the year of their 65th birthday in the UK. Patients with small, asymptomatic AAAs (<5.5 cm) are entered into surveillance programmes and have their cardiovascular risk factors managed aggressively. An AAA ≥5.5 cm diameter, or one which is symptomatic, should be considered for surgical repair to prevent rupture. Aneurysm repair can be undertaken using either an open surgical or endovascular approach; the decision should be tailored to the individual patient and made by the surgeon and patient, with input from a multi-disciplinary team.     

Abdominal aortic aneurysms: screening,epidemiology and open surgical repair

Abdominal Aortic Aneurysm (AAA) is a dilatation of the infra-renal abdominal aorta to greater than 3 cm. Population screening is offered to men in their 65th year in the UK. Patients with small AAAs (<5.5 cm) are entered into surveillance programs and should have cardiovascular risk factors managed aggressively. An AAA with ≥5.5 cm diameter should be considered for surgical repair to prevent rupture. Open surgical repair has proven to be a durable treatment for AAA and while less often performed than endovascular aneurysm repair (EVAR) it remains a common approach in the surgical management of AAA. While associated with higher short-term risks than EVAR, the long-term outcomes are similar and many younger patients have a preference for open repair as routine follow-up is not required.     

The rupture rate of large abdominal aortic aneurysms: is this modified by anatomical suitability for endovascular repair?

BACKGROUND: There are no precise estimates of the rate of rupture of large abdominal aortic aneurysms (AAA). There is recent suspicion that anatomic suitability for endovascular repair may be associated with a decreased risk of AAA rupture. METHODS: Systematic literature review of rupture rates of AAA with initial diameter > or =5 cm in patients not considered for open repair, with stratification by size (<6.0 cm and 6.0+ cm), and gender, combined using random-effects meta-analysis. Proportional hazards regression to analyze factors (including gender, diabetes, initial AAA diameter, aneurysm neck, and sac lengths) associated with rupture in patients anatomically suitable for endovascular repair (EVAR 2 trial). RESULTS: Previous studies (2 prospective, 2 retrospective, and 1 mixed) were identified for meta-analysis and patients with elective repair excluded. The pooled rupture rates was 18.2 [95% confidence interval (CI) 13.7-24.1] per 100 person-years. There was a 2.5-fold increase in rupture rates for patients with AAA of 6.0+ cm versus <6.0 cm, rupture rates = 2.54 (95% CI 1.69-3.85). The pooled rupture rates was nonsignificantly higher in women than men, rupture rates = 1.21 (95% CI 0.77-1.90). For EVAR 2 patients with 6+ cm aneurysms the rupture rates was 17.4 [95% CI 12.9-23.4] per 100 person-years significantly lower than the pooled rate from the meta-analysis, rupture rates = 27.0 [95% CI 21.1-34.7] per 100 person-years, P = 0.026. Patients with shorter neck lengths appeared to have a higher rupture rates than those with longer necks, but this was of borderline significance P = 0.10. CONCLUSIONS: Rupture rates of large AAAs reported in different studies are highly variable. There is emerging evidence that patients anatomically suitable for endovascular repair have lower rupture rates.     

Prediction of rupture risk in abdominal aortic aneurysm during observation: wall stress versus diameter

OBJECTIVES: We previously showed that peak abdominal aortic aneurysm (AAA) wall stress calculated for aneurysms in vivo is higher at rupture than at elective repair. The purpose of this study was to analyze rupture risk over time in patients under observation. METHODS: Computed tomography (CT) scans were analyzed for patients with AAA when observation was planned for at least 6 months. AAA wall stress distribution was computationally determined in vivo with CT data, three-dimensional computer modeling, finite element analysis (nonlinear hyperelastic model depicting aneurysm wall behavior), and blood pressure during observation. RESULTS: Analysis included 103 patients and 159 CT scans (mean follow-up, 14 +/- 2 months per CT). Forty-two patients were observed with no intervention for at least 1 year (mean follow-up, 28 +/- 3 months). Elective repair was performed within 1 year in 39 patients, and emergent repair was performed in 22 patients (mean, 6 +/- 1 month after CT) for rupture (n = 14) or acute severe pain. Significant differences were found for initial diameter (observation, 4.9 +/-.1 cm; elective repair, 5.9 +/-.1 cm; emergent repair, 6.1 +/-.2 cm; P <.0001) and initial peak wall stress (38 +/- 1 N/cm(2), 42 +/- 2 n/cm(2), 58 +/- 4 N/cm(2), respectively; P <.0001), but peak wall stress appeared to better differentiate patients who later required emergent repair (elective vs emergent repair: diameter, 3% difference, P =.5; stress, 38% difference, P <.0001). Receiver operating characteristic (ROC) curves for predicting rupture were better for peak wall stress (sensitivity, 94%; specificity,81%; accuracy, 85% [with 44 N/cm(2) threshold]) than for diameter (81%, 70%, 73%, respectively [with optimal 5.5 cm threshold). With proportional hazards analysis, peak wall stress (relative risk, 25x) and gender (relative risk, 3x) were the only significant independent predictors of rupture. CONCLUSIONS: For AAAs under observation, peak AAA wall stress seems superior to diameter in differentiating patients who will experience catastrophic outcome. Elevated wall stress associated with rupture is not simply an acute event near the time of rupture.     

The US AneuRx Clinical Trial: 6-year clinical update 2002

A total of 1193 patients with infrarenal abdominal aortic aneurysms were treated with the AneuRx Stent Graft System at 19 US investigational centers from 1996 to 1999. This report summarizes clinical data collected and analyzed as of August 28, 2002. There have been 10 late (>30 days) aneurysm ruptures, 8 late (>30 days) aneurysm-related deaths, and 38 late (>30 days) surgical conversions, including 8 for rupture. Kaplan-Meier analyses of the primary outcome measures at 4 years indicate the following: a freedom from rupture rate of 98.4%; a freedom from surgical conversion rate of 90.4%; a freedom from aneurysm-related death rate of 96.9%; and a probability of survival rate, based on all-cause mortality, of 62.4%. Secondary outcome measures at 4 years include stent graft patency in 96.4%, endoleak in 13.9%, aneurysm enlargement in 11.5% and stent graft migration in 9.5% of patients. These results provide evidence that the AneuRx Stent Graft System continues to be a safe and effective treatment option for appropriately selected patients with infrarenal abdominal aneurysms.     

Current results of elective aortic reconstruction for aneurysmal and occlusive disease

Decisions to resect small aortic aneurysms or employ non-operative treatment for aorto-iliac occlusive disease must depend on current rather than historical surgical results. To assess current morbidity and mortality, we reviewed 200 consecutive aortic resections in two groups of patients treated from 1981 to 1989: those undergoing elective aortofemoral bypass for occlusive disease (AFB, no. 100) or resection of infrarenal abdominal aortic aneurysms (AAA, no. 100). Indications for AFB included claudication (54%), rest pain (32%), and gangrene (13%). AAA size ranged from 3 to 14 cm (mean 6.5 +/- 2.4 cm); 45% presented with abdominal or back pain. Patients undergoing AFB were younger (AFB 61.5 +/- 10 years vs AAA 68.7 +/- 8.9 years) with a higher incidence of some atherosclerotic risk factors, diabetes mellitus 30% vs 10%, tobacco use 77% vs 49%, hyperlipidemia 21% vs 7%; p less than 0.001). Coronary artery disease (CAD) was more prevalent in AAA patients (49% vs 34%; p less than 0.001). Postoperative mortality was not different in occlusive or aneurysmal disease (3% AFB vs 2% AAA), nor was the occurrence of serious complications such as myocardial infarction (2% vs 1%) or pulmonary embolism (2% vs 3%). Improvements in patient selection, perioperative care and surgical technique have lowered the mortality of elective aortic surgery. Given the current standard of care, an aggressive approach to AAA even in high risk patients is appropriate. The low morbidity of AFB for occlusive disease mandates a critical appraisal of less effective nonoperative therapies.     

Aortic Aneurysm Sac Shrinkage after Endovascular Repair Is Device–dependent: A Comparison of Zenith and AneuRx Endografts

Aneurysm sac shrinkage after endovascular aneurysm repair (EAR) provides objective evidence of successful aneurysm exclusion and absence of endotension. Attainment of this outcome parameter may be device-dependent. In this study, 169 patients underwent EAR with an AneuRx (n = 118) or Zenith (n = 51) endograft at a single institution. A prospectively maintained database was examined for significant changes in aneurysm sac diameter (> or = 5 mm) on the basis of computed tomography (CT) measurements at 6 and 12 months follow-up. Significant aneurysm sac shrinkage (> or = 5 mm) occurred in 73.1 % (19/26) vs. 43.1% (28/65) of patients in the Zenith and AneuRx groups, respectively, at 12 months (p = 0.03). At 6 months follow-up, sac shrinkage rates were 51.4% (19/37) vs. 25.8% (16/62) in the Zenith and AneuRx groups, respectively (p = 0.04). Mean reduction of sac diameter at 12 months was -7.6 +/- 1.6 mm vs. -3.5 +/- 0.8 mm in the Zenith and AneuRx groups, respectively (p = 0.01). There was a trend toward fewer Type I and III endoleaks at 1 month in the Zenith group (0 vs. 8.3%) that did not achieve statistical significance (p = 0.067). The presence of any endoleak (> or = 1 month) was associated with reduced 12 month shrink rates from 47.1% (25/51) to 28% (4/14) in the AneuRx group (p = 0.35) and from 77.3% (17/22) to 50% (2/4) in the Zenith group (p = 0.25). Patients treated with the Zenith endograft demonstrated a significantly higher rate and amount of aneurysm sac shrinkage than patients treated with an AneuRx device. Endoleaks appeared to negatively influence shrink rates with both endografts.