Are we ignoring the importance of ankle pressures in patients with abdominal aortic aneurysm?

Long-term cardiovascular outcome after elective abdominal aortic aneurysm open repair

BACKGROUND

We analyzed the incidence of late cardiovascular events and mortality after elective infra-/juxtarenal abdominal aortic aneurysm open repair (AAA-OR).

METHODS

We included patients who survived AAA-OR in our center in 1988-2006. We registered late cardiac, cerebrovascular, and peripheral vascular events, as well as all-cause and cardiovascular mortality. We calculated patient survival and freedom from cardiovascular events (Kaplan-Meier) and evaluated risk factors (multivariate analysis).

RESULTS

We studied 297 patients: 292 (98.3%) men, aged 67 +/- 7 (44-83) years, 143 (48.1%) bifurcated grafts. In a mean follow-up of 78.7 +/- 52.9 months, we registered 203 cardiovascular events in 123 (41.4%) patients, at a rate of 0.16 cardiovascular events/patient-year. Eleven (3.7%) patients suffered graft-related complications. Freedom from cardiovascular events was 94.2%, 67.2%, 45.7%, and 27.6% at 1, 5, 10, and 15 years, respectively. Survival was 96.6%, 74.7%, 50.7%, and 31.5%, respectively. The main cause of death was cardiovascular disease (n = 54, 18.2%), followed by cancer (n = 43, 14.5%). Only four (1.3%) deaths were graft-related. Coronary artery disease and chronic renal failure were predictive of cardiovascular mortality (p = 0.033 and 0.006).

CONCLUSION

Although long-term survival is similar to that in the general population, successful AAA-OR patients remain at increased risk of cardiovascular events throughout their lifetime. Graft-related complications are rare, confirming the durability of the procedure.

Analysis and computer program for rupture-risk prediction of abdominal aortic aneurysms

BACKGROUND

Ruptured abdominal aortic aneurysms (AAAs) are the 13th leading cause of death in the United States. While AAA rupture may occur without significant warning, its risk assessment is generally based on critical values of the maximum AAA diameter (> 5 cm) and AAA-growth rate (> 0.5 cm/year). These criteria may be insufficient for reliable AAA-rupture risk assessment especially when predicting possible rupture of smaller AAAs.

METHODS

Based on clinical evidence, eight biomechanical factors with associated weighting coefficients were determined and summed up in terms of a dimensionless, time-dependent severity parameter, SP(t). The most important factor is the maximum wall stress for which a semi-empirical correlation has been developed.

RESULTS

The patient-specific SP(t) indicates the risk level of AAA rupture and provides a threshold value when surgical intervention becomes necessary. The severity parameter was validated with four clinical cases and its application is demonstrated for two AAA cases.

CONCLUSION

As part of computational AAA-risk assessment and medical management, a patient-specific severity parameter 0 < SP(t) < 1.0 has been developed. The time-dependent, normalized SP(t) depends on eight biomechanical factors, to be obtained via a patient's pressure and AAA-geometry measurements. The resulting program is an easy-to-use tool which allows medical practitioners to make scientific diagnoses, which may save lives and should lead to an improved quality of life.

The Validity, Reliability, Reproducibility and Extended Utility of Ankle to Brachial Pressure Index in Current Vascular Surgical Practice

BACKGROUND

Despite the increasing sophistication of vascular surgical practice, more than three decades after its introduction to clinical practice, the ankle to brachial pressure index (ABPI) remains the cornerstone of non-invasive assessment of the patient with symptomatic peripheral arterial disease (PAD).

AIM

To summarise what is known about ABPI and critically appraise its validity, reliability, reproducibility and extended utility.

METHODS

A MEDLINE (1966-2004) and Cochrane library search for articles relating to measurement of ABPI was undertaken; see text for further details.

RESULTS

There is considerable disagreement as to how ABPI should be measured. Furthermore, various factors, including the type of equipment used, and the experience of the operator, can result in significant inter- and intra-observer error. As such, care must be taken when interpreting data in the literature. ABPI is valuable in the assessment of patients with atypical symptoms, venous leg ulcers and after vascular and endovascular interventions. However, absolute pressures are probably more valuable in patients with critical limb ischaemia. ABPI is also useful in subjects with asymptomatic PAD where it correlates well with, and may be used in screening studies to quantify, cardiovascular risk.

CONCLUSIONS

While its apparent simplicity can beguile the unwary, ABPI will continue to have a key role in the assessment of symptomatic PAD. ABPI is also likely to have extended utility in health screening and institution of best medical therapy in asymptomatic subjects.

Carotid ultrasound findings as a predictor of long-term survival after abdominal aortic aneurysm repair: a 14-year prospective study

PURPOSE

Several factors have been related to long-term survival after open abdominal aortic aneurysm (AAA) repair. The effect of carotid stenosis on outcome has not yet been examined. We performed an open prospective study to evaluate the prognostic significance of carotid stenosis on long-term survival of patients who had undergone elective operative repair of AAA.

METHODS

Two hundred eight patients who underwent elective open AAA repair in our department between March 1987 and December 2001 were included in the study. All patients were evaluated preoperatively with color duplex ultrasound (US) scanning of the carotid arteries, and were followed up with clinical examination and carotid duplex US scanning 1 month after the operation and every 6 months thereafter. Median duration of follow-up was 50 months (range, 5-181 months). Cardiovascular morbidity and mortality, as well as all causes of mortality, were recorded and analyzed with regard to traditional risk factors and carotid US findings.

RESULTS

Twenty-seven fatal and 46 nonfatal cardiovascular events were recorded. Both univariate and multivariate analysis showed that carotid stenosis 50% or greater and echolucent plaque were significantly associated with cardiovascular mortality and morbidity. Carotid stenosis was a stronger predictor of cardiovascular death than was ankle/brachial index. Age, hypercholesterolemia, coronary artery disease, and diabetes mellitus were also associated with higher mortality and morbidity from cardiovascular causes.

CONCLUSION

Patients electively operated on for AAA repair and with stenosis 50% or greater and echolucent plaque at duplex US scanning are at significantly increased risk for cardiovascular mortality and morbidity. Carotid US can therefore be used to select a subgroup of patients with AAA who might benefit from medical intervention, including antiplatelet and lipid-lowering agents.

Preoperative cardiac assessment for patients with infrarenal abdominal aortic aneurysms: a survey of current practice by vascular surgeons in New South Wales and Australian Capital Territory

BACKGROUND

The reported mortality rate following open elective repair of abdominal aortic aneurysm (AAA) varies between 0 and 12%. Much of the mortality and major morbidity is caused by cardiac events. The evidence regarding best practice for cardiac assessment and optimization of this patient group is unclear. The aim of the present study was to evaluate current practice of cardiac risk factor assessment by vascular surgeons in New South Wales (NSW) and Australian Capital Territory (ACT) for patients undergoing open elective repair of infrarenal AAA.

METHODS

A postal questionnaire was sent to 46 surgeons in NSW and ACT identified as expressing a principal or major interest in vascular surgery. If no response was received within 3 weeks, a second questionnaire was sent and if no response was received after the second mailing, a telephone survey of non-responders was conducted. Data were collated regarding the importance of risk factors elicited by clinical history, preoperative investigation, referral for cardiological opinion, use of perioperative beta-blockade and the timing of aortic surgery in relation to coronary artery revascularization and acute myocardial infarction.

RESULTS

The overall response rate was 87% (40/46) and the median (range) response time was 14 (4-109) days. Only 22 of 40 and 23 of 40 surgeons consider diabetes mellitus or renal impairment, respectively, to be important when assessing cardiac risk and 34 of 40 surgeons do not employ a validated risk index in preoperative assessment. Sixteen of 40 surgeons refer all patients needing AAA repair to a cardiologist, while 24 of 40 would initiate cardiac investigations themselves (either stress electrocardiography, scintigraphy or echocardiography). Seventeen surgeons always or usually commenced perioperative beta-blockade with wide variations in the commencement (1 to > 28 days preoperatively) and duration (< 1 week to > 28 days postoperatively) of treatment. The timing of AAA repair following coronary revascularization ranged from < 1 week to 6 months and delay in surgical repair of AAA following myocardial infarction ranged from < 1 week to > 6 months.

CONCLUSION

Preoperative assessment of cardiac risk in patients for repair of AAA lacks consensus among vascular surgeons in NSW and ACT. The diversity of clinical practice may rest with the paucity of prospective trials published in the medical literature or the influence of local institutional facilities.

Antiplatelet therapy in peripheral arterial disease. Consensus statement

OBJECTIVES

Antiplatelet agents are commonly prescribed to reduce the risk of myocardial infarction, stroke and graft occlusion in patients with peripheral arterial disease (PAD). The objective was to summarise current evidence and provide recommendations on the use of antiplatelet agents in PAD.

METHODS

A consensus group was assembled including 20 specialists from a variety of fields involved in the management of patients with PAD. Data was circulated in a systematic manner prior to a main consensus meeting held in November 2001. The document subsequently produced was circulated within the group to ensure agreement in the interpretation and presentation of its findings.

RESULTS

Consensus recommendations are provided in 7 common or contentious scenarios in PAD. The recommendations are graded to reflect the evidence available and interpretations of the group. Although the document provides recommendations, it is stressed that they must be interpreted in the light of individual patient circumstances.

CONCLUSION

Antiplatelet agents have an important role in the management of patient with PAD. Although this document provides consensus recommendations, the optimum treatment in many scenarios remains unclear due to a lack of focussed clinical trials in PAD.

Ankle-brachial index and mortality in a cohort of questionnaire recorded leg pain on walking

OBJECTIVE

To study the association between the ankle-brachial pressure index (ABPI), premature death and the need for surgical treatment for lower limb ischaemia.

DESIGN

Population based cohort study.

SUBJECTS

Three hundred and fifty-three men and women, 50-89 years old, underwent a leg pain questionnaire and measurement of ABPI and was then followed for 10 years.

OUTCOME MEASURES

All cause mortality, vascular procedures and major amputations.

RESULTS

A low ABPI was independently associated with premature all cause mortality in the multiple regression analysis, carrying a relative risk of 3.4 (95% confidence interval 2.0-5.9) and 2.1 (1.3-3.3) for ABPIs <or=0.50 and 0.51-0.80, respectively, compared to those with ABPI >or=1.0. Individuals with an ABPI in the interval 0.81-0.99 suffered only a slight, not statistically significant risk increase compared to normals. A low ABPI at baseline implied a continuous constant increased risk of death throughout the study period. The same risk was observed among elderly (70-89, median 77 years), and in the middle aged (50-69, median 63 years) individuals. The vast majority of those subjected to vascular intervention or major amputation during follow-up had an ABPI<or=0.8 at baseline (83 and 89%, respectively). However, within that group, the individual ABPI was not predictive for surgical intervention.

CONCLUSION

The association found between an ABPI <or=0.8 and premature mortality in this cohort of symptomatic subjects implies that the ABPI is a powerful, independent predictor for premature death. The prognostic information carried by an ABPI in the interval 0.81-0.99 remains uncertain. Septuagenarians and octogenarians carry the same risk increase associated with a low ABPI as those in the middle ages.

Outcome of endovascular abdominal aortic aneurysm repair in patients with conditions considered unfit for an open procedure: a report on the EUROSTAR experience

OBJECTIVE

Endovascular abdominal aortic aneurysm repair (EAR) can be performed in patients whose conditions were previously considered unfit for conventional treatment of the aneurysm. However, because the life span in this category of patients often is limited because of serious comorbidity, the efficacy of EAR in prolonging life expectancy remains uncertain. This study involves the evaluation of preoperative risk classification and an assessment of the outcome of interventions.

METHODS

The data of 3075 patients, who underwent operation in 101 European institutions that collaborated in the EUROSTAR Registry, were assessed. Only the patients who had been prospectively enrolled in the registry were used for this analysis. Patient characteristics, operative risk factors, procedural details, and types of devices were correlated with preoperative estimates of operative risk, early and late mortality, complications, and primary and secondary outcome success rates. In addition, the intermediate-term survival rates in patients with unfit conditions with EAR (observed series) and with conservative approaches of the aneurysms (rupture rates as derived from the literature) were compared in a mathematical model.

RESULTS

Of the overall study group, 2525 patients were at "normal" risk for a surgical procedure (group A), 399 patients had conditions that were considered unfit for open surgery (group B), and 151 patients had conditions that were unfit for general anesthesia (group C). Both unfit categories had significantly more comorbid factors and larger aneurysms than did the patients in good medical condition. Differences were observed in comorbidities between the two high-risk categories, groups B and C. Factors that influenced the abdominal approach (previous laparotomies, hostile abdomen, and obesity) and local anatomic factors (eg, retroperitoneal fibrosis, inflammatory aneurysm, dissections, and enterostomy) were present in 19% of the patients with conditions that were unfit for open surgery and in only 1% of the category unfit for anesthesia. In contrast, severe pulmonary disease was present in 33% of the patients with conditions that were unfit for anesthesia as opposed to 11% of the patients with conditions that were unfit for open surgery. The early and late mortality rates were significantly higher in the unfit categories (groups B and C). Life table results showed a 3-year survival rate of 83% in patients at normal operative risk and of 68% in patients with unfit conditions (P =.0001). An independent correlation with late death was shown for the clinical classification into high-risk groups B and C, pulmonary disease, team experience of less than 60 procedures, and the diameter of the aneurysm. In groups B and C, aneurysms smaller than 6.0 cm were associated with a 2-year survival rate of 80% and larger aneurysms with a rate of 68% (P =.02). This difference was caused by an increased non-aneurysm-related mortality rate in the group with aneurysms of more than 6 cm. The mathematical model showed an advantage of EAR with regard to the reduction of the death rate in patients with unfit conditions as compared with no intervention after 1 year. The advantage of EAR was observed in patients with AAAs between 5 and 6 cm and with larger aneurysms.

CONCLUSION

Early and late mortality rates were increased in patients with the preoperative clinical diagnosis "unfit for open surgery and general anesthesia" as compared with patients at "normal" operative risk. EAR appeared of potential benefit in patients with unfit conditions, regardless of the aneurysm diameter. The life expectancy of patients at high risk who are considered for EAR should be longer than 1 year before any realistic gain in life span can be anticipated.

Aortic aneurysm diameter and risk of cardiovascular mortality

After successful surgical repair of an abdominal aortic aneurysm, patients have for many years an increased risk of death from cardiovascular causes. We have tested the hypothesis that for patients with abdominal aortic aneurysms, the risk of nonaneurysm cardiovascular mortality before and after surgery increased with aneurysm diameter. Records of aneurysm repair or rupture and mortality were available from 2305 patients entered into the UK Small Aneurysm Trial and Study. Two hundred fifty-nine deaths occurred before aneurysm repair or rupture (mean follow-up 1.7 years), and 325 occurred after surgical repair (mean follow-up 3.6 years). The risk of nonaneurysm-related mortality and cardiovascular death before and after surgery increased with aneurysm diameter at baseline, even after adjustment for other known risk factors. The adjusted hazard ratios for cardiovascular mortality, per standard deviation (0.8-cm) increase in aneurysm diameter, were 1.34 (95% CI 1.01 to 1.79) and 1.31 (95% CI 1.06 to 1.63) in the periods before aneurysm repair or rupture and after aneurysm repair, respectively. The significant association between aortic diameter and cardiovascular mortality, excluding aneurysm-related deaths, suggests that aneurysm diameter is an independent marker of cardiovascular disease risk.