Magnetic resonance angiography of collateral compensation in asymptomatic and symptomatic internal carotid artery stenosis

AbstractObjective: In patients with stenosis of the internal carotid artery (ICA), the presence of collateral circulatory pathways may be crucial to maintain cerebral perfusion pressure, metabolism, and function. The purpose of the present study was to determine whether patients with asymptomatic stenosis of the ICA have a better collateral ability of the circle of Willis when compared with patients with symptomatic ICA stenosis. Method: Magnetic resonance angiography consisting of the circle of Willis was performed in 19 patients with severe asymptomatic ICA stenosis and in 21 patients with severe symptomatic ICA stenosis prior to carotid endarterectomy and in 53 control subjects. Between group comparisons were made for function (directional flow) and anatomy (diameter). Results: In patients with asymptomatic ICA stenosis, the prevalence of collateral flow via the anterior communicating artery was significantly increased (37%, 7 of 19) compared with symptomatic patients (10%, 2 of 21) and control subjects (0%; P < .001). Patients with asymptomatic ICA stenosis demonstrated the largest mean diameter of the anterior communicating artery (1.33 ± 0.18 mm) compared with patients with symptomatic ICA stenosis (1.22 ± 0.18 mm) and control subjects (1.06 ± 0.10 mm, P < .05). No differences in collateral flow pattern or diameter were found for the posterior communicating artery between the groups. Conclusions: The present cross-sectional study demonstrates the importance of an adequate hemodynamic compensation via the circle of Willis in patients with ICA stenosis. Whether differences in collateral compensation can be used to select patients for CEA has yet to be determined. (J Vasc Surg 2002;36:799-805.

Carotid artery stenosis in patients with peripheral arterial disease: The SMART study

AbstractPurpose: The prevalence of asymptomatic internal carotid artery stenosis (ICAS) in patients with peripheral arterial disease (PAD) and characteristics that are associated with ICAS were studied. Methods: We used data from the first 600 patients enrolled in the Second Manifestations of ARTerial disease (SMART) study, a single-center, prospective cohort study among patients referred with a manifestation of cardiovascular disease, diabetes mellitus, hypertension, or hyperlipidemia. Included in the analysis were 162 patients with PAD or a history of PAD, who were not known to have ICAS at the time of referral and who had no history of cerebrovascular symptoms or previous carotid endarterectomy. ICAS was detected with duplex scanning and defined as a peak systolic velocity more than 150 cm/s (diameter reduction 50% or higher) on at least one side. Cardiovascular risk factors were measured. Logistic regression analysis was performed to investigate associations between these characteristics and ICAS. Results: The prevalence of previously unknown ICAS was 14%. A patient age of 67 years or older, body weight of 68 kg or less, and diastolic blood pressure of 75 mm Hg or lower were independently associated with ICAS. The Prevalence Of Icas In Patients With One Of These Characteristics (38% Of The Patients) Was 8%, In Those With Two Characteristics (21% Of The Patients) Was 32%, And In Those With Three Characteristics (6% Of The Patients) Was 50%. Conclusions: The prevalence of ICAS increases as much as 50% in patients who have PAD and the risk indicators of an age of 67 years or older, a body weight of 68 kg or less, and a diastolic blood pressure of 75 mm Hg or lower, and, therefore, these characteristics may be used as a means of increasing the likelihood of detecting ICAS. (J Vasc Surg 1999;30:519-25.

Quality of life after infrainguinal bypass grafting surgery

AbstractPurpose: The purpose of this study was to compare quality of life in patients with and without various ischemic complications after infrainguinal bypass grafting surgery for occlusive vascular disease. Methods: A sample of patients (n = 746) randomized in the Dutch BOA study (n = 2645), a multicenter trial that compared the effectiveness of oral anticoagulant therapy with aspirin in the prevention of infrainguinal bypass graft occlusions, was entered in this study. On the basis of clinical outcomes of the trial, the patients were grouped as follows: patients with patent grafts (n = 409); patients with nontreated graft occlusions, subdivided into an asymptomatic group (n = 32) and a symptomatic group (n = 65); patients with subsequent revascularizations (n = 194); patients with amputations (n = 36); and patients with failed secondary revascularizations followed by secondary amputation (n = 38). In case an outcome event occurred, the patients were regrouped accordingly. Every half year, the patients completed a Short Form–36 and a EuroQol questionnaire. A multilevel model was used for repeated measure analysis. Results:The mean follow-up time was 21 months. The quality of life in patients with nontreated asymptomatic occlusions was roughly similar to the quality of life in patients with patent grafts. Patients with symptomatic nontreated occlusions had the lowest outcome with regard to pain as compared with the other groups. Furthermore, physical and social functioning was lower for these patients than for patients with patent grafts. Revascularizations, successful or not, negatively affected pain, social functioning, and physical and emotional role. After successful revascularization, some improvement was observed in pain, physical and social functioning, and general and mental health as compared with the group with nontreated symptomatic occlusions. Amputation deteriorated physical functioning strikingly, especially after failed secondary revascularization. These patients also had the lowest scores of all the groups in the dimensions of social functioning, physical and emotional role, and mental health. EuroQol score showed deterioration of quality of life after all events, except for asymptomatic occlusions. The same patterns emerged if we stratified our analysis according to the indication for the initial operation: claudication or limb salvage. Quality of life was constant over time in all the groups in the observed period. Conclusion: Quality of life in patients with asymptomatic occluded grafts is similar to quality of life in patients with patent grafts. Revascularization of symptomatic occluded grafts improves quality of life to a certain extent. Amputation, in particular after failed secondary revascularization, seemed to be the lowest possible outcome. The results of the Short Form-36 and EuroQol measurements were in line with the clinical expectations. The association of disease severity with scores on the instruments supports the construct validity of these outcome measures for an objective assessment of quality of life in controlled studies. (J Vasc Surg 1999;29:913-9.

Cost-effectiveness of oral anticoagulants versus aspirin in patients after infrainguinal bypass grafting surgery

AbstractPurpose: Several antithrombotic therapies are available for the treatment of patients with peripheral vascular diseases. It is unknown how quality of life and costs of treatment are influenced by different therapies. This study assessed the cost-effectiveness of oral anticoagulants versus aspirin in patients after infrainguinal bypass grafting surgery. Methods: Clinical outcome events and event-free survival were collected from 2650 patients in 77 centers who participated in the Dutch Bypass Oral anticoagulants or Aspirin trial. Approximately half the patients had critical ischemia; 60% received vein grafts, and 20% had femorocrural bypass grafts. A model that was primarily driven by clinical outcome events was used as a means of determining quality of life (EuroQol EQ-5D) and costs for each patient. The main outcome measure was the incremental health care costs in relation to the additional number of quality-adjusted life years and the additional number of event-free years. Results: The mean costs during the 21 months of follow-up were ϵ 6875 per patient in the oral anticoagulants group versus ϵ 7072 in the aspirin group (difference, 197; 95% CI, –746 to 343). The event-free survival was 1.10 years in the group treated with oral anticoagulants versus 1.09 years in the group treated with aspirin (difference, 0.01; 95% CI, –0.07 to 0.08), whereas the corresponding quality-adjusted life years were 1.06 and 1.05, respectively (difference, 0.01; 95% CI, –0.03 to 0.06). Conclusion: Health care costs, event-free survival, and quality-adjusted life years in patients after infrainguinal bypass surgery were not different in patients treated with aspirin and patients treated with oral anticoagulants. The extra costs of monitoring patients treated with oral anticoagulants were limited and play no role in the decision for treatment. (J Vasc Surg 2001;34:254-62.

Optimal oral anticoagulant intensity to prevent secondary ischemic and hemorrhagic events in patients after infrainguinal bypass graft surgery

AbstractObjectives: The purpose of this study was to determine the optimal intensity of oral anticoagulation in patients who participated in a randomized trial of oral anticoagulants or aspirin after infrainguinal bypass graft surgery. Methods: The distribution of patient-time spent in international normalized ratio (INR) classes of 0.5 INR unit was calculated assuming a linear change between successive measurements. INR-specific incidence rates of ischemic and hemorrhagic events were calculated as the ratio of the number of events at a certain INR category and the total patient-time spent in that class. The relationship between INR class and event rates was quantified by rate ratios calculated in a Poisson regression model. Results: In 1326 patients (mean age, 69 years) 41,928 INR measurements were recorded in 1698 patient-years. Patients spent 50% of the total time within the target range of 3.0 to 4.5 INR. Most of the patient-time (60%) was spent between 2.5 and 3.5 INR. For each increasing class of 0.5 INR, the incidence of ischemic events (n = 154, INR data on event available in 49%) decreased by a factor of 0.97 (95% CI, 0.87-1.08). The incidence of major bleeding (n = 123, INR data on event available in 65%) increased significantly by a factor of 1.27 (95% CI, 1.19-1.34) for each increasing 0.5 INR category. The optimal target range was 3.0 to 4.0 INR, with an incidence of 3.8 events (0.9 ischemic and 2.9 hemorrhagic) per 100 patient-years. Conclusions: The target range of 3.0 to 4.0 INR is the optimal range of achieved anticoagulation intensity and is safe for the prevention of ischemic events in patients after infrainguinal bypass graft surgery. (J Vasc Surg 2001;33:522-7.

Concerns for the durability of the proximal abdominal aortic aneurysm endograft fixation from a 2-year and 3-year longitudinal computed tomography angiography study

AbstractObjective: To provide a long-term perspective on the durability of the proximal abdominal aortic aneurysm endograft fixation from a single device series with perpendicular neck measurements in two groups of patients with complete 2- and 3-year follow-up. Design: This was a prospective study of postoperative, radiologic images. Setting: The study used a referral center, institutional practice, and ambulatory patients. Subjects: From January 1994 until May 1998, 37 endografts were implanted for abdominal aortic aneurysm. In the first postoperative year, there were four unrelated deaths and six conversions, leaving 27 patients with complete 24-month data and 13 with complete 36-month data. Main Outcome Measure: Computed tomography angiograms were processed on a work station to measure the neck perpendicular to the central lumen line of the aorta. The surface area at the proximal endovascular anastomosis was recorded at each follow-up interval and related to the postoperative size at the same level. Results: Significant dilatation of the surface area was found: 20% (16% to 27%) at 24 months (c2 = 30; P < .001, Friedman) and 23% (18% to 28%) at 36 months (c2 = 27; P < .001, Friedman). This increase in neck size was continuous and linear, with a yearly rate of approximately 10% surface area; translated into diameter, this approximates 1 mm/y. Conclusion: A continuous aortic enlargement of approximately 1 mm/y at the level of the proximal endovascular anastomosis was found. Because of the practice of oversizing the endograft relative to the infrarenal aortic neck, a loss of the endovascular seal may not become apparent until several years after endovascular abdominal aortic aneurysm repair is performed. (J Vasc Surg 2001;33:S64-9.