Assessment of 'on-treatment platelet reactivity' and relationship with cerebral micro-embolic signals in asymptomatic and symptomatic carotid stenosis.

INTRODUCTION: The relationship between on-treatment platelet reactivity and cerebral micro-embolic signals (MES) is unknown, and has not been previously simultaneously assessed in asymptomatic and symptomatic carotid stenosis patients. METHODS: Consecutive eligible patients with ≥50% asymptomatic or recently symptomatic carotid stenosis (≤4weeks following TIA/ischaemic stroke) were recruited to this pilot study. Symptomatic patients were followed up to the 'late' phase (≥3months) following symptom onset or carotid intervention; longitudinal data were analysed from symptomatic patients with data available at both time-points. Platelet function/reactivity was assessed with the PFA-100® to measure collagen-ADP (C-ADP) and collagen-epinephrine (C-EPI) closure times in citrate-anticoagulated whole blood. Bilateral simultaneous 1-hour transcranial Doppler ultrasound (TCD) monitoring of the middle cerebral arteries was performed to classify patients as MES +ve or MES -ve. RESULTS: 31 patients with ≥50% asymptomatic and 46 with early symptomatic carotid stenosis or occlusion were included. 35 symptomatic patients were followed up to the late phase (23 following carotid intervention). Prevalence of 'high on-treatment platelet reactivity' (HTPR) on the C-EPI cartridge did not differ between asymptomatic and symptomatic patients overall, but was lower in 'symptomatic post-intervention' than asymptomatic patients on aspirin monotherapy (10% vs. 50%; p=0.03). The prevalence of HTPR on the C-EPI cartridge decreased between the early and late phases in symptomatic patients (63% vs. 34%; p=0.017), including those on aspirin monotherapy (p=0.016). There were no significant differences in HTPR status between asymptomatic vs. early or late symptomatic MES +ve or MES -ve patients. DISCUSSION: Carotid interventional treatment, presumably in combination with resolution of the acute phase response, may decrease the prevalence of HTPR in patients with recently symptomatic carotid stenosis over time. Preliminary subgroup analysis suggests that successful intervention may reduce the prevalence of aspirin-HTPR in symptomatic patients to lower levels than asymptomatic medically-treated patients on aspirin monotherapy. Larger, longitudinal studies are warranted to reassess the impact of more intensive secondary preventive treatment on ex vivo platelet function at different levels of shear stress in carotid stenosis patients.

Duplex ultrasound in aneurysm surveillance following endovascular aneurysm repair: a comparison with computed tomography aortography.

OBJECTIVES: Cumulative radiation dose, cost, and increased demand for computed tomography aortography (CTA) suggest that duplex ultrasonography (DU) may be an alternative to CTA-based surveillance. We compared CTA with DU during endovascular aneurysm repair (EVAR) follow-up. METHODS: Patients undergoing EVAR had clinical and radiological follow-up data entered in a prospectively maintained database. For the purpose of this study, the gold standard test for endoleak detection was CTA, and an endoleak detected on DU alone was assumed to be a false positive result. DU interpretation was performed independently of CTA and vice versa. RESULTS: One hundred thirty-two patients underwent EVAR, of whom 117 attended for follow-up ranging from six months to nine years (mean, 32 months). Adequate aneurysm sac visualisation on DU was not possible in 1.7% of patients, predominantly due to obesity. Twenty-eight endoleaks were detected in 28 patients during follow-up. Of these, 24 were initially identified on DU (four false negative DU examinations), and eight had at least one negative CTA with a positive DU prior to diagnosis. Twenty-three endoleaks were type II in nature and three of these patients had increased sac size. There was one type I and four type III endoleaks. Two of these (both type III) had an increased sac size. Of 12 patients with increased aneurysm size of 5 mm or more at follow-up, five had an endoleak visible on DU, yet negative CTA and a further five had endoleak visualisation on both DU and CTA. Of six endoleaks which underwent re-intervention, all were initially picked up on DU. One of these endoleaks was never demonstrated on CTA and a further two had at least one negative CTA prior to endoleak confirmation. Positive predictive value for DU was 45% and negative predictive value 94%. Specificity of DU for endoleak detection was 67% when compared with CTA, because of the large number of false positive DU results. Sensitivity for DU was 86%, with all clinically significant endoleaks demonstrated on CTA also detected on DU. CONCLUSION: Despite its low positive predictive value, we found DU to be a sensitive test for the detection of clinically significant endoleaks. Given concerns about cumulative radiation exposure and cost, and the surprisingly low sensitivity of CTA for endoleak detection in this series, selective CTA based on DU surveillance may be a more appropriate long-term strategy.

Two-year outcome with preferential use of infrainguinal angioplasty for critical ischemia.

OBJECTIVE: Infrainguinal angioplasty provides a minimally invasive alternative to bypass surgery in patients with critical ischemia. This study aimed to determine the 2-year patency, limb salvage, and survival rates in patients who underwent infrainguinal angioplasty in a unit where angioplasty is used preferentially whenever possible for critical ischemia. METHODS: A total of 333 consecutive patients who presented with rest pain, tissue loss, or both and who underwent an infrainguinal intervention in the 4-year period between January 1998 and January 2002 were divided into femoropopliteal and femorodistal groups. The TransAtlantic Inter-Society Consensus angiogram scoring system was used to classify the lesions. Angioplasty was the preferred procedure in all patients for whom a stump or portion of a superficial femoral artery was patent. Exclusion criteria included the concomitant or sequential treatment of iliac lesions. Patients were followed up after surgery with ankle-brachial indices and duplex ultrasonography. RESULTS: A total of 180 patients underwent 198 angioplasties. Primary cumulative patency, limb salvage, and survival for femoropopliteal angioplasty (n = 166) at 2 years were 75%, 90%, and 88%, respectively, and 60%, 76%, and 82% for infrapopliteal angioplasty (n = 32). At 30 days, mortality was 2.7%, and the complication rate was 8.3%. There was a restenosis rate (>50%) of 68% and 65% at 2 years for the femoropopliteal and infrapopliteal angioplasty groups, respectively. Seven patients required repeat angioplasty of the same site, 30 underwent subsequent bypass, and 16 of 43 occluded limbs were amputated. A total of 153 comparative control patients underwent 162 bypass procedures during the same period. Primary cumulative patency, limb salvage, and survival for femoropopliteal bypass (n = 80) at 2 years were 69%, 87%, and 76%, respectively, and were 53%, 57%, and 64% for infrapopliteal bypass (n = 82). The 30-day mortality for bypass was 5.2%, the complication rate was 35%, and 31 limbs were amputated. CONCLUSIONS: The results of this study on the intermediate-term outcome of angioplasty suggest that angioplasty, when used preferentially for critical ischemia, in anatomically suitable patients provides very acceptable limb salvage and survival despite a relatively high restenosis rate.

Stroke after varicose vein foam injection sclerotherapy.

This report describes an ischemic stroke after foam injection sclerotherapy of varicose veins in a patient with a patent foramen ovale. Foam injection sclerotherapy has created resurgence in the minimally invasive treatment of varicose veins. The United States Food and Drug Administration halted a clinical phase 2 trial of a commercial preparation of polidocanol microfoam in 2003 because of concerns relating to possible gas embolism. These trials were recommenced in July 2005. Neurologic complications such as transient visual disturbances and transient confusional states have previously been reported. This case, with its strong circumstantial evidence, illustrates the previously unconfirmed potential for embolic complications using this technique.