This year, 1,118 delegates from over 40 countries attended the Leipzig Interventional Course (LINC), held in Leipzig from 24-27 January 2007. For the first time, the format of structured debates on important and controversial clinical topics was introduced, to stimulate a consensus-oriented discussion.
The objective of LINC is to illustrate new technological developments and indications and contribute to a systematic scientific evaluation and interdisciplinary discussion of new methods allowing conclusions for daily interventional practice.
Since the beginning, LINC was designed to provide a global platform, permitting the interdisciplinary discussion of the 'vascular patients' by integrating colleagues of different specialities who are performing endovascular interventions.
This article highlights some of the presentations featured at the meeting.
Things to avoid during carotid stenting
Dr Horst Sievert, CardioVascular Center, Frankfurt, Germany, presented the talk entitled, 'Predictors of complications during carotid stenting - things to avoid'. He explained that patient selection plays a key role in carotid stenting. For example patients with difficult vascular access or elongated aortic arch ('type III'), 'kinking' of the common or internal carotid artery, long or heavily calcified or ulcerated lesions are not good candidates, especially if someone is starting a carotid stenting program. Bilateral carotid stenting during the same session is rarely indicated and should be avoided
Sievert then discussed medication and said that sufficient pre-treatment is mandatory and recommended that Aspirin plus Plavix should be given at least five days before, as this prevents fresh thrombus on the plaque. Between 5000-7500 units of Heparin should be given along with plenty of fluids.
He then explained the malpositioning of protection devices, such as excentric filters and parachute filters, and explained that the malposition of occlusion devices is easier to recognise because contrast dye disappears as soon as the occlusion balloon is not occlusive anymore. He also stated that malposition of occlusion devices immediately results in zero protection.
When advancing the stent, atropine should be administered at this point as it needs some time to prevent bradycardia, said Sievert. He advised not to move the filter because it may cause spasm. It is important, always to de-air the sheath before the contrast is injected. He then said not to aspirate, but to let it bleed.
Sievert delivered some 'not necessary' points, which included the following:
• ...to postdilate the distal common
• ...to dilate the stent to obliterate gaps between the stent struts and the vessel wall
• ...to over-expand the stent to produce zero residual stenosis
• ...to dilate the external carotid artery
He then explained that if the stent delivery system can not be retrieved then it is important to do the following:
• Re-sheath
• Advance the guide into the stent
• Turn the head, extend/flex the neck
• External manual compression of the neck
• Buddy wire - requires a large sheath, low profile stent delivery system or a second vascular access
• Expand the stent with a balloon (second vascular access required)
In regards to post-dilation, Sievert said the balloon should be 20-30mm long, with a diameter not more than the diameter of internal carotid artery (ICA). Furthermore, nominal pressure and long inflation (if possible) is required.
To avoid and treat bradycardia
and hypotension, atropine is always recommended, also in patients after endarterectomy. Sievert suggested that 0.5-1mg of atropine is ideal, and he stressed that it is important to start 3-5 mins before balloon inflation. Dopamine is rarely needed but occasionally has to be used up to 48 hours. He also said it was important to discontinue drugs inducing bradycardia, eg. Beta-Blocker and Ca antagonists.
To retrieve embolic protection devices, Sievert said to keep away from the stent struts, it may occasionally be necessary and helpful to re-advance and rotate the device, and use a buddy wire. He then carried on to explain the risk factors and symptoms of Hyperperfusion Syndrome. The risk factors include high grade stenosis, contralateral occlusion or high grade stenosis, and hypertension. Sievert explained the symptoms to be headache and intracranial bleeding. In terms of prevention of this disease, he said to keep the blood pressure as low as possible.
In conclusion, Sievert stated that the complication rate of carotid stenting can be kept considerably low following these rules and using meticulous technique.
Thrombolysis versus surgical thrombectomy
Dr Gunnar Tepe, University of Tuebingen, Germany, presented the talk 'Thrombolysis versus surgical thrombectomy - a critical review' at the meeting. He explained that acute peripheral arterial occlusion (aPAO) affects up to 200,000 people worldwide each year. There are certain problems associated with surgery for acute limb ischaemia, such as major morbidity and mortality in a high proportion of patients. Tepe recited the results of amputation and mortality rates from five studies. He stated that Blaisdell et al. reported a 25% amputation rate and 30% mortality rate in a study conducted in 1978. However, in 1998 the results from the Thrombolysis or Peripheral Arterial Surgery (TOPAS) trial, which established catheter-based thrombolysis as an alternative to surgery for peripheral occlusions, showed a 2% amputation rate and 5% mortality rate.
In the Rochester Trial, 1994, the purpose of the trial was to compare urokinase therapy to immediate operation in patients with peripheral arterial occlusion. It was hypothesised that if thrombolytic agents were effective, the subgroup with the highest chance of success would be those with the most severe ischaemia. In this series of patients, operative therapy had a poor track record with a high rate of amputation and death. Therefore, the trial included only patients with the most severe ischaemia, in whom amputation would be inevitable if intervention were not undertaken. The primary endpoint was amputation-free survival.
Over a three years, 114 patients with upper and lower extremity thrombotic or embolic peripheral arterial occlusion were randomly selected for intra-arterial urokinase or immediate surgery.
Although no difference in the rate of major amputation was detected (approximately 18% at 12 months in each group), mortality was significantly lower in the thrombolytic group (16% vs. 42% at 12 months).
According Tepe, the higher mortality rate in the operative group could be due to cardiopulmonary complications, which were higher in the operative arm or because there were less re-interventions in the thrombolysis group.
Tepe then discussed the results from the 'surgery versus Thrombolysis for Ischemia of the Lower Extremity' (STILE) trial, which was the second prospective study to compare thrombolysis and surgery. In the multi-centre investigation, administration of two different thrombolytic agents -recombinant tissue plasminogen activator (rtPA) and urokinase - were compared with immediate operation in patients with lower extremity ischaemic symptoms lasting less than six months. The primary endpoint was a composite outcome index that included ongoing or recurrent ischaemia; death or major amputation; life-threatening haemorrhage; any perioperative complication (eg. cardiopulmonary, anaesthetic-related); renal failure; vascular complications requiring surgical repair (eg. dissection, occlusion, false aneurysm); or post-interventional wound complications, such as haematoma formation. Amputation and mortality were not, in themselves, primary endpoints. The goal was to enrol 1000 patients into the trial and conduct two interim analyses.
Patients were randomly selected to receive thrombolytic therapy with rtPA or urokinase or immediate operation. Tepe recited that at less than 14 days, there was a 6% amputation rate for the thrombolysis patients vs. 18% for the surgery patients, and after 14 days, there was a 5% amputation rate for the thrombolysis patients vs. 2% for the surgery patients.
Following this, Tepe again discussed the TOPAS study, the third multi-centre trial to evaluate thrombolytic therapy. Recombinant urokinase (r-UK) (4000 IU per minute for four hours followed by 2000 IU per minute) was compared to primary operation in 544 patients with lower extremity native artery or bypass graft occlusions of 14 days' duration or less. The amputation-free survival rates six months after randomisation were not significantly different. Tepe explained that, "r-Urokinase was associated with similar mortality and major amputation rate as surgery, but 46% of patients left the hospital alive, with their limb, and with nothing more than a percutaneous intervention."
Tepe then asked if there was a better drug and again referred to the STILLE trial, concluding that there was no difference according to success and side effects between urokinase (UK, n=112) or rt-PA (recombinant tissue plasminogen activator, n=137), however rtPA was quicker.
He further explained that Ouriel et al. (2000) reported on bleeding in 483 UK patients vs. 144 rt-PA patients (Table 1). In UK patients who were treated with a sheath, it was found that bleeding occurred in 21.9% of these patients. The result was greater in rt-PA patients, with 43.8% of patients experiencing bleeding.
In terms of transfusion, bleeding occurred in 12.4% of UK patients and 22.2% of rt-PA patients.
Tepe discussed the qualities of alfimeprase and described the practical features as:
• A direct fibrinolytic
• Not plasminogen dependent
• Not inactivated by PAI-1
Safety features include:
• Lytic activity confined to the site of drug delivery
• No systemic 'lytic state' at clinically relevant doses
Asking whether there is an adjunctive drug, Tepe discussed GP IIb/IIIa inhibitors - eg. ReoPro (abciximab). He stated that they may improve the rate of lytic dissolution and referred to the PROMPT (Platelet receptor antibodies in order to manage peripheral artery thrombosis) trial. The trial prospectively evaluated the combination of abciximab and UK. Patients were randomised in a 2:5 ratio to receive UK and placebo (n=20) or UK and abciximab (n=50) in addition to aspirin and low-dose UFH.
The researchers reported that the amputation-free survival at three months was 96% in the combination group and 80% in the placebo group (P=0.04). At 90 days, the rates of survival without surgery or major amputation were 90% and 75%, respectively (P=0.053). There was no significant difference in the patency rates of the occluded vessels (66% vs. 70%, respectively). Tepe said that more rapid thrombolysis when abciximab was added to UK.
He then addressed the RELAX trial and said that evidence supporting the safety of abciximab and reteplase in patients with acute ischaemia. He summarised the RELAX substudy on fibrinogen and explained that, "Fibrinogen levels decreased over the period of study drug infusion although there was no significant difference between dose panels. Eight percent in the entire study had at least one measured fibrinogen level less than 100mg/dl. There was no clear dose dependence."
Finally, Tepe discussed the limitations of current treatments and explained the treatment options for acute thrombotic conditions (eg. acute PAO), which he split into three categories (Table 2).
There were many other sessions addressing important and controversial issues at the LINC meeting, along with plenty of live-case demonstrations. Dr D Raithel, Nurnemberg, Germany, presented a discussion on surgery and how it is still the gold standard for the majority of the case. He explained that: "The benefit of carotid endarterectomy (CEA) is based on low morbidity and mortality and very low restenosis rates. Thus, it can quite compete with carotid angioplasty (CAS).
Dr Jorn O Balzer, Frankfurt, Germany, presented 'Cryoplasty in PAOD - indications, techniques and results, and concluded that cryoplasty is a safe technique with no prolonged on-table treatment time and that initial results demonstrates good long-term patency rates in infrainguinal lesions. He also stated that in comparison to conventional angioplasty the need for stent implantation can be reduced.
Next year's LINC meeting will take place from January 23-26 at the Westin Hotel, Leipzig.
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