Wanted: More interventionalists

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As the number of patients eligible for endovascular treatment of acute ischaemic stroke increases, centres across Europe must consider whether there are enough interventionalists to fight the burden of stroke. According to Urs Fischer (University of Bern, Bern, Switzerland), while some countries, like Germany, might have an adequate number of interventionalists capable of providing thrombectomy procedures, the rest of Europe does not.

Speaking at the European Society for Minimally Invasive Neurological Therapy annual meeting (ESMINT; 8–10 September, Nice, France) Fischer compared the eligibility of patients for endovascular therapy based on the strict criteria adhered to in trials versus the more liberal criteria of clinical practice. One study from Switzerland (Stroke. 2016;47:1844–1849, originally published 14 June, 2016) he described showed that 12% of all stroke patients coming into hospital are eligible for IV tPA and 45% of patients are arriving in the time window of six hours. Regarding endovascular therapy Fischer said: “If you apply strict criteria for endovascular therapy, 10% of patients presenting within six hours are eligible for endovascular therapy and if you take the soft criteria you are reaching numbers of 18%. However, if you look only at the local population, which means people living in the suburb of Lausanne and Lausanne itself, then the numbers are slightly different—you have 40% within the six-hour time window eligible for IV t-PA and 8% for endovascular therapy with the strict criteria and 16% with the soft criteria. They have also been looking at this in Glasgow (European Stroke Journal. December 2016 vol. 1 no. 4 264–271), and their estimate is that roughly 15% of patients presenting within the first six hours might be eligible.”

Addressing the increasing demand for thrombectomy across Europe, Fischer presented a study from Sweden (J NeuroIntervent Surg. doi:10.1136/neurintsurg 2016–012575) that seeks to estimate how many more patients could have been treated in a certain period. The study indicates that five times more patients could have been treated than have been treated now. “So the estimation according to current data is that 10% for sure, but in the future even more, roughly 20% of stroke patients are candidates for endovascular stroke therapy,” he said.

If there are 1.3 million acute stroke patients in Europe, that makes 130,000 to 230,000 patients per year who might be candidates for endovascular therapy, which brings up the question of how many centres are needed now to treat all these patients. Normally, Fischer pointed out, a stroke unit with 1,000 patients has a thrombolysis rate of 25%, and the normal catchment area of these centres is roughly one million.

“We believe that a stroke centre should perform at least 100 thrombectomies per year, and ideally it should be even more. How many stroke centres are necessary? My assumption is that we have 1.3 million stroke patients annually, and if you have 10% of eligible cases, and every centre is doing 100 cases per year, then we need 1,300 centres. If the centres are doing 300 cases, they go dramatically down to 433,” he said.

Using the example of his home country of Switzerland, where stroke centre requirements are put in place to ensure that centres are certified—which means that each certified centre must have a stroke neurologist, a stroke unit, 24/7 IV t-PA and endovascular therapy, MRI and CT and neurosurgeons—Fischer explained that there was a top down initiative for highly specialised medicine.

“Stroke intervention is a highly specialised medicine and the government decided that we have five university stroke centres and four non-university stroke centres with these criteria. In our region of Bern, we have stroke units in the area and if they detect a patient with large vessel occlusion, they are sending the patient to our centre and we are treating them endovascularly. The model of the future is that you need planning in your region to get things done. Thrombolysis and thrombectomies increased in our institution dramatically over the last few years, and last year we had 356 cases; 128 intravenous thrombolysis and 228 endovascular interventions. This also reflects that we are a tertiary care centre and have quite a lot of referrals. In our centre 10% of patients were candidates for IV t-PA and 18% for endovascular therapy in 2015,” he reported.

Urs Fischer

In line with that, Fischer announced that the European Stroke Organisation is now offering stroke unit and stroke centre certification.

But how many stroke interventionalists are needed to operate these centres? Fischer maintained that based on the above data, he has calculated how many stroke interventionalists are likely to be needed. “I think you need to run a 24/7 service, and for that you need probably four interventionalists, five would be ideal, three is the lower margin, and based on this assumption, if you have a centre with 100 interventions per year, you already need 6,500 interventionalists throughout Europe, if the numbers of patients who are eligible increase, we will even need 13,000. The more centres you have, the more you are going to dilute the expertise of these people, and if you have 100 cases and three interventionalists in a centre then you only have 30 cases per year. As we also know a little bit from cardiology, experience matters and therefore we really have to think about whether we should not have high volume centres with a lot of cases rather than many small centres. It depends also on the density of your population. It is probably better to have fewer centres with very well trained interventionalists,” he argued.

Are there enough interventionalists in Europe to meet these high numbers? According to a recent article, Germany is the only country in Europe that has enough interventionalists, but the rest of Europe says it is a clear no, Fischer said, maintaining that more people need to be trained.

To become a neurointerventionalist is still a major challenge for young physicians, Fischer added. In most countries physicians have first to be trained as general radiologists for 4–6 years before then being trained in general neuroradiology for another two years. Only thereafter can training in neurointervention be started. In Switzerland, for instance, training to become a neurointerventionalist takes 8–10 years. Therefore, new curricula have to be set up to train neurointerventionalists more efficiently.

As for who should be trained to perform stroke interventions, Fischer’s belief is in line with that of many other leading neurointerventionalists—the background does not matter as long as they have the required commitment and training. “The potential players are neuroradiologists, radiologists fully trained in neurointervention, neurosurgeons, and vascular neurologists. Stroke is a neurological disorder and stroke patients have to be treated in the environment of a neurocentre. The background (ie. the basic training) of the interventionalists is not that important. What is important is a passion for neurointerventions and stroke. The adequate training has to include the interpretation of neuroimaging, the dedicated training on the full spectrum of neurointerventions but also clinical skills. Endovascular stroke intervention is not a hobby or a part-time job, it is a full-time commitment. Interventionalists should have profound knowledge of the brain and its function. In order to get enough interventionalists in the future with a deep knowledge in neuroscience we need a common trunk of clinical neuroscience and from this trunk you then become a neurosurgeon, a neuroradiologist, a neurointerventionalist, a psychiatrist or a neurologist,” he explained.

Recently, an international multi-society consensus document on training guidelines for endovascular stroke intervention has been published (Neuroradiology DOI 10.1007/s00234-016-1667-0), and previously featured in Issue 21 of NeuroNews. However, it has become apparent that many countries have still not adopted these recommendations. Therefore, it has been suggested that healthcare authorities in all European countries should be contacted to adapt their curricula. “If we do not change the formation of neurointerventionalists in order to get a thorough but fast training we will not have enough interventionalists in many areas of the world to fight the burden of stroke,” said Fischer.