The key is to triage early and effectively.
Time is brain and delaying the initiation of treatment can lead to an 80% increase in the risk of further strokes.
Thrombolytic treatment and thrombectomy had transformed the outlook for patients who had a stroke, but time was critical, says Professor Bruce Campbell, neurologist and Head of Stroke care at the Royal Melbourne Hospital.
“The probability of an excellent outcome and getting back to usual activities is a lot higher if treated earlier rather than later,” he says. In keeping with the goal of timely treatment, mobile stroke units, offering thrombolysis in the pre-hospital setting, have been shown to improve outcomes for people with acute stroke. However only one such unit currently exists in Australia, in Melbourne but another is planned for Sydney in the near future.
Another major advance to improving stroke morbidity has been CT perfusion imaging, available in many emergency departments. This imaging is helping to identify patients who might still benefit from intervention despite exceeding the usual window of opportunity which is four and a half hours from onset of symptoms for thrombolytic therapy and six hours for thrombectomy.
CT perfusion imaging can detect the presence of ‘ischaemic penumbra’ – this is where the blood supply to the brain tissue has been compromised to the point where the cells cannot function, hence the stroke symptoms but there still exists sufficient blood supply to keep the cells alive. This is of course, temporary.
The cells within the penumbra will die if not reperfused but the presence of an ischaemic penumbra represents an opportunity to salvage brain tissue. The CT perfusion scan can identify where an ischaemic penumbra exists, helping to inform the decision whether intervention is worthwhile, even if it is outside the usual post-stroke time limits.
Professor Campbell reiterated the importance of dialling ‘000’ and getting the patient to an appropriate thrombolytic capable centre or, in the case of a rural location, to a centre with telemedicine. Reception staff in general practices needed to be trained in FAST triage to ensure stroke patients are immediately sent to hospital.
In the event of a TIA, initiation of thrombolytics as early as possible post event is the most effective means to reduce the risk of recurrence, Professor Campbell said.
“The risk of a recurrent event is very front loaded, in the first week particularly” he noted.
Loading doses of 300mg of both aspirin and clopidogrel, followed by ongoing therapy with both aspirin 100mg and clopidogrel 75mg daily for the next three weeks is effective. However, after three weeks, there is no added benefit of persisting with dual therapy over using a single agent on its own.
In the case of atrial fibrillation, anticoagulants should be used but correct dosing is critical. Professional Campbell reflected that, “one of the major causes of stroke that I see is un-anticoagulated AF or under anticoagulated AF”.
Lipid lowering therapy needs to be initiated and titrated to achieve an LDL level of 1.8 or less, in most cases. The target for blood pressure, perhaps the most significant risk factor for stroke, “should be consistently below 140/90, perhaps lower, particularly after intracerebral haemorrhage”, Professor Campbell concluded. Lifestyle advice is of course extremely important post TIA/stroke.
Prof Campbell will be delivering this highly rated lecture at the next Healthed Webcast on 8 November. Register here to attend for free.
Dr Stuart Cooper is a GP based in Queensland and is also the clinical editor for Health Pathways.
