Arrhythmia

Patience is everything in secondary stroke prevention


Patience, patience and more patience are the keys to initiating anticoagulation after an atrial fibrillation (AF)-related ischaemic stroke.

Neurologist Associate Professor John Worthington, director of stroke services at the Royal Prince Alfred Hospital, Sydney, said anticoagulants were not recommended in the first few days post-stroke because of the risk of haemorrhage or haemorrhagic transformation.

Speaking at CSANZ 2018, he said the new guidelines for secondary stroke prevention in AF recommended that anticoagulation could be delayed for two weeks – but should be made before discharge.

“That’s highly pragmatic,” he said. “Decisions should be made before discharge to rehab or follow-up in a regional centre, etcetera as patients can get lost and we might see them in eight weeks time, never anticoagulated.”

However, early commencement of anticoagulants may be considered after transient ischemic attack (TIA) or in mild stroke where the risk of haemorrhage is determined to be low.

But there were some nuances, he said.

“You must keep in mind that if your patient is diagnosed with a TIA in an emergency department, if they undergo expert review, 30% actually have a stroke and 38% have scanning changes on MRI.”

“Risk versus benefit is really uncertain for most patients with AF, with a quite substantial risk of harm and a paucity of evidence to confirm a benefit.”

Professor Worthington said in long-term follow-up, about 7% of ischaemic stroke patients would go on to have an intracranial haemorrhage.

“And haemorrhagic transformation in acute stroke is just part of the natural history.”

The reported incidence on CT scan ranges from 0.6 to 20% depending on how you look, the cohort, etc.”

Petechial haemorrhage was quite common on CT scan but seen in about 40% of patients on MRI, he added.

“Post-contrast staining bedevils all of us in the stroke trade. It mimics haemorrhage. But you can help inform your decisions by doing a dual energy CT scan – to decide whether it is haemorrhage or contrast.”

According to Professor Worthington, defining a mild stroke was not entirely straightforward despite common measures of stroke severity such as the National Institutes of Health Stroke Scale (NIHSS).

“A mild stroke is less than or equal to eight. But if you have the right symptoms and signs in that score, you’ve got a stroke that could stop you working again and may require that you need assistance from other people for the rest of your life. So mild is a relative term.”

He said patient factors for transformation included frailty, organ injury and stroke severity.

“AF, cardioembolic stroke and large vessel occlusion travel together and have higher transformation as does infarct size and clinical severity, but there are no clear thresholds here.”

“Size, severity and location – they all matter when assessing these patients.”

He said the posterior fossa stroke for example was ‘unforgiving of oedema; unforgiving of haemorrhage’, often catastrophic and requiring great care.

Acute hyperglycaemia also increased the risk of haemorrhagic transformation and was relatively common in patients.

Treatment factors for haemorrhage also had to be considered.

“We know that the patients who get alteplase have a higher risk of symptomatic and sometime fatal haemorrhage. We know that even commencing aspirin increases haemorrhagic transformation in the acute period but has a small net benefit.”

In a meta-analysis of heparin delivered before 48 hours there was no significant reduction in recurrence, death or disability but increased intracranial bleeding.

“Bridging also increases the risk of haemorrhage and often confers no benefit.”

“The trick here is we often give an instruction when bridging someone with an acute stroke to continue heparin therapeutically until we get to a INR of 2. But 1.5 to 2 is fairly anticoagulated and we are probably going to be over anticoagulating with patients particularly at risk for haemorrhagic transformation.”

Professor Worthington also noted that most of the evidence for DOACs was in the setting of primary prevention.

“Overall early stroke recurrence is 1 to 10%. We shouldn’t be too scared of how many strokes these patients might have in the few days we are going to wait.”

He said the consensus was that anticoagulants be commenced urgently in TIA, at 5 to 7 days after a moderate stroke and at 10 to 14 days after severe stroke – but not before a second scan to confirm the size of the stroke.

Associate Professor Worthington said a number of studies such as TIMING and START would provide more evidence in the next couple of years.

“At this stage, patience is probably needed in the first few days after stroke, more patience is needed in all but the smallest of strokes. And unless the risk of recurrence is high, which it often is not, patience is required.”

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