Revolution needed to optimise prevention of stroke and
other arterial disease complications
A Monash University review has analysed decades of global evidence in relation to common treatments for advanced (at least 50 per cent) carotid artery stenosis.
This is arterial disease causing narrowing of the origin of the internal carotid artery (the main brain artery). Carotid stenosis increases in prevalence from mid-age and affects about 10 per cent of people by their 8th decade. It is a risk factor for stroke and other arterial disease complications.
The analysis has found that, overall, non-invasive measures (lifestyle interventions and appropriate medications) are better than carotid artery procedures at reducing the risk of stroke associated with carotid stenosis. The analysis concludes that there is currently a very limited role for carotid artery procedures (such as carotid artery surgery/endarterectomy and stenting) and no current proven benefit for any carotid artery procedure. Further, carotid artery procedures are not a substitute for non-invasive measures to lower stroke risk.
The comprehensive review, published in the open science journal Frontiers in Neurology, has brought together more than four decades of research with respect to best managing carotid stenosis.
The review’s author, Associate Professor Anne Abbott from the Central Clinical School at Monash University, says this analysis has been 24 years in her making and it seeks to dispel misinformation – which she describes as “common furphies” – “encouraging inappropriate healthcare that causes large scale patient harm, premature death and economic waste in Australia and beyond.”
“Knowing how to best manage carotid arterial disease is imperative because it is common in older people and the impact of non-invasive measures to reduce the risk of stroke and other arterial disease complications is very powerful,” says Associate Professor Abbott.
“People need to understand that they have the most power to prevent their own stroke. Just about all the power lies in them adopting healthy life habits and appropriate medication which reduce, or remove, risk factors such as high blood pressure, high blood cholesterol, cigarette smoking and physical inactivity. The combined impact of addressing risk factors is great and is the most powerful weapon we have in reducing the risk of stroke and other arterial disease complications.”
Associate Professor Abbott added that, “This ‘big picture’ review is a ground-breaking publication because of its global relevance, unique objectivity, scientific rigour and concise comprehensiveness in a field overgrown with misinformation that favours over-use of carotid artery procedures, while non-invasive interventions continue to be under-appreciated.”
Currently there are four types of intervention done in the name of reducing stroke risk associated with carotid stenosis; carotid surgery (endarterectomy), carotid stenting; a new hybrid procedure known as trans-carotid arterial revascularisation (TCAR); and medical (non-invasive) intervention (lifestyle coaching and medication).
Associate Professor Abbott says it is now well-recognised that the stroke prevention benefit of medical/non-invasive intervention alone has improved significantly over the last 30-40 years in people with advanced carotid stenosis whether or not they are symptom-free (without past same-sided stroke or transient ischaemic attack [TIA]) or symptomatic (with past same-sided stroke or TIA).
“Stroke prevention has become much more effective, less invasive and cheaper over the last three-to-four decades and since past randomised trials of carotid surgery versus medical intervention alone. In fact, the stroke risk in symptom-free people with advanced carotid stenosis has fallen by at least 65 per cent to 1 per cent per year or less using non-invasive measures alone,” she says. “This is lower than with carotid artery procedures in past trials.”
Associate Professor Abbott says this indicates that carotid artery procedures no longer provide proven benefit in individuals with symptom-free carotid stenosis. Further, stroke rates are now so low with current standards of non-invasive intervention alone that carotid artery procedures are unlikely to provide benefit for these people even if new trials are done. However, carotid artery procedures are still commonly done in Australia and overseas and they continue to cause significant complications including stroke, death and heart attack, and they are costly.
Meanwhile, only highly selected symptomatic people with stroke or TIA and same-sided carotid stenosis have ever been shown to benefit in trials from carotid artery surgery (endarterectomy). But that evidence was collected 30-40 years ago and is long outdated.
Associate Professor Abbott says carotid artery stenting has been shown in randomised trials to be more harmful than carotid surgery. Meanwhile, there is a push to roll out the hybrid TCAR procedure into routine practice despite no trials against current best non-invasive measures alone.
“This Frontiers analysis is of critical benchmarking importance to professionals and the public if we are going to put aside misguided opinions and use the current evidence objectively to move ahead in a scientifically justified way and so optimise patient outcomes,” says Associate Professor Anne Abbott.
“Among the highest research priorities now is to properly document the nature of current best practice medical (non-invasive) intervention for reducing the risk of stroke and other arterial disease complications and measure its impact,” she says. “Studies should include risk stratification with the goal of identifying symptom-free and symptomatic people likely to benefit from more aggressive or specialised medical and/or procedural interventions.”