Stroke - Prevention

Stroke prevention involves many different aspects. These measures are particularly important for people who have had a transient ischaemic attack Any neurological problem caused by an interruption in the blood supply to the brain that resolves within 24 hours. Abbreviated to TIA.(TIATransient ischaemic attack; any neurological problem caused by an interruption in the blood supply to the brain that resolves within 24 hours.), who are at higher risk of a stroke in the future,[1] and for those who have experienced a stroke in the past (secondary prevention).

Primary prevention

The primary prevention of stroke is defined as preventative measures that can be taken by people who have never had a stroke. There are many different aspects to primary prevention, which may be summarised as:

Lifestyle changes

Lifestyle changes that can be made in order to lower your blood pressure The pressure of blood within the arteries.(one of the most important aspects of stroke prevention) include:

  • Modifying your diet
  • Eating more fruit and vegetables
  • Lowering your salt and saturated fatOne of the three main food constituents (with carbohydrate and protein), and the main form in which energy is stored in the body. intake
  • Losing weight
  • Taking aerobic exercise
  • Stopping smoking
  • Moderating your alcohol intake.[2,3]

As well as improving bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. pressure, weight loss and dietary changes are also associated with a fall in lipidOne of a group of compounds that are an important energy source. levels and can reduce the risk of diabetes mellitusDisordered energy metabolism and high levels of glucose in the blood owing to a lack of insulin, or poor response of the body to insulin., or delay its onset. Diabetes increases the risk of stroke.[3] Such lifestyle changes can also improve bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. control in those who have already been diagnosed with diabetes.

Finally, quitting smoking is highly effective in reducing the risk of stroke. Help is available in the form of counselling and medicines, such as nicotineAn addictive substance found in tobacco and nicotine replacement therapies.-replacement therapy and the drugs bupropion and varenicline.[3]

Medication

People with higher bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. pressures may need to take bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. pressure-lowering medication if lifestyle measures alone are not sufficient to lower their pressure. In terms of stroke prevention, the best medication for this is not yet known, nor is the ideal level of blood pressure reduction.[3]

Certain medications can also help to delay the onset of diabetes mellitusDisordered energy metabolism and high levels of glucose in the blood owing to a lack of insulin, or poor response of the body to insulin., or help to prevent it altogether - which, in turn, can influence stroke risk.[3] Learn more about diabetes prevention. For those who have already been diagnosed with diabetes, tight control of bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. glucoseA simple sugar that is an important source of energy in the body. levels is important.

Anti-clotting drugs (anticoagulants, usually warfarin) are recommended for many people with atrial fibrillationA common abnormal heart rhythm causing a rapid, irregular pulse and failure of the upper chambers of the heart (atria) to pump properly. Abbreviated to AF., an abnormal heart rhythm, and those who have had a heart attackThe death of a section of heart muscle caused by an interruption in its blood supply. Also called a myocardial infarction..

However, it is important to assess the ratio of risk to benefit as taking anticoagulants does carry with it the risk of a serious haemorrhageThe internal or external loss of blood from a blood vessel.. In fact, it can increase the risk of haemorrhagic stroke, even while reducing the risk of ischaemic stroke.[3]

Sometimes, aspirin is taken rather than warfarin.[3] However, the benefits of aspirin in the primary prevention of stroke are debatable; this is because the reduction in clot formation may be offset by an increased risk of bleeding.[4]

Statins are a group of drugs used to lower lipidOne of a group of compounds that are an important energy source. levels, and taking them has been demonstrated to lower stroke risk. They may lower stroke risk by other means as well, rather than simply by lipidOne of a group of compounds that are an important energy source. lowering; for example, by stabilising atherosclerotic plaques.[3] Learn more about atherosclerotic plaques.

Surgery

Carotid endarterectomyThe removal of atherosclerotic plaque from the inner wall of an artery. involves the removal of any atherosclerotic plaqueFatty plaques that form in the inner walls of arteries in atherosclerosis. from either of the main arteries in the neck, the carotid arteriesThe two main arteries in the neck..[5]

Reports have suggested that the risk of stroke or death immediately following this procedure is actually greater than for those who have received non-surgical therapy.  However, over the 3 years following the procedure, the risk of stroke or death is reduced - although this reduction is quite small.[6]

Further research is needed to identify those people with atherosclerosisDisease leading to fatty deposits in the inner walls of the arteries, which reduce and may eventually obstruct blood flow. of the carotid arteriesThe two main arteries in the neck. who have the lowest risk of surgical complications following this procedure, and as such would benefit most.[ 7]

Secondary prevention

Secondary prevention measures, that is, measures taken by someone to avoid having a second stroke, have developed fairly recently, progressing since the introduction of aspirin for this purpose in the late 1970s.[5] Secondary prevention measures are summarised as follows.

Lifestyle changes

Lifestyle changes include weight loss, exercise and dietary improvements such as lowering salt and saturated fatOne of the three main food constituents (with carbohydrate and protein), and the main form in which energy is stored in the body. intake. Such improvements can lead to blood pressure reduction and better control of conditions such as diabetes mellitusDisordered energy metabolism and high levels of glucose in the blood owing to a lack of insulin, or poor response of the body to insulin..[2,3] Stopping smoking is again very important.[8]

Medication

Medicines that reduce the risk of a repeat ischaemic stroke include the antiplatelet drugs aspirin, dipyridamole and clopidogrel. Such medications reduce the grouping together (aggregation) of platelets, so that the bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. does not clot as easily. Sometimes, more than one antiplatelet drug may be given.[5]

The anti-clotting medicine warfarin is usually given to people who have an abnormal heart rhythm called atrial fibrillationA common abnormal heart rhythm causing a rapid, irregular pulse and failure of the upper chambers of the heart (atria) to pump properly. Abbreviated to AF., to protect against ischaemic stroke. As discussed above, however, the risk of haemorrhagic stroke is increased; this risk is greater with increasing age and bloodA fluid that transports oxygen and other substances through the body, made up of blood cells suspended in a liquid. pressure.[5]

Medicines can also help to improve control of diabetes mellitus, lower blood pressure and reduce cholesterol levels.[5]

One group of cholesterolA substance present in many tissues and an important constituent of cell membranes although high concentrations of a certain type of cholesterol in the blood are unhealthy.-lowering medications is the statinsA class of drugs that inhibit cholesterol formation in the liver.. These are effective in secondary prevention even if someone's initial cholesterolA substance present in many tissues and an important constituent of cell membranes although high concentrations of a certain type of cholesterol in the blood are unhealthy. levels are not too high. This suggests that they may have further benefits in addition to their cholesterolA substance present in many tissues and an important constituent of cell membranes although high concentrations of a certain type of cholesterol in the blood are unhealthy.-lowering effects, for example, they may have additional anti-inflammatoryAny drug that suppresses inflammation properties.

Statins appear to be effective in reducing the risk of a further stroke in those who have had an ischaemic stroke; however, it is not clear whether they benefit those who have had a haemorrhagic stroke in the past.[9]

Surgical procedures

As discussed above, carotid endarterectomyRemoval of atherosclerotic plaque from the inner wall of one of the carotid arteries, the two main arteries in the neck. is a procedure that removes atherosclerotic plaqueFatty plaques that form in the inner walls of arteries in atherosclerosis. from the inner walls of one of the two main arteries in the neck, the carotid arteriesThe two main arteries in the neck..

This procedure may be considered in those who have had an ischaemic stroke or a TIATransient ischaemic attack; any neurological problem caused by an interruption in the blood supply to the brain that resolves within 24 hours. and in whom one of the carotid arteriesThe two main arteries in the neck. is largely blocked. It is best if this procedure is carried out soon after a stroke, as the more time that passes, the less beneficial it is.[5]

Secondary prevention of haemorrhagic strokes involves the surgical clipping of the damaged arteries or ruptured aneurysmAn abnormal swelling in the wall of an artery., to prevent a recurrent bleed.[5]

References: 
  1. Wu CM, McLaughlin K, Lorenzetti DL et al. Early risk of stroke after transient ischemic attack: a systematic review and meta-analysis. Arch Intern Med 2007; 167: 2417-22.
  2. Zhang H, Thijs L and Staessen JA. Blood pressure lowering for primary and secondary prevention of stroke. Hypertension 2006; 48; 187-95.
  3. Romero JR, Morris J and Pikula A. Stroke prevention: modifying risk factors. Ther Adv Cardiovasc Dis 2008; 2: 287-303.
  4. Antithrombotic Trialists' (ATT) Collaboration. Aspirin in the primary and secondary prevention of vascular disease: collaborative meta-analysis of individual participant data from randomised trials. The Lancet 2009; 373: 1849-60.
  5. Donnan GA, Fisher M, Macleod M et al. Stroke. Lancet 2008; 371: 1612-23.
  6. Benavente O, Moher D and Pham B. Carotid endarterectomyThe removal of atherosclerotic plaque from the inner wall of an artery. for asymptomatic carotid stenosisNarrowing of a tubular structure or valve.: a meta-analysis. BMJ 1998; 317: 1477-80.
  7. Ezekowitz JA, Straus SE, Majumdar SR et al. Stroke: strategies for primary prevention. Am Fam Physician 2003; 68:2379-86,2389-90.
  8. Kogan AJ. Stroke prevention: much can be done. AJMC 2009; 15: S168-9.
  9. Manktelow BN and Potter JF. Interventions in the management of serum lipids for preventing stroke recurrence. The Cochrane Library 2009; Issue 4.