Download Stroke Secondary prevention

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Keeping abreast of developments in an ever-changing health service
CONTINUING PROFESSIONAL DEVELOPMENT is essential for
nurses and midwives practising in an ever-changing healthcare
environment. With this in mind the WIN Continuing Education
section 2006 is focusing on two clinical areas which impact on
all areas of the Irish health service – cardiology and diabetes.
As comorbidity with these two conditions is common, the
two modules inevitably overlap. Diabetes is one of the primary
risk factors for the development of coronary heart disease.
MODULE 12:
Cardiology
The Cardiology Module to date has focused on: Cardiac risk
and type 2 diabetes; Women and stroke; Cardiac rehabilitation;
Blood pressure management; Sudden cardiac death; Lipid
management; and ECG recording and interpreting.
This month we have the second in a two-part article on the
management and prevention of stroke. Last month we
examined assessment of stroke and in-hospital management.
This part focuses on the secondary prevention of stroke.
Stroke types
Ischaemic
– TIA
– Atherthrombotic
– Cardio embolic
– Lacunar
– Cryptogenic
PART 10
Stroke
Secondary prevention
By Elizabeth Dempsey
SURVIVORS of stroke or transient ischaemic attack (TIA) have an
increased risk for another stroke, myocardial infarction, vascular
death and premature morbidity.1 Identification of stroke type,
establishment of mechanism and addressing risk factors are crucial for secondary prevention.
Ischaemic strokes account for 80% of all stroke types; they
occur from a vascular event caused by a blockage from either
thrombus or embolus. Haemorrhagic strokes account for approximately 15% of stroke types (see Table).
Subtypes of ischaemic stroke
Classification of ischaemic stroke is divided into many categories according to presumed mechanism of focal brain injury
and also type and localisation of vascular lesion.1
The benefits of classification are that we can distinguish
between ischaemia and haemorrhage, establish vascular territory
effected, and promote uniformity of diagnosis.Two familiar classification subtypes – TOAST and OCSP – are outlined below.
The Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification2 identifies five subtypes of ischaemic stroke:
• Large artery atherosclerosis (embolus/thrombosis)
• Cardio-embolism (high risk/medium risk)
• Small vessel occlusion (lacunar)
• Stroke of other determined etiology
• Stroke of undetermined etiology.
The Oxfordshire Community Stroke Project (OCSP) classification classifies patients according to clinical syndrome at the time
of stroke onset. Cases are categorised by suspected anatomic location:3
• Total anterior circulation syndrome (TACS)
• Partial anterior circulation syndrome (PACS)
• Lacunar syndrome (LACS)
• Posterior circulation syndrome (POCS).
Haemorrhagic
– Intra cerebral
– Sub arachnoid
Definition of TIA and stroke
Focal cerebral symptoms of vascular origin lasting more than
24 hours are defined as stroke. Symptoms of a duration of less
than 24 hours with complete recovery are categorised as TIA.
TIAs are an important determinant of stroke: 10.5% of people
who have a TIA are at risk of stroke within 90 days following the
TIA, with the greatest risk in the first week.1
Education is key for risk factor control and secondary prevention measures for patients with stroke. Prevention is the most
effective strategy for reducing the health and financial impact of
stroke.4 Primary prevention is particularly important as many
strokes are preceded by TIA. Nurses specific to stroke care have
been identified as being invaluable in reducing modifiable risk
factors and improving stroke knowledge.5
Risk factors
The risk factors for stroke are classified as non-modifiable or
modifiable.
Non-modifiable risk factors
• Age is the strongest risk factor for all stroke types. Stroke prevalence increases after the age of 55 years6
• Gender – greater risk in middle to older age men, most stroke
survivors are women
• Ethnicity – Afro-American, Asian and Hispanic people have
greater incidence of stroke than Caucasians
• Family history of stroke in a relative is a significant risk factor.
Modifiable risk factors
Hypertension: Hypertension is the most important risk factor for
stroke.6 Anti-hypertensive treatment is recommended for prevention of recurrent stroke and vascular events that are beyond the
acute phase.1 Blood pressure medication includes thiazide, diuretics, beta blockers, ACE inhibitors, calcium channel antagonists.
Medication choice depends on the patient’s characteristics, occlusive disease, renal impairment, cardiac disease and diabetes.
Lifestyle modifications should be included with blood pressure
medications. Reduced salt intake and exercise should be encouraged. Guidelines for BP management are < 140/80mmHg. In the
This module is supported by MSD Ireland (Human Health) Ltd.
Cardiology-AM-TH
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Continuing Education
diabetic population < 130/80mmHg is desirable.The use of blood
pressure diaries, both to record pressures and as a means to monitoring at the outpatient setting, is encouraged.
Diabetes: Diabetes is a known risk factor for stroke. Glucose control of near normoglycaemic levels is recommended among
people with diabetes and stroke. Diet, exercise and oral hypoglycaemics or insulin therapy are recommended for adequate
glycaemic control.
Cholesterol: Raised cholesterol levels are considered another
risk factor for stroke. Reduction of low density lipoprotein < 2.5 is
targeted. The SPARCLE study (Stroke Prevention by Aggressive
Reduction in Cholesterol Levels) demonstrates the use of statin
therapy to prevent recurrent stroke is effective.7 Lifestyle modifications with low cholesterol diet, exercise and statin therapy
encourage cholesterol reduction.
Smoking: Cigarettes have demonstrated strong convincing
evidence as an independent risk factor for stroke. Smoking has
being shown to double the risk of stroke compared with nonsmokers.1 Smoking cessation can reduce stroke risk. Effective
treatments are required to manage the dependence of smoking.
Education, support groups and pharmacotherapy treatments are
useful.
Alcohol: Consumption of alcohol should be eliminated or
reduced. Light to moderate levels are tolerated. Most studies suggest a protective effect with light or moderate drinking and an
elevated stroke risk with heavy alcohol consumption.1 Education
and screening are important measures in tackling heavy alcohol
consumption.
Obesity: Obesity is an independent risk factor for coronary heart
disease and premature mortality. It is strongly related to several risk
factors, hypertension, diabetes and dyslipidaemia. Some studies
suggest abdominal obesity is strongly related to stroke risk.8
Weight reduction should be considered for all overweight stroke
patients with a body mass index 18.5-24.9kg/m2 and waist circumference of > 35 inches in women and > 40 inches in men.1
Education of balanced dietary intake and physical activity
should be encouraged. Evidence demonstrates that exercise has a
beneficial effect on cardiovascular and stroke risk factors – 30
minutes a day is encouraged in stroke patients to reduce comorbid conditions.
Atrial fibrillation: Persistent and paroxysmal atrial fibrillation
are predictors of first and recurrent stroke.1 Warfarin reduces the
risk of stroke in about two-thirds of patients with little increase in
major bleeding or intracranial haemorrhage.6 Patients with proven
cardio-embolic stroke should be anticoagulated if the risk of
recurrence is high.9
Oral anticoagulation is of concern in other comorbid conditions, falls, epilepsy, dementia or gastro-intestinal haemorrhages,
also if compliance with medication or excessive alcohol intake are
noted. Anticoagulation treatment is delayed in cases of large
infarcts or uncontrolled hypertension as the risk of haemorrhagic
transformation is high in the first two weeks.6
Previous stroke or TIA: Recurrent strokes are likely to be more disabling and fatal than first strokes.10 Patients with recent TIA or
stroke within six months and stenosis between 70%-99% should
be reviewed by the vascular surgeon for possible carotid surgery.
The morbidity and mortality rate for carotid surgery should be
40
WIN November 2006
less that 6%.1 Risk factors and scheduling of surgery are subject to
local policies.
Antiplatelet agents reduce the risk of recurrent stroke and
other cardiovascular events. Daily aspirin +/- combination of
extended release dipyridomole and aspirin,or clopidogrel are
options for treatment.
Hormone therapy: Premenopausal women have fewer strokes
than men of similar age.11 Recent studies demonstrate that
hormone replacement therapy increases the risk of stroke and
heart disease.Women with TIA or ischaemic stroke are not recommended HRT.12
Preparations of the oral contraceptive pill with high oestrogen
content have been associated with both arterial and venousthromboembolism.11 OCP preparations have being linked with a
mild increase in reversible blood pressure. Smoking, older than 35
years, hypertensive and having had a previous thrombo-embolic
event raise stroke risk dramatically.
Homocysteine: Homocysteine (tHcy) reduction has been
reported to improve markers of atherosclerosis in patients with
stroke and vascular disease.6,13 Stroke risk has being demonstrated
to be increased with raised homocysteine levels. Screening for
tHcy is costly; some centres recommend that younger stroke
patients are tested. Homocysteine levels greater than 10umol/L,
suggest multivitamin preparations of B6, B12 or folate are recommended.1 Dietary intake of fresh fruit and vegetables are
encouraged with vitamin supplementation.
Resources
Resource allocation for stroke prevention should be directed
at detection and management of hypertension, smoking cessation,
diabetes control, and other lifestyle issues such as diet and exercise.4
Increased public awareness and education of healthcare
providers about the preventable nature of stroke, as well as
recognition of warning symptoms of the disease and the need for
rapid response are essential for stroke care.
Stroke services should include acute care and rehabilitation in a
designated stroke unit, multidisciplinary team management, and
pharmacological and surgical treatments to achieve lower risk of
complications and recurrence of further vascular events.12 Identification and intervention with medical treatment of risk factors
and those amenable to lifestyle modification is powerful for
stroke risk reduction.
The older age group has been noted to be less aware of signs
and symptoms, risk factors and appropriate course of action
needed when a stroke occurred.14
The benefit of repeated explanation of the condition, cause,
prognosis and risk factors has been demonstrated by feedback
from patients and families or carers.15
Ensuring continuum of care from hospital to community is
essential in monitoring secondary stroke prevention measures.16
Stroke preventative treatments are noted to be well understood –
it is the application of these treatments that is lacking. Better
education of the general public is needed.
Elizabeth (Noddy) Dempsey is a clinical nurse specialist in neurology, specialising
in stroke and epilepsy at the Mater University Hospital, Dublin
Acknowledgement:The author would like thank the nursing staff and management of
St Brigid’s Acute Stroke Unit at the Mater University Hospital
References on request from [email protected] (quote: Dempsey E.WIN 2006; 14(10): 39-40)