Secondary Prevention of Ischaemic Heart Disease

The recently revised Joint British Societies' guidelines on prevention of cardiovascular disease (CVD) in clinical practice recommend that cardiovascular disease prevention should focus equally on the following three groups of patients who are at high risk of cardiovascular disease:¹

• People with established atherosclerotic CVD
• People with diabetes mellitus (type 1 or 2)
• Apparently healthy individuals at high risk (CVD risk of 20% or greater over 10 years) of developing symptomatic atherosclerotic disease.

There are separate articles that discuss Primary Prevention of Cardiovascular Disease, How to use the coronary risk prediction charts for primary prevention and Cardiac Rehabilitation.

• Consider setting up disease register and systematic recall with nurse-led secondary prevention clinic.^2,3
• Smoking cessation: all patients should be actively discouraged from smoking. Repeated brief supportive advice combine with nicotine replacement therapy when needed.
• Keep total dietary intake of fat a maximum of 30% of total energy intake, with intake of saturated fats 10% or less of total fat intake and the intake of dietary cholesterol to less than 300 mg/day. Saturated fats should be replaced with an increased intake of monounsaturated fats.
• Consumption of fresh fruit and vegetables should be increased to at least 5 portions per day. A mediterranean diet has been shown to reduce mortality. Regular intake of fish and other sources of omega 3 fatty acids (at least two servings of fish per week).
• Limit the intake of salt to less than 100 mmol/l day (less than 6 g of sodium chloride or less than 2.4 g of sodium per day)
• Alcohol consumption should be limited to 3 units/day (21 units/week) for men and 2 units/day (14 units/week) for women.
• Patients should be encouraged to exercise regularly:
  • Regular aerobic physical activity of at least 30 mins per day, most days of the week, should be taken (e.g. fast walking/swimming).
  • Exercise training has been shown to slow the progression or partially reverse the severity of coronary atherosclerosis.
  • Aerobic exercise can modify all the components of the metabolic syndrome with a decrease in blood pressure and triglycerides, increase in HDL, and an improvement of insulin sensitivity.
• Weight control:
  • Overweight patients should be encouraged to lose weight through a combination of diet and exercise.
  • Maintain ideal body weight for adults (body mass index 20-25 kg/m²) and avoid central obesity (waist circumference in white caucasians less than 102 cm (40 inches) in men and less than 88 cm (35 inches) in women; in Asians the recommended targets are less than 90 cm in men and less than 80 cm in women.¹

The recently revised Joint British Societies' guidelines on prevention of cardiovascular disease have made the following recommendations for secondary prevention and for other high risk groups.¹

Blood pressure

See separate article on Hypertension:

• The optimal blood pressure target is less than 140 mm Hg systolic and less than 85 mm Hg diastolic.
• In selected higher risk people, e.g. established atherosclerotic disease, diabetes, and chronic renal failure, a lower blood pressure target of less than 130 mm Hg and less than 80 mm Hg may be more appropriate.
• Beta-blockers:
  • Recommended for all people following myocardial infarction unless there are contraindications.
• ACE inhibitors:
  • Recommended for people with symptoms or signs of heart failure at the time of myocardial infarction, or those with persistent left ventricular systolic dysfunction (ejection fraction less than 40%) following infarction.
  • Should be considered for others with coronary artery disease, especially if the blood pressure is not below the target of less than 130 mm Hg systolic and less than 80 mm Hg diastolic.
  • An angiotensin II receptor blocker is an alternative to an ACE inhibitor if an ACE inhibitor is associated with side effects.
  • An ACE inhibitor should be considered in combination with a thiazide diuretic in all people with an established stroke, especially if the blood pressure is not below the target of less than 130 mm Hg systolic and less than 80 mmHg diastolic.
• Calcium channel blockers and diuretics:
  • Should be considered in all high risk people if the blood pressure is not below the target, though purely as secondary prevention agents CCBs are ineffective.

See separate article on Hyperlipidaemia:

• The optimal total cholesterol target is less than 4.0 mmol/l and LDL cholesterol less than 2.0 mmol/l, or a 25% reduction in total cholesterol and a 30% reduction in LDL cholesterol, whichever gets the person to the lowest absolute value.
• Fasting lipids should be estimated at least eight weeks after an acute cardiovascular event and, if necessary, the dose of statin up-titrated to achieve the total and LDL cholesterol targets. HDL cholesterol and fasting triglycerides should be measured and considered at the same time.
• Statins are recommended for:
  • All high risk people with established atherosclerotic disease
  • In the following people with diabetes:
    • All those who are aged 40 years or more with either type 1 or 2 diabetes
    • People aged 18-39 years with either type 1 or 2 diabetes and who have at least one of the following:
      • Retinopathy (pre-proliferative, proliferative, maculopathy)
      • Nephropathy, including persistent microalbuminuria
      • Poor glycaemic control (HbA1c greater than 9%)
      • Elevated blood pressure requiring antihypertensive therapy
      • Raised total blood cholesterol (greater than 6.0 mmol/l)
      • Features of metabolic syndrome (central obesity and fasting triglyceride greater than 1.7 mmol/l (non-fasting > 2.0 mmol/l) and/or HDL cholesterol less than 1.0 mmol/l in men or less than 1.2 mmol/l in women)
      • Family history of premature CVD in a first degree relative.
  • Primary prevention for those who are at high total risk of developing CVD if the total cholesterol and LDL cholesterol targets have not been achieved.
• Other classes of lipid lowering drugs (particularly fibrates, bile acid sequestrants, cholesterol absorption inhibitors, nicotinic acid, omega-3 (n-3) fatty acids) should be considered in addition to a statin if the total and LDL cholesterol targets have not been achieved, or if there are other lipid abnormalities, e.g. HDL cholesterol or triglycerides.

Blood glucose and diabetes

• In all high risk people the optimal fasting glucose is less than 6.0 mmol/l.
• For people with impaired fasting glycaemia or impaired glucose tolerance: review annually to reassess glucose regulation and all other cardiovascular risk factors.
• People with type 1 and 2 diabetes mellitus: rigorous control of glycaemia. The optimal target for glycaemic control in diabetes is a fasting or pre-prandial glucose value of 4.0-6.0 mmol/l and an HbA1c less than 6.5%.

Antithrombotic therapy

• Coronary or peripheral atherosclerosis
  • Aspirin 75 mg daily is recommended for life for all people with coronary or peripheral atherosclerotic disease.
  • If aspirin is contraindicated, or there are side effects, then clopidogrel is appropriate.
  • Anticoagulation should be considered for selected people at risk of systemic embolisation from large myocardial infarctions, heart failure, left ventricular aneurysm, or paroxysmal tachyarrhythmias.
• Cerebral atherosclerotic disease (non-haemorrhagic)
  • All people with a history of cerebral infarction, or transient ischaemic attack, and who are in sinus rhythm, should take low dose aspirin plus dipyridamole M/R for two years following the initial event to prevent stroke recurrence as well as other vascular events.
  • For those who have a further ischaemic cerebrovascular event while taking aspirin and dipyridamole M/R, then changing aspirin for clopidogrel should be considered.
  • Anticoagulation should be considered for all people with atrial fibrillation who are at moderate (aged 60-75 years without additional risk factors) to high risk (over 75 years, or over 60 years with other risk factors such as hypertension, diabetes, or left ventricular dysfunction) to reduce the risk of a further stroke.
  • If oral anticoagulation is contraindicated, or cannot be tolerated, antiplatelet therapy should be considered instead.
  • There is no evidence of benefit for anticoagulation in people with ischaemic stroke who are in sinus rhythm.
• Primary prevention of CVD in those at high risk:
  • Aspirin 75 mg daily is recommended for all people over the age of 50 years who have a total CVD risk greater than 20%, and in selected people with diabetes (greater than 50 years, or who are younger but have had the disease for more than 10 years, or who are already receiving treatment for hypertension), once the blood pressure has been controlled to at least less than 150mm Hg systolic and less than 90 mm Hg diastolic.

Antiarrhythmic agents

• Amiodarone significantly reduces the risk of cardiac and all-cause mortality after MI and in those with high risk of arrhythmic death.
• Beta-blockers (see above) have a favourable interaction with amiodarone, with additional reduction in mortality (however sotalol increases mortality after MI in those with LV dysfunction).

Surgery

After assessment with exercise tolerance test, echocardiography, angiography, and scanning, the following may be beneficial where appropriate:

• Coronary artery bypass grafting: reduces mortality compared to medical treatment alone, particularly in those with poor left ventricular function.
• Percutaneous transluminal coronary angioplasty.
• Intracoronary stent: particularly useful for restenosis after PTCA.
• Atherectomy by various methods, and transmyocardial laser revascularisation are less common procedures used.