Cardiovascular risk calculation

Whenever risk factors are identified they should not be considered in isolation, but the 10-year CVD risk should be calculated and used as the basis for recommendations to reduce the risk.

Risk assessment should include ethnicity, smoking habit history, family history of CVD and measurements of weight, waist circumference, blood pressure, lipids (total cholesterol and high-density lipoprotein (HDL) cholesterol) and glucose. The American Heart Association (AHA) guidelines also recommend recording the pulse rate and rhythm to screen for atrial fibrillation.^[2]

For further details see Cardiovascular risk assessment article.

Interventions

Reduction of risk of developing CVD involves lifestyle modifications, drug treatment and effective management of any overt underlying medical condition, eg diabetes, hypertension, hyperlipidaemia.^[1][2]

Lifestyle modifications^[1]

All patients with CVD can benefit from programmes to encourage behavioural change.^[3] However, greater access for patients could be achieved through the automatic referral of all eligible patients to cardiac rehabilitation;^[4] hospital-based programmes are effective, and evidence suggests that patients who choose not to access them can also benefit from home-based or community-based schemes.^[5]

• Consider setting up a disease register and systematic recall with a nurse-led secondary prevention clinic. Evidence supports their efficacy in the short term, but is lacking over a 10-year follow-up.^[6]
• Smoking cessation: all patients should be actively discouraged from smoking^[7] - repeated brief supportive advice, combined with nicotine replacement therapy when needed.
• Keep total dietary intake of fat to 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 five portions per day. A Mediterranean diet has been shown to reduce mortality. Regular intake of fish (twice a week) and at least one of those to be oily fish.^[8]
• Limit the intake of salt to less than 100 mmol/L per day (less than 5 g of salt per day).^[8]
• Alcohol consumption should be limited to 3 units per day (21 units per week) for men and 2 units per day (14 units per week) for women.
• Patients should be encouraged to exercise regularly:
  • 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 an 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]

Blood pressure management

See separate article Management of 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, eg established atherosclerotic disease, diabetes, and chronic kidney disease, 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 contra-indications.
• Angiotensin-converting enzyme (ACE) inhibitors:
  • Recommended for people with symptoms or signs of heart failure at the time of myocardial infarction, or for 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 antagonist 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 (CCBs) and diuretics:
  • These should be considered in all high-risk people if the blood pressure is not below the target (although purely as secondary prevention agents, CCBs are ineffective).

Lipid management

See separate article Hyperlipidaemia:

• The optimal total cholesterol target is less than 4.0 mmol/L and low-density lipoprotein (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.^[9]
• 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 type 2 diabetes.
    • People aged 18-39 years with either type 1 or type 2 diabetes and who have at least one of the following:
      • Retinopathy (preproliferative, 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.
• There is a greater risk of developing muscle problems when the patient is also taking amlodipine or diltiazem.^[10]  The dose of statin may need adjusting.
• 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, eg HDL cholesterol or triglycerides.

Blood glucose and diabetes

• In all high-risk people the optimal fasting glucose is less than 6.0 mmol/L.^[8]
• For people with impaired fasting glycaemia or impaired glucose tolerance: review annually to reassess glucose regulation and all other cardiovascular risk factors.
• People with types 1 and 2 diabetes mellitus: rigorous control of glycaemia. The optimal target for glycaemic control in diabetes is a fasting or preprandial 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 contra-indicated, or there are side-effects, then clopidogrel is appropriate.
  • Results in primary prevention are inconclusive.^[11] Recent studies have found that aspirin doubles the risk of gastrointestinal bleeding and current opinion is that this outweighs any benefits which might be conferred in reducing the onset of CVD.^[12]
  • 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 modified-release (MR) dipyridamole 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 MR dipyridamole, then changing aspirin for clopidogrel should be considered.
• Anticoagulation with warfarin 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 contra-indicated, 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.

Anti-arrhythmic agents

• Amiodarone significantly reduces the risk of cardiac mortality after myocardial infarction in those with high risk of arrhythmic death.^[13]
• Beta-blockers (see above) have a favourable interaction with amiodarone, with additional reduction in mortality (however, sotalol increases mortality after myocardial infarction in those with left ventricular dysfunction).

Surgery

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

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