Coronary artery disease is the leading cause of mortality in resource-rich countries, and is becoming a major cause of morbidity and mortality in resource-poor countries. Secondary prevention in this context is long-term treatment to prevent recurrent cardiac morbidity and mortality in people who have had either a prior acute myocardial infarction (MI) or acute coronary syndrome, or who are at high risk due to severe coronary artery stenoses or prior coronary surgical procedures. Secondary prevention in people with an acute MI or acute coronary syndrome within the past 6 months is not included.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of antithrombotic treatment; other drug treatments; cholesterol reduction; blood pressure reduction; non-drug treatments; and revascularisation procedures? We searched: Medline, Embase, The Cochrane Library, and other important databases up to May 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
We found 137 systematic reviews or RCTs that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
In this systematic review, we present information relating to the effectiveness and safety of the following interventions: advice to eat less fat, advice to eat more fibre, advice to increase consumption of fish oils, amiodarone, angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers, angiotensin II receptor blockers plus ACE inhibitors, antioxidant vitamin combinations, antiplatelet agents, aspirin, beta-blockers, beta-carotene, blood pressure reduction, calcium channel blockers, cardiac rehabilitation including exercise, class I antiarrhythmic agents, coronary artery bypass grafting (CABG), fibrates, hormone replacement therapy (HRT), Mediterranean diet, multivitamins, non-specific cholesterol reduction, oral anticoagulants, oral glycoprotein IIb/IIIa receptor inhibitors, percutaneous coronary intervention (PCI), psychosocial treatment, smoking cessation, statins, vitamin C, and vitamin E.
Coronary artery disease is the leading cause of mortality in resource-rich countries, and is becoming a major cause of morbidity and mortality in resource-poor countries.
Secondary prevention in this context is long-term treatment to prevent recurrent cardiac morbidity and mortality in people who have had either a prior MI or acute coronary syndrome, or who are at high risk due to severe coronary artery stenoses or prior coronary surgical procedures.
Of the antithrombotic treatments, there is good evidence that aspirin (especially combined with clopidogrel in people with acute coronary syndromes or MI), clopidogrel (more effective than aspirin), and anticoagulants all effectively reduce the risk of cardiovascular events.
Oral anticoagulants substantially increase the risk of haemorrhage. These risks may outweigh the benefits when combined with antiplatelet treatments.Adding oral glycoprotein IIb/IIIa receptor inhibitors to aspirin seems to increase the risk of mortality compared with aspirin alone.
Other drug treatments that reduce mortality include beta-blockers (after MI and in people with left ventricular dysfunction), ACE inhibitors (in people at high risk, after MI, or with left ventricular dysfunction), and amiodarone (in people with MI and high risk of death from cardiac arrhythmia).
There is conflicting evidence on the effect of calcium channel blockers. Some types may be effective at reducing mortality in the absence of heart failure, whereas others may be harmful.Contrary to decades of large observational studies, multiple RCTs show no cardiac benefit from HRT in postmenopausal women.
Lipid-lowering treatments effectively reduce the risk of cardiovascular mortality and non-fatal cardiovascular events in people with CHD.
There is good evidence that statins reduce the risk of mortality and cardiac events in people at high risk, but the evidence is less clear for fibrates.
The magnitude of cardiovascular risk reduction in people with coronary artery disease correlates directly with the magnitude of blood pressure reduction.
Cardiac rehabilitation (including exercise) and smoking cessation reduce the risk of cardiac events in people with CHD.
Antioxidant vitamins (such as vitamin E, beta-carotene, or vitamin C) have no effect on cardiovascular events in high-risk people, and in some cases may actually increase risk of cardiac mortality.We don't know whether changing diet alters the risk of cardiac episodes, although a Mediterranean diet may have some survival benefit over a Western diet.
Advice to increase fish oil consumption or fish oil consumption may be beneficial in some population groups. However, evidence was weak.Some psychological interventions may be more effective than usual care at improving some cardiovascular outcomes. However, evidence was inconsistent.
In selected people, such as those with more-extensive coronary disease and impaired left ventricular function, CABG may improve survival compared with an initial strategy of medical treatment. We don't know how PTCA compares with medical treatment.
We found no consistent difference in mortality or recurrent MI between CABG and PTCA with or without stenting, because of varied results among subgroups and insufficient evidence on stenting when comparing the interventions. CABG may be more effective than PTCA with or without stenting at reducing some composite outcomes, particularly those including repeat revascularisation rates.
PTCA with stenting may be more effective than PTCA alone.