New evidence-based guidance on the management of stable angina provides advice on investigations, models of care, relief of symptoms, and psychological issues, says Dr Alan Begg

T he Scottish Intercollegiate Guidelines Network (SIGN) guideline 96 on the management of stable angina,1 which was published in February 2007, supersedes SIGN 51,2 from 2001, on the same topic, as well as SIGN 323 from 1998, which covered the coronary revascularisation of patients with stable angina.

Comprehensive guidance

The guideline covers all aspects of stable angina, including assessment and the need to establish a diagnosis of the underlying pathogenesis. The medical management both to alleviate the symptoms and to prevent future vascular events is covered extensively, as well as when to consider interventional revascularisation and cardiac surgery.

There is comprehensive coverage of the psychological factors affecting angina patients, as well as specific patient issues, including long-term follow-up. Uniquely, the guideline authoritatively advises on management of patients with angina who are undergoing non-cardiac surgery. The evidence statements and recommendations within the guideline follow the standard SIGN methodology (see Figure 1).

Figure 1: Key to evidence statements and grades of recommendations

 
Levels of Evidence
1++ High quality meta-analyses, systematic reviews of RCTs, or RCTs with a very low risk of bias.
1+ Well conducted meta-analyses, systematic reviews of RCTs, or RCTs with a low risk of bias.
1- Meta-analyses, systematic reviews of RCTs, or RCTs with a high risk of bias.
2++ High quality systematic reviews of case control or cohort studies.
High quality case control or cohort studies with a very low risk of confounding or bias and a high probability that the relationship is causal.
2+ Well conducted case control or cohort studies with a low risk of confounding or bias and a moderate probability that the relationship is causal.
2- Case control or cohort studies with a high risk of confounding or bias and a significant risk that the relationship is not causal.
3 Non-analytic studies, e.g. case reports, case series.
4 Expert opinion.
 
Grades of Recommendation
Note: The grade of recommendation relates to the strength of the evidence on which the recommendation is based. It does not reflect the clinical importance of the recommendation.
A At least one meta-analysis, systematic review of RCTs, or RCT rated as 1++ and directly applicable to the target population; or
  A body of evidence consisting principally of studies rated as 1+, directly applicable to the target population, and demonstrating overall consistency of results.
B A body of evidence including studies rated as 2++, directly applicable to the target population, and demonstrating overall consistency of results; or
  Extrapolated evidence from studies rated as 1++ or 1+
C A body of evidence including studies rated as 2+, directly applicable to the target population and demonstrating overall consistency of results; or
  Extrapolated evidence from studies rated as 2++.
D Evidence level 3 or 4; or
  Extrapolated evidence from studies rated as 2+.
Good practice points
? Recommended best practice based on the clinical experience of the guideline development group.
RCT=randomised controlled trials
This material was reproduced with kind permission of the Scottish Intercollegiate Guidelines Network

Why the guideline is important?

Although there has been a decline in the rate of major coronary events and deaths from coronary heart disease (CHD) in recent years,4 a diagnosis of angina can have a significant impact on a patient's level of functioning and increase demands on general practice. Patients with symptoms suggestive of angina invariably present in the first instance to their GP. The initial assessment and the arrangement and prioritisation of investigations to establish the presence of CHD can have a significant impact on the patient's long-term management.5 The SIGN 96 guideline is the only current national UK guideline on the management of stable angina,6 and its implementation by health authorities and general practices across the UK is, therefore, of increased importance.

The need for an updated guideline

The description of angina as a symptom and its effect has changed little from that used by the GP and cardiologist Sir James McKenzie in 1923.7 However, since the publication of SIGN 51,2 there has been increased development of rapid access chest pain clinics,8 and the publication of a large number of outcome trials for the secondary prevention of CHD, mainly using statins,9 and angiotensin-converting enzyme (ACE) inhibitors.10,11 There has also been a rapid rise in the number of percutaneous coronary interventions (PCIs), with the insertion of bare metal or coated stents, but over the same period the number of coronary artery bypass grafting (CABG) operations has levelled off.4

 

Clinical assessment

The initial assessment by the GP should include the following:1

  • full history
  • clinical examination to include blood pressure evaluation
  • haemoglobin
  • thyroid function
  • cholesterol and glucose levels.

Angina can be graded using the Canadian Cardiovascular Society Angina Classification (Table 1). If the diagnosis is uncertain, it is important that the clinician does not give the impression that the patient has angina, as false beliefs may be difficult to correct if all the subsequent investigations are negative.1 (Good Practice Point)

Table 1: Canadian Cardiovascular Society Angina Classification

Class Description
Class I Ordinary activity such as walking or climbing stairs does not precipitate angina.
Class II Angina precipitated by emotion, cold weather or meals and by walking upstairs.
Class III Antioxidant vitamin supplementation is not recommended for the prevention or treatment of CHD.
Class IV Inability to carry out any physical activity without discomfort — anginal symptoms may be present at rest.
Reproduced from Campeau L. Grading of angina pectoris. Circulation 1976; 54 (3): 522–523, with kind permission from Wolters Kluwer

Confirming the diagnosis

An exercise tolerance test remains the initial investigation of choice, along with a 12-lead electrocardiogram. (Grade C) If facilities exist, the latter can be carried out by the GP. The exercise test for angina has a better sensitivity level than in patients with acute coronary syndrome (ACS) because of the underlying pathogenesis, which involves a fixed flow-limiting stenosis. The guideline recommendations relating to investigation of the patient are shown in Figure 2.

Figure 2: Recommendations relating to investigation of the patient

 
C Patients with suspected angina should usually be investigated with a baseline ECG and an exercise tolerance test.
B Patients unable to undergo exercise tolerance testing or who have pre-existing ECG abnormalities should be considered for myocardial perfusion scintigraphy.
? Coronary angiography should be considered after non-invasive testing where patients are identified as being at high risk or where a diagnosis remains unclear.
ECG=electrocardiogram
This material was reproduced with kind permission of the Scottish Intercollegiate Guidelines Network

Waiting times

Rapid access chest pain clinics have been promoted as a means of providing an earlier diagnosis,8 and also as being a cost-effective way of reducing unnecessary hospital admissions. On the basis of the evidence, however, it is the low waiting times that are important, regardless of the model, which should take into account local circumstances. This also applies to further investigations and waiting time for cardiac surgery (see Figure 3).

Figure 3: Recommendations relating to relating to model of care and waiting times

 
B Following initial assessment in primary care, patients with suspected angina should, wherever possible, have the diagnosis confirmed and the severity of the underlying coronary heart disease assessed in the chest pain evaluation service that offers the earliest appointment, regardless of model.
C Early access to angiography and coronary artery bypass surgery may reduce the risk of adverse cardiac events and impaired quality of life.
This material was reproduced with kind permission of the Scottish Intercollegiate Guidelines Network

Pharmacological treatment

Although sublingual glyceryl trinitrate should be used for immediate relief of angina, beta blockers remain the first-line choice for regular therapy (see Figure 4). By reducing heart rate and blood pressure, beta blockers improve the balance between oxygen supply and demand. They also decrease the end systolic stress and contractility, with an increase in diastolic perfusion time leading to increased coronary blood flow.

On this basis, a rate-limiting calcium channel blocker would be the logical alternative to use in a patient intolerant of beta blockers, but a new drug, ivabradine,12 which also lowers heart rate, has been shown to be on a par with atenolol in relieving symptoms.13 In routine practice, patients are usually given a second or third drug when they have become refractory to their existing treatment.1 As there is little evidence of benefit of adding a third drug, before doing so the medication should be reviewed and the possible need for revascularisation considered. Either CABG or PCI are suitable treatment choices for those patients who it is felt would benefit from revascularisation.1

Figure 4: Main recommendations relating to relating to relief of symptoms

 
A Sublingual glyceryl trinitrate tablets or spray should be used for the immediate relief of angina and before performing activities that are known to bring on angina.
A

Beta blockers should be used as first-line therapy for the relief of symptoms of stable angina.

A Patients who are intolerant of beta blockers should be treated with either rate-limiting calcium channel blockers, long-acting nitrates, or nicorandil.
A When adequate control of anginal symptoms is not achieved with beta blockade, a calcium channel blocker should be added.
? Rate-limiting calcium channel blockers should be used with caution when combined with beta blockers.
? Patients whose symptoms are not controlled on maximum therapeutic doses of two drugs should be considered for referral to a cardiologist.
A Patients who have been assessed and are anticipated to receive symptomatic relief from revascularisation should be offered either coronary artery bypass grafting or percutaneous coronary interventions.
This material was reproduced with kind permission of the Scottish Intercollegiate Guidelines Network

Prevention of new vascular events

The benefits of aspirin and statin therapy for patients with CHD are not in doubt. For those with an intolerance or hypersensitivity to aspirin, the use of clopidogrel as an alternative would have to be based on the extrapolation from the CAPRIE trial, as all patients recruited to this trial had previously experienced an episode of ACS.14 The use of ACE inhibitors in patients with CHD without an episode of ACS and with preserved left ventricular systolic function has previously been considered controversial. A meta-analysis of six randomised controlled trials of 33,500 such patients has shown that ACE inhibitors significantly reduce cardiovascular and all-cause mortality.10 Combining the results in a meta-analysis of the HOPE, EUROPA, and PEACE trials, featuring a total of 29,805 patients, showed an additional benefit in the reduction of non-fatal myocardial infarction and all strokes.11 On balance, for prognostic benefit, the evidence favours CABG over PCI for those patients requiring revascularisation (see Figure 5). (Grade A)

Figure 5: Long-term prevention of vascular events

 
A All patients with stable angina due to atherosclerotic disease should receive long-term standard aspirin and statin therapy.
A

All patients with stable angina should be considered for treatment with angiotensin-converting enzyme inhibitors.

A Patients with triple vessel disease should be considered for coronary artery bypass grafting to improve prognosis, but where unsuitable they should be offered percutaneous coronary intervention.
This material was reproduced with kind permission of the Scottish Intercollegiate Guidelines Network

Patients undergoing surgery

Off-pump surgical techniques were developed with the aim of reducing cognitive impairment after surgery,1 although there was no evidence to recommend this approach, and it should not be used to provide long-term protection against cognitive decline. (Grade C) However, a Grade B recommendation is that patients should be advised that cognitive decline is relatively common in the first 2 months following surgery and should be taken into account in those at higher risk when discussing revascularisation. These higher risk groups include the elderly, and those with other manifestations of atherosclerosis or pre-existing cognitive decline. Depression is a significant factor influencing mortality and morbidity after CABG, and patients should be screened for anxiety and depression prior to surgery and for the following year and managed appropriately.1 (Grade D)

Patient well-being

Psychological factors exert an influence on patients with angina in several ways. The main guideline recommendations relating to these issues are shown in Figure 6 (above), but they include the following:1

  • limitations and concerns related to living with angina and their influence on mood, degree of disability, quality of life, and mortality
  • beliefs and misconceptions about heart disease and the effect on outcomes
  • the presence of depression and its influence on mortality and morbidity
  • cognitive changes noticed by patients after CABG.

Figure 6: Main recommendations relating to psychological issues

 
D Patients with angina should be assessed for the impact of angina on mood, quality of life, and function, to monitor progress and inform treatment decisions.
?

Mood, quality of life, and function in angina patients can be assessed using validated measures such as:

    • SF-36
    • Hospital Anxiety and Depression Scale (generic)
    • The Dartmouth Primary Care Co-operative Information Project Functional Health Assessment Chart
    • Seattle Angina Questionnaire — UK version
    • Cardiovascular Limitations and Symptoms profile (CHD specific).
B Patients with stable angina whose symptoms remain uncontrolled or who are experiencing reduced physical functioning despite optimal medical therapy should be considered for the Angina Plan.
? Any psychoeducational treatments that are shown to reduce distress should be considered alongside interventional treatments.
D Patients’ beliefs about angina should be assessed when discussing management of risk factors and how to cope with symptoms.
B Interventions based on psychological principles designed to alter beliefs about heart disease and angina, such as the Angina Plan, should be considered.
This material was reproduced with kind permission of the Scottish Intercollegiate Guidelines Network

Follow-up in primary care

Multidisciplinary disease management programmes for patients with CHD have a beneficial impact on the uptake of secondary prevention drugs and on addressing risk factors.15 The Grade A recommendation that patients with angina and with a diagnosis of CHD should receive long-term structured care is, however, reflected in the current QOF recommendation that blood pressure and total cholesterol levels should be recorded every 15 months.16

Conclusion

The SIGN guideline contains credible and robust recommendations that are relevant for implementation in all UK general practices. The associated National Clinical and Resource impact assessment indicates that this can be achieved without major cost implications.17 This assessment, as well as the full guideline, the quick reference guide, and information for patients, is available from the SIGN website (www.sign.ac.uk).

  • Acute chest pain is one of the commonest causes of hospital admission
  • Rapid access to outpatient exercise ECG assessment can reduce the need for acute admission (even shorter than 14 day national target)
  • Bypass grafting is more expensive yet more effective for triple vessel disease than PCI
  • Tariff price for acute chest pain admission = £453, exercise ECG = £1551
  • Patients with stable angina should now be prescribed ACE inhibitors (most now available generically and inexpensively)
  1. Scottish Intercollegiate Guidelines Network. Management of stable angina. A national clinical guideline (SIGN 96). Edinburgh: SIGN, 2007.
  2. Scottish Intercollegiate Guidelines Network. Management of stable angina. A national clinical guideline (SIGN 51). Edinburgh: SIGN, 2001.
  3. Scottish Intercollegiate Guidelines Network. Coronary revascularisation in the management of stable angina pectoris. A national clinical guideline (SIGN 32). Edinburgh: SIGN, 1998.
  4. British Heart Foundation Statistics. www.heartstats.org
  5. Best R. Living with chest pain. Br J Cardiol 2005; 12 (2): 85–87.
  6. Minhas R. SIGN guidelines point to the evidence. MIMS Cardiovascular 2007; 2 (2): 15.
  7. McKenzie J. Angina Pectoris. London: Henry Frowde, 1923.
  8. Department of Health. Coronary heart disease: national service framework for coronary heart disease—modern standards and service models. London: DH, 2000.
  9. Baigent C, Keech A, Kearney P et al. Cholesterol Treatment Trialists' (CTT) Collaborators. Efficacy and safety of cholesterol-lowering treatment: prospective meta-analysis of data from 90,056 participants in 14 randomised trials of statins. Lancet 2005; 366 (9493): 1267–1278.
  10. Al-Mallah M, Tleyjeh M, Abdel-Latif A, Weaver W. Angiotensin-converting enzyme inhibitors in coronary artery disease and preserved left ventricular systolic function: a systematic review and meta-analysis of randomized controlled trials. J Am Coll Cardiol 2006; 47 (8): 1576–1583.
  11. Dagenais G, Pogue J, Fox K et al. Angiotensin-converting-enzyme inhibitors in stable vascular disease without left ventricular systolic dysfunction or heart failure: a combined analysis of three trials. Lancet 2006; 368 (9535): 581–588.
  12. Scottish Medicines Consortium. www.scottishmedicines.org.uk/smc/homepage.html
  13. Tardif J, Ford I, Tendera M et al. and the INITIATIVE Investigators. Efficacy of ivabradine, a new selective I(f) inhibitor, compared with atenolol in patients with chronic stable angina. Eur Heart J 2005; 26 (23): 2529–2536.
  14. A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). CAPRIE Steering Committee. Lancet 1996; 348 (9038): 1329–1339.
  15. McAlister F, Lawson F, Teo K, Armstrong P. Randomised trials of secondary prevention programmes in coronary heart disease: systematic review. Br Med J 2001; 323 (7319): 957–962.
  16. British Medical Association. Revisions to the GMS contract 2006/2007: Delivering Investment in General Practice. London: BMA, 2006.
  17. Scottish Intercollegiate Guidelines Network. Management of coronary heart disease—A national clinical and resource impact framework. Edinburgh: SIGN, 2007. G

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