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Stable Angina: How Does the SIGN Guideline Compare With NICE?

Dr Alan Begg Compares SIGN and NICE Recommendations on the Diagnosis, Assessment, and Treatment of Stable Angina

Read This Article to Learn More About:
  • the clinical characteristics of angina
    Dr Alan Begg
  • non-invasive and invasive investigations
  • the role of medication
  • revascularisation options.

Find implementation actions for STPs, ICSs, and clinical pharmacists in general practice at the end of this article

In April 2018, SIGN published Guideline 151 on the Management of stable angina1 replacing Guideline 96, which was published in 2007.2 The SIGN methodology has changed in the intervening years with the recommendation grading changed from A, B, C levels to two levels of ‘strong’ or ‘conditional’, with recommendations that ‘should’ or ‘should not’ (be implemented) or those that should be ‘considered’ for implementation, respectively.

In the 2018 guideline, there are 19 new sections and two new algorithms. A further 21 sections are completely revised, nine are updated, with six sections receiving minor updates. SIGN guidance is the national clinical guidance for use in Scotland but NICE guidance is often quoted, especially if there is an opportunity for cost-saving or reduction of an existing service.

The NICE guidance equivalent to SIGN 151 is the part of NICE Clinical Guideline (CG) 95 that relates to people presenting with stable chest pain and also NICE CG126, Stable angina: management.3,4 The former was published in 2010 and the latter in 2011; both were updated in 2016.

Clinical Characteristics of Angina and Making a Diagnosis

Certain characteristics of angina pain will increase the likelihood of making a diagnosis. Those outlined in SIGN 151 are shown in Box 1.1

Box 1: Typical Characteristics of Angina1

There are several typical characteristics which should increase the likelihood of making a diagnosis of angina. These include:

  • type of discomfort—often described as tight, constricting, dull, or heavy
  • location—often retrosternal or left side of chest and can radiate to left arm, neck, jaw, and back
  • relation to exertion—angina is often brought on with exertion or emotional stress and eased with rest
  • duration—typically the symptoms last up to several minutes after exertion or emotional stress has stopped
  • other factors—angina may be precipitated by cold weather or after a large meal.

Scottish Intercollegiate Guidelines Network (SIGN). Management of stable angina. Edinburgh: SIGN, 2018. (SIGN 151). Available at:

Reproduced with permission

NICE describes three features of angina pain that can help determine a diagnosis:3

  • constricting discomfort in the front of the chest, or in the neck, shoulders, jaw, or arms
  • pain precipitated by physical exertion
  • pain relieved by rest or glyceryl trinitrate (GTN) within about 5 minutes.

The presence of all three features represents typical angina, two features signifies atypical angina, and if one or none of the three features are present, the pain is defined as non-anginal.1,3

The likelihood of a diagnosis of angina increases with the number of cardiovascular risk factors in individual patients, such as:1,3

  • smoking
  • hypertension
  • diabetes
  • previous history of coronary artery disease (CAD) or other vascular disease
  • family history of CAD
  • hyperlipidaemia
  • chronic kidney disease.

SIGN defines a positive family history as a history of premature CAD in a male first-degree relative aged less than 55 years or female first-degree relative aged less than 65 years.1 NICE CG95 gives a similar list of cardiovascular risk factors but also states that a diagnosis of stable angina is more likely in men; however, the defining typical and atypical features are the same in men and women and different ethnic groups.3 NICE CG95 states that a diagnosis of angina is less likely if the chest pain is continuous and/or very prolonged, unrelated to activity, brought on by breathing in, or associated with symptoms such as dizziness, palpitations, tingling, or difficulty swallowing.3 Both guidelines outline what they individually consider to be the important aspects of clinical examination, with SIGN outlining the necessary baseline laboratory investigations. Conditions that exacerbate angina, such as anaemia, should be identified by appropriate blood tests.

SIGN makes it clear that if the diagnosis is uncertain, the clinician should avoid giving the patient the impression that they have angina as it may lead the patient to have false beliefs, which may be difficult to change even after further investigations have ruled out angina as the diagnosis.1 Both guidelines agree that diagnostic tests for myocardial ischaemia should not be offered to those with non-cardiac/non-angina chest pain unless there are resting electrocardiogram (ECG) ST-T changes or Q waves.1,3

Assessment Approach

A 12-lead ECG is an essential part of the assessment and NICE gives guidance on changes that may indicate ischaemia or previous infarction:3

  • pathological Q waves
  • left bundle branch block
  • ST-segment and T wave abnormalities (such as flattening or inversion).

Deciding on Diagnostic Investigations

SIGN indicates that in patients with suspected angina, if there is diagnostic uncertainty from the history, a CT-coronary angiogram should be carried out as an anatomical investigation to determine the presence of obstructive CAD (Figure 1). Those with non-obstructive CAD should receive medical therapy and only invasive coronary angiography if they have ongoing symptoms despite optimal medical therapy (Figure 2). Those with left main-stem or severe three-vessel disease should receive invasive coronary angiography.1

Figure 1: Management options in patients with suspected angina1
CT=computerised tomography; CAD=coronary artery disease; PCI=percutaneous coronary intervention; CABG=coronary artery bypass grafting
Scottish Intercollegiate Guidelines Network (SIGN). Management of stable angina. SIGN 151. Edinburgh: SIGN, 2018. (SIGN 151). Available at:
Reproduced with permission
Figure 2: Management options in patients with a definite diagnosis of stable angina1
CAD=coronary artery disease; CMR=cardiac magnetic resonance imaging; PCI=percutaneous coronary intervention; CABG=coronary artery bypass grafting
Scottish Intercollegiate Guidelines Network (SIGN). Management of stable angina. SIGN 151. Edinburgh: SIGN, 2018. (SIGN 151). Available at:
Reproduced with permission

NICE CG95 states that clinical judgment, ECG changes, as well as people’s preferences and co-morbidities should be taken into account when considering diagnostic testing using a 64-slice (or above) CT-coronary angiography.3

Both guidelines agree that in patients with previously diagnosed CAD, non-invasive functional testing should be considered.1,3 SIGN includes exercise tolerance testing in the list of choices,1 with the NICE options being:3

  • myocardial perfusion scintigraphy with single photon emission computed tomography (MPS with SPECT)
  • stress echocardiology
  • first-pass contrast-enhanced magnetic resonance (MR) perfusion
  • MR imaging for stress-induced wall motion abnormalities.

NICE is clear that exercise ECG or MR coronary angiography should not be used to diagnose stable angina. SIGN states that an exercise tolerance test (exercise ECG) should not be used as a first-line diagnostic test, and only discusses cardiac MR in the context of stratifying risk.

Exercise Tolerance Testing (ETT) versus Computed Tomography–Coronary Angiography (CT-CA)

Exercise tolerance testing (ETT) as an initial test for patients with angina symptoms and suspected to have CAD should be replaced by computed tomography-coronary angiography (CT-CA). The latter is noted to have an excellent diagnostic performance with a sensitivity of up to 99%, specificity of up to 92%, and a negative predictive value approaching 100%.1 The diagnostic accuracy of ETT, by contrast, varies depending on many features such as age and gender and the cohort of patients studied. A major drawback to the implementation of this new approach, however, is the lack of CT-CA capacity to implement the guidance; however, cardiologists in the author’s area are hopeful that this will not be too slow to change.

Medical Therapy

General practice has an important role in the management of angina, which is predominately medical therapy especially if there is a clear history of stable angina (Figure 2). This consists of two separate approaches: relieving symptoms (Table 1) and using therapeutic preventative therapy (Table 2) to prevent secondary vascular events. SIGN and NICE recommendations vary slightly, especially in symptom relief, so practices should consider developing their own implementation approach based on local prescribing policies and cost-reduction initiatives. Both guidelines show less variation in the therapeutic approach to prevention of cardiovascular events.

Table 1: Symptomatic Management of Stable Angina1,4

  SIGN 1511 NICE CG1264
Immediate relief of symptoms Sublingual glyceryl trinitrate tablets or spray should be used for the immediate relief of angina and before performing activities known to bring on angina

Offer short-acting nitrate for preventing and treating angina episodes

Repeat the dose after 5 minutes if pain has not gone

Call an emergency ambulance if pain has not gone 5 minutes after taking second dose

First-line therapy for relief of symptoms

Use BBs as first-line therapy

Consider rate-limiting CCB when BBs are contraindicated

Treat Prinzmetal (vasospastic) angina with a dihydropyridine derivative CCB

Offer a BB or CCB

Decide which one to use based on co-morbidities, contraindications, and person’s preference

If unable to tolerate BB or CCB or symptoms not satisfactorily controlled, consider switching to the other

If BB or CCB or both are contraindicated, monotherapy with:

  • long-acting nitrate or
  • ivabradine or
  • nicorandil or
  • ranolazine

Decide which drug to use based on co-morbidities, contraindications, the person’s preference and drug costs*

Combination therapy

If BB inadequate to control symptoms consider adding a CCB

Rate-limiting CCB should be used with caution when combined with BB

Adding IMN to BB or to CCB improves performance on range of clinical end points

Adding ivabradine to atenolol relieves symptoms and improves exercise capacity

Adding nicorandil to other anti‑anginal drugs is effective at reducing combined cardiac events

The combination of ivabradine and a BB or rate‑limiting CCB is not recommended by the SMC in Scotland

Ranolazine improves exercise tests in refractory chronic stable angina. Ranolazine is not recommended by the SMC in Scotland

Patients whose symptoms are not controlled on maximum therapeutic doses of two drugs should be considered for referral to a cardiologist

If a BB or a CCB does not adequately control symptoms, consider using a combination of the two

If either BB or CCB monotherapy is contraindicated or ineffective, add in alternative therapy:

  • long-acting nitrate or
  • ivabradine or
  • nicorandil or
  • ranolazine

Decide which drug based on co‑morbidities, contraindications, the person’s preferences, and drug costs*

Do not offer a third drug if stable angina is controlled with two drugs

Consider adding a third drug if:

  • symptoms not satisfactorily controlled with two drugs and
  • the person is waiting for revascularisation or revascularisation is not felt to be appropriate or acceptable.

* Since NICE Clinical Guideline 126 was produced, the Medicines and Healthcare products Regulatory Agency (MHRA) has published new advice about safety concerns related to ivabradine (June 2014 and December 2014) and nicorandil (January 2016). 

 When combining a calcium channel blocker with a beta blocker, use a dihydropyridine calcium channel blocker, for example, slow release nifedipine, amlodipine, or felodipine.

Developed by Alan Begg (2018) from the following guidelines:

Scottish Intercollegiate Guidelines Network. Management of stable angina. SIGN 151. Edinburgh: SIGN, 2018. Available at:

NICE. Stable angina: management. Clinical Guideline 126. NICE, 2011 (updated 2016). Available at:

CG=clinical guideline; BB=beta blocker; CCB=calcium channel blocker; IMN=isosorbide mononitrate; SMC=Scottish Medicines Consortium

Table 2: Drugs to Prevent New Vascular Events1,4

  SIGN 1511 NICE CG1264
Antiplatelet therapy All patients with angina due to atherosclerotic disease should receive long-term standard aspirin therapy Consider aspirin 75 mg daily, taking into account the risk of bleeding and co-morbidities
Lipid lowering All patients should receive long-term statin therapy Offer statin therapy in line with NICE CG675 [now replaced by NICE CG1816]
ACE-I All patients should be considered for treatment with ACE-I Consider ACE-I for those with stable angina and diabetes. Offer or continue ACE-I for other conditions in line with relevant NICE guidance
High blood pressure treatment   Offer drug treatment in line with NICE CG1277
SIGN=Scottish Intercollegiate Guidelines Network; ACE-I=angiotensin-converting enzyme inhibitor; CG=clinical guideline


The path to invasive coronary angiography for possible revascularisation is clear in SIGN 151 (Figures 1 and 2):

  • obstructive left main-stem or severe three-vessel disease on CT-CA
  • non-obstructive CAD on CT-CA but patient remains symptomatic on optimal medical therapy
  • patient high risk on functional assessment.

In all other situations, optimal medical treatment is the ideal and if there are still symptoms and the patient is not suitable for revascularisation then treatments for refractory angina should be considered.1

Choice of Revascularisation

Percutaneous coronary intervention (PCI) involves dilating the artery by inflating a fine balloon and inserting a fine lattice scaffold (stent) to prevent the artery from recoiling. Stents are coated with drugs to prevent or retard endothelialisation.1

Coronary artery bypass grafting (CABG) involves bypassing a section of the coronary artery narrowed by atheroma by a section of healthy saphenous vein or internal mammary artery. SIGN does not come to a conclusion as to whether CABG is superior to PCI in terms of prognostic benefit.1

NICE CG126 says that when either procedure is appropriate, take into account the potential survival advantage of CABG over PCI for people with multi-vessel disease and who:3

  • have diabetes or
  • are over 65 years or
  • have anatomically complex three-vessel disease, with or without involvement of the left main stem.

NICE 126 also indicates that CABG should be offered if symptoms are not controlled medically, if the anatomy is suitable, and if PCI is felt not to be appropriate; conversely, offer PCI when CABG is not appropriate.

Ideally, revascularisation options should be agreed following review by a multidisciplinary ‘heart team’ including cardiac surgeons, cardiac anaesthetists, and interventional cardiologists, and discussion with the patient.

The Society of Thoracic Surgeons recommends that aspirin should be stopped for 3–5 days before elective CABG and then restarted early after surgery.1,8 The routine use of perioperative beta-blocker therapy to reduce perioperative myocardial infarction in patients undergoing non-cardiac surgery is now not recommended.1 Similarly, the use of aspirin to reduce perioperative cardiac events in patients undergoing non-cardiac surgery, including those with known stable CAD, is also not recommended.1 Patients undergoing non-cardiac surgery should have their statin therapy continued through the perioperative period.1

Managing Refractory Angina

Refractory angina is defined in SIGN 151 as ‘persisting unsatisfactory control of angina symptoms despite maximal tolerated medical therapies and without further revascularisation options’. SIGN does not, however, make any recommendations for invasive interventions for refractory angina. Comprehensive rehabilitation is suggested, with patients following an ‘educational and rehabilitative approach, progressing to a cognitive behaviourally-informed approach where appropriate’.1 The one recommendation made is that patients with angina should be assessed by appropriately trained staff for the impact of angina on mood, quality of life, and function.1

NICE CG126 advises against the use of transcutaneous electrical nerve stimulation (TENS), enhanced external counterpulsation (EECP), or acupuncture to manage stable angina.4 SIGN states that transmyocardial laser revascularisation is not recommended for the treatment of stable angina.1

For patients who have not responded to drug treatment and/or revascularisation, comprehensive re-evaluation and advice may include:4

  • exploring the patient’s understanding of their condition
  • exploring the impact of symptoms on the person’s quality of life
  • reviewing the diagnosis and considering non-ischaemic causes of pain
  • reviewing drug treatment and considering future drug treatments and revascularisation options
  • acknowledging the limitations of future treatment
  • explaining how the person can manage the pain themselves.

Psychological Health in Patients with Angina

Angina can have an adverse effect on the patient’s wellbeing and quality of life. It is important that patients are assessed for this effect and managed appropriately. Interventions such as the Angina plan can help.9 This is a patient-held workbook and relaxation programme delivered in primary care, which has been shown to significantly reduce the mean number of self-reported angina attacks and physical limitation, with a reduction in anxiety and depression.1


With the publication of the SIGN 151 angina guideline,1 practitioners now have access to professionally produced guidance that gives an up-to-date overview of the evidence, especially in relation to assessment, medical management, and revascularisation. Primary care has an important role in the first two of these aspects even though there has been an increase in revascularisation in recent years, with more insertion of drug-eluting stents in particular. The use of CT-CA as the main investigation to determine the presence and extent of obstructive CAD does, however, stand out as requiring significant investment before this guideline can be successfully implemented.

Dr Alan Begg

GP, Montrose; GPwSI in cardiovascular disease; trustee of Chest, Heart, and Stroke Scotland (CHSS); and trustee of Scottish Heart and Arterial Risk Prevention Group (SHARP); specialist reviewer of SIGN 151

Implementation Actions for STPs and ICSs

Written by Dr David Jenner, GP, Cullompton, Devon

The following implementation actions are designed to support STPs and ICSs with the challenges involved with implementing new guidance at a system level. Our aim is to help you consider how to deliver improvements to healthcare within the available resources. 

  • Convene a local STP implementation group to assess the relevant guidance (NICE or SIGN) for your area
    • ensure this group includes specialists, radiographers, GPs, and public health professionals alongside commissioners
  • Agree and publish a local care pathway for the diagnosis, management, and ongoing care for people suspected of having angina
  • Make sure sufficient CT angiography is commissioned, as both SIGN and NICE define this as a key first-line diagnostic intervention
  • Consider local education programmes to help primary care clinicians to understand and implement the new care pathway, ensuring prompt referral and then good medical management of those diagnosed with angina.

STP=sustainability and transformation partnership; ICS=integrated care system; SIGN=Scottish Intercollegiate Guidelines Network; CT=computed tomography.

Implementation Actions for Clinical Pharmacists in General Practice

Written by Gupinder Syan, Training and Clinical Outcomes Manager, Soar Beyond Ltd

The following implementation actions are designed to support clinical pharmacists in general practice with implementing the guidance at a practice level. 

  • Agree the scope of patients to be seen within your competence—most clinical pharmacists should feel competent to review stable angina patients as part of their scope of practice in annual CVD reviews or medication reviews
  • Set up searches to identify patients to see in clinic; coding is essential for evaluating interventions, e.g. search for patients coded with angina who are not on an antiplatelet/statin/ACE-I
  • Familiarise yourself with local guidelines and formularies to ensure cost-effective practice 
  • Adopt an MDT approach and involve other HCPs when managing more complex patients
  • Know when and how to refer patients to other local services
  • Assess the following areas in your patient reviews:
    • symptom relief—check if the patient is on a GTN spray and review usage. If the patient is still symptomatic refer them to the GP or secondary care for further investigations, or consider medicines optimisation if it is within your scope of competence 
    • therapeutic preventative therapy—ensure the patient is on the correct preventative medications in line with the NICE and SIGN guidelines (including secondary prevention measures e.g. statins, ACE-I, nitrates). Check doses, adherence, interactions, side‑effects, and patient understanding, and ask about any upcoming surgery and provide appropriate medication advice 
    • lifestyle and mood—reinforce diet and lifestyle advice, establish current QoL and where they would like to be, assess mood, and refer on appropriately 
    • agree on a care plan, which aims to improve symptoms, QoL, and prevent deterioration by setting realistic and achievable goals with the patient
  • Evaluate your contribution to patients that you have managed in angina reviews, thinking about the following:
    • how many patients with stable angina have you reviewed?
    • how much time have you saved and freed up for additional appointment slots for other HCPs? 
    • what local cost-effective switches have you made? 
    • how many patients have experienced improvements in angina symptoms, QoL, or mood following your intervention?
    • how many patients have you optimised preventative therapy for by initiating an ACE-I/statin/nitrate?

CVD=cardiovascular disease; ACE-I=angiotensin-converting-enzyme inhibitor; MDT=multidisciplinary team; HCPs=healthcare professionals; GNT=glyceryl trinitrate; QoL=quality of life