Footnotes:

1. An exercise test is a poor diagnostic test in patients with low risk of CHD. There is a high risk of false positive results.
2. Even when the diagnosis of angina is clear further investigation is appropriate for most patients.
3. Patients with proven coronary artery disease and stable symptoms may not need further investigation if revascularisation is not wanted by the patient or is considered inappropriate.
4. A negative exercise test does not exclude coronary artery disease, especially if performed while taking antianginal medication.

Summary version of evidence based guideline for the primary care management of stable angina

Extracted from: North of England Stable Angina Guideline Development Group

BMJ, 1996; 312 : 827 32

Throughout this guideline categories of evidence (cited as I, II, and III) and the strength of recommendations (A, B, or C) are noted. (I = best evidence, A = strongest recommendation).

Investigation of angina

Patients being investigated for angina should have the following investigations

• Haemoglobin measurement to identify anaemia (C)
• Thyroid function measurements to identify thyroid disease (C)
• Blood glucose measurement to identify diabetes mellitus (C)
• Serum cholesterol measurement (see risk factor management) (A).

Resting 12 lead electrocardiogram

• All patients with angina should have a resting 12 lead electrocardiogram (B).
• A normal resting 12 lead electrocardiogram does not exclude coronary artery disease (11).

Exercise testing

• Exercise testing is effective in prognostically grouping patients, all patients with clinically certain angina should have an exercise test (13).
• Patients having an exercise test for prognostic investigation and treatment should have the test performed while taking their normal medication (B).

People who should not have an exercise test are

• Those whose symptoms arc uncontrolled by maximal medical treatment (they should be referred to a cardiologist for angiography, not exercise testing) (C)
• Those in whom the diagnosis is currently uncertain.
• Those who are physically incapable of performing the test (C)
• Those with comorbid illness that is currently more important (C).
• Those who decline the test (C).

An open access exercise testing service can be used appropriately by general practitioners (11).

Management of risk factors

• All patients with angina should have their serum cholesterol concentration measured (A).
• All patients should have their blood pressure measured (C).
• Patients with angina who smoke should be advised to stop (A).
• No one strategy is effective for all patients; advice and strategies should be tailored to individual circumstances (C).
• Nicotine patches can safely be used to help patients with coronary artery disease stop smoking (A).
• Moderate exercise within a patient's capabilities should be recommended to improve general fitness and well-being (C).
• Patients with a raised body mass index should be encouraged to reduce their weight until their body mass index is normal (C).

Driving

The law requires notification by an applicant or licence holder to the Driver and Vehicle Licensing Agency immediately on diagnosis of any disability that is likely to affect safe driving. The medical practitioner's role is to advise the patient on the basis of the severity of the condition.

Drug treatment

All recommendations for drug treatment apply only in the absence of recognised contraindications, side effects, or interactions as documented in the British National Formulury.

• It is important to ensure that patients are complying with treatment and that any side effects are known (C).
• Within any drug class patients should be treated with the cheapest preparation that they can tolerate, will comply with, and which controls their symptoms (C).

Secondary prophylactic treatment

• All patients should be treated with aspirin 75 - 300 mg daily (A). Aspirin in high risk groups lowers the risk of subsequent vascular events (I).

Initial symptomatic treatment

• Patients with angina should take sublingual glyceryl trinitrate as required (C).
• For all but minimal symptoms patients should be given regular symptomatic treatment (C).

Regular symptomatic treatment

• All patients who require regular symptomatic treatment should be treated with a B blocker (B).
• Patients should be warned not to stop B blockers suddenly or allow them to run out (B).

Patients who have a myocardial infarction and are given B blockers have a subsequently lower mortality (I). B blockers are as effective as other drug groups when used as monotherapy (I).

Substitution monotherapy in patients intolerant of B blockers

• Patients intolerant of B blockers should be treated with verapamil (C).
• If a patient cannot tolerate a B blocker or verapamil, then there is no clear basis from the evidence for choosing substitution monotherapy. Patients should therefore be given the cheapest drug with which they can comply and which controls their symptoms (C).

Nitrates

Oral nitrates are effective when used as a sustained release preparation, as an eccentrically dosed twice daily preparation, or as a thrice daily preparation (I),

• All nitrates, both oral and patches, should be used in a way that avoids nitrate tolerance (A).
• Nitrate patches should be used in dosages of at least 10 mg (A).

Calcium channel blockers

Calcium channel blockers when used alone are more effective than placebo (I) and are all equally effective (I).

Choosing a second drug

• In patients taking B blockers add a dihydroprydine (A). (eg Nifedipine, amlodipine etc)
• In patients taking B blockers who cannot tolerate dihydropyridines add isosorbide mononitrate (A).
• In patients taking dihydropyridines add isosorbide mononitrate (C).
• In patients taking nitrates add any calcium channel blocker (C).

Choosing a third drug

• If patients are not adequately controlled by maximal therapeutic dose of two drugs, then the remaining evidence based therapeutic options are very limited. These patients should be referred rather than given a third drug (C).
• If a third drug is introduced - for instance, while the patient is awaiting an outpatient appointment - its effect should be monitored and if it has no effect it should be stopped (C).

Referral to a specialist

Referral from a general practitioner to a specialist will be for one of three reasons:

• to identify whether the patient falls into a group that would benefit from prognostic investigation and treatment;
• to establish a diagnosis;
• for management advice.

The point of referral will be influenced by whether open access exercise testing facilities are available.

In patients considered for referral the decision will be influenced by:

• Clinical factors - pain on minimal exertion, nocturnal pain, rapidly progressive symptoms, possible aortic stenosis, failure to respond to medical treatment, previous myocardial infarction.
• Age and duration of disease
• Comorbidity
• Risk factors
• Patient preference
• Threat to employment or unacceptable interference with lifestyle or recreation.

These factors represent a range for most patients and their effect on the decision will be additive. The referral decision cannot be taken in isolation and needs to be set in the current context of the patient.

Emergency Admission to Hospital

1. Possible acute myocardial infarction
   Patients with stable angina are at greatly increased risk of myocardial infarction. Patients with stable angina should telephone 999 for an ambulance in the event of pain of unusual severity or lasting longer than 15 minutes despite appropriate drug treatment.
2. Unstable angina
   Unstable angina is defined as angina that is rapidly worsening in frequency, severity or duration. The risk of MI in this group is high (around 20% in the first month) and reduced by in-hospital intervention. Emergency admission is appropriate for patients

• with an abrupt worsening of previously stable angina or
• new angina angina occurring without provocation (exertion, anxiety etc)

Bradley Cheek 1999