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Annie is 69 years old and has recently registered as a new patient.

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Please answer the questions by filling in the free text box after each question. Once you submit your answer a 'model' answer for the question will be shown. The answers given for each section are example answers and do not necessarily mean that the answers you give are wrong.

Annie is 69 years old and has recently registered as a new patient. She has moved into the area recently to be nearer her daughter and son-in-law (patients of yours), but lives independently and alone. On joining the practice she is seen by the practice nurse who finds it difficult to take her blood pressure (recorded twice at the clinic visit, using a mercury sphygmomanometer, range 134-166/82-96mmHg). Examination reveals an irregularly, irregular pulse, and Annie confirms that for "the last few years" she has had infrequent episodes of palpitations. Annie feels well, is experiencing no medical problems or symptoms. She was diagnosed with hyperthyroidism six years ago but is not currently taking any medication.

1

What risk factors does Annie have for the development of atrial fibrillation (AF)?

Suggested answer:

Hypertension and hyperthyroidism are two of the most common causes of atrial fibrillation. [1] The prevalence of AF also increases with age. [1]

References

1. Clinical Knowledge Summaries. Atrial fibrillation. Last revised August 2009

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2

What other information about her family or clinical history would you like to know?

Suggested answer:

This may include the following -

  • Does she have any other personal or family history of cardiovascular disease (CVD) e.g. stroke, myocardial infarction, or any other relevant co-morbidities, particularly those that may be associated with AF e.g. diabetes?
  • Is she a smoker, or has she ever smoked?
  • What are the results of any relevant monitoring e.g. renal function, cholesterol, thyroid function, blood glucose?
  • What is her body mass index (BMI)?
  • Does she eat healthily, take regular exercise, and avoid excessive alcohol intake? [1]
  • Dietary and lifestyle factors that may be associated with AF include excessive caffeine, obesity and excessive alcohol consumption. [2]

References

1. NICE. Clinical guideline 67. Lipid modification. Cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease. May 2008.

2. Clinical Knowledge Summaries. Atrial fibrillation. Last revised August 2009

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3

Your investigations reveal that Annie is tee-total and a life-long non-smoker. She doesn't have any other personal or family history of CVD. She likes to walk 0.5 miles into town most days but often eats convenience foods. Her BMI is 22 kg/m2. Recent routine blood test results are:

  • Random plasma glucose level well within the reference range.
  • Urea and electrolytes, liver function and full blood count tests not remarkable.
  • Total Cholesterol is 5.2 mmol/L and her HDL Cholesterol is 1.3 mmol/L.
  • Thyroid function test (TFT) was last undertaken two years ago: T3 and T4 were within normal limits, but TSH was suppressed.

At this consultation, which of the interventions/treatments below would you initiate? More than one answer may be appropriate.

A. Lifestyle advice on healthy eating, salt intake, exercise etc.

B. Referral for an electrocardiogram (ECG)

C. Routine thyroid function test

D. Referral for specialist advice on management of thyroid function

E. Drug treatment for hypertension

F. Antiplatelet treatment with aspirin

G. Antiplatelet treatment with clopidogrel

H. Anticoagulation with warfarin

I. Statin therapy

J. Treatment to control heart rate

K Treatment to control heart rhythm

Suggested answer: : A, B and C

Annie's last TFT two years ago appeared to show subclinical hyperthyroidism, however this should be re-checked. Referral is not required at this stage, but should overt hyperthyroidism be confirmed, Annie should then be referred for specialist advice. [1]

It is likely that Annie has AF ― she has an irregular pulse and several important risk factors for the development of AF. However, antithrombotic or antiarrhythmic treatments should not be initiated until this is confirmed. NICE recommend that an ECG should be performed on all patients in whom AF is suspected because an irregular pulse has been detected. [2] If AF is confirmed, antithrombotic therapy will be indicated (see question 4), as well as considering heart rate and/or rhythm control (see questions 5 and 6), but these treatments should not be initiated at this consultation.

Smoking, raised blood pressure and raised cholesterol are the three modifiable risk factors that make a major contribution to CVD risk, particularly in combination. [3] Annie has never smoked but may be hypertensive and does have a slightly elevated cholesterol. NICE recommends calculating 10-year CVD risk using the Framingham risk equations. Annie currently has around a 10-20% risk of developing CVD over the next 10 years, therefore statin therapy would not currently be indicated. [3] Therefore, all other modifiable CVD risk factors should be considered and their management optimised if possible. [3] For Annie, this involves dietary and lifestyle advice, including looking at her salt intake, and most importantly management of her blood pressure.

It is important to confirm a diagnosis of hypertension (persistent raised blood pressure above 140/90 mmHg) by repeated readings at two future clinic visits. Starting antihypertensive treatment would not be appropriate at this stage. [4] NICE recommend that antihypertensive drug therapy is offered to patients with persistent high blood pressure of 160/100 mmHg or more, or patients at a 10-year risk of CVD of 20% or more or existing CVD or target organ damage with persistent blood pressure of more than 140/90 mmHg. [4] However, decisions about the diagnosis and management of hypertension and AF in combination may require specialist advice.

References

1. Clinical Knowledge Summaries. Hyperthyroidism. Last revised March 2008

2. NICE. Clinical guideline 36. Atrial fibrillation ― The management of atrial fibrillation. June 2006

3. NICE. Clinical guideline 67. Lipid modification. Cardiovascular risk assessment and the modification of blood lipids for the primary and secondary prevention of cardiovascular disease. May 2008.

4. NICE. Hypertension - Management of hypertension in adults in primary care. June 2006

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4

Annie's diagnosis of persistent AF is confirmed by a 24 hour ECG. Her blood pressure on subsequent readings is found to be around 150-158/90-96 mmHg. Her TFT now shows raised T3 and T4, with negligible TSH, and you refer her for specialist advice.

Firstly, what are her options for antithrombotic therapy?

A. Aspirin alone

B. Warfarin alone

C. Clopidogrel alone

D. Aspirin and clopidogrel

E. Aspirin and dipyridamole

F. Aspirin and warfarin

Answers: A and B

According to the NICE stroke risk stratification algorithm (see figure 1 below), either anticoagulation with warfarin or the use of aspirin is recommended for someone like Annie, who is at moderate risk of stroke/thromboembolism. [1] The choice of treatment is a trade-off between the risks and benefits. Warfarin is more effective than aspirin - it reduces the relative risk of all strokes by about 60%, compared with placebo, while aspirin reduces the risk by about 20%, in people with AF. [2] Warfarin would certainly be preferable to aspirin in people with AF at a high risk of stroke, e.g. those with a previous TIA or stroke. [1] But, for people like Annie, this has to be weighed against the excess risk of bleeds and the acceptability of treatment to the patient, taking into account her individual risk of stroke/thromboembolism.

Clopidogrel is unlicensed for AF and there is no trial evidence to support its use as monotherapy. [3] However, there is no reason to think that clopidogrel would be any more effective or better tolerated than aspirin. There is good evidence from the ACTIVE W trial that people with AF at moderate to high risk of stroke taking a combination of aspirin plus clopidogrel are more likely to suffer major cardiovascular events and bleeding than those taking warfarin. [4] The combination of modified-release dipyridamole and aspirin is recommended for people who have had an ischaemic stroke or a TIA for a period of two years from the most recent event, which is not applicable to Annie. [5] Aspirin and warfarin combination therapy provides no additional benefit over monotherapy. [1]

Figure 1

References

1. NICE. Clinical guideline 36. Atrial fibrillation ― The management of atrial fibrillation. June 2006

2. Hart RG, et al. Antithrombotic therapy to prevent stroke in patients with atrial fibrillation: a meta-analysis. Ann Intern Med 1999;131:492-501

3. Clinical Knowledge Summaries. Atrial fibrillation. Last revised August 2009

4. The ACTIVE Writing Group. Clopidogrel plus aspirin versus oral anticoagulation for atrial fibrillation in the Atrial fibrillation Clopidogrel Trial with Irbesartan for prevention of Vascular Events (ACTIVE W): a randomised controlled trial. Lancet 2006;367:1903-12

5. NICE. Technology appraisal 90. Clopidogrel and modified-release dipyridamole in the prevention of occlusive vascular events. May 2005

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5

After careful discussion using the NPCi Patient decision aid, Annie decides to start warfarin. The aim is to keep her INR in the range 2.0 to 3.0, with a target value of 2.5.

Is an approach based on rate control or rhythm control preferable for Annie?

Although Annie does seem to experience occasional episodes of symptomatic AF, as we heard earlier, the results of the 24-hour ECG confirms that it is present all the time, i.e. it is persistent rather than paroxysmal. Following the NICE treatment strategy decision tree (see Figure 2 below), either rhythm control or rate control would be appropriate for a person with persistent AF. [1] However, Annie is over 65 years, does not appear to be particularly bothered by symptoms, nor does she have congestive heart failure. Therefore, the use of a rate control strategy may be more appropriate. NICE recommends that the potential advantages and disadvantages of each approach should be discussed with patients, taking into account their particular circumstances. [1] The use of rate control rather than rhythm control is not associated with any greater risk of stroke or overall mortality, and gives similar relief of symptoms in most patients, compared with rhythm control - although rhythm control gives better exercise tolerance in younger people. [2] Rate control is associated with fewer adverse effects of treatment and reduced need for hospitalisation. [2]

Figure 2

References

1. NICE. Clinical guideline 36. Atrial fibrillation ― The management of atrial fibrillation. June 2006

2. Chung MK, et al. Atrial fibrillation: Rate control is as good as rhythm control for some, but not all. Clev Clin J Med 2003; 70: 567-73

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6

Assuming a rate-control strategy is chosen, what, if any, of the following would be your next medication(s) for Annie?

A. Atenolol

B. Verapamil

C. Digoxin

D. Bendroflumethiazide

E. Amlodipine

F. Enalapril

G. None

Answers: A or B

Either a standard beta-blocker or a rate-limiting calcium antagonist are the first choice treatments for rate-control of persistent AF. [1] Atenolol and verapamil are licensed for both hypertension and control of arrhythmias, so might be considered for Annie.

Annie's blood pressure is approaching the threshold for treatment with antihypertensive therapy (160/100 mmHg). [2] However, the introduction of atenolol or verapamil for her AF, in addition to lifestyle measures, including reduced salt consumption, should help to improve this. Clearly, her blood pressure and cardiovascular risk should be reviewed regularly, and consideration given to initiating blood pressure lowering therapy, and/or a statin to reduce her CVD risk, should that become necessary.

References

1. NICE. Clinical guideline 36. Atrial fibrillation ― The management of atrial fibrillation. June 2006

2. NICE. Hypertension - Management of hypertension in adults in primary care. June 2006

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