Arrhythmia - focus on primary care

Dr Matthew Fay and Dr Andreas Wolff highlight the place of the GP in diagnosing patients with AF.

Arrhythmias are common, affecting 700,000 patients in the UK, of which 500,000 have AF. In a normal day in general practice at least one patient in the clinic will complain of symptoms potentially associated with cardiac dysrhythmia.

Symptoms
Palpitation is the uncomfortable awareness of the heart rhythm. Normal palpitations occur with exercise, emotion and stress, or after taking substances that increase adrenergic activity or decrease vagal activity.

Abnormal palpitations may occur for no reason and may be fast, or strong and slow, regular or irregular. The elderly are more likely to be aware of their heart beat. Many patients with rhythm disturbances will not have palpitations, instead experiencing syncope, shock and chest pain.

Syncope is a sudden but brief loss of consciousness caused by inadequate blood supply to the brain. Recovery is spontaneous and rapidly complete. Syncope is common, disabling and possibly associated with sudden cardiac death.

Vertigo describes a hallucination of movement of the environment about the patient, or of the patient with respect to the environment. It is not synonymous with dizziness.

Vertigo may be central, due to a disorder of the brainstem or the cerebellum, or peripheral, due to a disorder in the inner ear or the eighth cranial nerve.

The importance of history
When assessing a patient with potential cardiac problems it is important to know if they are experiencing their symptoms at the time of review. The haemodynamically unstable patient needs a rapid assessment of their state and history before calling for an ambulance.

It is important when taking a history from a patient that you clarify exactly what the patient means. Commonly patients will refer to 'dizziness', meaning light-headed rather than vertigo. Similarly, 'palpitations' can also refer to discomfort in the chest that a patient has associated with a cardiac symptom.

It is important to clarify how often they experience their symptoms, and if there are precipitating or relieving factors. Problems occurring when lying down or at rest may be more suggestive of simple ectopy.

If the presenting symptom is a palpitation then obtaining information about rhythm (regular or irregular) and rate is important. Asking the patient to tap out the nature of the palpitation on a desk can be informative. Associated features such as breathlessness and sweating are important to document.

Chest pain and the nature of that pain are always of concern when associated with palpitations or collapse.

Deeper discussion around the family history of cardiac problems should always be undertaken. Particular attention should be paid to sudden unexpected deaths, not only sudden cardiac deaths but also road traffic accidents or drowning, which could be hidden manifestations of inherited dysrhythmic problems.

A family history of epilepsy or fits could similarly be an expression of familiar dysrhythmic illness showing itself as hypoxic seizures. A strong family history of ischaemic heart disease is also of note.

The social health questions on smoking and alcohol are important. The most common cause of AF in people aged below 50 is alcohol excess.

Use of illicit drugs could be an indicator of medication-induced palpitations.

Examination
A standard physical examin-ation should be undertaken, assessing the general state of the patient and paying particular attention to any symptoms of thyroid disease, normal cardiovascular parameters of heart rate, rhythm and BP, and auscultation of the heart.

This can be augmented in the patient suffering from dizzy periods or funny turns with an erect and supine BP. This is performed with the patient lying for a period of at least 10 minutes before being asked to stand, with the BP taken within a minute of being erect.

Although the history and examination are not diagnostic, they can assist in risk-stratifying the patient (see box for high-risk features). If there is no access to a 12-lead ECG, a simple algorithm can be applied (see figure).

High-risk factors
High-risk features include:
  • Pre-existing structural heart disease.
  • History of heart failure.
  • History of syncope or presyncope.
  • Family history of sudden cardiac death (<40 years).
  • Exertion cardiac symptoms (including exertional palpitations).

If ECG is available with a practitioner skilled in the interpretation, the pathway is enhanced further.

Investigations
The symptom of palpitations can be a physiological response to other pathological processes, so a simple battery of blood tests should be performed.

These should include FBC to exclude anaemia and thyroid function to exclude both hyperthyroidism and hypothyroidism. LFTs and gamma GT can be of use in younger patients, because of the strong links between AF and alcohol use in the under 50s.

For true reassurance about the electrical activity of the heart, a 12-lead ECG is essential. Giving the basic outline of activity at rest can provide a clear diagnosis, as in the shortening of the P-R interval in Wolff-Parkinson-White syndrome, or the lack of P waves and the erratic rhythm of AF.

Unfortunately, a normal 12-lead ECG performed without symptoms cannot reassure that nothing is amiss. Even a 'normal' corrected Q-T interval can be a pathological problem in certain patients.

Further caution should be taken when examining the ECG of children, where the timings of the ECG are different. This should probably remain the remit of specialists.

If the patient's symptoms are sufficiently frequent, occurring two to three times a week, 24-hour ambulatory ECG may be able to detect a dysrhythmia; easy access to such devices in primary care has been shown to change referral practice.1

A detailed personal diary is important to use these devices to full effect, as a note of a patient's symptoms during a period of normal rhythm can be of assistance in excluding dysrhythmic illness.

Further investigations are available, frequently in secondary care, to help assess patients with exercise-induced symptoms or potentially high-risk arrhythmias that occur infrequently. These methods include exercise testing, tilt table testing and insertion of loop recorders.

Patient support
Support from charitable bodies
  • Dr Fay and Dr Wolff are GPSIs in cardiology at the Westcliffe Cardiology Service, Shipley, West Yorkshire
  • 8-14 June is Arrhythmia Awareness week. For more information visit www.aaaw.org.uk

References

1. Standing P, Dent M, Craig A, Glenville B. Changes in referral patterns to cardiac outpatient clinics with ambulatory ECG monitoring in general practice. Br J Cardiol 2001; 8: 394-8.

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