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28 September, 2015 00:00 00 AM
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Atrial fibrillation and stroke risk

he writer can be reached at [email protected]
Atrial fibrillation and stroke risk
EASY WAY TO JUDGE ARM WEAKNESS IS TO ASK THE PATIENT TO STRETCH OUT HIS/HER ARMS. IF HE/SHE HAS A STROKE HE WONT BE ABLE TO SO

Dr. Wrishi Raphael
The management of stroke is a multi faceted problem and requires a fair bit of clinical skills and professional acumen, on part of the emergency doctor. Stroke is one of the leading causes of death around the world. In developed countries like Australia it is the third most common cause of mortality. When a stroke occurs, the brain does not get enough oxygen or nutrients, which causes brain cells to die. Strokes occur due to problems with the blood supply to the brain; either the blood supply is blocked or a blood vessel within the brain ruptures. There are three main kinds of stroke; ischemic, hemorrhagic and TIA.
Stroke A focal neurological deficit lasting longer than 24 hours caused by intracerebral haemorrhage (bleeding due to rupture of blood vessels inside the brain) or infarction (the obstruction of the blood supply to a portion of the brain).
Stroke in evolution An enlarging neurological deficit, presumably due to infarction, which increases over 24- 48 hours.
Transient cerebral ischaemic attack (TIA) is a neurological deficit due to cerebral ischaemia (restriction of blood supply to
tissues), lasting less than 24 hours. TIA’s are very significant in clinical settings as one in ten patients with TIA may have a full blown stroke within 48 hours of a TIA. It is therefore very important to take preventive measures in patients with TIA so that they may not succumb to stroke in the future.
One of the commonest and potentially lethal cardiac
problems which are responsible for stroke is Atrial Fibrillation. Atrial Fibrillation may be defined as an abnormal and irregular heart rhythm in which electrical signals are generated chaotically throughout the upper chambers (atria) of the heart. Atrial Fibrillation is one of the strongest risk factors of stroke and other related conditions like TIA.
Some common causes of atrial fibrillation are rheumatic heart disease, hypertension and coronary artery disease like heart attack. Those who have atrial fibrillation may experience signs and symptoms such as:
Palpitations, which are sensations of a racing, uncomfortable, irregular heartbeat or a flip-flopping in your chest
Weakness
Reduced ability to exercise
Fatigue
Lightheadedness
Dizziness
Confusion
Shortness of breath

Chest pain
Lone, asymptomatic atrial fibrillation with no risk factors has very little association with stroke but for a patient with TIA or heart disease it is vital to do a bed side ECG and check for the presence or absence of atrial fibrillation. The CHADS2 score is a valuable tool to determine whether a patient with atrial fibrillation will develop a stroke or not.
If a person with atrial fibrillation has no risk factors for stroke as shown in the figure, he must be started on Aspirin (100-300 mg daily). If he scores 1 point, medications like Warfarin or Aspirin is recommended.
If the score is greater than 1, Warfarin must be started. The efficacy of Warfarin can only be evaluated by checking INR (target INR for such patient is 2-3). The INR or International Normalized Ratio reflects the patient’s ability of produce blood clots. If INR is high the patient’s ability to produce clots is simultaneously reduced and vice versa. In short it may be discerned that treatment with Warfarin subsequently reduces a patient’s ability to have a stroke which is so common in patients with atrial fibrillation.       
It is good for emergency room doctors to remember that if a patient with rheumatic heart disease or any other problems of heart valves presents with atrial fibrillation; such a patient is at a much higher risk of developing stroke. Such patients should be started on warfarin as soon as possible.  
The ECG findings of atrial fibrillation are given below:
Irregularly irregular rhythm.
No P waves.
Absence of an isoelectric
baseline.
Variable ventricular rate.
QRS complexes usually  < 120 ms unless pre-existing bundle branch block, accessory pathway, or rate related aberrant conduction.
Fibrillatory waves may be present and can be either fine (amplitude < 0.5mm) or coarse (amplitude >0.5mm).
Fibrillatory waves may mimic P waves leading to misdiagnosis.
This screening tool is useful as a predictor for risk of stroke in the first 7 days of a TIA.
A = Age ≥60 years (1 point)
B = BP ≥140 systolic or ≥ 90 diastolic (1 point)
C = Clinical features: any unilateral limb weakness (2 points), speech impairment without weakness (1 point)
D = Duration: ≥6o minutes (2 points), 10-59 minutes (1 point)
D = Diabetes: 1 point
Maximum 7 points
>4 = high risk
≤4 = low risk.
The writer can be reached at
[email protected]

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Editor : M. Shamsur Rahman

Published by the Editor on behalf of Independent Publications Limited at Media Printers, 446/H, Tejgaon I/A, Dhaka-1215.
Editorial, News & Commercial Offices : Beximco Media Complex, 149-150 Tejgaon I/A, Dhaka-1208, Bangladesh. GPO Box No. 934, Dhaka-1000.

Editor : M. Shamsur Rahman
Published by the Editor on behalf of Independent Publications Limited at Media Printers, 446/H, Tejgaon I/A, Dhaka-1215.
Editorial, News & Commercial Offices : Beximco Media Complex, 149-150 Tejgaon I/A, Dhaka-1208, Bangladesh. GPO Box No. 934, Dhaka-1000.

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