Cardiology Series: Case 5

ANSWERS WILL BE POSTED TOMORROW 7/2/17

A 79-year old gentleman presents to A&E with fatigue, chest discomfort and palpitations with increased shortness of breath. These symptoms started just two hours before presentation.

You obtain the ECG result below:

Image result for atrial fibrillation ecg

Source: http://www.healio.com/cardiology/learn-the-heart/ecg-review/ecg-archive/atrial-fibrillation-with-rvr-ecg-3

1. Describe the ECG findings without making a diagnosis.

2. What is the most likely diagnosis in this patient ?

3. How would you investigate this patient even further ? 

4. How would you manage this patient ? 

5. What are the major complications that may arise in this patient ?

6. Comment on the overall prognosis.

Source: http://almostadoctor.co.uk/content/systems/-cardiovascular-system/atrial-fibrillation


ANSWERS

1. Rate= 120 beats/min
Irregularly Irregular Rhythm
ECG shows absent P waves and irregular R-R intervals across all the leads.
Narrow QRS complexes (normal= 3-5 small squares) can also be seen.

2. Atrial Fibrillation (AF). Paroxysmal if intermittent AF, defined as AF that resolves with or without treatment in less than 7 days.

3. Investigations

Primary Investigations

  • Complete history and physical examination
  • Transthoracic echocardiogram
  • Complete Blood Count
  • Thyroid stimulating hormone (TSH) serum level

Secondary Investigations

  • Chest X-ray
  • Transesophageal echocardiogram
  • Ambulatory Holter monitoring for 24 hours to assess the heart rate and rhythm.
  • Exercise Stress Testing

4. Management

Rate and Rhythm control are used to prevent circulatory instability. Where as anticoagulation is used to prevent the prevalence of stroke. Immediate cardioversion is indicated if cardiovascularly unstable due to uncontrolled tachycardia.

Rate and Rhythm control

Rate control lowers the heart rate closer to normal values (60-100 b.p.m.) and is important in the chronic phase of AF. Rhythm control restores the rhythm of the heart by cardioversion and is vital in the acute phase of AF (<48H).

Rate Control

This is achieved by increasing the degree of block at the level of the AV node. Hence, reducing the number of impulses that conduct into the ventricles. The following medications are used:

  • Beta-blockers e.g. metoprolol, atenolol, bisoprolol
  • Non-dihydropyridine calcium channel blockers e.g. diltiazem or verapamil
  • Cardiac Glycosides e.g. digoxin

In those with Chronic AF, Beta-blockers and Calcium channel blockers are used.

When agents are contraindicated, particularly due to hypotension, Amioderone is used intravenously.

Rhythm control 

Cardioversion is available as two types- electical and chemical cardioversion.

Electrical cardioversion involves the application of a DC electrical shock.

Chemical cardioversion is achieved through the administration of drugs such as:

  • Amiodarone
  • Procainamide
  • Flecainide

Anticoagulation

The risk of stroke is estimated using the CHA2DS2-VASc score.

Anticoagulation is routinely achieved through the oral administration of vitamin K antagonists e.g. warfarin. Aspirin is less effective at reducing the risk of stroke.

Surgery
Radiofrequency ablation is also used to achieve rhythm control in young people with minimal or absent structural cardiac defects.

Note: In those with a fast ventricular response, intravenous magnesium significantly increases the chances of successful rate and rhythm control in the emergency setting without any major side-effects.

5. Complications of AF 

  • Stroke
  • Heart Failure

6. Prognosis

Atrial fibrillation increases the risk of heart failure by 11 per 1000, kidney problems by 6 per 1000, death by 4 per 1000, stroke by 3 per 1000, and coronary heart disease by 1 per 1000.[63] Women have a worse outcome overall than men.

 

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