Atrial Fibrillation


Q1. Doctor, I have a cousin who is suffering from a condition known as atrial fibrillation. What is it really?

A1. Atrial fibrillation is a clinical condition characterised by rapid, irregular, and ineffective contraction of both the upper chambers of the heart (=atria, auricles).

Q2. What may be the cause of her atrial fibrillation?

A2. Atrial fibrillation may be caused by several diseases. The common causes include rheumatic heart disease, ischemic heart disease, sick sinus syndrome, thyrotoxicosis, cardiomyopathy, and certain types of congenital heart disease such as atrial septal defect. It may be caused by binge drinking (Holiday Heart Syndrome), and overdose of certain forms of medicine. In a pretty large number of patients, no cause is discovered even after thorough investigation; these are examples of lone atrial fibrillation.

Q3. What are the common complaints of a person who has atrial fibrillation?

A3. The patient may complain of palpitations, breathlessness, chest pain, and shortness of breath. There may be other symptoms, mostly related to the complications of atrial fibrillation; I shall discuss them later.

Q4. My cousin has frequent bouts of atrial fibrillation during her day-to-day activities. Can I give her a tablet under the tongue (isosorbide dinitrate, or glyceryl trinitrate)?

A4. The tablets mentioned by you may sometimes be useful in the initial management of chest pain, but have no role in atrial fibrillation. They should not be used in the management of this condition.

One or more tablets of flecainide can be quickly be swallowed to get rid of atrial fibrillation. There are many contra-indications for using flecainide, including ischemic heart disease. Therefore, your cousin must consult a cardiologist before taking that medicine.

Q5. Is atrial fibrillation a dangerous condition?

A5. Atrial fibrillation is a potentially dangerous condition because it may give rise to several complications.

Sometimes, the heart rate may rise to 200-250 beats per minute. This may give rise to breathlessness (= acute left ventricular failure), or precipitate a heart attack.

Ineffective contraction of the upper chambers can cause stasis of blood in the heart, leading to the formation of clots. A clot formation in the heart is potentially dangerous.

Q6. Why do you say that the clots are dangerous?

A6. Clots are dangerous because they can dislodge and settle in various parts of the body where they obstruct the flow of blood in the arteries. Absence of blood flow may lead to irreversible damage to the organ that is involved.

A common site is the brain, where it gives rise to stroke, and paralysis of one half of the body.

Another site is the eye, where it causes blindness.

A third site is the kidney, where it leads to the passage of copious amounts of blood, and blood-clots in the urine.

Yet another site is the lower limb, where it can give rise to gangrene, and eventual loss of the limb by way of amputation.

Q7. I can very well understand the gravity of the situation when a person has a clot in the heart. How can you tell whether a particular patient who comes to your chamber has a clot in their heart?

A7. Yes, this can be done with the help of trans-esophageal echocardiography (TEE).In this system, an echo probe is mounted on an endoscope. The latter is slowly swallowed by the patient until it reaches the food pipe. It is then gradually pushed down by the doctor until it reaches the level of the cardiac structures. The probe is carefully manipulated to get an excellent view of the 4 chambers of the heart. This is an excellent way to visualise clots inside the heart.

Q8. How can you prevent the formation of clots inside the heart?

A8. This can be done by administering oral anti-coagulants such as warfarin.

Q9. Please tell me some of the precautions that must be observed by someone who is being treated with warfarin.

A9. The patient must have their prothrombin time & INR (International Normalized Ratio) tested at regular intervals. This is done at monthly intervals for most patients, but it has to be individualised depending on the requirements of the subject.

Learn from your health care-giver the correct range of INR for you. A very low INR means that anti-coagulation is inadequate. It may predispose to the formation of clots inside the heart. On the contrary, a very high INR may be a risk factor for excessive bleeding in various places in the body, such as the brain.

It is extremely important to consult the doctor every time an INR test is done.

Q10. Are there antidotes for the people who develop high INR levels because of excessive warfarin intake?

A10. Yes, this condition is treated with the help of intravenous vitamin K injections, and/or fresh frozen plasma.

Q11. Getting a prothrombin time & INR test done and visiting a doctor frequently may be bothersome for people, especially for those coming from remote areas in the districts. Don’t you have any alternatives to warfarin?

A11. Newer Oral Anti-Coagulants (NOACs) such as dabigatran, rivaroxaban, and apixaban are suitable alternatives for warfarin. But they have their advantages as well as disadvantages.

The advantage of using these NOACs is that one need not get the prothrombin time & INR tested regularly and then go to the doctor.

Disadvantages are many. They are expensive. The monthly expenditure may range from Rs. 2,400/- to Rs.4,000/-. Moreover, they cannot be used in many patients who have damaged valves, or prosthetic heart valves.

Q12. Do you administer warfarin or the newer anti-coagulants (NOACs) to all your patients who have atrial fibrillation?

A12. No, we do not prescribe these medicines to each and every patient who has atrial fibrillation. The decision regarding anti-coagulation is based on the total number of points of the patient when we apply the CHA2DS2-VaSc score, as outlined below.

  • Age
  • <65: 0 points

    65-74: +1 point

    >=75: +2 points

  • Sex
  • Female: +1 point

    Male: 0 points

  • Congestive heart failure ( history)
  • No: 0 points

    Yes: +1 point

  • Hypertension (history)
  • No: 0 points

    Yes: +1 point

  • Stroke/TIA/thrombo-embolism
  • No: 0 points

    Yes: +2 points

  • Vascular disease (history)
  • No: 0 points

    Yes: +1 point

  • Diabetes mellitus (history)
  • No: 0 points

    Yes: +1 point

Total: 9 points (maximum)

Interpretation:
  • 0 points: no anti-coagulation
  • 1 point: “low-moderate risk”; anti-platelet therapy; some workers argue that anti-platelet
    therapy is not supported by adequate evidence
  • >=2 points: “moderate-high risk”; anti-coagulation
Q13. Now, all the anti-coagulants, be it warfarin or the newer oral anti-coagulants (NOACs), have a bleeding risk. Can you predict the bleeding risk of your patients who happen to be taking any of these agents?

A13. This can be done with the help of the HAS-BLED score, as outlined below.

  • Hypertension (i.e., uncontrolled blood pressure, >= 160 mmHg systolic): 1 point
  • Abnormal kidney*/liver** function : 1 or 2 points
  • Stroke: 1 point
  • Bleeding tendency or predisposition: 1 point
  • Labile INR (unstable/high INR, time in therapeutic range < 60%): 1 point
  • Age( >65): 1 point
  • Drugs (concomitant aspirin/NSAIDs), alcohol>8 drinks /week: 1 point

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Total: 9 points

* Abnormal kidney function = Creatinine > 2.25 mg/dl, or > 200 micro mol/L

** Abnormal liver function= cirrhosis, or bilirubin > 2 x normal with AST/ALT/AP > 3 x normal

Interpretation:
  • A score >= 3 points indicates high risk. Caution and regular review of the patient is needed.
Odds of having a bleed:
  • 0 points: 1.13 bleeds/100 patient years
  • 1 point : 1.02 bleeds/100 patient years
  • 2 points : 1.88 bleeds/100 patient years
  • 3 points : 3.74 bleeds/100 patient years
  • 4 points : 8.70 bleeds/100 patient years
  • 5-9 points : insufficient data

Disclaimer

The information given in this article is for the general knowledge of the members of the public, and is not intended to be a substitute for medical consultation. Please contact your health care provider for all advice regarding diet, life style, and medicines.