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Back to Cardiovascular Diseases
Atrial fibrillation
Treatment
Left untreated, the overactive heart muscle can weaken and stretch
out. This makes it harder for the atria to contract properly, so blood
backs up even more. This problem not only increases the risk of stroke,
but it can also lead to congestive heart failure. Treating AF correctly
is the best way to reduce stroke risk. Therapy is indicated in patients
with persistent, permanent or recurrent paroxysmal AF. The goals of treatment plans for
AF are:
- Prevent blood clots from forming
- Heart rate control within a relatively normal range
- Restore a normal heart rhythm, if symptomatic
Medicine to prevent clots
To lower the risk of stroke either aspirin or Warfarin are generally
prescribed. Aspirin has an antiplatelet effect and is less likely to
cause abnormal bleeding, but Warfarin seems to be more effective at
preventing clot-caused strokes. Regular INR tests are carried out to
monitor the dose of Warfarin. INR should usually test between 2.0 and
3.0.
The choice of giving a patient Warfarin or aspirin depends on the
patient's risk factors for development of thromboembolic disease. This
can be determined by assessing a patient's CHADS2 score.[5]
- CHF (1 point)
- Hypertension (1 point)
- Age 75 (1 point)
- Diabetes (1 point)
- Second stroke (2 points)
A patient with a low score (0) can receive aspirin 325 mg daily for
prophylaxis against coagulation. Those with an intermediate score (1-2)
can receive either aspirin or Warfarin depending on the patient's
preference. Those with a high CHADS2 score (3 or more) should receive
Warfarin prophylaxis to maintain an INR of 2.0-3.0, unless
contraindicated (e.g., history of falls, clinically significant GI
bleeding, inability to obtain regular INR screening).
Rate control
- Beta-blockers (like metoprolol, carvedilol or propanolol) and
calcium-channel blockers (like verapamil or diltiazem), which slow
the heart rate;
- Digoxin, which slows the heart rate through the AV node,
therefore decreasing the rate at which the electrical impulses
conduct from the atria to the ventricles.
- In cases who are refractory to the above measures or in those
with heart failure or pre-exitation syndrome, use amiodarone,
consider cardiac consultation,
Rhythm control (cardioversion)
Cardioversion changes an abnormal heart rate back to a normal one.
Cardioversion can be done through medication or through electricity.
Based on the AFFIRM, RACE and STAF trials rate control with
anticoagulation is the preferred treatment. Rhythm control
(cardioversion) in asymptomatic patients does not appear to affect
survival. Electrical or chemical cardioversion may be required in
symptomatic cases or in emergency situations such as those with
cardiovascular instability and heart failure.
Medicines include amiodarone, dofetilide, disopyramide, flecainide
and procainamide.
Electrical cardioversion is typically used to treat cases of persistent
or permanent AF, and it is often used with medication.
There are two types of electrical cardioversion: external and
internal. For external cardioversion, two external paddles are placed on
the patient?s chest or on the chest and back. A high-energy electrical
shock is sent through the patches, through the body to the heart. The
energy shocks the heart out of AF and back into normal rhythm.
Internal cardioversion uses a similar approach, but instead of using
paddles on the outside of the body, a catheter is inserted through a
vein to the heart. The electrical energy is delivered through the
catheter to the inside of the heart to stop the AF. Internal
cardioversion has met with high success and provides an alternative to
external cardioversion.
Ablation
Cardiac ablation is a medical procedure performed to prevent abnormal
electrical impulses from ever beginning in the first place. In an
ablation procedure, the electrophysiologist first does mapping, which
means the precise area in the heart at which the abnormal signals start
are pin-pointed. The electrophysiologist then eliminates the small area
of tissue that is causing the arrhythmia.
There is also a procedure called AV nodal ablation. This involves
ablating the AV node, keeping the abnormal impulses from traveling to
the heart?s lower chambers. A pacemaker is used to regulate the
heartbeat after this therapy.
AF Suppression
AF Suppression is designed to suppress atrial fibrillation (AF). An
implanted pacemaker stimulates the heart in a way that preempts any
irregular rhythms.
A clinical study has found that a software-based AF Suppression
algorithm can suppress symptomatic paroxysmal and persistent AF better
than standard pacing. The AF Suppression algorithm is available in
certain ICDs and pacemakers manufactured by St. Jude Medical.
Prognosis and survival
Prognosis is related to the underlying cause; it is excellent when
due to idiopathic atrial fibrillation and relatively poor when due to
ischemic cardiomyopathy. Healthy life style, regular checks on blood
pressure and treatment for raised blood pressure can reduce the chances
of developing the heart problems that cause atrial fibrillation.
Some study results
Among people with atrial fibrillation who not are taking the
anticoagulant drug Warfarin, women are more likely to form dangerous
blood clots than men, according to a study.
Men who explode with anger or expect the worst from people are more
likely to develop an irregular heart rhythm called atrial fibrillation,
according to another study report.
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