Answer: Dear Ms. Johnson! Normally, the electrical activity of the heart spontaneously starts from the region of the heart’s electrical system called Sinus node which is sort of a built in internal pacemaker. This normally fires from 60-100 beats per minute. When your heart goes into atrial fibrillation the upper chambers can beat ineffectively up to 400-600 beat per minute. This rapid rhythm will automatically suppress the sinus node. When the atrial fibrillation terminates, the sinus node which has been suppressed takes a few seconds to recover. This slight delay in recovery to resume the heart’s electrical activity is what is termed as post conversion pause. Factors that will suggest if these conversion pauses are pathologic are not – age, was there any evidence of sinus node problems in the absence of AF, antiarrhythmic medication type and dose, and the severity of symptoms. A small percentage of elderly patients have underlying sinus node dysfunction along with AF – which is termed as tachybrady syndrome in medical terms. These patients exhibit severe slowing of heart rates along with rapid heart rates when they are in atrial fibrillation. The medications like beta blockers, calcium channel blockers, digoxin and antiarrhythmic drugs (flecainide, propaphenone, sotalol, amiodarone and dofetalide etc) can make their heart rates much slower exacerbating symptoms.
There is strong evidence that once the AF is addressed the sinus node function seems to improve significantly. A study from Michel Haissaguerre’s group has clearly demonstrated this phenomenon in their paper in Circulation in 2003. I suggest you should probably think of AF ablation if your physician considers you to be an appropriate candidate. If you continue to have severe symptomatic pauses despite excellent rhythm control then you will need a pacemaker at that point.