How fast do atria dilate due to afib and is this process reversible?

Does paroxysmal fibrillation cause dilatation of atria? And can atria shrink if patient is afib free for, say, 4 weeks?

Yes, it does. It depends on the length and frequency of episodes.

Nothing’s going to change much in 4 weeks. There may be some “reverse remodeling” that happens as a result of prolonged NSR, but that takes years. Whether or not there’s a reduction in the left atrial dimensions I’m not sure. Haven’t read any studies on atrial size post-ablation.

Atria can shrink once afib is halted, but it takes many months at a minimum. Like wolfpack said, nothing much is going to happen in four weeks.

I've paroxysmal afib since Nov 2015. In three years, I've had more than 250 afib episodes, for a total time exceeding 500hrs.
My heart chambers are still perfectly normal.

It's very individual. I know of people with severely enlarged atria who've experienced less afib than you.

Sleep apnoea will dilate the left atria very ‘effectively’ all by itself.

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Carey
It's very individual. I know of people with severely enlarged atria who've experienced less afib than you.

Of course, you're right, we're all different. But do those people have enlarged atria because of afib or the opposite? Or does their afib enlarge already enlarged atria?
And what's "less afib"? I don't know how it works in this case, but having 250*2h afib in three years is likely different for the heart than having, say, 5*100h afib during the same time...

Knowing the cause and effect would also be individual. A hard-core endurance athlete? Enlarged atria are probably the cause. A couch potato? Enlarged atria are probably the effect.

When I say "more" or "less" afib I mean afib burden, which is just the percent of time spent in afib at a tachycardic rate. People with persistent afib who are on effective rate control don't usually experience enlarged atria, but the ones who can't/don't control the rate do.

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Pompon

Of course, you're right, we're all different. But do those people have enlarged atria because of afib or the opposite? Or does their afib enlarge already enlarged atria?
And what's "less afib"? I don't know how it works in this case, but having 250*2h afib in three years is likely different for the heart than having, say, 5*100h afib during the same time...

About 2 months in to my afib "career", over 14 years ago, I had a 2.5 month persistent episode. Over 1800 hours in afib during that episode. My path to afib was chronic fitness. An echocardiogram 5 or 6 weeks into that episode showed an EF of 54%. I do recall a somewhat enlarged atria, but don't recall the measurement - which could have been from the chronic fitness. Also, I thought that I should continue exercising as much as I could while in afib (I was not on rate control). I would not use that approach today. I never repeated the echo as my afib burden has dropped dramatically (between 0.01-0.22% depending on the year). I'm quite convinced that reverse remodeling occurred for me. This is because, though I don't do endurance training or exercise, I remain quite fit for my age (63). I easily carry a climbing pack (50-70 #'s, 23-32 kg) up long, steep approaches at 7,000+' (2,100m), climb for 6 or more hours and ski the steeps off piste for 6 or more hours non-stop. When I say reverse remodeling, I do not mean I've "cured" afib. Far from it. If I stop doing my protocol, afib will make a visit to me in very short order!

George



Edited 1 time(s). Last edit at 12/29/2018 02:11PM by GeorgeN.

Can my moderate (below 130bpm) avg HR during afib explain that my atria are still normal after more than 500 hrs in afib in three years? Or is it the shortness of the episodes?
Okay. It's both, Sir.

Thanks, George.
The fact is I'm far less stressed with my short but frequent episodes than I was when they were longer but less frequent. Persistent afib must be awful.

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Pompon
Persistent afib must be awful.

I think it varies significantly between persons. At that time, my resting afib heart rate was in the 80's (now more like 100-130, but doesn't last very long). I've always been asymptomatic in afib. I did have lower heart output, so when I tried to exercise, I was limited compared to what I could do in NSR. Now I don't try to exercise in afib, not sure how I'd address this if I were in long persistent afib. Several reasons for not exercising in afib. One is I'm not sure it helps the atria to push them harder - i.e. perhaps more remodelling. Two, with the exception of the last conversion, seven months ago, where I used exhaled breath holding to convert, I've used flecainide. Doing very little after I take flec, and generally remaining prone, is my strategy to minimize the possibility of flutter (I don't use rate control).

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Pompon
Persistent afib must be awful.

Actually, a lot of people with persistent afib don't feel it at all. It's often diagnosed incidentally during an exam for some other issue. There don't seem to be many (any?) persistent afibbers here, but there are a number of them on stopafib.org and most report feeling few if any symptoms.

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Carey

Persistent afib must be awful.

Actually, a lot of people with persistent afib don't feel it at all. It's often diagnosed incidentally during an exam for some other issue. There don't seem to be many (any?) persistent afibbers here, but there are a number of them on stopafib.org and most report feeling few if any symptoms.

Question about persistent Afib....

does this mean your heart is quivering 24/7? So, the blood is pooling in the top chambers of your heart? Doesn't this cause heart failure pretty quickly?

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katesshadow
Question about persistent Afib....

does this mean your heart is quivering 24/7? So, the blood is pooling in the top chambers of your heart? Doesn't this cause heart failure pretty quickly?

Yep, persistent afib means you're constantly in afib and have been for a week or more. After months of persistent afib, it's called longstanding persistent. And if you decide you're not going to attempt to stop it with drugs or ablation, it's called permanent afib.

It doesn't cause heart failure as long as you take effective rate control medications to keep your ventricular rate under 100. Most people with persistent afib take a beta blocker daily for this purpose. I know a guy who's 70, he's in permanent afib and has been for years. He takes a daily beta blocker and an anticoagulant. His resting heart rate is in the 70s with the beta blocker, and he competes in senior marathons. He's completely asymptomatic and doesn't feel the afib at all.

It's a high ventricular rate that leads to heart failure. People with afib and rates over 100 who don't control that rate can indeed end up in heart failure. I know a guy that happened to because he allowed atrial flutter at 125 to continue for months without controlling it.

Your atria quivering away endlessly can lead to atrial enlargement, but atrial enlargement isn't really harmful. It only matters if you're going to try and stop the afib because it makes ablations more difficult.



Edited 1 time(s). Last edit at 12/31/2018 02:33PM by Carey.

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Carey

Question about persistent Afib....

does this mean your heart is quivering 24/7? So, the blood is pooling in the top chambers of your heart? Doesn't this cause heart failure pretty quickly?

Yep, persistent afib means you're constantly in afib and have been for a week or more. After months of persistent afib, it's called longstanding persistent. And if you decide you're not going to attempt to stop it with drugs or ablation, it's called permanent afib.

It doesn't cause heart failure as long as you take effective rate control medications to keep your ventricular rate under 100. Most people with persistent afib take a beta blocker daily for this purpose. I know a guy who's 70, he's in permanent afib and has been for years. He takes a daily beta blocker and an anticoagulant. His resting heart rate is in the 70s with the beta blocker, and he competes in senior marathons. He's completely asymptomatic and doesn't feel the afib at all.

It's a high ventricular rate that leads to heart failure. People with afib and rates over 100 who don't control that rate can indeed end up in heart failure. I know a guy that happened to because he allowed atrial flutter at 125 to continue for months without controlling it.

Your atria quivering away endlessly can lead to atrial enlargement, but atrial enlargement isn't really harmful. It only matters if you're going to try and stop the afib because it makes ablations more difficult.

So "quivering" is still beating, just faster?

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katesshadow
So "quivering" is still beating, just faster?

Well, no, not really. It's so uncoordinated that there is little, if any, effective pumping. The important thing to remember is that what your atria are doing isn't as important as what your ventricles are doing. During afib your atria are just quivering away, doing nothing useful, but your ventricles continue to pump normally. The problem arises when your atria drive your ventricles to beat very rapidly, and that's harmful. Rate control drugs limit how fast they can make your ventricles beat, and that's how rate control drugs prevent harm from occurring.

Hi Pompon,

As your heard above, enlargement of the atria is strongly associated with AFIB/Aflutter, be that in a causal way, or simply as an associated marker of other CV issues (i.e. the ole' chicken or the egg debate). An enlarged-LA volume also can be associated with LV-diastolic dysfunction related to mitral valve stenosis or regurgitation and including (as both George and Carey noted) from the impact on the heart of overdoing chronic fitness as well.

Basically, LA enlargement is mostly due to pressure or volume overload (i.e. as one might logically expect from AFIB/Aflutter) as well as from LV dysfunction secondary to mitral valve stenosis. LA Enlargement is also often indicative of left atrial remodeling which we know is also strongly connected with AFIB/Flutter.

To understand reverse atrial remodeling, first we need to understand the two forms of atrial remodeling that occur. The initial phase of atrial remodeling, called "electrical remodeling" typically begins fairly early after the onset of an AFIB episode.

Our bodies are amazingly adaptable to a host of maladies or injuries that can befall us during life and we have evolved to adapt to often less than ideal scenarios and that flexibility is a key part of our survival as a species. Normally, a fully healthy heart has a strong preference for NSR making it very hard, at first, to go out of rhythm. But once we start to experience AFIB episodes more often, our adaptation system kicks allowing us to gradually begin to accept (or settle for) being out of rhythm as a more or less reasonable alternative to NSR. This process of adaptation begins via electrical remodeling as the heart begins to accept being in AFIB. This is how the mechanism behind the saying "AFIB Begets more AFIB" is manifest.

Fortunately, electrical remodeling is readily, and relatively quickly reversible once durable NSR is re-established either with drugs, life style risk reduction or most often after completion of an expert ablation process when durable NSR is truly restored for the long haul.

On the other hand, the second and more intractable form of remodeling called 'structural remodeling' is not so easy to fully reverse. Structural remodeling most typically is associated with longer term AFIB/Aflutter, though it can begin even as early as after several months or more of either more frequent PAF (paroxysmal AF) episodes or persistent AFIB.

Less frequent PAF episodes can also lead to structural remodeling as well, but usually over a longer period of time. Most structural remodeling is accompanied by structural fibrotic changes in the myo-cytes of the left and/or right atria over time. However, the onset of structural fibrosis over time as well as in intensity is often mediated genetically as well. Some folks will develop fibrotic 'scarring' fairly quickly after onset of frequent or persistent AFIB episodes and the longer, more lasting is one's AFIB/Flutter burden, usually the more fibrotic scarring of the atria may occur.

But there are exceptions, some folks with gifted genetics can show very little fibrosis even after 15 or more years of PAF and that may have morphed into persistent AFIB/Flutter (persistent-AF is strictly defined as more than 7 days of continuous AFIB/Flutter, while Long Standing Persistent AFIB (LSPAF) is strictly defined as continuous persistent AFIB lasting more than 365 days, or 1 full year. Other folks with less favorable genetics may show significant scarring in the atria in as little as a few months after onset of even PAF. The average Afibber falls some where in between these two extremes of fibrotic tendency associated with atrial arrhythmia.

Once NSR has been durably re-established, by whatever means, and in this case we are discussing via a successful ablation process, the electrical remodeling will tend to reverse entirely in fairly short order (within a few weeks to a couple months or less typically). However, while some degree of reverse structural remodeling is possible after solid and unbroken restoration of NSR, the more long term the fibrosis has evolved, the less likely it is that those longer term fibrotic scars can be reversed.

Nevertheless, any degree of reverse structural remodeling one can achieve via restoration of durable NSR is beneficial for the heart, and the degree of structural reverse remodeling is measurable by a corresponding reduction in LA-enlargement or dilatation, and with the greater the reverse structural remodeling one has, the lesser are the odds of arrhythmia recurrence ... to some degree.

This is also a very good reason NOT to overly procrastinated in restoring NSR by getting rid of one's atrial arrhythmia. Accepting or acquiescing to ongoing AFIB/Flutter in one'as life as if it is no big deal, based on one rationale or another, is not a wise decision in my book.

Shannon



Edited 1 time(s). Last edit at 01/03/2019 01:18AM by Shannon.

Is it probable that remodeling occurs less frequent in people that when in AF their heart rate does not go very high, stays in the 70s and 80s (which mine does). As you may know I have had AF episodes off and on for almost 20 years. I have had an echocardiogram 3 years ago and one this past August, I was told there were no changes, of which I am profoundly grateful.

Liz

Thanks, Shannon.
It's somewhat complex and, as always, highly individual.
My cardiologist was surprised, about two months ago, seeing my atria were still normal.
But it's likely that patients having frequent (1 or 2 / week) and short (less than 2h) afib episodes aren't jostling each other in the waiting rooms.