Substrate modification

[va_tony]

I'm a 62 year old male, 6' 5", 260 lbs. My AFIB is currently under control with the help of 225 mg/3X daily of Rythmol. I'm generally in normal sinus ryhthm except for episodes of several hours duration every month or so. I'm also prescribed tiazac, altace and coumadin and otherwise in excellent health, regularly working out at a gym 3-4 times a week.

It's likely that the AFIB is a consequence of an enlarged left atrium (5.2 cm)and mild mitral valve regurgitation. From my reading on the subject, I understand that antiarrhythmics like Rythmol will eventually fail over time to keep afib in check.  So, I've resigned myself to the prospect of having a future ablation to cure this problem. Much of my concern about an ablation focuses on the possibility that my enlarged atria will contribute to the eventual return of AFIb afterwards.  

I felt a lot better about this prospect after CCF-MD-RCJ's answer to my question of 3/30.  CCF-MD-RCJ mentioned the use of "substrate modification" in addition to the usual pulmonary vein isolation to help counterbalance the disadavantage caused by the atrial enlargement.  I've searched the web and although there wasn't much written on the subject, I gather it consists of making long linear rf-induced lesions on the atrium to electrically isolate different portions and so stop the formation of reentrant wavelets. Is this correct? Wouldn't electrically isolating sections of the atrium affect it's ability to pump normally? Are there any negative issues associated with this procedure?

Thanks for taking the question.

[Momto3]

Just caught up with this thread....WOW!  Great discussion on the ventricular ectopy study conducted by Michael Lauer, M.D. Some of you know that I had very frequent pvcs and NSVT prior to my ablations last year. Well, when my ectopies were really high and my mitral regurgitation looked like it was worsening, my EP referred me to Dr. Lauer for an evaluation. Because my EP believes that the CCF is best place for valve surgery, she wanted me to have a CCF doctor. Dr. Lauer did a thorough exam, studied my test results, ordered some additional tests and fortunately found that I was not a "candidate for MV/MR surgery."  Whew!!! He is quite the doctor and researcher!! For me, when his research hit the NEJM, it was really cool to put a name and face to the study. It is great to know that practicing cardiologists continue to research everday!!

[bigmick]

Not yet my friend: I'll let you know as soon as I do. However, what I do know is that it cannot have been anything bad as the hospital said thay would read the tape in the day or two following my returning the Holter and would call me back asap if anything nasty showed up. They haven't called, so I'm guessing/hoping/assuming that nothing overly ominous showed up. I'll keep you posted via this or another newer (and not un-connected) thread.

Regards from the UK,

BM

[bigmick]

Had a quick look further to recent gray hair comments.............. since I'm well gray at 43 yrs old (but baby-faced in every other respect!). Here is the only pertinent study that came up on a pubmed search:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=1809864

So, all you gray-haired dudes and ladies, chill out (-:

BM

[va_tony]

To Pluto,

I guess you and I are in agreement after all because I also interpreted Dr. RCJ's as being consistent with what I said above!! As I stated, the "frequent" PVCs "was defined as having seven or more PVCs per minute (or more serious nonsustained VT, V bigeminy, etc.)." Since Dr. Lauer's paper did not break down the relative populations of those who specifically had PVCs, VT, V bigeminy, etc., I assumed (and still do) that the frequent PVC sufferers were in the majority since PVCs are generally more common than VT, etc.!

In the end, Dr. RKJ did not say frequent PVC's after exercise were harmless. He said instead, "Extrapolating this paper's results to each person will require a careful analysis of that particular person. You'll want to let your doctor help you with this analysis."

I also believe that the PVCs, as exerperienced by many on this page, are largely harmless. However, under certain circumstances PVCs portend more ominous heart problems even in those who appear to have a structurally healthy heart. Post exercise PVCs is one such example, when they occur at rates of 7 a minute or more.



To Dr. RCJ,

Thanks for taking the time out of your extremely busy schedule to clarify the results of Dr. Lauer's study.  Your explanation was very helpful. I and I'm sure everyone on the board greatly appreciates the efforts you and Dr. BKJ make daily (yes, even on weekends!)on our behalf.

Best regards,

Tony

[CCF-M.D.-RCJ]

Hey there,

The discussion regarding Michael Lauer's VEA paper in the NEJM has been a spirited one, and I though it might benefit from a few comments.

Firstly, Mike Lauer is one of the world's most respected authorities on exercise testing.  His research is top-notch, and he uses very rigorous statistical methods.  I hold him in high regard, in fact, he was my research mentor on two publications.

In his paper, frequent ventricular ectopy (VE) was defined to include PVCs, NSVT, ventricular tachycardia and fibrillation; not just PVCs.  Only 2% of the population had VE just after exercise, which is very different from what most of the readers here describe.  VE during exercise was only present in 3%, and was not associated with mortality in adjusted analysis (for instance patients with VE were more obese and has higher blood pressure).  Lastly, patients who had normal EF and "less severe VE" (meaning not VT of VF) were not specifically examined as a subgroup.

Extrapolating this paper's results to each person will require a careful analysis of that particular person.  You'll want to let your doctor help you with this analysis.

Hope that helps.

[va_tony]

Dquenzer's on to something! Both of my successful attempts to get through with a question were also made at about 8:00 AM (8:00 AM EST and 7:59 AM EDT on my computer clock, which could be off a minute). I was actually trying to follow an earlier dquenzer suggestion posted two months ago but mistakenly used my local time and succeeded on first try. It could very well be that medhelp begins accepting questions precisely at 8:00 am but varies the time zones on a daily basis. Based on the high percentage of lucky hits I had (2 questions out of about 6 tries), I would even speculate that medhelp is only cycling between US time zones.  So, if you really wish to pose a question, I suggest trying at 8 AM EST, 8 AM CST, 8 AM MST and 8 AM PST (or, this time of year, the respective daylight savings time).

Best of luck

Tony

[arthur]

One needs to be careful about causality.
Often correlations are made between various observations which then lead the investigator to conclude causality, ie, an increase in event 1 is correlated with an increase in event 2, thus, event 2 may be caused by event 1.  This is often simply wrong.  For example, an increase in grey hair can be definitely correlated with an increase in death rate.  Absurd, however, the correlation is there.  It's absurd, since hair or it's condition is not going to cause death (at least for most people).  It's much more likely that a common mechanism exists which causes both the grey hair and death.  Note, however, that you could get grey hair from other sources besides the one that causes death, for example, dye.

Looking at the PVC issue, it seems to me that the post-exercise increase in PVCs and an increase in death rate (albeit very small), may more likely be due to a common cause, for example, a hidden ischemia.  Having said that, the increased post-exercise PVC event could also be caused by other factor(s), which are not correlated with an increase in death (for example, a particulary lively focus sensitive to adrenaline levels).  

One more note...I can't believe someone on this board actually believes that I post negative comments!  (that was my rant, now I feel better)

-Arthur

[va_tony]

Last Friday and Saturday (4/31 & 5/1) there was a heated discussion on exercise and PVCs that pitted (mostly) erikwithouthtedoctor, barbarella, and pluto against fwilson, wmac and (belatedly) myself.  Since, the maximum number of comments on that thread was reached and the debate shut off prematurely, I'd like to take this opportunity to say a few more words about the Cleveland Clinic study under debate.

The study is reported in the Journal of the New England Journal of Medicine (cite: "Frequent ventricular ectopy after exercise as a predictor of death", Froklis J. P. et al, NEJM, 348(9) 781-790 (27 Feb 2003)]. I was able to get a copy by logging onto the NEJM website,  http://content.nejm.org , and registering.  Registration is free but only entitles you to articles over 6 months old (fortunately this article is).  Newer articles and the highly favorable Editorial written about this study require a paid subscription. The four authors of the paper are all Cleveland Clinic staff and three are MDs (NOT laymen).

The study appears very credible and, I'm sure, had to pass both internal CCF and external peer review boards to be submitted and published in this prestgious medical journal.  The clinical trial involved 29,244 patients (70% men, age 56 plus/minus 11 years) who underwent routine treadmill stress tests.  Patients known to have arrhythmias, other heart related problems and serious medical conditions were excluded. Those with "frequent" PVCs during and after the stress test were noted.  Frequent PVCs was defined as having seven or more PVCs per minute (or more serious nonsustained VT, V bigeminy, etc.).

The results were as follows: 5% of those ahowing no signs of PVCs during/after exercise died within 5 years of the test for one reason or another (i.e., normal societal death rate at that age).  Of those showing frequent PVCs afterwards, 11 % had died (from all causes)within 5 years.  That's over twice as many as in the non-PVC group!!!  When the data is reduced to take into account confounding variables, the hazard ratio was still 1.5 (i.e., death rate is about 8% over 5 years).  This is clear evidence that "frequent" PVCs, while harmless themselves, are indicative of hidden heart problems. The group who experienced frequent PVCs during exercise had a hazard ratio of 1.1 (within statistical error).

So, unless Cleveland Clinic publically disavows this study or another more credible study from elsewhere is published, I would think that the medical community as a whole would necessarily have to accept this view of frequent PVCs post exercise.

This doesn't mean that PVC sufferers on this board should be alarmed, especially if they are not 50 or older and don't experience "frequent" PVCs after exercise.  There's no evidence that PVCs before or during exercise carry a higher mortality risk.

Tony

[va_tony]

Pluto,

   I'm sure you didn't intend to impune the reputation of the authors of the study. I have confidence that they are well respected members of CCF and accurately characterized the overall health condition of those tested. But, for the sake of argument, let's assume you are correct - - that those tested were already at some risk.  The fact that there was a distinct difference (5% vs 8%)between the mortality rate of both the control group and those who exhibited frequent PVCs post exercise (even if both groups were already at risk) illustrates that there is some merit to the authors' premise. Also, if those tested were, on average, already at risk, then the number of deaths would have been higher in the control group. Instead the control group had a 5% death rate, which is about normal for those of the same average age in the general population. No, I think this is a valid result and the large number of those tested makes the statistics very believable.

I agree with you that the doctors here don't pull punches. I do notice that they like to keep their answers very brief. It's often said that answers can be brief or they can be accurate. So, when asked about PVCs, I'm not surprised that the doctors' short answer is "They are harmless unless you have underlying problems". I think if you asked for the long (and more accurate) answer, you'd hear something slightly different. In fact, they might even say that if, after a stress test, a patient exhibits frequent PVCs, s/he has an underlying heart problem! So, I don't think the doctor's short answer necessarily implies that they don't believe the results of the study.

Tony

[va_tony]

Arthur,

    I mostly agree with what you write. There is a distinct difference between cause and effect.  I tried to be very careful with my wording so as not to imply causality; i.e., that the PVCs were causing the deaths.  On the contrary, I specifically wrote, referring to the post-exercise data, "This is clear evidence that frequent PVCs, while harmless themselves are indicative of hidden heart problems". Even the authors of the study were careful not to imply PVCs were a cause.  Their title uses the term "predictor of death" and their results support using treadmill testing as a predictive diagnostic.

And, yes, gray hair doesn't cause death.  However, its presence has a strong correlation with the natural aging process and it's this aging which degrades critical organs to the point of eventual failure, with death following. So, looking at someone's hair color is a rough "predictor" of how close they are to the end. Would you say that, on average, gray haired individuals are expected to live as long as those with hair color? Of course not!  By the way, by "on average" I mean averaged over a great number of individuals. Even the authors of the study state that the PVCs are a byproduct of some other hidden problem.  They speculate that it's related to the vagal reactivation that normally occurs immediately after exercise. Apparently, earlier clinical studies have shown that the absence of normal vagal reactivation, where the heart-rate recovery is sluggish, is associated with increased mortality. I think the only statement of yours I could quibble with is your characterization of the observed increase in death rate as being "very small".  An increase in rate from 5% (for general population) to 8% (for frequent PVCs) over a five year period is, in my opinion, a "significant" increase.

Tony

[dquenzer]

I understand your frustration if you have a heart problem.

However unlike other forums, these forum questions are being answered by doctors.  If they didn't limit the questions being asked they wouldn't be able to keep up with the demand.  These are busy doctors.  

If you have a particular problem you might be able to find the answer if you search the database.  I have found this forum very helpful in determining my specific treatment for AFIB.  However it is NOT a substitute for a visit to a cardiologist.  It provides information that may provide possible treatment options, thus making you an informed patient.

Also if you really want to get a question in I suggest you try at about 8 AM CST.  But don't abuse the privelege.  

Hope you can get your question in.

[Clenn Camp]

After only two questions and only two responses to each we get this message:

Dear Friends,

We are very sorry, but this Forum has reached its limit for new questions today. Med Help has to limit the number of questions we accept on a daily basis, due to limitations of staffing and funding. Our forums 'reset' to new questions at a different time every day. We do this in order to give people in all time zones a chance of getting their questions answered. In the meantime please feel free to:

I think this is pitiful limiting the board to only two questions and two responses.

Glenn Camp

[va_tony]

Thanks for your helpful comments! You are now my favorite doctor at Cleveland Clinic!

Fortunately, I probably won't need an ablation for a few years yet, hopefully giving centers like the Cleveland Clinic a chance to better pefect treatment of AFIB.  At least, substrate modification won't be "so new" by that time.

When you quoted complication rates on the order of between 1 to 5%, I gathered you meant for rf ablation in general. My original question was intended to be a bit more specific, namely: What problems might later develop because of substrate modification and the excessive scarring that's an unavoidable by-product? Any thoughts on that?

Once again, thanks for answering my question. I appreciate it!

Tony

[CCF-M.D.-RCJ]

va_tony,

Thanks for the post.  I'm glad I could help last time.

Q:"I gather it consists of making long linear rf-induced lesions on the atrium to electrically isolate different portions and so stop the formation of reentrant wavelets. Is this correct?"

The afib ablation procedure(s) are so new that each center does them a little differently.  But what you described is one method.

Q:"Wouldn't electrically isolating sections of the atrium affect it's ability to pump normally?"

The transport function of the atrium may be mildly affected, but it is difficult to measure changes.  One thing is for sure, a mildly dysfunctional atrium is certainly better than a fibrillating atrium.

Q:"Are there any negative issues associated with this procedure?"

Yes.

Most top centers quote around a major complication rate on the order of between 1 to 5%, depending on the center, the patient, and what the centers count as complications.  Major complications typically include stroke, major bleeding, and death.

Hope that helps.