Increase in Ex Induced LBBB

[casey_quest]

I'm a 50 year old male that excercises 3 to 5 times per week.  In April 2007, I began to develop chest pain while excercising.  The frequency increased significantly in October 2007.  In October thru December 2007 I went through a serious of stress tests, nuclear stress test, echo cardiograms, and a catherization.  The process validated that I have Excercised Induced LBBB and that I feel it when it occurs.  My cardiologist debated on the cause.  The catherization indicated the major arteries to be normal, the heart is normal size and shape.  One of the cardioligist specialized in arythmias reviewed the ECGs and felt they all had normal waves except when the LBBB occurred and after the LBBB the waves would return to normal.  He felt that there may be a blockage in a small artery that the catherization could not see.  The other 2 cardiologist did not agree and felt the problem was most likely electrical.

In October 2007, my heart rate ranged from 145 to 155 when the LBBB would occur only while running.  It would disapppear in 5 to 10 minutes after I stopped excercing.  Then I could continue my work out without further incident.  I completed all of the test mentioned above over a course of 3 months and by January 2008 the LBBB would occur when my heart rate was in a ranger of 135 to 145.  

Now it's June 2008, the LBBB occurs with my heart rate in the range of 105 to 120.  I can no longer run because my heart rate hits this level within 5 minutes.  I now excercise on an elliptical machine but I experience the LBBB within the first 10 to 20 minutes.  I slow down and wait for it to pass then continue on with my workout.  I've never had the LBBB occur more than once during a single workout.  I use a polar heart monitor to check my heart rate.

Is the lowering hr triggering the LBBB a major concern?  What is the potential impact?  Are there additional test that can be done to determine the cause of the LBBB?  Can you give me any additional advice?

[Michael J. McWilliams, M.D.]

Is the lowering hr triggering the LBBB a major concern?

Not a big concern other than the fact that it cause you symptoms. This can be caused by blockages in your heart but if your angiogram is normal, is likely an electrical issue.  LBBB suggest a slightly increased risk of cardiovascular disease but it does ont mean that you have cardiovascular disease.  Many people live very normal lives with incidentally discovered left bundle branch blocks.

What is the potential impact?

As I mentioned above, probably no clinical impact other than a slightly higher risk of developing cardiovascular disease and the fact that you have symptoms.  It is very possible that you will eventually have a left bundle branch block at rest too.


Are there additional test that can be done to determine the cause of the LBBB?

None that I would do.  An EP study to test the electrical system in your heart would not be that helpful.

Can you give me any additional advice?

I have seen several patients with similar symptoms to yours, most were runners.  Running does not increase the risk but you are probably more in tune with how your body functions when it is working perfectly.  The best advice I can give is to learn to live with it and slow down your runs.  This is probably not a correctable problem and you need to make sure that it doesn't get in the way of your quality of life.

I hope this helps.

[casey_quest]

The LBBB incedents continue to occur at lower heart rates.  As you mentioned, I may experience a LBBB at rest.  The way I have been manageing these events is to dramatically reduce my pace and wait for my heart rate to come down and the LBBB goes away.

Will I be able to do anything to manage the LBBB if it occurs during rest or is it something that I have to wait for it to pass on its own.  I used to run through the LBBB which took about 15 minutes before it would pass.  My primary cardiologist said to stop doing this and felt it was not a good idea.

I've been reading articles on LBBB and came across pacing as a way to eliminate the LBBB.  At what point shoud a patient consider going down this path?