Positive t wave alternans ?EP studies

[cutiger]

I am 46 year old male with over 24 year history of inverted t waves in V3-V6.  No symptoms but had become aware of fairly high BP lately.  Originally though to be non-specific but recently after insurance exam and subsequent stress test, echo, and cardiac cath found to be associated with mild cardiomyopathy.  EF 40-45% Mild global hypokinesis and severe apical hypokinesis.  Coronaries clean, valves normal, upper limit of normal LV size, normal right ventricle size and function.   Cardiac output around 5.5L.  Cardiologist felt I must have had a virus years ago with subsequent heart damage.  Placed on Coreg and Altace.  Decided to do t wave alternans "just to make sure everything ok."  The study was positive and we are trying to decide whether to do EP studies. A signal averaged EKG was negative.  I have only had one  near sycopal episode that I know of and it was over 20 years ago and associated with a mild viral illness.  I do have frequent PVC's that have improved with Coreg.  
Questions:
Since with increasing heart rate my t waves normalize and knowing that the T wave alternans looks for microvolt t wave changes would that not make this test less reliable.
Are T wave alternan studies reliable in general?
What would a EP study add and given my history do i even need one done?
Would I go ahead with ICD placement with what is now known?
Would the Coreg provide reasonable protection against arrythmias?
Is it still safe to walk 1-3 miles per day?

[Michael J. McWilliams, M.D.]

I will give you questions for asking the question of the year.  That is a tough questions.  The short answer is that the role for T wave alternans is still to be decided.  The following is a quote from Alan Kadish, a leading authority in ICD therapy and sudden cardiac death.

http://www.medscape.com/viewarticle/565455

Kadish concluded: "Despite the large number of clinical studies done, more studies are necessary to better define the predictive ability of TWA testing. There is not enough concordance among the data at the present time to produce clear indications for TWA use, which is frustrating for all of us who were hoping for a consensus of results and for a clear indication of TWA use for predicting outcomes."

I personally do not use T wave alternans testing yet.  I do not have clear understanding of how it helps me treat patients yet and your situation is a case in point.  I would have not ordered the test for you.  As a general rule, I do not order a test unless it has the potential to change patient care.  In your case with your ejection fraction and no history of syncope, you are not a candidate for an ICD or an EP study, the test itself only confuses the picture.  There is not study that I am aware of designed to address your particular clinical scenario.

The problem is, now you have a positive test result and I'll bet most people don't know what to do with it and it is probably causing you significant stress as well.

Are T wave alternan studies reliable in general?

I don't know how to interpret the case in your scenario.  In general a negative test suggests a less future cardiovascular events.  A non negative or positive test suggests a higher risk for cardiac events.  The problem is a population of people with your clinical characteristics has not been studied, so interpreting the results is not possible.

What would a EP study add and given my history do i even need one done?

I would not do an EP study in someone with an EF of 40-45% and no history of syncope or ventricular arrhythmias.

Would I go ahead with ICD placement with what is now known?

There are no studies to suggest that ICDs are beneficial in your case.  I would not implant an ICD and even if I wanted to, I am not sure that insurance would pay for it because it is outside the guidelines and you don't have high risk features.

Would the Coreg provide reasonable protection against arrythmias?

Coreg and an ACEI are your best protection against arrhythmia and progression of your cardiomyopathy.

Is it still safe walk 1-3 miles per day?

For you have told me, I would not advise against it, but would leave ultimate recommendations up to your doctor who knows you best.

If you are being offered an ICD, I would consider getting a second opinion by someone that can review all your records.  I am not saying you shouldn't have one (I don't have all the records to review), but I would approach it cautiously because I do not see a clear indication in the current guidelines.

Does this answer your questions?  Check back because I am going to do some more reading about this question.

Thanks for posting.

[cutiger]

Thanks for you answers.  You are right it appears that everyone is stumped.  It's not that I feel bad physically because I don't.  Mentally, well thats a different story when you're told you have a test positive for predicting sudden death.  Just for what it's worth I didn't get the insurance(lol).