Thal Pals Comic Strip – Epsiode 9

(The following information on T2* is reprinted from the September 2007 CAF MEDICAL UPDATE.) 

People with thalassemia are encouraged to

get T2* measurements to help assess their

cardiac health. What is a T2*?

T2* is the measure of how fast an MRI image of

the heart darkens.

When a person gets a T2* score, exactly what

is that score measuring?

The lower the T2*, the greater the amount of

iron in the heart. (Editor’s note: T2* provides a

measurement that reflects the amount of iron

in the heart.) A T2* greater than 20 ms means

that there is no detectable cardiac iron. The

risk of heart trouble increases steeply as heart

T2* falls below 10 ms. Having an abnormal T2*

is like having an abnormal cholesterol. Many

patients with elevated cholesterol feel fine and

have normal heart function….but they are at

higher risk over time.

Is the MRI measuring the amount of iron in

the heart, or is it providing a different kind of

measurement?

It depends. Variation in T2* for values greater than 20 ms can reflect differences in factors

besides iron, such as blood flow, cardiac

motion, and image artifacts. However, changes

in T2* for values less than 20 ms are

determined almost exclusively by tissue iron.

Sometimes, a person may have a T2* score

that is low enough to cause concern, but

his/her serum ferritin may be at a very

reasonable level and s/he may have a clear

echo. How concerned should a person in

this situation be?

High ferritin values and high liver iron

concentrations should always be concerning,

regardless of the heart T2* value. However,

the converse is also true. Some patients have

severe cardiac iron deposition (low T2*) and

heart problems, despite apparently good

chelation as measured by ferritin and liver iron

values. The situation of high heart iron with

low liver iron occurs because the heart and

liver take up and release iron at different rates

and by different chemical pathways. These

patients need changes in their chelation

regimen to specifically improve their cardiac

chelation, such as 24/7 Desferal (Desferal

administered 24 hours a day/7 days a week)or

oral chelation therapy, with careful observation

to prevent overchelation.

In situations where there is a low T2* and a

clear echo, what do you recommend the

patient do? Should chelation regimens be

changed?

A low cardiac T2* should prompt a complete

review of the patient’s transfusion and chelation regimens, as well as the ferritin and liver iron histories. The change in cardiac T2* over time is much more helpful than a single value. If the

cardiac T2* is improving (rising) and the patient has normal function, no change in the chelation regimen is necessarily indicated.

If no action is taken, how soon until you

observe changes in the echo indicating a

serious cardiac condition?

The time between detection of an abnormal

heart T2* and development of new

echocardiogram abnormalities has not been

well characterized. It is on the order of a few

months to a few years and appears to be

shorter for higher cardiac iron levels. Waiting

until echocardiographic parameters change,

however, is a bad idea because not all patients

can be rescued with intensive chelation.

CAF Patient Services is here to help!

Eileen Scott, CAF Patient Services Manager, (800-522-7222, x205 oreileen.s@cooleysanemia.org) can answer a wide range of patient services questions.

And CAF Social Worker Kathleen Durst (800-522-7222, x 202,k.durst@cooleysanemia.org) can talk to you about things that get in your way, especially in terms of thalassemia, and help you develop strategies to deal with them.

You’re not alone!  Call CAF today!