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Heart Disease (Expert Forum)
Re: thallium stress test
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Re: thallium stress test
by CCF Cardio MD-SGM, Jan 01, 1995 12:00AM
Posted By CCF Cardio MD-SGM on March 19, 1998 at 21:31:50:
In Reply to: thallium stress test posted by wade wright on March 10, 1998 at 19:55:00:
: i am a 34 year old male and have had high colest in 265 range for 8 to 10 years that has not been treated. my father had high colest. and had his first heart attack before age 50. he died at age 54 with his second. my mother had a blockage at age 60. my sister had a 90% blockage at age 42. i have had some symptoms that have been similar to heart disease. i just went to a heart specialist and he order a thallium stress test. how accurate is the test in discovering heart disease? how good is it when you dont have any thing to compare it to? should i ask my doctor to do a cath. to be sure? i really feel insecure and am not sure if i will feel better unless a cath. is done. thanks.
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Dear Mr. Wright,
You pose a good question about the accuracy of exercise stress testing. As we all intuitively know, no test is perfect, but some are better than others at uncovering the true answer to a particular question. In your case, you describe several risk factors for coronary artery disease, including elevated cholesterol and positive family history. Given the symptoms you've experienced, and considering your young age, your approximate risk of significant coronary disease is in the range of 30%. This is not a negligible risk, and it will increase as you age-- especially if you neglect the cholesterol problem with dietary modifications and possibly medical treatment (with cholesterol lowering medications).
Regarding the thallium stress test: At experienced centers that perform this study with some regularity, the sensitivity is estimated to be around 85%. That is to say that given a patient who does have significant coronary disease, there's an 85% chance that the test will detect it. This is not perfect since it will miss significant disease in the other 15% of patient. However, factors like exercise capacity (the time you can exercise on the treadmill), symptoms that do or don't develop during the test, and changes on the ECG that is done during the test can all help your doctor decide whether the test is on the right track. If you have a negative test (normal thallium) and can perform a reasonable duration of exercise without significant symptoms of angina, then it is very likely that you don't have significant coronary disease. Also, I should note that the thallium stress test has a "specificity" of around 70%. This means that thirty percent of patients it finds abnormal actually don't have significant disease. This is usually discovered when patients with abnormal thallium results are referred for cardiac catheterization to look at the coronary arteries using a special dye and x-rays. So, the thallium isn't perfect since it will result in some patients being sent for additional test (catheterization) even though they don't have a serious problem.
What to do? We face questions like this on a daily basis in cardiology. In your particular case, I believe that there is great value in doing a stress test (with or without thallium) instead of a catheterization because of the additional information that an exercise test provides, (such as exercise duration and symptom evaluation as I mentioned above). The catheterization may show mild coronary disease in many patients, but it often won't be clear whether such mild disease is important or not. Also, invasive tests like cardiac catheterization have a small but significant risk of serious complications. The risk of serious problems arising as a result of cardiac cath in a patient such as yourself is less than one percent, but it's not zero.
Again, I agree with your cardiologist that a thallium test is an excellent place to start. If it's normal, you can be greatly reassured. Then, if your symptoms continue or worsen, you can consider a catheterization in the future. In the meantime, you'll be able to avoid the discomfort and the small risk associated with catheterization. Also, I think you should address the cholesterol issue with your doctor.
Hope this has been helpful. Information provided in the Heart Forum is for general purposes only. Specific diagnoses and therapies can only be provided by your physician.
In Reply to: thallium stress test posted by wade wright on March 10, 1998 at 19:55:00:
: i am a 34 year old male and have had high colest in 265 range for 8 to 10 years that has not been treated. my father had high colest. and had his first heart attack before age 50. he died at age 54 with his second. my mother had a blockage at age 60. my sister had a 90% blockage at age 42. i have had some symptoms that have been similar to heart disease. i just went to a heart specialist and he order a thallium stress test. how accurate is the test in discovering heart disease? how good is it when you dont have any thing to compare it to? should i ask my doctor to do a cath. to be sure? i really feel insecure and am not sure if i will feel better unless a cath. is done. thanks.
___
Dear Mr. Wright,
You pose a good question about the accuracy of exercise stress testing. As we all intuitively know, no test is perfect, but some are better than others at uncovering the true answer to a particular question. In your case, you describe several risk factors for coronary artery disease, including elevated cholesterol and positive family history. Given the symptoms you've experienced, and considering your young age, your approximate risk of significant coronary disease is in the range of 30%. This is not a negligible risk, and it will increase as you age-- especially if you neglect the cholesterol problem with dietary modifications and possibly medical treatment (with cholesterol lowering medications).
Regarding the thallium stress test: At experienced centers that perform this study with some regularity, the sensitivity is estimated to be around 85%. That is to say that given a patient who does have significant coronary disease, there's an 85% chance that the test will detect it. This is not perfect since it will miss significant disease in the other 15% of patient. However, factors like exercise capacity (the time you can exercise on the treadmill), symptoms that do or don't develop during the test, and changes on the ECG that is done during the test can all help your doctor decide whether the test is on the right track. If you have a negative test (normal thallium) and can perform a reasonable duration of exercise without significant symptoms of angina, then it is very likely that you don't have significant coronary disease. Also, I should note that the thallium stress test has a "specificity" of around 70%. This means that thirty percent of patients it finds abnormal actually don't have significant disease. This is usually discovered when patients with abnormal thallium results are referred for cardiac catheterization to look at the coronary arteries using a special dye and x-rays. So, the thallium isn't perfect since it will result in some patients being sent for additional test (catheterization) even though they don't have a serious problem.
What to do? We face questions like this on a daily basis in cardiology. In your particular case, I believe that there is great value in doing a stress test (with or without thallium) instead of a catheterization because of the additional information that an exercise test provides, (such as exercise duration and symptom evaluation as I mentioned above). The catheterization may show mild coronary disease in many patients, but it often won't be clear whether such mild disease is important or not. Also, invasive tests like cardiac catheterization have a small but significant risk of serious complications. The risk of serious problems arising as a result of cardiac cath in a patient such as yourself is less than one percent, but it's not zero.
Again, I agree with your cardiologist that a thallium test is an excellent place to start. If it's normal, you can be greatly reassured. Then, if your symptoms continue or worsen, you can consider a catheterization in the future. In the meantime, you'll be able to avoid the discomfort and the small risk associated with catheterization. Also, I think you should address the cholesterol issue with your doctor.
Hope this has been helpful. Information provided in the Heart Forum is for general purposes only. Specific diagnoses and therapies can only be provided by your physician.
