healthy with abnormal tests

During a recent insurance medical conducted by my DAME an exercise stress test indicated an S-T segment depressed by 4.5mm although I was asymptomatic of any heart disease. Subsequently a thallium scan suggested left coronary artery disease and my medical certificate was suspended even though my cardiologist was confident that no coronary artery disease was likely - even with two tests indicating positive. An angiogram was then performed which showed no sign of arterial obstruction and the suspension of my medical certificate was lifted.

My cardiologists says that it is possible that future exercise stress tests may also show S-T depression. In these circumstances would my medical certificate again be cancelled? Would catheterisation again be required with the inherent risks of invasive procedures.

I am 48 years old, non-smoker, low cholesterol and no family history of heart disease

Let's look at this problem step-by-step.

You were wanting to buy insurance from a company. To allow an assessment of your risk of death or incapacitation they required you to, among other things, have a exercise stress test.

This 'stress test' involves a gradually increasing level of work, usually walking on a treadmill or pedalling a fixed base bicycle, while your heart is monitored with an ECG (ElectroCardioGraph) machine. No test is perfect but this one is pretty good at detecting problems with blood getting through to the heart muscle.

This test reported "4.5mm of S-T segment depression" which is pretty meaningless to most people. What this means is that the line of the ECG trace runs a different course to 'normal' , specifically one segment (arbitrarily called the S-T segment) was 4.5mm 'lower' than normal. This, in turn, usually means that part of the heart isn't getting enough blood to it and is usually interpreted as meaning there is a degree of blockage of the arteries of your heart.

While these ECG changes alone, in the absence of symptoms such as chest pain, are less conclusive they would warrant further investigation.

Given this, it doesn't seem unreasonable for your DAME to proceed with caution. He/she would want to be sure whether, or not, you had serious heart disease. Another test was ordered - a thallium scan.

A thallium scan is a method of photographing the amount of blood running through the arteries feeding your heart. A special dye is injected into your blood and 'photos' taken as it runs through your heart. Areas that get less blood flow show up as dark - where there is no dye.

While, again, accepting that no single test is perfect it did appear that you had an abnormal test. Given the findings of an 'abnormal' stress ECG and an 'abnormal' thallium scan it is very easy to understand why your DAME would not be keen to issue you with a full medical certificate. I'm not sure what information your cardiologist had that caused him to suggest otherwise but, on the face of it, your DAME seems to have taken the best course - for you and CASA.

An angiogram is another dye test but it gives better resolution pictures of the blood feeding the heart than a thallium scan does. Again a dye is injected, this time via a long tube inserted (usually) at your groin and run up fairly close to the heart, and photographs taken as the dye-blood runs through your heart. In expert hands this is a very effective test to see if there are any blockages of your coronary arteries.

The downside of an angiogram is that it is a much more 'invasive' procedure than either the stress test ECG or the thallium scan. There is a small, but real, risk of it going wrong and causing permanent injury or death. Understandably this test was left as a last resort.

The angiogram showed that there was, indeed, no significant blockages of your coronary arteries despite the 'positive' stress test and thallium scan. Everyone is happy that your heart is OK and CASA is going to let you continue flying. You, however, have the concern that future stress test ECGs will show the same 4.5mm S-T segment depression and that this will, again, cause a suspension of your certificate.

I think your DAME has acted very sensibly here and I also think that the CASA medical department have taken the only sensible road open to them. I have no doubt that the CASA medical department will continue to take a sensible approach on this matter. I expect that they will only require further cardiac investigation of you if your S-T depression changes significantly.

Since you exhibit 4.5mm of S-T depression in the absence of any angiogram detectable abnormality of your heart this state could be considered as your 'normal' and any change from this should be considered 'abnormal'. I think you'll find that the CASA medical department will apply this style of reasoning to your case.

This could, of course, lead to a rather bizarre situation. If a future stress ECG were to come back reported as 'perfectly normal' (i.e. No 4.5mm S-T segment depression) CASA are probably (quite reasonably) going to ask for further investigation of your heart. Let's hope that your heart is not only healthy but that the 4.5mm of S-T depression is not going to change.

You know that you can always phone the Medical Director at CASA, Dr. Rob Liddell, when you have concerns like this - or you could write to him. He is a very, very reasonable man who's Department seems to be bending over backwards to try and keep us flying - within reason.