The 'arteries' refers to the four coronary arteries around the heart, as these become 'furred up' there are normally symptoms.
(The heart is deprived of blood , in a heart attack large areas of muscle can be damaged causing permanant loss of tissue .)
From personal experience these symptoms are:
General increase in blood pressure , Normal is 120/70 ish but increases with age. Above 140/90 see your doc.
Cholesterol level: Crew food is not ideal and the fatty deposits left around the system can clog up the arteries(atheroma) .
If you have a high level , more than about 5.5 see your doc.
As the blockage increases you would definately be aware of shortage of breath , possibly chest pains which feel as they could be indigestion.Especially squash, running etc.
A pilot reaction to this lot is often to try and ignore it and just work out harder!( The medical requirements, thoughts of losing the licence, personal 'failure' ..can't- -be -me attitude )
Age , well, 40's is early but if there is a family history then the furring up can start in the 20's .
Most problems occur in early 50's (recent BA 747 Capt. with stroke)
ECG . our little annual check is only a rough guide and often only provides information of an angina or heart attack that has happened, not an incipient one.
Other tests are stress ECG ,you are wired up on a treadmill, later on Electro Cardiogram, and best of all the delightful 'angiogram' where dye is inserted in the heart via a catherter, this is the definative check and it is possible to see the blocks.
Minor single blockages can be treated with a 'stent', a small metal tube inserted through the femoral artery, allowing normal bloodflow.
You need 6 months off and then subject to certain restrictions get your licence back unless re-furring has occurred.
More serious blockages may require you to be unzipped and the arteries replaced with handy spare ones from the arm or leg.
Again there are pilots flying with these.
I hope this is of some interest. in summary:
Family history
Smoking, smoking and smoking.
Overweight. Body mass over 25?
High Chol. National average 5.7 but ideal less than 4.
High Blood pressure.
Pain in chest with exercise
Pain in neck and arm
Generally tired
Tingling in fingers
Nasty indegestion with reflux,
May all be early warning signs.
Good Luck!