CT coronary use a dye and radiation. So unless there is a strong clinical suspicion of Coronary artery disease it should not be done. At your age if you have symptoms then the sequence of tests should be like 1) ECG and Troponin level 2) ECHO If both are negative then TMT or a Stress ECHO will help. If at all any suspicion arises for a CAD then only we advise CT coronary or a Conventional Angiography. Both have good diagnostic values for blockage in heart vessels. But in young individuals CT coronary are preferred as it also gives the Coronary Calcium burden too.