[sehugg]

If the chest pain is not relieved by resting (i.e. sitting down), it points towards a heart attack.

But if you have repeated episodes of chest pain relieved by resting, it might point to angina pectoris -- not technically a heart attack but potentially serious. If it's unpredictable pain and not relieved by rest, it could be unstable angina and much more serious. Yet another thing that makes heart trouble difficult to distinguish from anxiety.

[RafiqM]

Yes, that's true.