1) The presence of epicardial coronary artery stenosis caused by artherosclerotic plaques is by far the most frequent angiographic finding in any cardiac ischaemic syndrome.

2) Experimental studies in dogs showed that the acute reduction of coronary diameter by more than 50 per cent causes a measurable basal transstenotic pressure gradient. Further decreases in diameter cause an exponential increase of transstenotic pressure gradient and reduction of maximal coronary blood flow.

3) The stenosis resistance is linearly related to the length of the stenosis and to the flow turbulence caused by the stenosis irregularities.

4) The greater the basal transstenotic pressure gradient, the greater the reduction of coronary myocardial ischaemia appears during effort.

5) In presence of a decreased poststenotic pressure ischaemia initially occurs in subendocardial layers, because the subendocardium is more vulnerable to ischaemia than the subepicardium.