Narrowing of coronary artery: thresholds for the occurrence of angina pectoris

The degree of narrowing of coronary artery that caused angina pectoris, was estimated in female and male patients with single vessel coronary artery disease, with the aid of quantitative measurements of a single stenosis in arteriograms. In female patients, the onset of mild angina pectoris (NYHA, functional class I-II) occurred when the coronary artery diameter was reduced by an average of 41 per cent, whereas it could not be estimated reliably in male patients because they nearly all had well developed collaterals bypassing the stenosis. For severe angina pectoris (NYHA, functional class III-IV) the mean stenosis was 72 per cent in female and 78 per cent in male patients.