Distal vasoconstriction following coronary angioplasty--comparison of emergent and elective PTCA.

To examine the occurrence of distal vasoconstriction following primary percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction, quantitative coronary angiography was performed during and after acute myocardial infarction. An assessment of coronary artery vasoconstriction was made in patients undergoing primary and elective PTCA. The primary PTCA group was subdivided into two groups based on initial antegrade flow characteristics: group 1 (TIMI grade flow 0/1) and group 2 (TIMI grade flow 2/3). All balloon angioplasties were performed during continuous administration of nitrates. There was no significant difference with relation to lesion diameter, lesion stenosis, or diameter of the left circumflex coronary artery between the acute and chronic phase in both groups. The distal diameter, however, was smaller during the acute phase than in the chronic phase in both groups (1.7 +/- 0.5 vs 2.0 +/- 0.4 mm, p < 0.001; 2.0 +/- 0.4 vs 2.2 +/- 0.3 mm, p < 0.05, respectively). The percent vasoconstrictive response of the distal segment was greater in the primary PTCA group than in the elective PTCA group (11.2 +/- 18.1 vs -1.9 +/- 7.1%, p < 0.0001, respectively). In conclusion, nitrate-resistant coronary artery vasoconstriction following primary PTCA occurs distal to the site of balloon dilation.