Inability of coronary blood flow reserve measurements to assess the efficacy of coronary angioplasty in the first 24 hours in unselected patients

Abstract

To determine functional and anatomic changes in the first 24 hours after coronary angloplasty, we studied at random 15 patients (9 men, mean age 60 years) who underwent coronary angioplasty of 16 coronary arteries. Quantitative coronary angiography and coronary flow reserve measurements from digitized coronary angiograms were performed before, immediately after, and 24 hours after coronary angioplasty. Calculated were the minimal luminal diameter, obstruction area, and percentage diameter stenosis from two preferably orthogonal projections. Prior myocardial infarction in the myocardial region of interest was present in four patients. Seven patients had multivessel disease. Collateral vessels supplying the compromised flow region were observed in three patients. Six patients had refractory unstable angina pectoris. After coronary angioplasty, anglographically visible dissection was noted in six patients, whereas side branch occlusion was observed in one. Minimal luminal diameter before, immediately after, and 24 hours after was 0.93 ± 0.18 mm, 1.53 ± 28 mm, and 1.53 ± 0.21 mm, respectively; obstruction area was 0.70 ± 0.26 mm 2, 1.92 ± 0.69 mm 2, and 1.87 ± 0.51 mm 2, respectively; diameter stenosis was 60.4 ± 8.0%, 36.8 ± 11.4%, and 37.6 ± 5.3%, respectively. The coronary flow reserve (lower limit of normal with this technique 3.4) was essentially the same before and immediately after coronary angioplasty (1.26 ± 0.59 vs 1.30 ± 0.42, p = NS) with a slight improvement to 1.78 ± 0.90 ( p < 0.05) 1 day later. Coronary artery dimensions correlated poorly with coronary blood flow reserve before and after angioplasty. We conclude that on average no changes in minimal luminal diameter, obstruction area, and percentage diameter stenosis occurred in the first 24 hours after coronary angioplasty, although there were individual variations, and coronary flow reserve measurements from digitized coronary angiograms were only minimally improved 1 day after coronary angioplasty and correlated poorly with quantitative measurements of coronary artery dimensions. Therefore it is suggested that coronary flow reserve measurements from digitized coronary angiograms in the setting of coronary angioplasty have little value in unselected patients with conditions known to disturb coronary flow reserve.