DELAYED RECOVERY OF CORONARY RESISTIVE VESSEL FUNCTION AFTER CORONARY ANGIOPLASTY

Objectives. The aim of this study was to use Doppler catheterization and sequential dynamic positron emission tomography (PET) to investigate the role and time course of abnormal coronary resistive vessel function in the impairment of the coronary vasodilator response (maximal/basal coronary blood flow) after successful coronary angioplasty. Background. The coronary vasodilator response may be impaired immediately after coronary angioplasty, despite successful dilation of a flow-limiting stenosis. Methods. Twelve men (mean age 52 +/- 10 years) with single-vessel coronary artery disease and normal left ventricular function were studied. The coronary vasodilator response to intravenous dipyridamole (0.5 mg.kg-1 over 4 min) was determined from intracoronary Doppler measurement of coronary flow velocity, before and after successful angioplasty. Basal and maximal myocardial blood flow in the angioplasty region and a normal region were determined in nine patients with positron emission tomography with (H2O)-O-15 at 1 day (PET1), 7 days (PET2) and 3 months (PET3) after angioplasty. Results. The coronary vasodilator response, measured by Doppler catheterization, was similar before and immediately after angioplasty, 1.63 +/- 0.41 and 1.62 +/- 0.55, respectively (p = NS). After angioplasty, in seven of nine patients without restenosis, basal myocardial blood flow at PET1, PET2 and PET3 was 0.98 +/- 0.16, 0.94 +/- 0.09 and 0.99 +/- 0.13 ml.min-1.g-1, respectively, in the remote region and 1. 19 +/- 0.23 (p < 0.01 vs. remote region), 1.17 +/- 0.19 (p < 0.01 vs. remote region) and 1.10 +/- 0.08 ml.min-1. g-1 (p = NS vs. remote region), respectively, in the angioplasty region. Myocardial blood now after dipyridamole at PET1, PET2 and PET3 was 3.04 +/- 0.68, 3.00 0.71 and 3.00 +/- 0.60 ml.min-1.g-1, respectively, in the remote region and 2.11 +/- 0.80 (p < 0.01 vs. remote region), 2.28 +/-0.73 (p = NS vs. remote region) and 3.06 +/- 0.86 ml.min-1.g-1 (p = NS vs. remote region), respectively, in the angioplasty region. The coronary vasodilator response at PET1, PET2 and PET3 was 3.15 +/- 0.85, 3.18 +/- 0.68 and 3.08 +/- 0.75, respectively, in the remote region and 1.80 +/- 0.68 (p < 0.01 vs. remote region), 1.94 +/- 0.49 (p < 0.01 vs. remote region) and 2.77 +/- 0.74 (p = NS vs. remote region), respectively, in the angioplasty region. Conclusions. After successful angioplasty, basal myocardial blood flow is increased for greater-than-or-equal-to 7 days in the angioplasty region, with a reduction in the dipyridamole-induced increase in maximal myocardial blood flow for greater-than-or-equal-to 24 h after the procedure. Thus, the coronary vasodilator response is impaired for greater-than-or-equal-to 7 days after angioplasty, indicating that there is abnormal resistive vessel function in the coronary vascular bed distal to a coronary artery stenosis that persists for 7 days to 3 months.