CORONARY FLOW RESERVE IN PATIENTS WITH CHEST PAIN AND NORMAL CORONARY-ARTERIES

Background-Many studies have shown that coronary flow reserve is reduc ed in patients with chest pain and angiographically normal coronary ar teries. The methods used to assess coronary blood flow have varied, bu t in nearly all reports dipyridamole has been used to bring about vaso dilatation. This study was designed to assess whether the apparent imp airment of coronary flow reserve seen with dipyridamole could be repro duced with either papaverine or adenosine, which induce maximum corona ry blood flow by different mechanisms. Methods-25 patients with chest pain and angiographically normal coronary arteries were studied with a n intracoronary Doppler flow probe and quantitative angiography to det ermine epicardial coronary artery area, coronary blood flow velocity, coronary flow reserve, and coronary vascular resistance index (CVRI, t he ratio of resistance after intervention to basal resistance). All pa tients received papaverine 8 mg. Eight patients with positive exercise tests received intracoronary papaverine (8 and 10 mg), intracoronary adenosine (6, 20, 60 mu g), and high-dose intravenous dipyridamole (0 84 mg/kg). Results-The velocity ratio (peak after intervention: baseli ne) (mean (SEM)) after 8 mg papaverine was 3.3 (0.2) (n = 25) and the coronary flow reserve was 4.1 (0.3) (n = 25). There were no difference s between patients with a positive (n = 16) or negative (n = 9) exerci se test. In eight patients coronary flow reserve was measured after in creasing doses of papaverine, adenosine, and dipyridamole. Coronary fl ow reserve was 4.5 (0.3) with papaverine, 4.8 (0.3) with adenosine, an d 3.5 (0.4) with dipyridamole (p= 0.08 nu paverine and adenosine). CVR I was 0.22 (0.01) with papaverine, 0.21 (0.02) with adenosine, and 0.2 9 (0.03) with dipyridamole (p < 0 05 nu papaverine, p = 0 09 nu adenos ine). Conclusions-These results indicate that measurement of coronary flow reserve and CVRI in patients with chest pain and normal coronary arteries depends on the pharmacological stimulus. Normal values were o btained with papaverine in all patients, irrespective of the exercise test response. In patients with a positive exercise test significantly lower values were obtained with dipyridamole than with papaverine, or adenosine. The reported impairment of coronary flow reserve in patien ts with angina and normal coronary arteries may reflect the variabilit y in response to different pharmacological agents. The mechanism under lying this variability is unknown, but may involve an abnormality of a denosine metabolism in the myocardium.