Intracoronary Doppler assessment of moderate coronary artery disease: comparison with 201Tl imaging and coronary angiography. FACTS Study Group.

BACKGROUND: Coronary angiography may not reliably predict whether a stenosis causes exercise-induced ischemia. Intracoronary Doppler ultrasound may enhance diagnostic accuracy by providing a physiological assessment of stenosis severity. The goal of this study was to compare intracoronary Doppler ultrasound with both 201Tl imaging and coronary angiography. METHODS AND RESULTS: Fifty-five patients with 67 stenotic coronary arteries underwent coronary angiography with intracoronary Doppler ultrasound and had exercise 201Tl testing within a 1-week period. Coronary flow reserve was measured, and analyses were performed by independent core laboratories. The mean stenosis was 59+/-12%; 51 of 67 stenoses were intermediate in severity (40% to 70%). A coronary flow reserve < 1.7 predicted the presence of a stress 201Tl defect in 56 of 67 stenoses (agreement=84%; kappa=0.67; 95% CI=0.48 to 0.86). In the patients who achieved 75% of their predicted maximum heart rate, the Doppler and 201Tl imaging data agreed in 46 of 52 stenoses (agreement=88%; kappa=0.77; 95%CI=0.57 to 0.97). Scatter was evident when angiography was compared with coronary flow reserve (r=.43), and the angiogram did not reliably predict the results of the 201Tl stress test (kappa=0.21; agreement=57% to 63%). CONCLUSIONS: Doppler-derived coronary flow reserve accurately predicts the presence of exercise-induced ischemia on stress 201Tl imaging, and coronary angiography does not reliably assess the physiological significance of an intermediate coronary stenosis.

Blood flow velocity in the right coronary artery: assessment before and after angioplasty.

OBJECTIVES: This study attempted 1) to assess the utility of rest measurements of intracoronary blood flow velocity for the physiologic assessment of coronary stenoses before and after right coronary artery angioplasty, and 2) to compare the phasic flow pattern in the right coronary artery proper with the phasic flow pattern in its major branches to the left ventricle. BACKGROUND: Previous investigations have demonstrated that a reduction in distal blood flow velocity and a loss of distal diastolic predominant flow are characteristic of physiologically significant stenoses and that these indexes normalize after successful coronary artery dilation. However, these studies were predominantly performed in the left coronary artery. The utility of monitoring rest velocity variables during angioplasty of the right coronary artery has not been studied. METHODS: We studied 20 patients undergoing angioplasty of the right coronary artery with use of a Doppler angioplasty guide wire. RESULTS: Values were expressed as the mean value +/- 1 SD. The rest average peak velocity did not decrease distal to angiographically significant right coronary artery stenoses (23.3 +/- 9.4 cm/s proximal vs. 20.2 +/- 11.1 cm/s distal, p = 0.20). The proximal/distal velocity ratio was 1.4 +/- 0.9 before angioplasty and did not significantly decrease after angioplasty (p = 0.58). This study had a 99.4% power to detect a difference between proximal and distal average peak velocity. There was no relation between percent diameter stenosis and proximal/distal velocity ratios (r = 0.15, p = 0.55). Diastolic predominant flow was not observed in the proximal or distal right coronary artery. However, after angioplasty, diastolic predominant flow was observed in the posterolateral and posterior descending coronary arteries. CONCLUSIONS: Rest phasic Doppler flow velocity indexes are not useful for evaluating stenoses in the right coronary artery proper before or after angioplasty. In contrast to the right coronary artery proper, diastolic predominant flow is observed in the posterior descending and posterolateral coronary arteries. The utility of measuring hyperemic Doppler flow velocity indexes, such as distal coronary flow reserve, for assessing right coronary artery stenoses merits further investigation.