Slow runoff is not a good predictor of coronary microcirculatory dysfunction in patients with angiographically normal coronary arteries. A validation study versus absolute coronary flow reserve.

The meaning of angiographically assessed slow runoff in patients (pts) with angiographically normal coronary artery is controversial. Non-invasevely assessed absolute coronary flow reserve (CFR) in in the left anterior descending coronary artery (LAD) by Color guided pulsed-wave Doppler is a reliable parameter to assess coronary microcirculatory dysfunction (CMD). So this study aimed at assessing the value of slow runoff in predicting CMD. Results: We studied 38 consecutive pts with angiographically normal coronary artery that underwent non-invasive assessement of CFR in the LAD. We found that 9 pts out of 38 (group 1)had slow runoff and the remaining 29 had normal runoff (group 2). The CFR evaluated in the the 2 groups was not significantly different (see graph). CFR was infact, in the group 1 (Mean +/- SD) = 2,79+/- 0,8 and in the group 2= 2,89 +/- 0,7 (p= ns). In addition considering a CFR value =< 2,5 as index of coronary microcirculatory dysfunction, we found CMD in 3 pts of group 1 (33%) and in 8 pts of group 2 (27%) (p=ns). The calculated sensitivity and specificity of slow runoff in predicting CMD was at 44% and 64% respectively. Conclusion: Slow runoff is not a good predictor of coronary microcirculatory dysfunction and its clinical value, if any, is uncertain and probably multifactorial.