In the assessment of the acute results of percutaneous transluminal coronary angioplasty (PTCA), myocardial perfusion at maximal vasodilatation theoretically has fewer limitations than the coronary flow reserve measurements and quantitative coronary angiography. The purpose of this study was to compare the myocardial perfusion to the measurements of the severity of the lesion (minimal luminal diameter and percent area stenosis) and to relate it to the changes of left ventricular function after PTCA. Regional myocardial perfusion was assessed during intracoronary papaverine, using the inverse mean transit time of contrast medium (VT,,,,,), before, 15 min after, 16-24 hr after, and 6 months after successful single-vessel PTCA in 14 patients with stable angina. Left ventricular angiography (before angioplasty, 16-24 hr after, and 6 months later) was analysed by area-length and centerline methods. Immediately after PTCA, ln,,,, increased from 0.14 2 0.07 sec-' to 0.21 2 0.09 sec-' (P = .001). Maximal myocardial perfusion remained higher than the pre-PTCA value the day after angioplasty ( l n , , , , , of 0.23 2 0.09 sec-'), while it reduced to near pre-PTCA values at follow-up ( l n , , , , , of 0.16 & 0.05 sec-'). Before PTCA, three out of ten patients had ejection fraction of <65%, and seven had mild-to-moderate hypokinesis. The day after PTCA the ejection fraction and the regional dysfunction improved significantly. The change in ejection fraction 16-24 hr after PTCA did not correlate with minimal luminal diameter and percent area stenosis and correlated slightly with the improvement of perfusion (r = 0.54, P = .lo). At follow-up left ventricular function deteriorated in the whole group, despite the persistence of angiographic success of PTCA, possibly because of changes in the loading condition. Coronary artery stenosis measurements and l n , , , , , failed to correlate with the left ventricular function. Given the difficulties in routine application of the analysis of time-density curves, the measurement of minimal luminal diameter remains a more practical assessment of the results of the intervention. However, the improvement of myocardial perfusion may give more information than coronary artery dimensions of the early recovery of left ventricular function. o 1995 Wiley-Liss, Inc.