Background Coronary flow reserve can be estimated by transesophageal Doppler echocardiography (TDE). Objective To evaluate the coronary flow reserve by TDE, serially over 6 months' follow-up, after successful percutaneous transluminal coronary angioplasty (PTCA) of proximal left anterior descending coronary artery (LADA). Methods and results We performed TDE examination of 30 patients (mean age 55 +/- 9 years) 72 h, 3 months, and 6 months after PTCA of LADA, Selective angiography of LADA was repeated 72 h and 6 months after PICA of LADA. Velocity of flow in LADA was measured before and 2 min after cessation of intravenous infusion of dipyridamole (0.56 mg/kg in 4 min). The dipyridamole:rest mean diastolic velocity ratio was considered as an index of coronary flow reserve (CFR). For 20 of 21 patients with CFR > 2 there was no restenosis, whereas coronary angiography revealed restenosis in eight of nine patients with CFR < 2. The sensitivity was 88.9% and the specificity was 95.2%. For the 21 patients without restenosis mean CFR was 2.1 +/- 0.1 72 h after PTCA, had increased to 3.1 +/- 0.3 (P < 0.0001) 3 months after PTCA, and remained stable thereafter (3.0 +/- 0.9). Conclusion CFR after PICA of proximal LADA can be evaluated serially by transesophageal Doppler echocardiography, CFR of LADA in patients without restenosis is increased 3 months after PICA and remains stable thereafter. Coron Artery Dis 12:45-52 (C) 2001 Lippincott Williams & Wilkins.