The clinical features of tako-tsubo cardiomyopathy or transient left apical ballooning syndrome (LABS) have been clearly described, but the mechanisms are still unknown. Our objective was to prospectively assess coronary microcirculation at the acute phase of LABS and after functional recovery, using Doppler transthoracic echocardiography-coronary flow reserve (CFR). Twelve consecutive patients (11 women, mean age 68 +/- 10 years) satisfying the criteria for LABS underwent Doppler transthoracic echocardiography-CFR in the distal part of the left anterior descending coronary artery, using intravenous adenosine infusion (0.14 mg/kg/min over 2 minutes) at the acute phase and 25 +/- 3 days later. CFR was calculated as the ratio of hyperemic to basal mean diastolic flow velocity. Wall-motion score (WMS) was calculated using the 16-segment model during the same echocardiographic examination (normal WMS = 16). Doppler transthoracic echocardiography-CFR increased between the two examinations from 2.2 +/- 0.4 at the acute phase to 2.9 +/- 0.3 (P < .01), whereas WMS decreased (from 31 +/- 6 at the acute phase to 16.5 +/- 0.8, delta WMS = -14.6 +/- 6, P < .01). All patients exhibited an increase of CFR between the two tests (delta CFR = 0.73 +/- 0.39, range: 0.3-1.6). A significant correlation was observed between delta CFR and delta WMS (r = -0.89, P < .01). In conclusion, serial noninvasive CFR measurements performed in LABS suggested transient microcirculatory impairment during the acute phase of the syndrome. The wall-motion improvement parallel to the dynamic improvement of the microcirculation suggests a role of coronary microcirculatory damage in the pathogenesis of acute and transient wall-motion abnormalities in LABS.