BACKGROUND AND OBJECTIVES: Dilated cardiomyopathy(DCMP) is a primary myocardial disease of unknown cause characterized by left ventricular or biventricular dilatation and impaired myocardial contractility. In 1973, Kreulen et al. classified DCMP into two groups-one with generalized hypokinesia and the other with regional asynergy in addition to generalized hypokinesia. Diminished coronary flow reserve has been reported in DCMP with generalized hypokinesia but its mechanism remains obscure. The aim of this study was to investigate the relationship between the degree of microvascular dysfunction and the difference of regional wall motion abnormality in DCMP with regional asynergy. METHODS: The subjects of this study were 11 patients (M:F=:5, mean age:60 15yrs) a diagnosis of DCMP with regional asynergy, normal sinus rhythm without left bundle branch block and normal coronary angiogram who underwent Doppler wire from September 1997 to December 1999. Left ventricle was divided into three territories according to the coronary arterial distribution by echocardiography(A: coronary artery territory showing regional asynergy, I: coronary artery territory showing intermediate wall motion, P: coronary artery territory showing relatively preserved wall motion). Coronary flow reserve(CFR) was measured at the mid portion of left anterior descending artery(LAD), left circumflex artery(LCX) and right coronary artery(RCA) with 0.014 inch Doppler guide wire before and during intracoronary injection of 12-18 of adenosine. Relative coronary flow reserve(rCFR) was obtained by the ratio of the CFR in coronary artery of the territory showing regional asynergy and relatively preserved wall motion to the CFR in coronary artery of the territory showing intermediate wall motion (CFRA/CFRI, CFRP/CFRI). RESULTS: Regional asynergy was observed in LAD territory in 4(36%) patients, LCX territory in 4(36%) patients, RCA territory in 3(28%) patients (p=s). The mean CFR was 2.5 0.6 in LAD, 2.4 0.5 in LCX, 2.4 0.6 in RCA(p=s). The mean CFR and rCFR in coronary arteries showing regional asynergy were significantly lower than those in coronary arteries showing relatively preserved wall motion(2.1 0.5 vs 2.7 0.6, p<0.05, 0.84 0.12 vs 1.11 0.11, p<0.001). CONCLUSION: Degree of regional hypokinesia in DCMP with regional asynergy seems to be associated with that of microvascular dysfunction.