To evaluate the efficacy of stress Tc-99m MIBI myocardial perfusion imaging using intravenous dipyridamole in detecting coronary artery disease (CAD) and to determine if chest pain symptom is a proper index for detection of myocardial ischemia in post-infarction patients, we observed 73 cases (65 men, 8 women, 38-79 years old) between Sept. 1990 and May 1992. All patients were suffered from old myocardial infarction (MI) evidenced by history and ECG and were divided into two groups: group I involving 41 patients with post-infarction chest pain symptom and group II including 32 patients without post-infarction chest pain symptom. Among them, 19 (group IA) of group I and 11 (group IIA) of group II received coronary arteriography (CAG) for comparison. Of the 41 group I post-infarction chest pain patients, 17 suffered from old anterior or antero-septal wall (AW) MI, 21 from old inferior wall (IW) MI, 1 from old lateral wall (LW) MI and 2 from combined old AW and IW (AIW) MI by ECG. All 17 patients with AWMI suffered from AW perfusion defect (7 were MI, 10 were MI with ischemia) but 7 of them from multivessel disease (MVD) by Tc-99m MIBI. All 21 patients with IWMI suffered from IW perfusion defect (9 were MI, 12 were MI with ischemia) but 13 of them from MVD by Tc-99m MIBI. Of the patient with LWMI and 2 patients with AIWMI suffered from MVD by Tc-99m MIBI. Of the 32 group II post-infarction patients without chest pain symptom, 12 suffered from old AWMI, 14 from old IWMI, 2 from old LWMI, 3 from AIWMI and 1 from ALWMI by ECG. Of the 12 patients with AWMI, 11 suffered from AW perfusion defect (6 were MI, 5 were MI with ischemia) but 1 of them from MVD by TC-99m MIBI. All 14 patients with IWMI suffered from IW perfusion defect (12 were MI, 2 were MI with ischemia) but 4 of them from MVD by Tc-99m MIBI. Of the 2 patients with LWMI suffered from LW infarction by Tc-99m MIBI. Of the 3 patients with AIWMI and 1 with ALWMI suffered from MVD by Tc-99m MIBI. Of the 11 patients in group IA and 5 patients in group IIA with AWMI, CAG revealed the incidence of infarct-related recanalization of LAD was 9/11(82%) and 4/5(80%) respectively and the respective incidence of MVD was 6/11(55%) and 0/5(0%).(ABSTRACT TRUNCATED AT 400 WORDS)