OBJECTIVE Unrecognized left main coronary artery disease (LMCD) is often fatal; however, accuracy of non-invasive tests for diagnosing LMCD is still unsatisfactory. This study was performed to elucidate single-photon emission computed tomography (SPECT) detection of LMCD using quantitative coronary angiography (QCA) data.

MATERIALS AND METHODS Fifty-five patients (39 men; mean age, 68.1 ± 10.9 years) diagnosed with significant left main (LM) stenosis (≥ 50%) by invasive coronary angiography (ICA) were retrospectively reviewed. All study patients underwent SPECT with pharmacologic stress within 30 days of ICA. All coronary lesions were quantified via QCA, and SPECT findings were compared with QCA results.

RESULTS Only four patients (7.3%) had isolated LMCD; all others had combined significant stenosis (≥ 70%) of one or more other epicardial coronary arteries. Patients with more severe coronary artery disease tended to have higher values for summed difference scores in a greater number of regions, but the specific pattern was not clearly defined. Summed stress score of SPECT did not differ according to LM stenosis severity. Only three patients (5.4%) had a typical LM pattern of reversible perfusion defect on SPECT. A significant negative linear correlation between stenosis severity and stress perfusion percent was found in the left anterior descending artery region (r = -0.455, p < 0.001) but not in the left circumflex artery.

CONCLUSION Single-photon emission computed tomography findings were heterogeneous, not specific and poorly correlated to QCA data in patients with significant LMCD. This may be due to highly prevalent significant stenosis of other epicardial coronary arteries.