Mieko Tamura

Quantitative Measures of Coronary Stenosis Severity by 64-Slice CT Angiography and Relation to Physiologic Significance of Perfusion in Nonobese Patients: Comparison with Stress Myocardial Perfusion Imaging

Coronary stenosis severity by 64-slice CT angiography (CTA) is acceptably correlated with intravascular ultrasound. Stress myocardial perfusion imaging using SPECT is an established method for assessment of the functional significance of coronary stenosis. Our aim was to assess a clinical validation of quantitative measurements of coronary stenosis severity by 64-slice CTA and the relation to the physiologic significance of myocardial perfusion. Methods: One hundred four patients with suspected coronary artery disease underwent 64-slice CTA and stress 201Tl SPECT. The stenosis severities of 105 coronary lesions assessed by CTA with sufficient image quality were compared with the results of stress 201Tl SPECT. The body mass index (BMI) of the patients was 23.8 kg/m2 (range, 21.1–25.6 kg/m2). Results: Reversible defects began to increase progressively when the area of stenosis was at least 60%, and the prevalence of these reversible defects and their severity significantly increased as the degree of stenosis increased. When stenosis severity by CTA is < 60%, ischemia is seldom observed; when stenosis severity is ≥80%, ischemia is common (86%). For intermediate stenosis severity values of 60%–70%, the prevalence of reversible defects was 9 of 27 vessels (33%), and for stenosis severity values of 70%–80%, the prevalence was 20 of 37 vessels (54%). When evaluating the diagnostic accuracy of stenosis severity by CTA to identify patients with ischemia excluding all nonevaluable vessels, applying stenosis thresholds of >70% results in 79% sensitivity, 92% specificity, 66% positive predictive value, and 96% negative predictive value. A lesion minimal luminal cross-sectional area of < 3.7 mm2 was a good accurate cutoff value for significant coronary narrowing using stress SPECT, with a sensitivity of 88% and specificity of 83% by receiver-operating-characteristic analysis. Conclusion: Despite an excellent negative predictive value to rule out the presence of ischemia, 64-slice CTA alone is a poor discriminator of the functional significance of myocardial ischemia in a highly selected patient population with a low BMI.

Early validation study of 64-slice multidetector computed tomography for the assessment of myocardial viability and the prediction of left ventricular remodelling after acute myocardial infarction

AIMS We aim to validate the ability of multidetector computed tomography (MDCT) for assessing myocardial viability and predicting left ventricular (LV) remodelling after acute myocardial infarction (AMI). METHODS AND RESULTS In 52 consecutive patients with first AMI, 64-slice MDCT without iodine re-injection was performed immediately following coronary stenting. Electrocardiogram-gated thallium-201 single-photon emission tomography was performed using QGS programs within 5 days and 6 months after onset. Among the 52 patients, 18 patients (Group A) showed transmural contrast-delayed enhancement on MDCT images, 20 patients (Group B) showed subendocardial contrast-delayed enhancement, and 14 patients (Group C) had no contrast-delayed enhancement. In the acute phase, peak creatine kinase-MB [497 (189-744), 182 (90-358), 85 (40-204) IU/mL, respectively, P = 0.0004] was significantly higher in Group A, while the incidence of myocardial blush grade 3 (22, 67, 75%, respectively, P = 0.001) and LV ejection fraction (41 +/- 7, 53 +/- 12, 62 +/- 11%, respectively, P < 0.0001) were significantly lower in Group A. During the 6-month period, LV remodelling (P = 0.001) and the number of rehospitalization for heart failure (P = 0.0017) were more significantly observed in Group A. CONCLUSION Myocardial contrast-delayed enhancement patterns provide promising information regarding myocardial viability, LV remodelling, and prognosis in AMI.