SPECT myocardial perfusion imaging as an adjunct to coronary calcium score for the detection of hemodynamically significant coronary artery stenosis.

BACKGROUND: Coronary artery calcifications (CAC) are markers of coronary atherosclerosis, but do not correlate well with stenosis severity. This study intended to evaluate clinical situations where a combined approach of coronary calcium scoring (CS) and nuclear stress test (SPECT-MPI) is useful for the detection of relevant CAD. METHODS: Patients with clinical indication for invasive coronary angiography (ICA) were included into our study during 08/2005-09/2008. At first all patients underwent CS procedure as part of the study protocol performed by either using a multidetector computed tomography (CT) scanner or a dual-source CT imager. CAC were automatically defined by dedicated software and the Agatston score was semi-automatically calculated. A stress-rest SPECT-MPI study was performed afterwards and scintigraphic images were evaluated quantitatively. Then all patients underwent ICA. Thereby significant CAD was defined as luminal stenosis ≥ 75% in quantitative coronary analysis (QCA) in ≥ 1 epicardial vessel. To compare data lacking Gaussian distribution an unpaired Wilcoxon-Test (Mann-Whitney) was used. Otherwise a Students t-test for unpaired samples was applied. Calculations were considered to be significant at a p-value of <0.05. RESULTS: We consecutively included 351 symptomatic patients (mean age: 61.2 ± 12.3 years; range: 18-94 years; male: n=240) with a mean Agatston score of 258.5 ± 512.2 (range: 0-4214). ICA verified exclusion of significant CAD in 66/67 (98.5%) patients without CAC. CAC was detected in remaining 284 patients. In 132/284 patients (46.5%) with CS>0 significant CAD was confirmed by ICA, and excluded in 152/284 (53.5%) patients. Sensitivity for CAD detection by CS alone was calculated as 99.2%, specificity was 30.3%, and negative predictive value was 98.5%. An additional SPECT in patients with CS>0 increased specificity to 80.9% while reducing sensitivity to 87.9%. Diagnostic accuracy was 84.2%. CONCLUSIONS: In patients without CS=0 significant CAD can be excluded with a high negative predictive value by CS alone. An additional SPECT-MPI in those patients with CS>0 leads to a high diagnostic accuracy for the detection of CAD while reducing the number of patients needing invasive diagnostic procedure.

Lipoprotein (a) is independently correlated with coronary artery calcification.

INTRODUCTION: Lipoprotein a (Lp(a)) has been recognized as a risk factor for both coronary heart diseases and for cardiovascular events. Coronary artery calcification (CAC) is a well proven marker for coronary artery disease and risk factor for cardiovascular events. Still there are conflicting data regarding the relationship of Lp(a) and CAC. We therefore wanted to evaluate the influence of Lp(a) on CAC. METHODS: 1560 European patients (1123 men, age 59.3 ± 20.8 years) with typical or atypical chest pain underwent CAC scoring by a multi-slice CT-scanner, using a standard protocol. Blood samples were evaluated the same day using an automated particle enhanced immunoturbidimetric assay to determine Lp(a) serum levels. RESULTS: There was a positive correlation between CAC score, age, and common cardiovascular risk factors. Lp(a) serum levels were not associated with age but a positive correlation between Lp(a) serum levels and CAC was found. In the multivariate analysis age, diabetes, statin therapy, and Lp(a) could be identified as independent risk factors for CAC. (p<0.001). BMI, smoking, hypertension and LDL-C were not independently associated with CAC. CONCLUSION: Lp (a) could be identified as an independent predictor of CAC, a marker of coronary atherosclerosis. Further a positive correlation between increasing Lp (a) levels and CAC scores was found.