Prevalence of noncalcified plaques and coronary artery stenosis in patients with coronary calcium scores of zero.

OBJECTIVES: A higher coronary artery calcium score (CACS) is associated with increased coronary artery plaque burden resulting in increased cardiovascular risk. Conversely, the absence of calcium indicates a low risk of cardiovascular events. However, coronary plaque calcification is a late manifestation of atherosclerosis; earlier stages of atherosclerosis present noncalcified plaques (NCPs) A recent study demonstrated that the absence of coronary artery calcification deposit does not preclude obstructive stenosis or the need for revascularization in patients with a high suspicion of coronary artery disease (CAD). Our study aimed to investigate the prevalence of NCP and the severity of coronary artery stenosis in symptomatic patients in our local population who were referred for coronary artery computed tomography angiogram (CCTA) with 0 CACS. METHODS: A total of 299 patients who had undergone CACS and CCTA, and had scored zero for coronary artery calcium. Patients included had clinically appropriate indications, mainly chest pain with variable severity with no history of CAD. The presence of CAD risk factors, such as diabetes, hypertension, and smoking, was obtained from reviewing patient charts. The CCTA analysis was performed to evaluate for coronary artery stenosis and the presence of NCP. The severity of stenosis was quantified by visual estimation and divided into 0% stenosis, 1-25% stenosis, 26-50% stenosis, and more than 50% stenosis. RESULTS: The prevalence of NCP was 6.4% (19 of the 299). Among the 19 patients with NCP, 52.6% had no identified coronary artery stenosis, 26.3% had less than 25%, and 21% had stenosis between 25 and 50%. None had stenosis greater than 50%. There was a strong association between male sex (P = 0.001), smoking (P = 0.0.004), hypertension, and NCP (P = 0.042), but no association was found between NCP and age or diabetes. CONCLUSIONS: In patients with a high clinical suspicion of CAD, the absence of coronary artery calcification does not rule out CAD; up to 6.4% of these patients have early CAD as evidenced by NCP detected by CCTA, and none have more than 50% stenosis, However, future prognostic and long-term follow-up studies are needed to determine prognostic value of NCP in patients with 0 CACS.

Benthic foraminifera from polluted marine environment of Sulaibikhat Bay (Kuwait).

Quantitative analyses of recent benthic foraminiferal assemblages (living and dead) were carried out on the surface sediments of Sulaibikhat Bay. Marked contrast in foraminiferal assemblages between the shallow tidal mudflats and the deep tidal channel and their relation to the extent of pollution were observed. Cluster analysis of quantitative data on the distribution of foraminiferal tests revealed three assemblages that depend mainly on the intensity of pollution; (1) a highly polluted tidal flat assemblage, (2) normal (or less polluted) mud flat assemblage and, (3) tidal channel and subtidal assemblage. The highly polluted assemblage characterized by a drop in species densities (< 100 tests/20 cm(3) sediment) but with high average diversity (5.8 Yule-Simpson Index). The microfauna of the less polluted flat displays relatively lower diversity (4.6) but high density of tests (47.2% of the total picked tests). The most abundant species of this assemblage is Ammonia tepida, displays its maximum density in this assemblage. Ammonia tepida drops in density from 17.12% to 3.07% in the polluted assemblage. Tidal channel foraminiferal assemblages should normally display lower diversities than those of tidal flats, because tidal current in the channels tend to wash away most nutrient materials. However, this is not the case of the present study area which could be due to environmental setting of the Sulaibikhat Bay in which tidal currents bring in exceptionally high amounts of nutrients from Shatt Al-Arab Estuary and in which the tidal flats are strongly and adversely polluted.