Role of Agatston Scores in determining patients at risks of major cardiovascular events undergoing cardiac Computed Tomography at Muhimbili National Hospital.

Abstract

Background: Agatston score is a semi-automated tool to calculate a calcium score based on the extent of coronary artery calcification (CAC) detected by an unenhanced low-dose CT scan. The amount of calcification calculated has been applied in the clinical field as an indicator of major cardiovascular event risk. CT can predict coronary heart disease (CHD) events, even beyond the Framingham Risk Score (FRS). A score of over 300 signifies a high chance of developing major cardiovascular events. Broad Objective: To assess the role of Agatston scores in determining patients at risk of major cardiovascular events undergoing cardiac computed tomography at Muhimbili National Hospital. Methodology: This Hospital-based, cross-sectional study was done at Muhimbili National Hospital (MNH) - Dar Es Salaam, Tanzania, assessed the CACS in all cardiac patients referred for cardiac CT and asymptomatic Chest CT patients regardless of the order indicated, from November 2018 to April 2019. The study involved a total of 238 patients who underwent cardiac or chest computed tomography to determine their Agatston scores and online calculated Framingham risk scores for possible risks of major cardiovascular events. Standardized structured questionnaires were used for recording patients' demographics, clinical information, calculated FRS and the Agatston scores. The PI did the cardiac CT images evaluation and then was confirmed by a specialized cardiac radiologist, in case of disagreement a third radiologist was consulted. The imaging data were recorded only when consensus on the findings was reached. SPSS for Windows version 22.0 was used for the data analysis. Categorical variables the independent (age, sex) with the dependent (Agatston scores, FRS) and the comparison of the two scores were all analyzed by Chi-square test with a confidence interval of 95%, p-value < 0.05 was considered statistically significant. Results: This study involved 238 patients, (134 males, 104 females). The age ranged from 34 to 98 years with a mean age of 61years. The CACS ranged 0 to 1399 (mean score 94) showed that Agatston scores strongly associated (p<0.001) with aging, with the highest risk of developing major cardiovascular events observed at age group >80 years (75.9%) compared to other age groups, 70-79years (48.7%), 60-69 years (21.5%), 50-59 years (19.0%), 40-49 years and 30-39 years (0%). Also, an association (p<0.05) was observed between Agatston scores and male gender (29.9%) compared to females (15.4%). Strong associations (p<0.001) between FRS with aging were more seen with age group >80 years (82.8%) compared to other groups such as 70-79 (38.5%), 60-69 (7.7%) while 50-59, 40-49 and 30-39 had (0%) and male gender were more at risk with 26.1% compared to females (8.7%). The Agatston scores > 300 reclassified 5.6% low and 36.5% intermediate FRS to high-risk individuals to develop major CVE. The difference between Agatston score and FRS was strongly statistically significant (p<0.001). Conclusions: Agatston score and FRS increase with aging and males are more prone to high scores hence are at higher risk of developing major cardiovascular events. It is then recommended to use Agatston score routinely in CAD risk assessment. This will modify the patients‟ management prior to developing major cardiovascular events. The guidelines by SCCT and STR can be implemented as primary management to detect asymptomatic cases