Coronary artery calcium score and risk of cardiovascular events without established coronary artery disease: A systemic review and meta-Analysis

Background Coronary artery calcium (CAC) is an indicator of atherosclerosis, and the CAC score is a useful noninvasive assessment of coronary artery disease. Objective To compare the risk of cardiovascular outcomes in patients with CAC > 0 versus CAC = 0 in asymptomatic and symptomatic population in patients without an established diagnosis of coronary artery disease. Methods A systematic search of electronic databases was conducted until January 2018 for any cohort study reporting cardiovascular events in patients with CAC > 0 compared with absence of CAC. Results Forty-five studies were included with 192 080 asymptomatic 32 477 symptomatic patients. At mean follow-up of 11 years, CAC > 0 was associated with an increased risk of major adverse cardiovascular and cerebrovascular events (MACE) compared to a CAC = 0 in asymptomatic arm [pooled risk ratio (RR) 4.05, 95% confidence interval (CI) 2.91-5.63, P < 0.00001, I²= 80%] and symptomatic arm (pooled RR 6.06, 95% CI 4.23-8.68, P < 0.00001, I²= 69%). CAC > 0 was also associated with increased risk of all-cause mortality in symptomatic population (pooled RR 7.94, 95% CI 2.61-24.17, P < 0.00001, I²= 85%) and in asymptomatic population CAC > 0 was associated with higher all-cause mortality (pooled RR 3.23, 95% CI 2.12-4.93, P < 0.00001, I²= 94%). In symptomatic population, revascularization in CAC > 0 was higher (pooled RR 15, 95% CI 6.66-33.80, P < 0.00001, I²= 72) compared with CAC = 0. Additionally, CAC > 0 was associated with more revascularization in asymptomatic population (pooled RR 5.34, 95% CI 2.06-13.85, P = 0.0006, I²= 93). In subgroup analysis of asymptomatic population by gender, CAC > 0 was associated with higher MACE (RR 6.39, 95% CI 3.39-12.84, P < 0.00001). Conclusion Absence of CAC is associated with low risk of cardiovascular events compared with any CAC > 0 in both asymptomatic and symptomatic population without coronary artery disease.