Incremental prognostic value of coronary artery calcium score versus CT angiography among symptomatic patients without known coronary artery disease

Abstract

Objective To evaluate the prognostic value and test characteristics of coronary artery calcium (CAC) score for the identification of obstructive coronary artery disease (CAD) in comparison with coronary computed tomography angiography (CCTA) among symptomatic patients. Methods Retrospective cohort study at two large hospitals, including all symptomatic patients without prior CAD who underwent both CCTA and CAC. Accuracy of CAC for the identification of ≥50% and ≥70% stenosis by CCTA was evaluated. Prognostic value of CAC and CCTA were compared for prediction of major adverse cardiovascular events (MACE, defined as non-fatal myocardial infarction, cardiovascular death, late coronary revascularization (>90 days), and unstable angina requiring hospitalization). Results Among 1145 included patients, the mean age was 55 ± 12 years and median follow up 2.4 (IQR: 1.5–3.5) years. Overall, 406 (35%) CCTA were normal, 454 (40%) had <50% stenosis, and 285 (25%) had ≥50% stenosis. The prevalence of ≥70% stenosis was 16%. Among 483 (42%) patients with CAC zero, 395 (82%) had normal CCTA, 81 (17%) <50% stenosis, and 7 (1.5%) ≥ 50% stenosis. 2 (0.4%) patients had ≥70% stenosis. For diagnosis of ≥50% stenosis, CAC had a sensitivity of 98% and specificity of 55%. The negative predictive value (NPV) for CAC was 99% for ≥50% stenosis and 99.6% for ≥70% stenosis by CCTA. There were no adverse events among the 7 patients with zero calcium and ≥50% CAD. For prediction of MACE, the c-statistic for clinical risk factors of 0.62 increased to 0.73 (p < 0.001) with CAC versus 0.77 (p = 0.02) with CCTA. Conclusion Among symptomatic patients with CAC zero, a 1–2% prevalence of potentially obstructive CAD occurs, although this finding was not associated with future coronary revascularization or adverse prognosis within 2 years.

Statin therapy is associated with lower all-cause mortality in patients with non-obstructive coronary artery disease

“…In order to minimize verification bias, patients who underwent PCI or CABG within 90 days after CCTA (early coronary revascularization) were censored at the time of coronary revascularization to exclude revascularization procedures driven by CCTA results or symptomatic status [19]. Also, if a statin or aspirin was prescribed with or after coronary revascularization, these patients were censored at the time of revascularization.…”

Identification of coronary artery calcification can optimize risk stratification in patients with acute chest pain

“…As coronary artery calcification (CAC) represents direct evidence of coronary atherosclerosis (8) with excellent negative predictive values in patients without presence of CAC (13–16), it suggests itself to be beneficial for risk stratification of patients with suspected ACS and potentially advantageous as opposed to clinical risk scores alone. In fact, in this low-intermediate risk population only 10% of patients without CAC were shown to have any coronary plaque by CTA, whereas in 44% of patients with TIMI=0, plaque was present on CTA.…”

“…As shown in asymptomatic patients, CAC scoring has been studied extensively and is well established by using non-contrast ECG-gated computed tomography of the heart (9–11). Although the negative predictive value (NPV) was consistently demonstrated to be high, in symptomatic patients the assessment of CAC does not play a major role (1, 12), as obstructive CAD can not be ruled out completely using non-contrast scans of the heart (13–16). …”

Coronary Computed Tomographic Angiography

“…18 National Institute for Health and Clinical Excellence guidelines have adopted this strategy on the basis of estimates of the cost-effectiveness of this approach, 20 further studies are needed to examine the safety of CAC for ruling out ACS and potentially to guide the need and type of further testing (eg, discharge when CAC=0, CTA when CAC=1-99, and perfusion imaging for patients with CAC >100).…”