CT coronary calcification: What does a score of "0" mean?

Calcium score (CS) is a useful tool in evaluating the risk of cardiovascular events in asymptomatic patients. The absence of detectable calcification determines excellent cardiovascular prognosis, with event rates lower than that of negative stress studies, probably due to the latter's inability to detect nonobstructive coronary artery disease (CAD). There are few primary prevention medications that would be cost-effective in such a low-risk patient population. The interval for retesting patients with zero CS is still open for debate but it should not be in less than 4 to 5 years. CS should not be used to rule out obstructive CAD in symptomatic patients, as its correlation with coronary stenosis is poor and obstructive CAD is commonly found among symptomatic zero CS patients. Most studies have found very low specificity values for CS to detect obstructive CAD in symptomatic patients, meaning it has limited ability to detect the true negative cases (ie, zero CS without obstructive CAD).

Diagnostic accuracy of arterial phase 64-slice multidetector CT angiography for left atrial appendage thrombus in patients undergoing atrial fibrillation ablation.

INTRODUCTION: Multidetector CT (MDCT) is used prior to atrial fibrillation ablation (AFA) to anatomically guide ablation procedures. Whether 64-slice MDCT also can be used to diagnose left atrial thrombus is not known. METHODS: We sought to determine the accuracy and interobserver variability of MDCT in the evaluation of left atrial thrombus prior to AFA. We enrolled 50 patients scheduled for AFA who underwent 64-slice MDCT scan and transesophageal echocardiography prior to the procedure. Three experienced observers reviewed all the MDCT images for the presence of a left atrial thrombus, and two different readers interpreted the transesophageal echocardiograms (TEE), which were used as the gold standard. All observers were blinded to clinical data and each other. RESULTS: Interobserver variability between the three MDCT readers was poor (highest kappa statistic 0.43, P = 0.001). Diagnostic accuracy was highly variable, with sensitivities ranging from 100% to 50% and specificities ranging from 85% to 44%. TEE reader agreement was 98%. CONCLUSION: MDCT demonstrates high interobserver variability and has only modest diagnostic accuracy for the detection of left atrial thrombus in patients undergoing AFA procedure. Potential factors affecting the accuracy of MDCT include image quality and the difficulty of distinguishing clot from pectinate muscle. MDCT likely is not the optimal method to detect left atrial thrombus using current techniques and standards of interpretation.