Prevalence and Severity of Coronary Artery Disease and Adverse Events Among Symptomatic Patients With Coronary Artery Calcification Scores of Zero Undergoing Coronary Computed Tomography Angiography: Results From the CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes: An International Multicenter) Registry

Study Questions:

Does coronary artery calcification (CAC) in patients with cardiac symptoms correlate with severity of coronary artery disease (CAD) by coronary computed tomography angiography (CCTA)?

Methods:

The CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes: An International Multicenter) registry collected data on men and women between 2005 and 2009 at 12 centers from Canada, Germany, Italy, Korea, Switzerland, and the United States. All participants underwent 64-detector row CCTA. For the present analysis, only symptomatic patients without CAD who underwent CCTA and CAC scoring were included. Individuals with known CAD (previous myocardial infarction and/or coronary revascularization) were excluded. Chest pain was classified according to the Diamond and Forrester criteria. CAC was quantified according to the Agatston method. CAD lesions were quantified for lumen diameter stenosis by visual estimation and graded as none (0% luminal stenosis), mild (1-49%), moderate (50-69%), or severe (70%). Coronary lesions ≥50% in lumen stenosis severity were defined as obstructive. The primary outcome was time to death from any cause. Secondary outcomes included time to a composite endpoint of all-cause mortality, nonfatal myocardial infarction, and coronary revascularizations performed after CCTA. Early revascularizations (defined as <90 days post-CCTA) were reported separately.

Results:

A total of 10,037 patients were included in the present analysis (mean age 57 years, 56% men). Over one half (51%) of the patients had a CAC score of 0. Among patients with a CAC score of 0, 84% had no CAD, 13% had nonobstructive stenosis, and 3.5% had ≥50% stenosis by CCTA. Only 1.4% had stenosis ≥70%. A CAC score of >0 had a sensitivity, specificity, and negative and positive predictive values for stenosis ≥50% of 89%, 59%, 96%, and 29%, respectively. During a median of 2.1 years, there was no difference in mortality among patients with a CAC score of 0 irrespective of obstructive CAD. Among 8,907 patients with follow-up for the composite endpoint, those with a CAC score of 0 and ≥50% stenosis by CCTA had an increased risk of events compared to patients with a CAC score of 0 and no obstructive CAD (hazard ratio, 5.7; 95% confidence interval, 2.5-13.1). Receiver-operator characteristic curve analysis demonstrated that the CAC score did not add incremental prognostic information compared with CAD extent on CCTA for the composite endpoint.

Conclusions:

The investigators concluded that among symptomatic patients with a CAC score of 0, the presence of obstructive CAD is possible and is associated with increased risk for cardiovascular events. CAC scoring did not add incremental prognostic information to CCTA.

Perspective:

These data provide important clinically relevant information on the potential usefulness of both CAC scoring and the degree of CAD severity as detected by CCTA. Determining how such patients should be managed is the next question to be answered.

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Atherosclerotic Disease (CAD/PAD), Interventions and Coronary Artery Disease, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: Risk, Coronary Artery Disease, Myocardial Infarction, Republic of Korea, Follow-Up Studies, Sensitivity and Specificity, Canada, Germany, Constriction, Pathologic, Italy, Prevalence, Prognosis, Registries, Coronary Angiography, Tomography, Chest Pain, Confidence Intervals, ROC Curve, Switzerland, United States


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