ORONARY COMPUTED TOMOgraphic (CT) angiography is a noninvasive test that enables direct visualization of coronary artery disease (CAD) and correlates favorably with invasive coronary angiography (ICA) for measures of stenosis severity. 1 However, CT cannot determine the hemodynamic significance of CAD, and even among CTidentified obstructive stenoses confirmed by ICA, fewer than half are ischemia-causing. 2,3 These findings underscore an unreliable relationship of stenosis severity to ischemia and have raised concerns that use of CT may pre-cipitate unnecessary ICA and coronary revascularization for patients who do not have ischemia. 4,5 These concerns stem from recent randomized trials that have identified no survival benefit for patients who undergo angiographically based coronary revascularization. 6,7 As an ad-junct to ICA, fractional flow reserve (FFR) has served as a useful tool to determine the likelihood that a coronary For editorial comment see p 1269.

Statins were associated with slower progression of overall coronary atherosclerosis volume, with increased plaque calcification and reduction of high-risk plaque features. Statins did not affect the progression of percentage of stenosis severity of coronary artery lesions but induced phenotypic plaque transformation. (Progression of AtheRosclerotic PlAque DetermIned by Computed TomoGraphic Angiography Imaging [PARADIGM]; NCT02803411).

Background Guidelines for the management of patients with suspected coronary artery disease (CAD) rely on the age, sex, and angina typicality-based pre-test probabilities of angiographically significant CAD derived from invasive coronary angiography (“Guideline Probabilities”). Reliability of Guideline Probabilities has not been investigated in patients referred to noninvasive CAD testing. Methods and Results We identified 14048 consecutive patients with suspected CAD who underwent coronary computed tomographic angiography (CTA) Angina typicality was recorded using accepted criteria. Pre-test likelihoods of CAD with ≥50% diameter stenosis (CAD50) and ≥70% diameter stenosis (CAD70) were calculated using Guideline Probabilities. CTA images were evaluated by ≥1 expert reader to determine presence of CAD50 and CAD70. Typical angina was associated with the highest prevalence of CAD50 (40% in men, 19% in women) and CAD70 (27% men, 11% women) when compared to other symptom categories (p<0.001 for all). Observed CAD50 and CAD70 prevalence were substantially lower than that predicted by Guideline Probabilities in the overall population (18% vs. 51% for CAD50, 10% vs. 42% for CAD70, p<0.001), driven by pronounced differences in patients with atypical angina (15% vs. 47% for CAD50, 7% vs. 37% for CAD70) and typical angina (29% vs. 86% for CAD50, 19% vs. 71% for CAD70). Marked overestimation of disease prevalence by Guideline Probabilities was found at all participating centers and across all sex and age subgroups. Conclusion In this multinational study of patients referred for coronary CTA, determination of pre-test likelihood of angiographically significant CAD by the invasive angiography-based Guideline Probabilities greatly overestimates the actual prevalence of disease.

There was no difference between groups in the use of prospective gating, tube voltage, or scan length. The examinations performed using ASIR had a lower median tube current than those obtained using FBP (median [interquartile range], 450 mA [350-600] vs 650 mA [531-750], respectively; p < 0.001). There was a 44% reduction in the median radiation dose between the FBP and ASIR cohorts (4.1 mSv [2.3-5.2] vs 2.3 mSv [1.9-3.5]; p < 0.001). After adjustment for scan settings, ASIR was associated with a 27% reduction in radiation dose compared with FBP (95% CI, 21-32%; p < 0.001). Despite the reduced current, ASIR was not associated with a difference in adjusted signal, noise, or signal-to-noise ratio (p = not significant). No differences existed between FBP and ASIR for interpretability per coronary artery (98.5% vs 99.3%, respectively; p = 0.12) or per patient (96.1% vs 97.1%, p = 0.65). CONCLUSION. ASIR enabled reduced tube current and lower radiation dose in comparison with FBP, with preserved signal, noise, and study interpretability, in a large multicenter cohort. ASIR represents a new technique to reduce radiation dose in coronary CTA studies.

Coronary computed tomography angiography (CTA) assessment of calcified or complex coronary lesions is frequently challenging. Transluminal attenuation gradient (TAG), defined as the linear regression coefficient between luminal attenuation and axial distance, has a potential to evaluate the degree of coronary stenosis. We examined the value of TAG in determining the stenosis severity on 64-slice coronary CTA. The value of TAG of 370 major coronary arteries was measured from 7,263 intervals of 5-mm length. Compared with coronary CTA and invasive coronary angiography, TAG decreased consistently and significantly with maximum stenosis severity on a per-vessel basis, from -1.91 ± 4.25 Hounsfield units/10 mm for diameter stenosis of 0% to 49% to -13.37 ± 9.81 Hounsfield units/10 mm for diameter stenosis of 100% (p < 0.0001). Adding TAG to the interpretation of coronary CTA improved diagnostic accuracy (p = 0.001), especially in vessels with calcified lesions (N = 127; net reclassification improvement 0.095; p = 0.046). TAG appears to be able to contribute to improved classification of coronary artery stenosis severity in coronary CTA, especially in severely calcified lesions.

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on behalf of the CONFIRM InvestigatorsBackground-The predictive value of coronary computed tomographic angiography (cCTA) in subjects without chest pain syndrome (CPS) has not been established. We investigated the prognostic value of coronary artery disease detection by cCTA and determined the incremental risk stratification benefit of cCTA findings compared with clinical risk factor scoring and coronary artery calcium scoring (CACS) for individuals without CPS. Methods and Results-An open-label, 12-center, 6-country observational registry of 27 125 consecutive patients undergoing cCTA and CACS was queried, and 7590 individuals without CPS or history of coronary artery disease met the inclusion criteria. All-cause mortality and the composite of all-cause mortality and nonfatal myocardial infarction were measured. During a median follow-up of 24 months (interquartile range, 18 -35 months), all-cause mortality occurred in 136 individuals. After risk adjustment, compared with individuals without evidence of coronary artery disease by cCTA, individuals with obstructive 2-and 3-vessel disease or left main coronary artery disease experienced higher rates of death and composite outcome (PϽ0.05 for both). Both CACS and cCTA significantly improved the performance of standard risk factor prediction models for all-cause mortality and the composite outcome (likelihood ratio PϽ0.05 for all), but the incremental discriminatory value associated with their inclusion was more pronounced for the composite outcome and for CACS (C statistic for model with risk factors only was 0.71; for risk factors plus CACS, 0.75; for risk factors plus CACS plus cCTA, 0.77). The net reclassification improvement resulting from the addition of cCTA to a model based on standard risk factors and CACS was negligible.

Among individuals with CAC = 0, conversion to CAC >0 is nonlinear and occurs at low frequency before 4 years. No clinical factor seems to mandate earlier repeat CAC scanning.