After a decade of clinical use of coronary computed tomographic angiography (CCTA) to evaluate the anatomic severity of coronary artery disease, new methods of deriving functional information from CCTA have been developed. These methods utilize the anatomic information provided by CCTA in conjunction with computational fluid dynamics to calculate fractional flow reserve (FFR) values from CCTA image data sets. Computed tomography-derived FFR (CT-FFR) enables the identification of lesion-specific drop noninvasively. A three-dimensional CT-FFR modeling technique, which provides FFR values throughout the coronary tree (HeartFlow FFRCT analysis), has been validated against measured FFR and is now approved by the US Food and Drug Administration for clinical use. This technique requires off-site supercomputer analysis. More recently, a one-dimensional computational analysis technique (Siemens cFFR), which can be performed on on-site workstations, has been developed and is currently under investigation. This article reviews CT-FFR technology and clinical evidence for its use in stable patients with suspected coronary artery disease.

For a decade, coronary computed tomographic angiography (CCTA) has been used as a promising noninvasive modality for the assessment of coronary artery disease (CAD) as well as cardiovascular risks. CCTA can provide more information incorporating the presence, extent, and severity of CAD; coronary plaque burden; and characteristics that highly correlate with those on invasive coronary angiography. Moreover, recent techniques of CCTA allow assessing hemodynamic significance of CAD. CCTA may be potentially used as a substitute for other invasive or noninvasive modalities. This review summarizes risk stratification by anatomical and hemodynamic information of CAD, coronary plaque characteristics, and burden observed on CCTA.

Although invasive coronary angiography has been the gold standard for evaluating coronary artery disease (CAD), it should not be routinely performed as an initial test to assess CAD in subjects with suspected CAD by the recent guidelines, due to cost, invasiveness, and measurable risk. Coronary computed tomography angiography (CCTA) is a rapidly growing, noninvasive imaging modality that developed quickly over the last decade, and its role for evaluation of CAD becomes of great promise with high diagnostic accuracy. Although artifact issues have created some challenges for CCTA, recent advances-including the introduction of more detectors, leading to broader coverage, and faster and higher-definition scanners-allow improved precision and fewer uninterpretable studies. This review article summarizes the current key literature regarding the diagnostic accuracy of CCTA in native coronary arteries, stents, coronary artery bypass grafts, lesions with high calcification, and the functional assessment of CAD.

Coronary plaque progression is a multi-faceted process influenced by cardiovascular risk factors, as well as the presence, extent, stenosis, morphology, and vulnerability of plaque, which may ultimately result in myocardial infarction or death. Traditionally, intravascular ultrasound (IVUS) has been the primary modality to study atherosclerosis progression. However, it is invasive and impractical for screening or monitoring. While coronary artery calcium (CAC) scoring has been widely studied as a non-invasive method to measure plaque progression, it is limited to visualization of stenosis and non-calcified plaque. Coronary computed tomographic angiography (CCTA) allows for visualization of the severity of stenosis, plaque burden, plaque morphology, and ability to differentiate between plaque types. Furthermore, certain CCTA plaque features are useful in identifying vulnerable plaque including low attenuation plaque, positive remodeling, spotty calcification, and napkin-ring sign. This review covers multiple aspects of plaque progression—its pathophysiology, clinical implications, and use of novel non-invasive technology for the assessment of plaque progression over time.

Cardiovascular events, including myocardial infarction and stroke, are the primary causes of mortality in both type 1 and type 2 diabetes. Affected patients frequently have asymptomatic coronary artery disease. Studies have shown heterogeneity in cardiovascular risk among patients with diabetes. Imaging can help categorize risk of future cardiovascular events by identifying those patients with atherosclerosis, rather than relying on risk prediction based on population-based studies. In this article, we will review the evidence regarding use of atherosclerosis imaging in patients with diabetes to predict risk of coronary heart disease and mortality.

Coronary artery calcification (CAC) is an established marker of subclinical atherosclerosis and an independent predictor of future coronary heart disease in the asymptomatic primary prevention population, particularly in the intermediate risk cohort. CAC also helps in reclassifying those patients and their risk of cardiovascular events into higher or lower risk categories. MESA (Multi-Ethnic Study of Atherosclerosis) is a National Heart, Lung, and Blood Institute-sponsored population-based medical research study involving 6,814 men and women from 6 U.S. communities without a medical history of clinical cardiovascular disease. The evidence from this population cohort revealed that CAC scoring was independently predictive and highly effective at risk stratification of major adverse cardiac events. This review provides available data based on MESA. We focus on the utility of CAC for cardiovascular disease risk stratification of individuals, and we describe its diagnostic value in identifying patients at risk.

Invasive coronary plaque imaging such as intravascular ultrasound and optical coherence tomography has been widely used to observe culprit or non-culprit coronary atherosclerosis, as well as optimize stent sizing, apposition and deployment. Coronary computed tomographic angiography (CTA) is non-invasively available to assess coronary artery disease (CAD) and has become an appropriate strategy to evaluate patients with suspected CAD. Given recent technologies, semi-automated plaque software is available to identify coronary plaque stenosis, volume and characteristics and potentially allows to be used for the assessment of more details of plaque information, progression and future risk as a surrogate tool of the invasive imaging modalities. This review article aims to focus on various evidence in coronary plaque imaging by coronary CTA and describes how accurate coronary CTA can classify coronary atherosclerosis.

Assessing thromboembolic risk is crucial for proper management of patients with atrial fibrillation. Left atrial volume is a promising predictor of cardiac thrombosis. To determine whether left atrial volume can predict left atrial appendage thrombus in patients with atrial fibrillation, we conducted a prospective study of 73 patients. Left atrial and ventricular volumes were evaluated by cardiac computed tomography with retrospective electrocardiographic gating and then indexed to body surface area. Left atrial appendage thrombus was confirmed or excluded by cardiac computed tomography with delayed enhancement. Seven patients (9.6%) had left atrial appendage thrombus; 66 (90.4%) did not. Those with thrombus had a significantly higher mean left atrial end-systolic volume index (139 ± 55 vs 101 ± 35 mL/m2; P =0.0097) and mean left atrial end-diastolic volume index (122 ± 45 vs 84 ± 34 mL/m2; P =0.0077). On multivariate logistic regression analysis, left atrial end-systolic volume index (per 10 mL/m2 increase) was significantly associated with left atrial appendage thrombus (odds ratio [OR]=1.24; 95% CI, 1.03-1.50; P =0.02); so too was the left atrial end-diastolic volume index (per 10 mL/m2 increase) (OR=1.29; 95% CI, 1.05-1.60; P =0.02). These findings suggest that increased left atrial volume increases the risk of left atrial appendage thrombus. Therefore, patients with atrial fibrillation and an enlarged left atrium should be considered for cardiac computed tomography with delayed enhancement to confirm whether thrombus is present.

Background

Although several studies have shown promise for noninvasive angiography by coronary computed tomographic angiography (CCTA), few prospective multicenter trials have been conducted. This study evaluated the diagnostic accuracy of Visipaque enhanced CCTA to detect obstructive coronary stenosis compared with quantitative coronary angiography (QCA).

Patients and methods

Three sites prospectively enrolled 77 patients (58.1% men, 54 years) with chest pain referred for invasive coronary angiography (ICA). Patients underwent CCTA (Lightspeed VCT/Visipaque 320) before ICA. CCTAs were graded on a 15-segment American Heart Association model by a CCTA core lab with blinded readers for the presence of obstructive stenosis (>50% or >70%); ICAs were independently graded for %stenosis by QCA, considered the reference standard. The efficacy of CCTA was assessed including all vessel segments for per-patient and per-vessel analyses.

Results

A total of 46 more than 50% stenoses in 27 (35%) patients, and 31 more than 70% stenoses in 20 (26%) patients, were identified by QCA. Per-patient and per-vessel efficacy of CCTA compared with QCA yielded sensitivities of 85% and specificities of 90 and 95%, respectively.

Conclusion

This study shows the high accuracy of CCTA to reliably detect more than 50% and more than 70% stenoses in low-probability to intermediate-probability chest pain patients being referred for ICA. The high negative predictive values observed (92-100%) indicate that CCTA is also an effective noninvasive alternative to exclude obstructive coronary stenosis.