Prognostic value of coronary multidetector CT angiography in patients with an intermediate probability of significant coronary heart disease

State of the art of coronary computed tomography angiography

OBJECTIVES

The aim of this paper is to evaluate contrast media (CM) bolus geometry and opacification patterns in the coronary arteries with particular focus on patient, scanner and safety considerations during coronary computed tomography angiography (CCTA).

KEY FINDINGS

The rapid evolution of computed tomography (CT) technology has seen this imaging modality challenge conventional coronary angiography in the evaluation of coronary artery disease. Increases in spatial and temporal resolutions have enabled CCTA to become the modality of choice when evaluating the coronary vascular tree as an alternative in the diagnostic algorithm for acute chest pain. However, these new technologic improvements in scanner technology have imposed new challenges for the optimisation of CM delivery and image acquisition strategies.

CONCLUSION

Understanding basic CM-imaging principles is essential for designing optimal injection protocols according to each specific clinical scenario, independently of scanner technology.

IMPLICATIONS FOR PRACTICE

With rapid advances in CT scanner technology including faster scan acquisitions, the risk of poor opacification of coronary vasculature increases significantly. Therefore, awareness of CM delivery protocols is paramount to consistently provide optimal image quality at a low radiation dose.

Coronary Artery Disease Screening With Carotid Ultrasound Examination by a Primary Care Physician

Background

In this study, we investigated the feasibility of primary care physicians using carotid ultrasound to perform coronary artery disease screening in asymptomatic patients with multiple coronary risk factors.

Methods

We retrospectively collected the data of 135 consecutive asymptomatic patients (mean age: 68.5 ± 8.4 years; male, 75%) who were referred to our institution due to abnormal findings on a carotid ultrasound performed by a primary care physician and who underwent coronary computed tomography angiography.

Results

The mean number of risk factors was 4.1 ± 1.2 and the mean intima-media thickness was 2.00 ± 0.63 mm. Mild (≤ 50%), moderate (51-75%), and severe (> 76%) coronary stenosis was observed in 54 (40%), 27 (20%), and 25 patients (19%), respectively, while no plaque was found in 24 patients (18%), and five patients (4%) could not be evaluated due to calcification. Consequently, coronary angiography was performed in 56 (41%) patients and coronary intervention was required in 31 patients (23%). A multivariate logistic regression analysis demonstrated that the ratio of low-density lipoprotein cholesterol levels to high-density lipoprotein cholesterol levels, the use of calcium channel blockers and the value of the diastolic blood pressure were related to > 50% coronary stenosis.

Conclusions

The use of carotid ultrasound in the coronary artery disease screening by primary care physicians resulted in a high prevalence of coronary artery disease and high probabilities of coronary angiography and revascularization, and thus it is considered to be a useful and feasible strategy for the screening of asymptomatic patients.

Prognostic value of cardiac computed tomography angiography in patients with suspected coronary artery disease: a meta-analysis

OBJECTIVES

The diagnostic accuracy of cardiac computed tomography angiography (CCTA) is well reported. The prognostic value of CCTA has been described in several studies, but many of these were underpowered and an update of the meta-analysis is necessary to increase the power to predict rare events. The purpose of this study was to perform a meta-analysis of the ability of CCTA to predict future cardiovascular events.

METHODS

We searched multiple databases for longitudinal studies of CCTA with a follow-up of at least 12 months of symptomatic patients with suspected coronary artery disease (CAD) reporting major adverse cardiovascular events (MACE), death, myocardial infarction and revascularization. Summary test parameters and receiver-operating characteristic curves were calculated.

RESULTS

Eighteen studies evaluated 29,243 patients with a median follow-up of 25 months. For MACE in patients with negative findings on CCTA, there was a pooled negative likelihood ratio (LR) of 0.01 [95% confidence interval (CI) 0.00-0.08], a positive LR of 1.72 (95% CI 1.54-1.91), a sensitivity of 1.00 (95% CI 0.97-1.00), a specificity of 0.42 (95% CI 0.36-0.48) and a diagnostic odds ratio of 159.07 (95% CI 22.20-1,139.80). The weighted average annualized MACE rate for positive versus negative CCTA findings was 3.49 versus 0.21%. Stratifying by no CAD, nonobstructive CAD or obstructive CAD, there were incrementally increasing adverse events.

CONCLUSIONS

Adverse cardiovascular events among patients with normal findings on CCTA are rare. There are incrementally increasing future MACE with increasing CAD by CCTA.

Computed tomographic coronary angiography - is it ready as a screening tool for coronary artery disease?

Currently, there are no formal screening programmes for coronary artery disease (CAD). Computed tomographic coronary angiography (CTCA) has been suggested as a non-invasive and reliable method of atherosclerotic plaque assessment, with the potential for use in screening programmes. In this article, we briefly present the current understanding of atherosclerotic plaque formation, explain key technological aspects of CTCA and critique this method in the light of World Health Organisation (WHO) criteria for devising a screening programme. Current evolving and future insights are also considered. Overall, in our view, there is currently insufficient evidence to support the formal use of CTCA in a screening programme for CAD, although this viewpoint will undoubtedly evolve.

Coronary computed tomography angiography for selecting coronary artery bypass graft surgery candidates

BACKGROUND

There have been limited reports on the diagnostic performance and prognostic value of coronary computed tomography angiography (CCTA) for selecting coronary artery bypass graft (CABG) candidates.

METHODS

There were 1,018 patients with suspected coronary artery disease who underwent 64-slice multidetector CCTA between July 2009 and January 2010. Of them, we excluded 324 patients who denied further treatment (n=7), who were lost for unidentified reasons (n=107), or who were transferred to local clinics (n=210). The total analysis cohort consisted of 694 patients. We established eligible CABG criteria defined as three-vessel disease, left main coronary disease, and left main coronary artery equivalent disease. Diagnostic performance was determined using conventional coronary angiography as the reference standard. For assessment of the prognostic utility of CCTA, electronic medical records were reviewed to screen for the occurrence of a major adverse cardiac event, defined as cardiac death, nonfatal myocardial infarction, or revascularization.

RESULTS

The overall sensitivity, specificity, positive predictive value, and negative predictive value of CCTA for the selection of CABG candidates were 83.3%, 96.2%, 90.9%, and 92.7%, respectively. The presence of CABG criteria on CCTA was an independent prognostic factor for predicting a major adverse cardiac event (hazard ratio, 12.508; 95% confidence interval, 7.353 to 21.278; p<0.0001).

CONCLUSIONS

We found CCTA had a high diagnostic performance for selecting CABG candidates and predicted major adverse cardiac events in CABG candidates referred for CCTA owing to suspected coronary artery disease.

Coronary CT angiography: current status and continuing challenges

Coronary CT angiography has been increasingly used in the diagnosis of coronary artery disease owing to rapid technological developments, which are reflected in the improved spatial and temporal resolution of the images. High diagnostic accuracy has been achieved with multislice CT scanners (64 slice and higher), and in selected patients coronary CT angiography is regarded as a reliable alternative to invasive coronary angiography. With high-quality coronary CT imaging increasingly being performed, patients can benefit from an imaging modality that provides a rapid and accurate diagnosis while avoiding an invasive procedure. Despite the tremendous contributions of coronary CT angiography to cardiac imaging, study results reported in the literature should be interpreted with caution as there are some limitations existing within the study design or related to patient risk factors. In addition, some attention must be given to the potential health risks associated with the ionising radiation received during cardiac CT examinations. Radiation dose associated with coronary CT angiography has raised serious concerns in the literature, as the risk of developing malignancy is not negligible. Various dose-saving strategies have been implemented, with some of the strategies resulting in significant dose reduction. The aim of this review is to present an overview of the role of coronary CT angiography on cardiac imaging, with focus on coronary artery disease in terms of the diagnostic and prognostic value of coronary CT angiography. Various approaches for dose reduction commonly recommended in the literature are discussed. Limitations of coronary CT angiography are identified. Finally, future directions and challenges with the use of coronary CT angiography are highlighted.

Automatic vs semi-automatic global cardiac function assessment using 64-row CT

OBJECTIVE

Global cardiac function assessment using multidetector CT (MDCT) is time-consuming. Therefore we sought to compare an automatic software tool with an established semi-automatic method.

METHODS

A total of 36 patients underwent CT with 64 × 0.5 mm detector collimation, and global left ventricular function was subsequently assessed by two independent blinded readers using both an automatic region-growing-based software tool (with and without manual adjustment) and an established semi-automatic software tool. We also analysed automatic motion mapping to identify end-systole.

RESULTS

The time needed for assessment using the semi-automatic approach (12:12 ± 6:19 min) was reduced by 75-85% with the automatic software tool (unadjusted, 01:34 ± 0:29 min, adjusted, 02:53 ± 1:19 min; both p<0.001). There was good correlation (r=0.89; p<0.001) for the ejection fraction (EF) between the adjusted automatic (58.6 ± 14.9%) and the semi-automatic (58.0 ± 15.3%) approaches. Also the manually adjusted automatic approach led to significantly smaller limits of agreement than the unadjusted automatic approach for end-diastolic volume (±36.4 ml vs ±58.5 ml, p>0.05). Using motion mapping to automatically identify end-systole reduced analysis time by 95% compared with the semi-automatic approach, but showed inferior precision for EF and end-systolic volume.

CONCLUSION

Automatic function assessment using MDCT with manual adjustment shows good agreement with an established semi-automatic approach, while reducing the analysis by 75% to less than 3 min. This suggests that automatic CT function assessment with manual correction may be used for fast, comfortable and reliable evaluation of global left ventricular function.

The diagnostic performance of multi-slice coronary computed tomographic angiography: a systematic review

BACKGROUND

The use of coronary computed tomographic angiography (CCTA) for evaluation of patients with suspected coronary artery disease (CAD) is growing rapidly, yet questions remain regarding its diagnostic accuracy and its impact on clinical decision-making and patient outcomes.

METHODS

A systematic literature review was conducted to identify studies examining (a) CCTA's diagnostic accuracy; and (b) the impact of CCTA on clinical decision-making and/or patient outcomes. Diagnostic accuracy estimates were limited to patient-based analyses of occlusion; outcome studies were eligible for inclusion if they involved patients at low-to-intermediate risk of CAD. Pooled accuracy estimates were derived using bivariate random effects models; non-diagnostic CCTA results were conservatively assumed to be false positives.

RESULTS

A total of 42 diagnostic accuracy studies and 11 patient outcome studies were identified. The pooled mean sensitivity for CCTA in primary analyses was 98% (95% CI: 96%, 99%); specificity was 85% (81%, 89%). A small number of outcome studies set primarily in the emergency department found triage of low-risk patients using CCTA produced no serious adverse outcomes and was time-saving relative to standard triage care. Outcome studies in the outpatient setting were limited to four case series that did not directly compare patient care or outcomes with those of contemporaneous patients evaluated without CCTA.

CONCLUSIONS

CCTA appears to have high diagnostic accuracy in patients with suspected CAD, but its potential impact on clinical decision-making and patient outcomes is less well-understood, particularly in non-emergent settings.

Prognostic value of cardiac computed tomography angiography: a systematic review and meta-analysis

OBJECTIVES

The purpose of this study was to systematically review and perform a meta-analysis of the ability of cardiac computed tomography angiography (CCTA) to predict future cardiovascular events and death.

BACKGROUND

The diagnostic accuracy of CCTA is well reported. The prognostic value of CCTA has been described in several studies, but many were underpowered. Pooling outcomes increases the power to predict rare events.

METHODS

We searched multiple databases for longitudinal studies of CCTA with at least 3 months follow-up of symptomatic patients with suspected coronary artery disease (CAD) reporting major adverse cardiovascular events (MACE), consisting of death, myocardial infarction (MI), and revascularization. Annualized event rates were pooled using a bivariate mixed-effects binomial regression model to calculate summary likelihood ratios and receiver-operating characteristic curves.

RESULTS

Eighteen studies evaluated 9,592 patients with a median follow-up of 20 months. The pooled annualized event rate for obstructive (any vessel with >50% luminal stenosis) versus normal CCTA was 8.8% versus 0.17% per year for MACE (p < 0.05) and 3.2% versus 0.15% for death or MI (p < 0.05). The pooled negative likelihood ratio for MACE after normal CCTA findings was 0.008 (95% confidence interval [CI]: 0.0004 to 0.17, p < 0.001), the positive likelihood ratio was 1.70 (95% CI: 1.42 to 2.02, p < 0.001), sensitivity was 0.99 (95% CI: 0.93 to 1.00, p < 0.001), and specificity was 0.41 (95% CI: 0.31 to 0.52, p < 0.001). Stratifying by no CAD, nonobstructive CAD (worst stenosis <50%), or obstructive CAD, there were incrementally increasing adverse events.

CONCLUSIONS

Adverse cardiovascular events among patients with normal findings on CCTA are rare. There are incrementally increasing future MACE with increasing CAD by CCTA.