Computed tomography coronary angiography vs. stress ECG in patients with stable angina

Cardiac CT perfusion and FFRCTA: pathophysiological features in ischemic heart disease

Cardiac computed tomography (CCT) has rapidly evolved, becoming a powerful integrated tool for the evaluation of coronary artery disease (CAD), and being superior to other noninvasive methods due to its high accuracy and ability to simultaneously assess both lumen stenosis and atherosclerotic plaque burden. Furthermore, CCT is regarded as an effective gatekeeper for coronary angiography, and carries independent important prognostic information. In the last decade, the introduction of new functional CCT applications, namely CCT perfusion (CCTP) imaging and CT-derived fractional flow reserve (FFR_CTA), has opened the door for accurate assessment of the haemodynamic significance of stenoses. These new CCT technologies, thus, share the unique advantage of assessing both myocardial ischemia and patient-specific coronary artery anatomy, providing an integrated anatomical/functional analysis. In the present review, starting from the pathophysiology of myocardial ischemia, we evaluate the existing evidence for functional CCT imaging and its value in relation to alternative, well-established, non-invasive imaging modalities and invasive indices of ischemia (currently the gold-standard). The knowledge of clinical applications, benefits, and limitations of these new CCT technologies will allow efficient and optimal use in clinical practice in the near future.

Infarct characterization using CT

Myocardial infarction (MI) is a major cause of death and disability worldwide. The incidence is not expected to diminish, despite better prevention, diagnosis and treatment, because of the ageing population in industrialized countries and unhealthy lifestyles in developing countries. Nowadays it is highly requested an imaging tool able to evaluate MI and viability. Technology improvements determined an expansion of clinical indications from coronary plaque evaluation to functional applications (perfusion, ischemia and viability after MI) integrating additional phases and information in the mainstream examination. Cardiac computed tomography (CCT) and cardiac MR (CMR) employ different contrast media, but may characterize MI with overlapping imaging findings due to the similar kinetics and tissue distribution of gadolinium and iodinated contrast media. CCT may detect first-pass perfusion defects, dynamic perfusion after pharmacological stress, and delayed enhancement (DE) of non-viable territories.

Role of Cardiac Computed Tomography in the Evaluation of Coronary Artery Stenosis in Patients With Ascending Aorta Aneurysm Detected at Transthoracic Echocardiography

OBJECTIVE

The aim of our study was to evaluate the diagnostic performance of cardiac computed tomography (CCT) in the evaluation of coronary artery stenosis in patients with ascending aorta aneurysm detected at transthoracic echocardiography.

METHODS

We conducted a retrospective analysis of patients with an aneurysm 45 mm or greater at transthoracic echocardiography who underwent CCT from 2012 to 2014 in our hospital. We calculated the sensitivity, specificity, and positive and negative predictive values of CCT for the assessment of coronary artery stenosis (<50% or ≥50% stenosis) in patients who underwent conventional coronary angiography.

RESULTS

We included 104 patients (73 men, aged 64 [SD, 10.8] years) in our study. Obstructive coronary artery disease was found in 22.1% of patients. Sensitivity, specificity, and positive and negative predictive values of CCT for detecting significant stenoses were 100%, 98%, and 82% and 100% on a segment-by-segment analysis and 100%, 83%, and 65% and 100% on a per-patient analysis, respectively.

CONCLUSIONS

Cardiac computed tomography provides a comprehensive evaluation of ascending aorta aneurysms and coronary artery tree.

Diagnostic performance of coronary computed tomography angiography versus exercise electrocardiography for coronary artery disease: a systematic review and meta-analysis

BACKGROUND

Both coronary computed tomography angiography (CCTA) and exercise electrocardiography (ExECG) are non-invasive testing methods for the evaluation of coronary artery disease (CAD). However, there was controversy on the diagnostic performance of these methods due to the limited data in each single study. Therefore, we performed a meta-analysis to address these issues.

METHODS

We searched PubMed and Embase databases up to May 22, 2015. Two authors identified eligible studies, extracted data and accessed quality. Pooled estimation of sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), summary receiver-operating characteristic curve (SROC) and the area under curve (AUC) of CCTA and ExECG for the diagnosis of CAD were calculated using Stata, Meta-Disc and Review Manager statistical software.

RESULTS

Seven articles were included. Pooled sensitivity of CCTA and ExECG were 0.98 [95% confidence intervals (CIs): 0.95-0.99] and 0.66 (95% CIs: 0.59-0.72); pooled specificity of CCTA and ExECG were 0.84 (95% CIs: 0.81-0.87) and 0.75 (95% CIs: 0.71-0.79); pooled DOR of CCTA and ExECG were 110.24 (95% CIs: 35.07-346.55) and 6.28 (95% CIs: 2.06-19.13); and AUC of CCTA and ExECG were 0.9950±0.0046 and 0.7727±0.0638, respectively. There is no heterogeneity caused by threshold effect in CCTA or ExECG analysis. The Deeks' test showed no potential publication bias (P=0.17).

CONCLUSIONS

CCTA has better diagnostic performance than ExECG in the evaluation of CAD, which can provide a better solution for the clinical problem of the diagnosis for CAD.

Collateral non cardiac findings in clinical routine CT coronary angiography: results from a multi-center registry

PURPOSE

The aim of the study was to evaluate the prevalence of collateral findings detected in computed tomography coronary angiography (CTCA) in a multi-center registry.

MATERIALS AND METHODS

We performed a retrospective review of 4303 patients (2719 males, mean age 60.3 ± 10.2 years) undergoing 64-slice CTCA for suspected or known coronary artery disease (CAD) at various academic institutions between 01/2006 and 09/2010. Collateral findings were recorded and scored as: non-significant (no signs of relevant pathology, not necessary to be reported), significant (clear signs of pathology, mandatory to be reported), or major (remarkable pathology, mandatory to be reported and further investigated).

RESULTS

We detected 6886 non-cardiac findings (1.6 non cardiac finding per patient). Considering all centers, only 865/4303 (20.1 %) patients were completely without any additional finding. Overall, 2095 (30.4 %) non-significant, 4486 (65.2 %) significant, and 305 (4.4 %) major findings were detected. Among major findings, primary lung cancer was reported in 21 cases. In every center, most prevalent significant findings were mediastinal lymph nodes >1 cm. In 256 patients, collateral findings were clinically more relevant than coexisting CAD and justified the symptoms of patients.

CONCLUSIONS

The prevalence of significant and major collateral findings in CTCA is high. Radiologists should carefully evaluate the entire scan volume in each patient.

Korean guidelines for the appropriate use of cardiac CT

The development of cardiac CT has provided a non-invasive alternative to echocardiography, exercise electrocardiogram, and invasive angiography and cardiac CT continues to develop at an exponential speed even now. The appropriate use of cardiac CT may lead to improvements in the medical performances of physicians and can reduce medical costs which eventually contribute to better public health. However, until now, there has been no guideline regarding the appropriate use of cardiac CT in Korea. We intend to provide guidelines for the appropriate use of cardiac CT in heart diseases based on scientific data. The purpose of this guideline is to assist clinicians and other health professionals in the use of cardiac CT for diagnosis and treatment of heart diseases, especially in patients at high risk or suspected of heart disease.

Role of MDCT coronary angiography in the clinical setting: economic implications

PURPOSE

This study evaluated the incremental value and cost-effectiveness ratio of introducing coronary angiography (CA) with multidetector computed tomography (MDCT-CA) in the diagnostic management of patients with suspected coronary artery disease (CAD) compared with the traditional diagnostic workup.

MATERIAL AND METHODS

Five hundred and fifty consecutive patients who underwent MDCT-CA between January 2009 and June 2011 were considered. Patients with atypical chest pain and suspected obstructive CAD were directed to one of two diagnostic pathways: the traditional protocol (examination, stress test, CA) and the current protocol (examination, stress test, MDCT-CA, and CA, if necessary). The costs of each protocol and for the individual method were calculated. Based on the results, the cost-effectiveness ratio of the two diagnostic pathways was compared. A third, modified, diagnostic pathway has been proposed with its relative cost-effectiveness ratio (examination, MDCT-CA, stress test, and CA, if necessary).

RESULTS

Stress test vs. MDCT-CA had an accuracy of 66%, a sensitivity and specificity of 21% and 87%, respectively, and a positive (PPV) and negative (NPV) predictive value of 40% and 70%, respectively. Comparison between conventional CA (CCA) and MDCT-CA showed a sensitivity and specificity of 92% and 89%, respectively, a PPV and NPV of 89%, and an accuracy of 92%. The traditional protocol has higher costs than the second protocol: 1,645 euro against 322 euro (mean), but it shows a better cost-effectiveness ratio. The new proposed protocol has lower costs, mean 261 euro, with a better costeffectiveness ratio than the traditional protocol.

CONCLUSIONS

The diagnostic protocol for patients with suspected CAD has been modified by the introduction of MDCT-CA. Our study confirms the greater diagnostic performance of MDCT-CA compared with stress test and its similar accuracy to CCA. The use of MDCT-CA to select patients for CCA has a favourable cost-effectiveness profile.

Rationale, design and methods of CTCA-PRORECAD (Computed Tomography Coronary Angiography Prognostic Registry for Coronary Artery Disease): a multicentre and multivendor registry

PURPOSE

This study was done to assess the prognostic value of computed tomography coronary angiography (CTCA) in a large multicentre population of patients with suspected coronary artery disease (CAD) and, in particular, its incremental value compared with traditional methods for risk stratification.

MATERIALS AND METHODS

This is a retrospective observational study that began in January 2003 conducted on patients with suspected CAD assessed with CTCA on the basis of symptoms (chest pain, dyspnoea) and/or abnormal or equivocal stress test and/or a high cardiovascular risk profile. The participating centres will provide data obtained with CTCA performed with 16-slice or higher equipment. Exclusion criteria are renal insufficiency, allergy to iodinated contrast material, pregnancy and previous myocardial infarction or revascularisation (percutaneous coronary intervention and/or coronary artery bypass graft). All patients are stratified by means of clinical assessment and/or data retrieved from a clinical database. Risk factors considered are hypertension, dyslipidaemia, diabetes mellitus, smoking, family history and obesity. Symptoms are classified as absent, typical chest pain, atypical chest pain and dyspnoea. Primary endpoints are death, major adverse cardiovascular events (cardiac death, unstable angina requiring hospitalisation, acute myocardial infarction) and shifting of cardiovascular risk category on the basis of coronary plaque burden. The secondary endpoint is coronary revascularisation. Telephone interviews and/or clinical databases are used for the follow-up. The study will be conducted on a population >1,000 patients.

CONCLUSIONS

The information collected from the Prognostic Registry for Coronary Artery Disease (PRORECAD) will provide insight into the prognostic value of CTCA in addition to demographic and clinical features. The results will allow for better use and interpretation of CTCA for prognostic purposes.

Use of 3x2 tables with an intention to diagnose approach to assess clinical performance of diagnostic tests: meta-analytical evaluation of coronary CT angiography studies

OBJECTIVE

To determine whether a 3 × 2 table, using an intention to diagnose approach, is better than the "classic" 2 × 2 table at handling transparent reporting and non-evaluable results, when assessing the accuracy of a diagnostic test.

DESIGN

Based on a systematic search for diagnostic accuracy studies of coronary computed tomography (CT) angiography, full texts of relevant studies were evaluated to determine whether they could calculate an alternative 3 × 2 table. To quantify an overall effect, we pooled diagnostic accuracy values according to a meta-analytical approach.

DATA SOURCES

Medline (via PubMed), Embase (via Ovid), and ISI Web of Science electronic databases.

ELIGIBILITY CRITERIA

Prospective English or German language studies comparing coronary CT with conventional coronary angiography in all patients and providing sufficient data for a patient level analysis.

RESULTS

120 studies (10,287 patients) were eligible. Studies varied greatly in their approaches to handling non-evaluable findings. We found 26 studies (including 2298 patients) that allowed us to calculate both 2 × 2 tables and 3 × 2 tables. Using a bivariate random effects model, we compared the 2 × 2 table with the 3 × 2 table, and found significant differences for pooled sensitivity (98.2 (95% confidence interval 96.7 to 99.1) v 92.7 (88.5 to 95.3)), area under the curve (0.99 (0.98 to 1.00) v 0.93 (0.91 to 0.95)), positive likelihood ratio (9.1 (6.2 to 13.3) v 4.4 (3.3 to 6.0)), and negative likelihood ratio (0.02 (0.01 to 0.04) v 0.09 (0.06 to 0.15); (P<0.05)).

CONCLUSION

Parameters for diagnostic performance significantly decrease if non-evaluable results are included by a 3 × 2 table for analysis (intention to diagnose approach). This approach provides a more realistic picture of the clinical potential of diagnostic tests.

Role of coronary angiography MDCT in the clinical setting: changes in diagnostic workup in the real world

PURPOSE

The authors sought to evaluate the incremental value of introducing coronary angiography with multidetector computed tomography (MDCT-CA) compared with the conventional diagnostic workup in managing patients with suspected coronary artery disease (CAD) workup.

MATERIALS AND METHODS

A total of 531 consecutive patients underwent MDCT-CA between April 2008 and August 2010. For each patient the pretest probability of CAD was obtained by using the Morise score as well as the diagnostic performance of the exercise test and of MDCT-CA, considering conventional coronary angiography (CCA) as the gold standard. Based on these results, we calculated the posttest likelihood of CAD after stress testing, comparing the incremental diagnostic value for each category of cardiovascular risk with data obtained with MDCT-CA. The conventional diagnostic workup (without MDCT-CA) was then compared with the modified workup (including MDCT-CA).

RESULTS

The diagnostic performance of the exercise test for identifying patients with significant lesions had a sensitivity and specificity of 20% and 88%, respectively, with positive (PPV) and negative (NPV) predictive value of 41% and 72%, respectively. Taking CA as the gold standard, MDCT-CA had 93% sensitivity, 89% specificity, 88% PPV and 93% NPV compared with CCA in evaluating significant stenoses in the per-patient analysis. The overall diagnostic accuracy of MDCT-CA was 91%. The exercise tests provided no significant incremental diagnostic value compared with cardiovascular history in patients with a low to intermediate risk. Comparison of the diagnostic accuracy of these protocols showed improved performance results for the modified protocol.

CONCLUSIONS

MDCT-CA is the reference modality for the noninvasive exclusion of critical CAD. It provides a very high incremental diagnostic value compared with exercise testing in patients with a low to intermediate risk of CAD. The use of diagnostic protocols based on MDCT-CA ensures improved diagnostic performance compared with those involving conventional exercise electrocardiograms.

Comparison of usefulness of exercise testing versus coronary computed tomographic angiography for evaluation of patients suspected of having coronary artery disease

In patients suspected of having coronary artery disease (CAD), we compared the diagnostic sensitivity and specificity of exercise testing using ST-segment changes alone and ST-segment changes, angina pectoris, and hemodynamic variables compared to coronary computed tomographic angiography (CTA). Quantitative invasive coronary angiography was the reference method (>50% coronary lumen reduction). A positive exercise test was defined as the development of significant ST-segment changes (> or =1 mV measured 80 ms from the J-point), and the occurrence of one or more of the following criteria: ST-segment changes > or =1 mV measured 80 ms from the J-point, angina pectoris, ventricular arrhythmia (the occurrence of > or =3 premature ventricular beats), and > or =20 mm Hg decrease in systolic blood pressure during the test. Positive results on CTA were defined as a coronary lumen reduction of > or =50%. In 100 patients (61 +/- 9 years old, 50% men, and 29% prevalence of significant CAD), the diagnostic sensitivity and specificity of exercise testing using ST-segment changes was 45% (95% confidence interval 53% to 87%) and 63% (95% confidence interval 61% to 84%), respectively. However, the inclusion of all test variables yielded a sensitivity of 72% (95% confidence interval 53% to 87%) and a specificity of 37% (95% confidence interval 26% to 49%). The diagnostic sensitivity of 97% (95% confidence interval 82% to 100%) and specificity of 80% (95% confidence interval 69% to 89%) for CTA, however, were superior to any of the exercise test analysis strategies. In conclusion, in patients suspected of having CAD, the diagnostic sensitivity of exercise testing significantly improves if all test variables are included compared to using ST-segment changes exclusively. Furthermore, the superior diagnostic performance of CTA for the detection and exclusion of significant CAD might favor CTA as the first-line diagnostic test in patients suspected of having CAD.

Impact of tube current in the quantitative assessment of acute reperfused myocardial infarction with 64-slice delayed-enhancement CT: a porcine model

PURPOSE

This study evaluated the impact of tube current (mAs) in delayed-enhancement computed tomography (CT) imaging for assessing acute reperfused myocardial infarction in a porcine model.

MATERIALS AND METHODS

In five domestic pigs (mean weight 24 kg), the circumflex coronary artery was balloon-occluded for 2 h and then reperfused. After 5 days, CT imaging was performed following administration of iodinated contrast material. A 64-slice CT system was used to perform first-pass coronary angiography with a tube current of 15 mAs/kg [Arterial Phase (ART)] followed by two delayed-enhancement (DE) scans 15 min after contrast material administration, with a tube current of 15 mAs/kg and 37.5 mAs/kg, respectively (DE(1) and DE(2)). The mean heart rate decreased to 51±9 beats/min after administration of zatebradine (10 mg/kg IV). The data set was reconstructed during the end-diastolic phase of the cardiac cycle. Areas with DE, no reflow and remote myocardium [remote left ventricular (LV)] were calculated. CT values expressed in Hounsfield units (HU) were measured using five regions of interest (ROI): DE, no reflow, remote LV, LV cavity (LV lumen) and in air, respectively. Differences, correlations, image quality [signal-to-noise ratio (SNR)] and contrast resolution [contrast-to-noise ratio (CNR)] were calculated.

RESULTS

Significant differences were found between attenuation of areas of DE, no reflow and remote LV (p<0.001) within the different scans. There was a fair correlation between DE and no-reflow attenuation (r=0.6; p<0.001). In DE(1) vs. DE(2), areas of DE and no reflow were not significantly different (p>0.05). The SNR and CNR were not significantly different in DE(1) vs. DE(2) (p>0.05).

CONCLUSIONS

Tube current does not significantly affect infarction area, image quality or contrast resolution of DE imaging with CT.