Comparison of the degree of coronary stenoses by multidetector computed tomography versus by quantitative coronary angiography

Reliability of coronary computed tomography angiography in acute coronary syndrome in an emergency setting

Background

Cardiovascular computed tomography (cardiovascular CT) is currently used as a fast non-invasive method for the visualization of coronary plaques and walls and the assessment of lumen stenosis severity. Previous studies demonstrated the high negative predictive value of CT for the exclusion of coronary lumen stenoses. In this study we hypothesize that coronary CT angiography (CTA) represents a reliable method as diagnostic procedure in acute coronary syndrome (ACS) even in emergency settings.

Methods

36 patients (51 lesions) with ACS who underwent cardiovascular CT, intravascular ultrasound (IVUS) and invasive coronary angiography (ICA) within 48 h were included. The percentage of coronary stenoses were measured and compared by three methods. Influence of available predictors that can potentially affect the measurement results was assessed.

Results

Cardiac CTA provided comparable results to IVUS (mean difference -0.45%, PPV: 98%, NPV: 75%). ICA tends to estimate lower stenoses degrees than cardiac CTA and IVUS (mean difference 13.19% and 13.64%, respectively). The final diagnosis and positive remodeling did not lead to any significant influence on measurements.

Conclusions

The cardiovascular CT results show that even in emergency settings it is possible to identify morphological changes as sequels of coronary artery sclerosis with comparable results to the reference method IVUS. Deviations of IVUS and cardiovascular CT from ICA are comparable and can to a large extent be explained by differences in the measurement technique.

The Cardiovascular Trial of the Testosterone Trials: rationale, design, and baseline data of a clinical trial using computed tomographic imaging to assess the progression of coronary atherosclerosis

BACKGROUND

Data from prior studies have yielded inconsistent results on the association of serum testosterone levels with the risk for cardiovascular disease. There are no clinical trial data on the effects of testosterone replacement therapy on plaque progression.

OBJECTIVE

We designed a study to investigate the effect of testosterone therapy on coronary artery plaque progression using serial coronary computed tomographic angiography (CCTA). In this paper, we describe the study design, methods, and characteristics of the study population.

METHODS

The Cardiovascular Trial of the Testosterone Trials (TTrials; NCT00799617) is a double-blind, placebo-controlled trial of 1 year of testosterone therapy in men 65 years or older with clinical manifestations of androgen deficiency and unequivocally low serum testosterone concentrations (<275 ng/dl). CCTA performed at baseline and after 12 months of therapy will determine the effects of testosterone on the progression of the total volume of noncalcified plaques. All scans are evaluated at a central reading center by an investigator blinded to treatment assignment.

RESULTS

A total of 165 men were enrolled. The average age is 71.1 years, and the average BMI is 30.7. About 9% of men had a history of myocardial infarction, 6% angina, and 10% coronary artery revascularization. A majority reported hypertension and/or high cholesterol; 31.8% reported diabetes. Total noncalcified plaque at baseline showed a slight but nonsignificant trend toward lower plaque volume with higher serum testosterone concentrations (P=0.12).

CONCLUSION

The Cardiovascular Trial will test the hypothesis that testosterone therapy inhibits coronary plaque progression, as assessed by serial CCTA.

Cardiac magnetic resonance imaging and computed tomography in ischemic cardiomyopathy: an update

Ischemic cardiomyopathy is one of the major health problems worldwide, representing a significant part of mortality in the general population nowadays. Cardiac magnetic resonance imaging (CMRI) and cardiac computed tomography (CCT) are noninvasive imaging methods that serve as useful tools in the diagnosis of coronary artery disease and may also help in screening individuals with risk factors for developing this illness. Technological developments of CMRI and CCT have contributed to the rise of several clinical indications of these imaging methods complementarily to other investigation methods, particularly in cases where they are inconclusive. In terms of accuracy, CMRI and CCT are similar to the other imaging methods, with few absolute contraindications and minimal risks of adverse side-effects. This fact strengthens these methods as powerful and safe tools in the management of patients. The present study is aimed at describing the role played by CMRI and CCT in the diagnosis of ischemic cardiomyopathies.

Multidetector-row computed tomography for noninvasive coronary imaging

Computed tomography (CT) permits cross-sectional imaging of the heart. Temporal and spatial resolutions of the technique have been insufficient to cover the heart without motion artefacts until the recent advent of multidetector systems with more than 16 detector rows. The modality is now suited for noninvasive imaging of the coronary arteries, producing detailed morphologic images of the entire coronary tree with upto 0.4 mm of spatial resolution, within a single short breath-hold duration. CT imaging goes beyond the delineation of the coronary lumen as provided by selective invasive angiography; the plaque burden of the coronary artery wall can be visualized directly, utilizing soft-tissue contrast and a high sensitivity even for the small calcifications that are present in hard plaque formations. Therefore, CT combines elements of catheterization angiography for lumen imaging and of intravascular ultrasound imaging for coronary wall imaging. However current CT technology is not yet able to compete with the temporal or spatial resolution of catheterization angiography nor does it provide the detailed spatial or contrast resolution of intravascular ultrasound imaging. At present, its use is therefore restricted to complementing the invasive modalities in appropriate indications. Although CT entails significantly less risk than the invasive procedures, the risks of radiation dose exposure and contrast agent application are not negligible. In the foreseeable future, if the current rate of technological advancement continues, CT may replace the invasive modalities in routine care for diagnostic purposes.

Prevalence and prognostic implication of non-calcified plaque in asymptomatic population with coronary artery calcium score of zero

Background and Objectives

Non-calcified plaque (NCP) identified by coronary CT angiography (CCTA) has been reported in up to 10% of individuals with coronary artery calcium score (CACS) of zero. However, clinical risk factors and the prognostic value of NCP in asymptomatic subjects with CACS of zero are unknown.

Subjects and Methods

The study population consisted of consecutive asymptomatic subjects (48±8 years, 57% men) who underwent CCTA from December 2005 to January 2008 as part of a general health evaluation.

Results

Among 4491 of overall asymptomatic individuals with CACS of zero, 313 subjects (7%) had NCP: 279 patients (6%) with non-obstructive and 34 (1%) with obstructive. In multivariable analyses, age, male gender, diabetes, hypertension, and dyslipidemia were significantly associated with presence of NCP (all p<0.05). During the median follow-up duration of 22 months (interquartile percentile: 18 to 28 months) of subjects with NCP (n=313) and age, gender, and CCTA date matched individuals without NCP (n=313), there was no clinical event including all-cause death nor composite outcome of cardiac death, myocardial infarct, unstable angina requiring hospitalization, and revascularization after 90 days from index CCTA in both groups.

Conclusion

In the largest series of asymptomatic individuals with CACS of zero undergoing CCTA, age, male gender, diabetes, hypertension, and dyslipidemia were independently associated with NCP. However, a future risk of exclusive NCP in asymptomatic subjects with CACS of zero was negligible.

Computed tomography coronary angiography and invasive coronary angiography demonstrate high correlation for area stenosis quantification in noncalcified and mixed plaques

We compared the variance of area and diameter significant stenosis measurement between quantitative computed tomography coronary angiography (QCTA) and quantitative invasive coronary angiography (QCA). Fifty patients presenting 65 significant coronary artery stenoses (≥70% area stenosis) in QCTA and QCA were included. Spearman's rank correlation revealed that area stenosis measurement by QCTA and QCA yields higher correlation than diameter stenosis and is highest for noncalcified and mixed lesions.

Use of coronary CT angiography in the diagnosis of patients with suspected coronary artery disease: findings and clinical indications

Objective

To investigate the clinical applications of coronary CT angiography in patients with suspected coronary artery disease and identify factors that affect CT findings.

Methods

Medical records of patients suspected of coronary artery disease over a period of 12 months from a tertiary teaching hospital were retrospectively reviewed. Patient age, sex (male/female), duration of symptoms and abnormal rates of coronary CT angiography scans were analysed to investigate the relationship among these parameters. The patients by age were characterized into five groups: under 36 years, 36–45 years, 46–55 years, 56–65 years and more than 66 years, respectively; while the duration of symptoms was also classified into five groups: less than one week, one week to one month, one to three months, three to six months and more than six months.

Results

Of the 880 patient records reviewed, 800 met the above study criteria. Five hundred and forty nine patients demonstrated abnormal CT findings (68.6%). There was no significant difference in the percentage of abnormal CT findings based on patient sex and the duration of symptoms (P = 0.14). The abnormal rates of coronary CT angiography, however, increased significantly with increasing age (P < 0.001); with patients over 65 years of age 2.5 times more likely to have an abnormal CT scan relative to a patient under 45 years. A significant difference was found between abnormal coronary CT angiography and the duration of symptoms (P = 0.012).

Conclusions

Our results indicate coronary CT angiography findings are significantly related to the patient age group and duration of symptoms. Clinical referral for coronary CT angiography of patients with suspected coronary artery disease needs to be justified with regard to the judicious use of this imaging modality.

Imaging techniques in acute coronary syndromes: a review

Coronary heart disease (CHD) remains the leading cause of death in the United States. National review of Emergency Department (ED) visits from 2007 to 2008 reveals that 9% are for chest pain. Of these patients, 13% had acute coronary syndromes (ACSs) (Antman et al., 2004). Plaque rupture with thrombus formation is the most frequent cause of ACS, and identifying patients prior to this event remains important for any clinician caring for these patients. There has been an increasing amount of research and technological advancement in improving the diagnosis of patients presenting with ACS. Low-to-intermediate risk patients are the subgroup that has a delay in definitive treatment for ACS, and a push for methods to more easily and accurately identify the patients within this group that would benefit from an early invasive strategy has arisen. Multiple imaging modalities have been studied regarding the ability to detect ischemia or wall motion abnormalities (WMAs), and an understanding of some of the currently available noninvasive and invasive imaging techniques is important for any clinician caring for ACS patients.

Comparison of Plaque Composition in Diabetic and Non-Diabetic Patients With Coronary Artery Disease Using Multislice CT Angiography

BACKGROUND AND OBJECTIVES

Plaque composition rather than degree of luminal narrowing may be predictive of future coronary events in high risk patients. The purpose of this study was to compare degree of plaque burden and composition with multislice computed tomography (MSCT) angiography between diabetic and non-diabetic patients.

SUBJECTS AND METHODS

A total of 452 consecutive MSCT angiography examinations were performed between July 2007 and June 2009. Of these, the patients who underwent invasive coronary angiography were evaluated for the presence and type of atherosclerotic plaque and severity of luminal narrowing.

RESULTS

Ninety two (46 in the diabetic group and 46 in the non-diabetic group) patients underwent both MSCT angiography and invasive coronary angiography. Among them, 30 patients (65.2%) in the diabetic group and 26 patients (56.5%) in the non-diabetic group had significant coronary narrowing on MSCT angiography. Sixteen patients (34.8%) in the diabetic group and 15 patients (32.6%) in non-diabetic group underwent coronary angioplasty and stenting. Forty-two patients (93.3%) in the diabetic group and 39 patients (88.6%) in the non-diabetic group had multiple types of coronary plaque (p=0.485). MSCT angiography was similar to conventional coronary angiography in its ability to predict significant coronary artery disease in that the area under the curve was 0.88 (95% confidence interval, 0.81 to 0.95). Diabetic patients had more mixed plaque compared with non-diabetic patients.

CONCLUSION

Differences in coronary plaque composition between diabetic and non-diabetic patients can be determined noninvasively by MSCT angiography. In patients with diabetes, mixed plaque types contribute to the total plaque burden to a higher degree than in non-diabetic patients.

Atherosclerotic plaque composition among patients with stenotic coronary artery disease on noninvasive CT angiography

INTRODUCTION

Multidetector computed tomographic angiography (MDCTA) has emerged as a promising noninvasive tool to rule out significant coronary artery disease (CAD). In addition, MDCTA also provides additional information about atherosclerotic plaque composition. In this study, we aim to assess whether differences in plaque composition exist across patients with varying degree of stenotic CAD disease.

METHODS

Four hundred and sixteen patients with chest pain or shortness of breath thought to be related to CAD (64% males, mean age: 61+/-13 years), with 61 (15%) reporting type 2 diabetes mellitus, who underwent contrast-enhanced MDCTA were studied. Enrolled patients had an intermediate pretest probability of obstructive disease.

RESULTS

Overall 51 patients (12%) had normal coronaries without evidence of plaque. In the remaining 365 patients, 45 (12%) and 83 (23%) were found to have stenosis 50-70% and at least 70% in at-least one coronary artery segment, respectively. Those with a higher degree of stenotic CAD showed significantly more coronary segments with exclusively calcified and mixed plaques. With increasing severity of CAD (<50 vs. 50-70% vs. >70% stenosis), the overall proportion of plaque burden was more likely to be mixed (18 vs. 38% vs. 44%) in nature as well less likely to be exclusively noncalcified (39 vs. 20 vs. 16%). Only two of 108 (2%) patients without any underlying calcification had significant CAD (stenosis> or =50%).

CONCLUSION

Significant differences in plaque composition according to severity of CAD were observed in our study. Individuals with a higher likelihood of stenotic CAD were more likely to have higher underlying burden of exclusively calcified and mixed plaque. These findings should stimulate further investigations to assess the prognostic value of plaque according to their underlying composition.

Coronary artery disease: which degree of coronary artery stenosis is indicative of ischemia?

PURPOSE

To prospectively determine the best cut-off value of stenosis degree for low-dose computed tomography coronary angiography (CTCA) to predict the hemodynamic significance of coronary artery stenoses compared to catheter angiography (CA) using a cardiac magnetic resonance based approach as standard of reference.

MATERIALS AND METHODS

Fifty-two patients (mean age, 64±10 years) scheduled for CA underwent cardiac magnetic resonance (CMR) at 1.5-T and dual-source CTCA using prospective ECG-triggering the same day. Diagnostic performance of CTCA and CA to detect myocardial ischemia was evaluated with CMR as the standard of reference. The diagnostic performance and best cut-off values to predict the hemodynamic significance of coronary were determined from receiver operating characteristics analysis (ROC).

RESULTS

CA revealed >50% stenoses in 131/832 segments (15.7%) in 78/156 (50.0%) coronary arteries in 32/52 (62%) patients. CTCA revealed >50% stenoses in 148/807 (18.3%) segments, corresponding to 83/156 (53.2%) coronary arteries in 34/52 (65.4%) patients. CMR revealed ischemia in 118/832 (14.2%) myocardial segments corresponding to the territories of 60/156 (38.5%) coronary arteries in 29/52 (56%) patients. ROC analysis showed equal diagnostic performance for low-dose CTCA and CA with areas under the curve (AUC) of 0.82 and 0.83 (P=0.64). The optimal cut-off value was determined at stenosis of >60% for the prediction of hemodynamically significant coronary stenosis by CTCA. Using this cut-off value, sensitivity, specificity, NPV and PPV to predict hemodynamic significance by CTCA were 100%, 83%, 100%, and 88% on a per-patient basis and 88%, 73%, 83% and 81% on a per-artery analysis, respectively.

CONCLUSION

By considering coronary stenosis >60%, diagnostic performance for predicting the hemodynamic significance of coronary stenosis by CTCA is optimal and equals that of CA.

Three-dimensional vessel analyses provide more accurate length estimations than the gold standard QCA

OBJECTIVES

The aim of this study was to compare lesion dimensions as determined by a three-dimensional quantitative coronary angiographic (QCA) system to that of a validated two-dimensional QCA system.

BACKGROUND

In an era of drug-eluting stents, device sizing has become an important clinical application of online QCA. The CardiOp-B system integrates two standard angiographic projections to provide a three-dimensional reconstruction of the arterial segment of interest.

METHODS

Phase 1 - 47 stenoses from consecutive coronary angiograms were assessed in two projections with both systems providing two data sets for the CMS-Medis system and a single data set for CardiOp-B. Phase 2--a perspex phantom with a known lesion length, was analyzed at increasing degrees of foreshortening with acceptance criteria set at 5% from the absolute value.

RESULTS

Phase 1 demonstrated an adequate correlation between the CardiOp-B and Medis systems when minimal luminal diameter was measured in the optimal view (1.32 +/- 0.47 mm vs 1.42 +/- 0.49 mm respectively; r = 0.82). A stronger correlation was noted when length was measured (25.27 +/- 10.76 mm and 21.32 +/- 8.08 mm, respectively; r = 0.95); however CardiOp-B provided a consistently longer length (P < 0.0001). On phantom length measurements the mean accuracy result for the CardiOp-B system was -1.3%. This compared favorably with the two-dimensional system where all measures performed at greater than 20 degrees of for shortening were beyond the 5% criteria from the known length.

CONCLUSIONS

Three-dimensional QCA provides accurate and precise vessel diameter assessments. Length assessments are consistently longer than two-dimensional measures and are significantly less affected by foreshortened projections.

Relation of coronary artery plaque location to extent of coronary artery disease studied by computed tomographic angiography

BACKGROUND

Distal coronary artery disease (CAD) is less amenable to surgery or stenting compared with proximal disease. However, little is known about the epidemiology of distal versus proximal CAD.

METHODS

We determined the prevalence and factors associated with proximal, mid, and distally located plaque in the left anterior descending, left circumflex, and right coronary arteries in 418 subjects without prior CAD history who underwent coronary computed tomographic angiography for symptoms or stress test results. Clinical characteristics and coronary artery calcium (CAC) scores were also determined.

RESULTS

Most subjects (88%) had plaque, but only 18% of plaques were associated with stenosis >50%. In subjects with single-vessel plaque, only 7% had distal plaque, whereas 75% had proximal plaque. With 3-vessel plaque, 70% had distal and 100% had proximal plaques. Of subjects with a single location of plaque along a vessel, most had proximal plaque (69%); isolated distal-vessel plaque was rare (2%). Distal plaque was dominantly found in association with both proximal and mid plaque (88%). After multivariable adjustment for demographics, traditional, and nontraditional risk factors, both increasing number of vessels with plaque and clinically significant CAC scores were independently associated with higher odds of distal plaque, whereas associations of traditional risk factors were weaker. Distal plaque was independently associated with stenosis > 50%.

CONCLUSION

These data support the concept that early lesions are most often proximal and that CAC scoring may be a poor screening tool for detecting proximal disease. Furthermore, distal lesions are more associated with advanced disease than with traditional cardiovascular risk factors.

Comparison of dual-source CT coronary angiography and conventional coronary angiography for detecting coronary artery disease

To evaluate the diagnostic accuracy of dual-source CT coronary angiography for detecting coronary artery stenosis. From February 2008 to January 2009, dual-source CT coronary CT angiography (DSCT-CCTA) and conventional coronary angiography (CAG) were both performed in 84 patients who had either clinical symptoms or a high risk of coronary artery disease. The diagnostic accuracy of DSCT-CCTA was evaluated by comparing it with that of CAG, which was regarded as the gold standard for making the diagnosis of coronary artery disease. Occlusion or stenosis of various degrees was revealed by DSCT-CCTA in 244 segments of 84 patients. Compared to CAG, segment-based sensitivity, specificity, positive predictive value and negative predictive value of DSCT-CCTA were 97.4, 97.8, 92.2 and 100%, respectively. The diagnostic accuracy of DSCT-CCTA for the detection of coronary artery stenosis was 96.5%. The paired chi2 tests revealed no significant difference between DSCT-CCTA and CAG for making the diagnosis of coronary artery disease (P = 0.076). The diagnostic performance of DSCT-CCTA is generally as accurate as that of CAG. Thus, DSCT-CCTA is a reliable non-invasive method for detecting coronary artery stenosis.

Coronary CTA: stenosis classification and quantification, including automated measures

The development of larger multidetector computed tomography (CT) systems has allowed increased accuracy in quantifying obstructive lesions involving the coronary arteries. This article reviews the accuracy of coronary CT angiography (CTA) in quantifying obstructive lesions, evaluating the extent of coronary artery disease, and classifying the composition of coronary plaques. In addition, several outcomes studies and some promising automated techniques for quantifying coronary CTA are reviewed.

Noninvasive coronary angiography by 320-row computed tomography with lower radiation exposure and maintained diagnostic accuracy: comparison of results with cardiac catheterization in a head-to-head pilot investigation

BACKGROUND

Noninvasive coronary angiography with the use of multislice computed tomography (CT) scanners is feasible with high sensitivity and negative predictive value; however, the radiation exposure associated with this technique is rather high. We evaluated coronary angiography using whole-heart 320-row CT, which avoids exposure-intensive overscanning and overranging.

METHODS AND RESULTS

A total of 30 consecutive patients with suspected coronary artery disease referred for clinically indicated conventional coronary angiography (CCA) were included in this prospective intention-to-diagnose study. CT was performed with the use of up to 320 simultaneous detector rows before same-day CCA, which, together with quantitative analysis, served as the reference standard. The per-patient sensitivity and specificity for CT compared with CCA were 100% (95% confidence interval [CI], 72 to 100) and 94% (95% CI, 73 to 100), respectively. Per-vessel versus per-segment sensitivity and specificity were 89% (95% CI, 62 to 98) and 96% (95% CI, 90 to 99) versus 78% (95% CI, 56 to 91) and 98% (95% CI, 96 to 99), respectively. Interobserver agreement between the 2 readers was significantly better for CCA (97% of 121 coronary arteries) than for CT (90%; P=0.04). Percent diameter stenosis determined with the use of CT showed good correlation with CCA (P<0.001, R=0.81) without significant underestimation or overestimation (-3.1+/-24.4%; P=0.08). Intraindividual comparison of CT with CCA revealed a significantly smaller effective radiation dose (median, 4.2 versus 8.5 mSv; P<0.05) and amount of contrast agent required (median, 80 versus 111 mL; P<0.001) for 320-row CT. The majority of patients (87%) indicated that they would prefer CT over CCA for future diagnostic imaging (P<0.001).

CONCLUSIONS

CT with the use of emerging technology has the potential to significantly reduce the radiation dose and amount of contrast agent required compared with CCA while maintaining high diagnostic accuracy.

Comparison of atherosclerotic plaque burden and composition between diabetic and non diabetic patients by non invasive CT angiography

Type 2 diabetes mellitus (DM) is associated with a higher risk of cardiovascular disease and atherosclerotic burden. However little data exists in regards to plaque distribution and plaque composition in these patients. To assess for differences in the coronary plaques burden and composition among symptomatic patients with and without type 2 DM using multidetector computed tomography angiography (MDCTA). The 416 symptomatic patients (64% males, mean age: 61 +/- 13 years) with 61 (15%) reporting type 2 DM, who underwent contrast-enhanced MDCTA were studied. Enrolled patients had an intermediate to high pre-test probability of obstructive coronary artery disease. Multivariate analysis was used to correct for differences in age and gender. Patients with type 2 DM were more likely to have significant stenosis >or=70% in at least one coronary segments (33% in type 2 DM vs. 18% in non diabetic, P = 0.013), whereas 11% of both type 2 DM and non diabetics had stenosis of 50-70% (P = NS). Also type 2 DM patients had a higher number of coronary segments with mixed plaques compared to nondiabetic patients (1.67 +/- 2.01 vs. 1.23 +/- 1.61, P = 0.05), whereas no such differences were observed for non-calcified or calcified plaques. Nearly half (43%) of type 2 DM had coronary artery calcium scores (CACS) >or=400 vs. 29% in non diabetic patients (P = 0.03). Patients with type 2 DM tend to have atherosclerotic plaques which are more likely to be mixed in nature. Future studies need to elucidate the prognostic value of differences in plaque characteristics observed according to type 2 diabetic status.

Correlation between coronary computed tomographic angiography and fractional flow reserve

BACKGROUND

Coronary CT angiography (CCTA) has become an important modality to evaluate the presence of coronary artery disease. Coronary artery stenosis of intermediate severity remains a therapeutic dilemma. Measurement of fractional flow reserve (FFR) during coronary angiography is the most established technique to determine the hemodynamic severity of a coronary artery lesion. The aim of this study was to compare CCTA with FFR.

METHODS

In 56 coronary artery stenoses (42 patients) we performed CCTA, quantitative coronary angiography and FFR. CCTA measurements included diameter stenosis (DS, %), area stenosis (AS, %), minimal lumen diameter (MLD, mm), minimal lumen area (MLA, mm(2)), lesion length (LL, mm), plaque volume (mm(3)) and burden (%).

RESULTS

FFR averaged 0.81±0.14, and 10 lesions had an abnormal FFR (<0.75). We found significant correlations between FFR and DS (r=-0.67, p<0.001), AS (r=-0.68, p<0.001), MLD (r=0.58, p<0.001), MLA (r=0.53, p<0.001), LL (r=-0.36, p=0.02), plaque volume (r=-0.36, p=0.02) and plaque burden (r=-0.59, p<0.001). By multivariate regression analysis AS and LL were the strongest determinants of an abnormal FFR. The optimal cut-off value for AS was >73% (sensitivity 90%, specificity 80%, negative predictive value 97%, and positive predictive value 50%) and for LL >10 mm (sensitivity 60% and specificity 49%).

CONCLUSION

This study demonstrates that quantitative CCTA is correlated to FFR. Using our CCTA criteria of abnormality, significant coronary artery stenoses can be ruled out with a high negative predictive value.

Efficacy of pre-scan beta-blockade and impact of heart rate on image quality in patients undergoing coronary multidetector computed tomography angiography

OBJECTIVE

While beta-blockers are routinely administered to patients prior to coronary computed tomography angiography (CTA), their effectiveness is unknown. We therefore assessed the efficacy of beta-blockade with regards to heart rate (HR) control and image quality in an unselected patient cohort.

METHODS

We studied 150 consecutive patients (104 men/46 female; mean age, 56+/-13 years) referred for coronary CTA. Intravenous metoprolol (5-20mg) was administered to patients with a HR >65 beats per minute (bpm). The goal HR was defined as an average HR <65 bpm without a single measurement above 68 bpm.

RESULTS

Overall, 45% (68/150) of patients met the HR criteria for beta-blocker administration of which 76% (52/68) received metoprolol (mean dose 12+/-10mg). Of the 52 patients who received beta-blocker versus the 98 who did not, 18 (35%) versus 62 (64%) patients achieved the goal HR, respectively. All patients who achieved the target HR had an evaluable CTA while five patients who did not achieve the target HR had at least one non-evaluable coronary artery due to motion artifact. There was also a significant reduction in any motion artifact among those who achieved the goal HR as compared to those who did not (p=0.001). Logistic regression revealed an increase in the odds of stair step artifact of 11.6% (95% CI: 2.4% decrease, 27.5% increase) per 1 bpm increase in the standard deviation of scan HR.

CONCLUSION

Overall, efficacy of beta-blocker administration to reach target HR is limited. Improvements in CT scanner temporal resolution are mandatory to achieve consistently high image quality independent of HR and beta-blocker administration.

Accuracy of multidetector spiral computed tomography in detecting significant coronary stenosis in patient populations with differing pre-test probabilities of disease

AIM

To investigate the clinical impact of multidetector computed tomography (MDCT) in patients with a low versus a high pre-test likelihood of coronary artery disease (CAD).

MATERIALS AND METHODS

A cohort of 120 patients with suspected CAD, scheduled for conventional coronary angiography, underwent MDCT. Using the American Heart Association (AHA)/American College of Cardiology (ACC) guidelines, the population was divided into two groups: patients with a low (group 1) and a high (group 2) likelihood of CAD.

RESULTS

Analysis of all segments showed a high feasibility (92%), and a patient based-model showed excellent sensitivity and negative predictive values (NPV; both 100%) and acceptable specificity and positive predictive values (PPV; 86 and 90%, respectively), with an accuracy of 94%. Using MDCT in patients with lower pre-test likelihoods of CAD, according to the ACC/AHA guidelines, the accuracy remained high (93%); conversely, in patient groups with a high prevalence of CAD, a non-significant reduction in accuracy (85%) occurred using MDCT. Particularly, MDCT can be used effectively to exclude a diagnosis of CAD because of its high sensitivity and NPV (100%), but shows a significant reduction in specificity (58%). This reduction was due to an increase in the false-positive:true-negative ratio because of the higher percentage of calcified plaque (a relative but non-significant increase in false positives), and the high prevalence of CAD (significant reduction in true negatives). No differences were found between MDCT and quantitative coronary angiography (QCA) concerning the number of vessels narrowed.

CONCLUSION

Because of its excellent sensitivity and specificity in patients with a low pre-test likelihood of CAD, MDCT could be helpful in clinical decision-making in this population.

[Quantification of coronary artery stenoses: comparison of 64-slice and dual source CT angiography with cardiac catheterization]

BACKGROUND

Until now stenoses of the coronary arteries have been evaluated visually with CT angiography. Therefore, the results were highly dependent on subjective factors inherent in the examiner. New software tools for semiquantitative analysis (CT-QCA, quantitative coronary assessment) might be adequate to improve the diagnostic accuracy und reproducibility.

MATERIAL AND METHODS

CTAs of 20 patients were analyzed. Ten patients each were evaluated using 64-slice CT (64SCT) and dual source CT (DSCT) (Somatom Sensation 64 and Somatom Definition, Siemens Medical Solutions, Forchheim), respectively. Two radiologists independently evaluated the data visually and with the help of a software tool (Syngo Circulation, Siemens Medical Solutions, Forchheim). The results of the quantitative assessment of the invasive heart catheterization served as the reference standard. Sensitivity and specificity as well as the correlation coefficient, the systematic error, and the interobserver agreement (kappa) were determined.

RESULTS

In each of both patient groups 12 stenoses were detected. For the detection of stenoses >75%, sensitivity and specificity for the visual evaluation using the 64SCT were 100% and 90%, and with the CT-QCA both were 100%. For the DSCT sensitivity and specificity were 100% for both the visual and semiautomated evaluation. The Bland-Altman plot of the results of the 64SCT showed an overestimation of 3.3% (+/-62.7%/56.2%) compared to the heart catheterization. The results of the DSCT exhibited an overestimation of 6.2% (+/-33.1%/19.8%). The interobserver agreement of the CT-QCA and the visual evaluation showed a kappa value of 0.75 and for DSCT of 1.0.

CONCLUSION

The results showed a good correlation of grading stenosis between the software-assisted evaluation and the results of the coronary catheter angiography. The promising results of the DSCT are due to a superior temporal resolution compared to the 64SCT. Confirmation of these data by trials in larger patient collectives is warranted.

Intraindividual comparison of 3D coronary MR angiography and coronary CT angiography

RATIONALE AND OBJECTIVES

To compare the diagnostic value of magnetic resonance (MR) and computed tomography (CT) for the detection of coronary artery disease (CAD) with special regard to calcifications.

MATERIALS AND METHODS

Twenty-seven patients with known CAD were examined with a targeted, navigator-gated, free-breathing, steady-state free precession MR angiography sequence (repetition time = 5.6 milliseconds, echo time = 2.8 milliseconds, flip angle 110 degrees ) and 16-slice coronary CT angiography. Segment-based sensitivity, specificity, and accuracy for the detection of stenoses larger than 50% were determined as defined by the gold standard catheter coronary angiography along with the subjective image quality (Grade 1-4). The degree of calcifications in each segment was quantified using a standard calcium scoring tool.

RESULTS

Of 115 possible segments, 7% had to be excluded in MR imaging because of poor image quality. In CT, 3% were nondiagnostic because of image quality and 15% were not evaluable because of calcifications. Values for the detection of relevant coronary artery stenoses in the evaluated segments were: sensitivity: MR imaging 85% versus CT 96%; specificity: 88% versus 96%; accuracy: 87% versus. 96%. Average subjective image quality was 1.8 for MR imaging and 1.6 for CT. Of the 15% of segments that had to be excluded from CT evaluation because of calcifications, MR imaging provided the correct diagnosis segments in 67%.

CONCLUSIONS

CT provided a better image quality with superior accuracy for the detection of CAD. Despite its overall inferiority, MR imaging proved to be helpful method in interpreting coronary stenosis in severely calcified segments.

Left main coronary artery stenosis: state-of-the-art

Patients with stenosis of the left main coronary artery present difficult challenges. The risks associated with this lesion have been known since the early days of angiography when patients were found to have increased mortality during follow-up. This information led to the general guidelines that surgical revascularization should be considered the treatment of choice in patients with significant left main coronary artery stenosis. Current advances in invasive cardiology have brought important information to the field. Intravascular ultrasound is now used routinely to evaluate angiographically indeterminate lesions with criteria now set forward as to what constitutes an indication for revascularization. Stents have even further dramatically changed the landscape. There are substantial issues, however, that need to addressed. These include the following: (1) the effect of specific lesion location on outcome - it is known that patients with distal bifurcation left main disease have worse outcome; (2) the potential for subacute thrombosis of the left main coronary artery; (3) the impact of left ventricular function and patient comorbidities irrespective of the degree and location of left main coronary artery stenosis; and (4) the risk-benefit ratio of stenting versus coronary artery bypass graft surgery. These issues are currently being addressed in two seminally important trials including the SYNTAX trial, which randomizes patients with left main and/or three-vessel disease to either coronary artery bypass graft surgery or a TAXUS drug-eluting stent. This trial is in the final stages of patient recruitment and will have important implications for the field. The other trial is the COMBAT trial, which is focused exclusively on left main coronary artery stenosis and randomizes patients with left main coronary artery disease either to a Sirolimus-eluting stent (Cypher, Johnson and Johnson Cordis, USA) or to coronary artery bypass graft surgery. The field of left main coronary artery disease continues to expand in terms of the evidence available for optimal patient evaluation and selection of treatment modalities.

Comprehensive cardiac CT study: evaluation of coronary arteries, left ventricular function, and myocardial perfusion--is it possible?

With advances in multidetector computed tomography (MDCT) technology, the new generation of 64-slice MDCT scanners with submillimeter collimation and a faster gantry rotation allows imaging of the entire heart in a single breath-hold with excellent temporal and spatial resolution. This potentially permits a comprehensive assessment of coronary anatomy, left ventricular function, and myocardial perfusion. As will be seen in this review of the current literature regarding 16- and 64-slice MDCT, there is great promise for a comprehensive cardiac computed tomography (CT) study. The available data support the notion that CT coronary angiography may be an alternative to invasive coronary angiography in symptomatic patients with a low to intermediate likelihood of having coronary artery disease. By use of the same data acquired for CT coronary angiography, evaluation of global and regional left ventricular function and myocardial perfusion can be added to the MDCT evaluation without additional exposure to contrast medium or radiation and may provide a more conclusive cardiac workup in these patients. The potential applications and limitations of coronary stenosis detection, global and regional left ventricular function, and myocardial perfusion assessment by MDCT will be reviewed. The full potential of cardiac MDCT is just beginning to be realized.

The Emerging Role of Multi-Detector Computed Tomography in Heart Failure

BACKGROUND

Recent advances in cardiac multi-detector computed tomography (MDCT) technology now permits entire coronary tree evaluation in a single breath hold with submillimeter slice collimation and improved temporal resolution.

METHODS AND RESULTS

Besides excellent correlation with invasive angiogram for the detection of significant coronary occlusion, MDCT also provides reliable and reproducible data regarding various other cardiac anatomic and functional parameters that are pertinent to heart failure patients. These include left ventricular measurement (eg, ejection fraction, regional wall motion, dimensions, volumes), pulmonary vein anatomy and drainage, right ventricular function, and cardiac venous system, among many others. However, there are radiogenic and nonradiogenic risks associated with MDCT that should be considered before scanning the patients.

CONCLUSIONS

This review summarizes the existing literature of the various cardiac MDCT applications pertinent to heart failure patients.

Coronary Artery Stenosis Quantification Using Multislice Computed Tomography

RATIONALE AND OBJECTIVES

Reliable noninvasive detection of stenoses with multislice computed tomography (MSCT) is feasible. This study's aim was to analyze the agreement, correlation, and reliability of MSCT with conventional coronary angiography as the reference standard for quantification of coronary artery stenoses.

MATERIALS AND METHODS

A total of 118 significant (at least 50%) coronary artery stenoses with a reference vessel diameter of at least 1.5 mm in 62 patients were analyzed by MSCT using 16 detector rows (Aquilion, Toshiba, Otawara, Japan), multisegment reconstruction, and voxel sizes of 0.35x0.35x0.5 mm. The degree of stenosis on MSCT and quantitative coronary angiography (QCA) was measured by correlating the difference between the reference vessel diameter (average of 2 measurements directly proximal and distal to the stenosis) and the stenotic vessel diameter to the reference vessel diameter.

RESULTS

Correlation between the percent diameter stenosis determined by MSCT (78.2+/-13.6%) and QCA (76.0+/-14.8%) was significant (P<0.001) but only moderately so (R=0.51). Bland-Altman analysis revealed no systematic under- or overestimation with MSCT but large limits of agreements (+/-27.6%). Also the limits of agreement for interobserver agreement (reliability) of MSCT data were considerably large (+/-24.8%). Among the 27 coronary artery stenoses with a reference diameter of at least 3.5 mm, there was improved correlation (R=0.80) and the limits of agreement between MSCT and QCA were significantly smaller (+/-17.3%, P<0.008). The agreement between MSCT and QCA was not significantly different for stenoses with no calcification or only calcium spots (+/-28.2%) as compared with those with moderate-or-severe calcifications (+/-27.3%; P=0.8). MSCT allowed correct classification of coronary stenoses into low-grade (below 75%) and high-grade stenoses (at least 75%), in 62% (73 of 118).

CONCLUSIONS

The accuracy and reliability of coronary artery stenosis quantification with MSCT using isotropic voxel sizes and multisegment reconstruction is still too low to recommend routine clinical application because of rather low agreement, correlation, and reliability. Despite these limitations, the current results demonstrate the potential of MSCT for reliable and accurate quantification of coronary artery stenoses in the near future provided that further improvements in spatial and temporal resolution will be achieved.

Noninvasive imaging for coronary artery disease: a technology assessment for the Medicare Coverage Advisory Commission

This report describes a review of the available scientific evidence through 2005 on direct noninvasive imaging tests (NITs) for coronary artery disease. In particular, the report addresses 6 key questions provided by the Agency for Healthcare Research and Quality and the Centers for Medicare and Medicaid Services. The questions examine the degree to which current evidence supports confident judgments about the use of NITs in the assessment of native coronary artery stenosis in clinical practice. The 2 NITs that are examined in detail in this report are 16 (and higher)-multidetector computed tomography angiography and 1.5-T magnetic resonance angiography to evaluate for stenosis in native coronary arteries. Reported sensitivity of NITs ranged from 68% to 100%; reported specificity ranged from 57% to 100% (patient-based analysis). Limitations include the exclusion of significant numbers of segments and patients, with often only the proximal coronary segments visualized. There is no direct evidence assessing the clinical use of NITs in terms of the incremental benefits or risks compared to alternative testing strategies. Although the ability of noninvasive direct coronary imaging technologies is promising-particularly the 64-multidetector computed tomography angiography-the evidence does not provide strong guidance on whether and how such technologies should be used in the population generally, or for Medicare beneficiaries specifically. Informed clinical and policy decision making will require further study of these technologies in well-characterized clinical contexts, in typical practice settings, and with attention to impact on management and health outcomes.

Applications of multislice computed tomography in coronary artery disease

Multislice computed tomography (MSCT) provides high accuracy for noninvasive assessment of coronary artery disease (CAD). The introduction of the latest computed tomography (CT) technology allows comprehensive evaluation of various aspects of CAD, including the coronary calcium score, coronary artery stenoses, bypass patency, and myocardial function. Other applications, such as plaque characterization, first-pass perfusion imaging, and viability imaging using delayed contrast enhancement, are still under development and may demonstrate clinical utility in the future. Further improvements in CT hardware and imaging protocols are expected that may result in improved coronary artery imaging, new applications, and a significant reduction of radiation dose.

A practical guide to reading CT coronary angiograms--how to avoid mistakes when assessing for coronary stenoses

There are now many physicians, both radiologists and cardiologists who are reporting CT coronary angiography (CTCA) scans who may not be aware that there are many pitfalls present. For the inexperienced reader a significant stenosis in a coronary artery can be easily missed or a moderate stenosis overcalled as significant. Artifacts can also be misinterpreted as representing a significant lesion. It is important that the studies are correctly interpreted, especially as the reported high negative predictive value of CTCA scans is a major strength of this imaging technique. The learning curve of reading these scans is steep and access to conventional coronary catheterisation results is essential for feedback and to improve the readers results. We have developed some rules to aid beginners avoid some of the pitfalls that can occur as these studies are not as easy to read as they may appear initially.