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.     

Prognostic value of CT coronary angiography: focus on obstructive vs. nonobstructive disease and on the presence of left main disease

Purpose

The authors investigated the prognostic value of computed tomography coronary angiography (CTCA) for major adverse cardiac events (MACE) in patients with suspected or known coronary artery disease (CAD), with particular focus on left main (LM) disease and obstructive vs. nonobstructive disease.

Materials and methods

A total of 727 consecutive patients (485 men, age 62±11years) with suspected (514; 70.1%) or known (213; 29.9%) CAD underwent CTCA. Patients were followed up for the occurrence of MACE (i.e. cardiac death, nonfatal myocardial infarction, unstable angina, percutaneous/surgical revascularisation).

Results

A total of 117 MACE [five cardiac deaths, 11 acute myocardial infarctions (AMI), five unstable angina, 86 percutaneous coronary interventions, ten coronary artery bypass grafts] occurred during a mean follow-up of 20 months. Severity and extension of CAD was associated with a progressively worse prognosis. The event rate was 0% among patients with normal coronary arteries at CTCA. The presence of LM disease was not associated with a worse prognosis either in patients with no history of CAD or in those with a history of CAD. At multivariate analysis, presence of obstructive CAD and diabetes were the only independent predictors of MACE.

Conclusions

Evaluation of atherosclerotic burden by CTCA provides an independent prognostic value for prediction of MACE. Patients with normal CTCA findings have an excellent prognosis at follow-up.     

Prognostic value of Morise clinical score, calcium score and computed tomography coronary angiography in patients with suspected or known coronary artery disease

Purpose

Our aim was to determine the prognostic value of computed tomography coronary angiography (CTCA), coronary artery calcium scoring (CACS) and Morise clinical score in patients with known or suspected coronary artery disease (CAD).

Materials and methods

A total of 722 patients (480 men; 62.7±10.9 years) who were referred for further cardiac evaluation underwent CACS and contrast-enhanced CTCA to evaluate the presence and severity of CAD. Of these, 511 (71%) patients were without previous history of CAD. Patients were stratified according to the Morise clinical score (low, intermediate, high), to CACS (0?C10, 11?C100, 101?C400, 401?C1,000, >1,000) and to CTCA (absence of CAD, nonsignificant CAD, obstructive CAD). Patients were followed up for the occurrence of major events: cardiac death, nonfatal myocardial infarction, unstable angina and revascularisation.

Results

Significant CAD (>50% luminal narrowing) was detected in 260 (36%) patients; nonsignificant CAD (<50% luminal narrowing) in 250 (35%) and absence of CAD in 212 (29%). During a mean follow-up of 20±4 months, 116 events (21 hard) occurred. In patients with normal coronary arteries on CTCA, the major event rate was 0% vs. 1.7% in patients with nonsignificant CAD and 7.3% in patients with significant CAD (p<0.0001). Three hard events (14%) occurred in patients with CACS??100 and two (9.5%) in patients with intermediate Morise score; one revascularisation was observed in a patient with low Morise score. At multivariate analysis, diabetes, obstructive CAD and CACS >1,000 were significant predictors of events (p<0.05).

Conclusions

An excellent prognosis was noted in patients with a normal CTCA (0% event rate). CACS ??100 and low-intermediate Morise score did not exclude the possibility of events at follow-up.     

Assessment of coronary artery disease and calcified coronary plaque burden by computed tomography in patients with and without diabetes mellitus

Purpose

To compare the coronary atherosclerotic burden in patients with and without type-2 diabetes using CT Coronary Angiography (CTCA).

Methods and Materials

147 diabetic (mean age: 65?±?10?years; male: 89) and 979 nondiabetic patients (mean age: 61?±?13?years; male: 567) without a history of coronary artery disease (CAD) underwent CTCA. The per-patient number of diseased coronary segments was determined and each diseased segment was classified as showing obstructive lesion (luminal narrowing >50%) or not. Coronary calcium scoring (CCS) was assessed too.

Results

Diabetics showed a higher number of diseased segments (4.1?±?4.2 vs. 2.1?±?3.0; p??400 (p?p?p?p?=?0.003) and obstructive CAD (12.5% vs. 3.8%, p?=?0.01). Among patients with CCS????10 all diabetics with obstructive CAD had a zero CCS and one patient was asymptomatic.

Conclusions

Diabetes was associated with higher coronary plaque burden. The present study demonstrates that the absence of coronary calcification does not exclude obstructive CAD especially in diabetics.     

MDCT coronary angiography vs 2D echocardiography for the assessment of left ventricle functional parameters

Purpose

This study was done to compare the parameters of left ventricular (LV) function obtained by multidetector computed tomography coronary angiography (MDCT-CA) using 64-slice equipment with those obtained using twodimensional echocardiography (2D-SE) considered as reference standard.

Materials and methods

Between April 2008 and September 2009, 116 consecutive patients were studied with both techniques. We analysed the parameters commonly sampled in echocardiography and related them with those retrieved with MDCT-CA: septal thickness, posterior wall thickness, diameter of ascending aorta, diameter and volumes in end-systolic and end-diastolic phase, ejection fraction, stroke volume, cardiac output and heart mass.

Results

Good correlation was found measuring septal thickness (r=0.470; p=0.001), and diameters of the ascending aorta. Correlation between systolic and diastolic diameters obtained with the two techniques was good. Poor correlation was attained measuring thickness of the posterior wall (r=0.243; p=0.104). MDCT-CA consistently overestimated the average volumes; diastolic and systolic volumes showed significant correlation (r=0.0456; p= 0.002; r=0.640; p<0.001). Ejection fraction agreement showed a significant correlation (r=0.626; p<0.001).

Conclusions

MDCT-CA provides parameters of cardiac function comparable to those found in echocardiography. MDCT-CA although used primarily for coronary noninvasive imaging can provide additional information on ventricular function useful to the diagnostic workup of cardiac patients.     

Prognostic value of computed tomography coronary angiography in patients with chest pain of suspected cardiac origin

Purpose

The authors sought to determine the prognostic value of computed tomography coronary angiography (CTCA) in patients with acute chest pain (ACP).

Materials and methods

A total of 145 consecutive patients (75 men; 64??12 years) with ACP were referred from the Emergency Department for CTCA, which was performed with a standard protocol using a 64-slice scanner. Patients were stratified according to the Morise clinical score (low, intermediate, high) and to the CTCA findings [absence of coronary artery disease (CAD), nonobstructive CAD, obstructive CAD]. Patients were followed up for the occurrence of major events: cardiac death, nonfatal myocardial infarction, unstable angina and revascularisation.

Results

One hundred and twenty-seven (87.6%) patients were without a history of CAD, and 18 (12.4%) patients had a history of CAD. Obstructive CAD (>50% luminal narrowing) was detected in 35 (24%) patients; nonobstructive CAD (??50% luminal narrowing) in 62 (43%) and absence of CAD in 48 (33%) patients. During a mean follow-up of 20??3 months, 20 events occurred (four hard events). Sixteen events (three hard events) occurred in patients without a history of CAD, and four events (one hard event) occurred in patients with a history of CAD. In patients with absence of CAD as detected by CTCA, the rate of events was 0%. At multivariate analysis, hypercholesterolaemia and obstructive CAD were significant predictors of events (p<0.05).

Conclusions

An excellent prognosis was observed in patients with ACP and normal CTCA. CTCA shows the potential for optimal stratification of patients with ACP.     

Comparison between different kernel reformatting filters in 3D quantitative analysis of MDCT coronary angiography

Purpose

Coronary angiography with multidetector-row computed tomography (MDCT-CA) allows quantification of coronary artery stenosis with a high level of accuracy; however, a better estimation of stenosis can be achieved by using appropriate reformatting filters, especially in stents and calcified segments. Quantitative computed tomography angiography (QCTA) is intended to overcome the limitations of the visual score. The aim of this study was to evaluate the accuracy of QCTA with different filters in comparison with quantitative coronary angiography (QCA) and visual score.

Materials and methods

Two blinded operators visually scored 17 consecutive patients referred for MDCT-CA with a per-segment analysis. The degree of stenosis was classified as 0?C20%, 20?C50% (wall irregularities), 50?C70% (significant disease) and 70?C100% (vessel occlusion). Each segment was then analysed using the electronic callipers of the QCTA system with 15 different filters. No contour editing was performed. Data were compared with QCA and conventional coronary angiography (CCA). Comparison between QCTA, visual score and QCA were performed using Spearman??s rank correlation.

Results

Of 25 segments analysed (mean 1.4 diseased segment per patient), 375 measurements were considered. Good correlation was found between the visual score and QCA [Pearson correlation coefficient (rho=0.852; p<0.0001)] and between QCA and CCA (rho=0.804; p<0.0001). Moderate correlation was found between QCA and QCTA only using two filters (rho=0.444; p<0.0001 for YA filter and rho=0.450; p<0.0001 for YB filter).

Conclusions

Overall QCTA accuracy is low if contour editing is not applied, especially in calcified vessels. Certain filters can help to better estimate the exact percentage of stenosis.     

Learning curve in multidetector CT coronary angiography (MDCT-CA)

Purpose

Coronary angiography using multidetector computed tomography (MDCT-CA) is a recent technique for the nonivasive study of coronary arteries. This study assessed the diagnostic accuracy of coronary artery stenosis evaluation obtained by three readers at different levels of training or at different points of the learning curve proposed by the international guidelines.

Materials and methods

Three radiologists in training with different levels of experience in MDCT-CA scored 50 cases at various time points of the learning curve: baseline, 4 weeks, 8 weeks and 6 months. The trainee radiologists evaluated the degree of stenosis on each coronary segment, and overall accuracy was calculated on a per-segment, pervessel and per-patient basis.

Results

All readers improved analysis accuracy per segment (range, 73–90%); sensitivity reached 45% per segment, 84% per vessel and 93% per patient; specificity was 99% per segment and vessel and 98% per patient. Positive and negative predictive values increased to 94% and 92%, respectively.

Conclusions

Although all readers improved in diagnostic performance with growing experience with MDCT-CA, a longer training period may be necessary to achieve adequate levels of expertise in MDCT-CA to be able to perform as independent readers.     

Correlation and predictive value of aortic root calcification markers with coronary artery calcification and obstructive coronary artery disease

Objective

To evaluate the correlation between aortic root calcification (ARC) markers and coronary artery calcification (CAC) derived from coronary artery calcium scoring (CACS) and their ability to predict obstructive coronary artery disease (CAD).

Methods

We retrospectively analyzed 189 patients (47% male, age 60.3 ± 11.1 years) with an intermediate probability of CAD who underwent clinically indicated CACS and coronary CT angiography (CCTA). ARC markers [aortic root calcium score (ARCS) and volume (ARCV)] were calculated and compared to CAC markers: coronary artery calcium score (CACS), volume (CACV), and mass (CACM). CCTA datasets were visually evaluated for significant CAD (stenosis ≥ 50%) and the ability of ARC markers to predict obstructive CAD was assessed.

Results

ARCS (mean 67.7 ± 189.5) and ARCV (mean 67.3 ± 184.7) showed significant differences between patients with and without CAC (109.4 ± 238.6 vs 9.42 ± 31.4, p < 0.0001; 108.5 ± 232.4 vs 9.9 ± 30.5, p < 0.0001). A strong correlation was found for ARCS and ARCV with CACS, CACM, and CACV (all p < 0.0001). In a multivariate analysis, ARCS (OR 1.09, p = 0.033) and ARCV (OR 1.12, p = 0.046) were independent markers for CAC. Using a receiver-operating characteristics analysis, the AUC to detect severe CAC was 0.71 (p < 0.0001) and 0.71 (p < 0.0001) for ARCS and ARCV, respectively. ARCS (0.67, p < 0.0001) and ARCV (0.68, p < 0.0001) showed discriminatory power for predicting obstructive CAD, yielding sensitivities 61 and 78% and specificities of 62 and 80%, respectively.

Conclusion

ARC markers are associated with and independently predict the presence of CAC and obstructive CAD. Further testing is required in patients with severe ARC and significant CAD in order to reliably obtain these markers from thoracic-CT or X-ray for proper risk classification.

     

Diagnostic accuracy of combined coronary angiography and adenosine stress myocardial perfusion imaging using 320-detector computed tomography: pilot study

Objectives

To determine the diagnostic accuracy of combined 320-detector row computed tomography coronary angiography (CTA) and adenosine stress CT myocardial perfusion imaging (CTP) in detecting perfusion abnormalities caused by obstructive coronary artery disease (CAD).

Methods

Twenty patients with suspected CAD who underwent initial investigation with single-photon-emission computed tomography myocardial perfusion imaging (SPECT-MPI) were recruited and underwent prospectively-gated 320-detector CTA/CTP and invasive angiography. Two blinded cardiologists evaluated invasive angiography images quantitatively (QCA). A blinded nuclear physician analysed SPECT-MPI images for fixed and reversible perfusion defects. Two blinded cardiologists assessed CTA/CTP studies qualitatively. Vessels/territories with both >50 % stenosis on QCA and corresponding perfusion defect on SPECT-MPI were defined as ischaemic and formed the reference standard.

Results

All patients completed the CTA/CTP protocol with diagnostic image quality. Of 60 vessels/territories, 17 (28 %) were ischaemic according to QCA/SPECT-MPI criteria. Sensitivity, specificity, PPV, NPV and area under the ROC curve for CTA/CTP was 94 %, 98 %, 94 %, 98 % and 0.96 (P?<?0.001) on a per-vessel/territory basis. Mean CTA/CTP radiation dose was 9.2?±?7.4 mSv compared with 13.2?±?2.2 mSv for SPECT-MPI (P?<?0.001).

Conclusions

Combined 320-detector CTA/CTP is accurate in identifying obstructive CAD causing perfusion abnormalities compared with combined QCA/SPECT-MPI, achieved with lower radiation dose than SPECT-MPI.

Key Points

? Advances in CT technology provides comprehensive anatomical and functional cardiac information. ? Combined 320-detector CTA/adenosine-stress CTP is feasible with excellent image quality. ? Combined CTA/CTP is accurate in identifying myocardial ischaemia compared with QCA/SPECT-MPI. ? Combined CTA/CTP results in lower patient radiation exposure than SPECT-MPI. ? CTA/CTP may become an established imaging technique for suspected CAD.     

Integrated non-invasive approach to atherosclerosis with cardiac CT and carotid ultrasound in patients with suspected coronary artery disease

Objective

The aim of the study was to compare the atherosclerotic disease in the coronary and carotid arteries in patients who underwent non-invasive imaging for suspected stable coronary artery disease (CAD).

Materials and methods

107 patients (64 men, age 59 ± 12) with atypical chest pain underwent cardiac CT (CCT) and carotid ultrasound (US) on the same day. Severity (obstructive or not-obstructive disease), location, shape, and composition of atherosclerotic plaques in the two districts were evaluated.

Results

Patients presented normal coronary arteries in 36 % (n = 38), not-obstructive CAD in 36 % (n = 39), and obstructive CAD in 28 % (n = 30), while had normal carotid arteries in 53 % (n = 57), not-obstructive disease in 44 % (n = 47), and obstructive disease in 3 % (n = 3) (p < 0.05). The coronary plaques were located in 7 % at ostial sites, in 29 % at non-ostial sites, and in 64 % at both locations. The carotid plaques were located at the origin of the internal and external carotid arteries in 56 %, at the bifurcation in 20 %, and at both locations in 24 % (p < 0.05). Coronary plaques were calcified in 25 %, non-calcified in 19 %, and mixed in 56 %; carotid plaques were calcified in 8 %, non-calcified in 8 %, and mixed in 84 % of patients (p < 0.05).

Conclusion

Atherosclerotic disease presents different imaging findings in the coronary tree and in the carotid district with respect to lesion severity, position along the vessel course, and composition of plaque.

     

Restriction of the referral of patients with stable angina for CT coronary angiography by clinical evaluation and calcium score: impact on clinical decision making

Objective

To investigate the value of the calcium score (CaSc) plus clinical evaluation to restrict referral for CT coronary angiography (CTCA) by reducing the number of patients with an intermediate probability of coronary artery disease (CAD).

Methods

We retrospectively included 1,975 symptomatic stable patients who underwent clinical evaluation and CaSc calculation and CTCA or invasive coronary coronary angiography (ICA). The outcome was obstructive CAD (≥50 % diameter narrowing) assessed by ICA or CTCA in the absence of ICA. We investigated two models: (1) clinical evaluation consisting of chest pain typicality, gender, age, risk factors and ECG and (2) clinical evaluation with CaSc. Discrimination of the two models was compared. The stepwise reclassification of patients with an intermediate probability of CAD (10–90 %) after clinical evaluation followed by clinical evaluation with CaSc was assessed by clinical net reclassification improvement (NRI).

Results

Discrimination of CAD was significantly improved by adding CaSc to the clinical evaluation (AUC: 0.80 vs. 0.89, P?<?0.001). CaSc and CTCA could be avoided in 9 % using model 1 and an additional 29 % of CTCAs could be avoided using model 2. Clinical NRI was 57 %.

Conclusion

CaSc plus clinical evaluation may be useful in restricting further referral for CTCA by 38 % in symptomatic stable patients with suspected CAD.

Key Points

? CT calcium scores (CaSc) could proiritise referrals for CT coronary angiography (CTCA) ? CaSc provides an incremental discriminatory value of CAD compared with clinical evaluation ? Risk stratification is better when clinical evaluation is combined with CaSc ? Appropriate use of clinical evaluation and CaSc helps avoid unnecessary CTCA referrals     

Computed tomography coronary angiography in the selection of outlier patients: a feasibility report

Purpose

This study evaluated criteria, presence and distribution of outlier patients by means of computed tomography coronary angiography (CTCA) in a large institutional database.

Material and methods

From a population of 2,881 consecutive patients (1,842 men, mean age 62±13 years) in sinus rhythm who underwent CTCA, we extracted data on patients with suspected coronary artery disease (CAD). We selected patient outliers in the fifth and sixth decades of life with the following criteria: ??3 risk factors and absence of CAD, zero to one risk factors and ??5 diseased coronary segments. Diabetes was excluded from risk factors because of the different impact on CAD.

Results

The patient population consisted of 2,432 individuals with suspected CAD (1,495 men, age 62±13 years). The prevalence of obstructive CAD (??50% lumen reduction at CTCA) was 36% (863/2,432). Patients with normal coronary arteries accounted for 34% of the total (837/2,432; 431 men, age 55±14 years). Of these, 210 were in the fifth and 231 in the 6th decade (men 196, women 245); those with ??3 risk factors accounted for 4.2% of the total (102/2,432; men 42, women 60). Patients with ??5 diseased coronary segments accounted for 28% of the total (686/2,432; 510 men, age 68±10 years). Of these, 115 were in the fifth and 270 in the sixth decade (men 309, women 76); those with zero to one risk factors accounted for 3.0% (73/2,432; men 66, women 7).

Conclusions

CTCA is a reliable noninvasive diagnostic modality that can be used to identify outlier patients. This will enable dedicated trials aimed at characterising biomarkers and genomics of protective and nonprotective factors against CAD and its complications.     

Coronary calcium score and computed tomography coronary angiography in high-risk asymptomatic subjects: assessment of diagnostic accuracy and prevalence of non-obstructive coronary artery disease

Objectives

The aim of the study was to compare the coronary artery calcium score (CACS) and computed tomography coronary angiography (CTCA) for the assessment of non-obstructive/obstructive coronary artery disease (CAD) in high-risk asymptomatic subjects.

Methods

Two hundred and thirteen consecutive asymptomatic subjects (113 male; mean age 53.6?±?12.4 years) with more than one risk factor and an inconclusive or unfeasible non-invasive stress test result underwent CACS and CTCA in an outpatient setting. All patients underwent conventional coronary angiography (CAG). Data from CACS (threshold for positive image: Agatston score 1/100/1,000) and CTCA were compared with CAG regarding the degree of CAD (non-obstructive/obstructive; </≥50% lumen reduction).

Results

The mean calcium score was 151?±?403 and the prevalence of obstructive CAD was 17% (8% one-vessel and 10% two-vessel disease). Per-patient sensitivity, specificity, positive and negative predictive values of CACS were: 97%, 75%, 45%, and 100%, respectively (Agatston?≥1); 73%, 90%, 60%, and 94%, respectively (Agatston?≥100); 30%, 98%, 79%, and 87%, respectively (Agatston?≥1,000). Per-patient values for CTCA were 100%, 98%, 97%, and 100%, respectively (p?<?0.05). CTCA detected 65% prevalence of all CAD (48% non-obstructive), while CACS detected 37% prevalence of all CAD (21% non-obstructive) (p?<?0.05).

Conclusion

CACS proved inadequate for the detection of obstructive and non-obstructive CAD compared with CTCA. CTCA has a high diagnostic accuracy for the detection of non-obstructive and obstructive CAD in high-risk asymptomatic patients with inconclusive or unfeasible stress test results.     

Diagnostic performance of computed tomography coronary angiography to detect and exclude left main and/or three-vessel coronary artery disease

Objectives

To determine the diagnostic performance of CT coronary angiography (CTCA) in detecting and excluding left main (LM) and/or three-vessel CAD (“high-risk” CAD) in symptomatic patients and to compare its discriminatory value with the Duke risk score and calcium score.

Materials and methods

Between 2004 and 2011, a total of 1,159 symptomatic patients (61?±?11 years, 31 % women) with stable angina, without prior revascularisation underwent both invasive coronary angiography (ICA) and CTCA. All patients gave written informed consent for the additional CTCA. High-risk CAD was defined as LM and/or three-vessel obstructive CAD (≥50 % diameter stenosis).

Results

A total of 197 (17 %) patients had high-risk CAD as determined by ICA. The sensitivity, specificity, positive predictive value, negative predictive value, positive and negative likelihood ratios of CTCA were 95 % (95 % CI 91–97 %), 83 % (80–85 %), 53 % (48–58 %), 99 % (98–99 %), 5.47 and 0.06, respectively. CTCA provided incremental value (AUC 0.90, P?<?0.001) in the discrimination of high-risk CAD compared with the Duke risk score and calcium score.

Conclusions

CTCA accurately excludes high-risk CAD in symptomatic patients. The detection of high-risk CAD is suboptimal owing to the high percentage (47 %) of overestimation of high-risk CAD. CTCA provides incremental value in the discrimination of high-risk CAD compared with the Duke risk score and calcium score.

Key Points

? Computed tomography coronary angiography (CTCA) accurately excludes high-risk coronary artery disease. ? CTCA overestimates high-risk coronary artery disease in 47?%. ? CTCA discriminates high-risk CAD better than clinical evaluation and coronary calcification.     

The prognostic value of transient ischemic dilatation with otherwise normal SPECT myocardial perfusion imaging: A cautionary note in patients with diabetes and coronary artery disease

Background

The prognostic implications of transient ischemic dilatation (TID) of the left ventricle with otherwise normal single-photon emission computed tomography myocardial perfusion imaging (MPI) remain controversial. Whether this finding may have prognostic implications only in high-risk populations, such as patients with diabetes or manifest coronary artery disease (CAD), is uncertain.

Methods

We conducted a prospective cohort study of 1,236 consecutive patients with normal ^99mTc-sestamibi MPI, defined as normal perfusion (summed stress score = 0) and normal left ventricle volume and function. TID was defined as >2 standard deviations above the mean of patients with low likelihood of CAD.

Results

The study subjects were followed for 27 ± 9 months. The 76 (6%) patients with TID had a greater rate of cardiac death or myocardial infarction (MI) [4 (5.3%) vs 11 (0.6%), P = .003] independent of covariates [hazard ratio = 6.4, P = .004]. This finding was entirely derived from the subgroup of 294 patients with diabetes or CAD [4 (13.3%) with TID vs 1 (0.4%) without TID, P = .001] independent of covariates. However, TID was not predictive of cardiac death or MI among the 941 patients without diabetes or CAD. Furthermore, TID was not predictive of coronary revascularization.

Conclusions

This study confirms a benign prognosis of TID with otherwise normal MPI in patients without diabetes or CAD, but cautions against extending this conclusion to high-risk individuals, particularly those with diabetes or CAD.     

Diagnostic accuracy of low-dose 256-slice multi-detector coronary CT angiography using iterative reconstruction in patients with suspected coronary artery disease

Objectives

To evaluate the accuracy of low-dose coronary CTA with iterative reconstruction (IR) in the diagnosis of coronary artery disease (CAD) in patients with suspected CAD.

Methods

Ninety-six patients with suspected CAD underwent low-dose prospective electrocardiogram-gated coronary CTA, with images reconstructed using IR. Image quality (IQ) of coronary segments were graded on a 4-point scale (4, excellent; 1, non-diagnostic). With invasive coronary angiography (ICA) considered the “gold standard”, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of coronary CTA were calculated on segment-, vessel- and patient-based levels. The patient data were divided into two groups (Agatston scores of ≥ 400 and <400). The differences in diagnostic performance between the two groups were tested.

Results

Diagnostic image quality was found in 98.1 % (1,232/1,256) of segments. The sensitivity, specificity, PPV, NPV and accuracy were 90.8 %, 95.3 %, 81.8 %, 97.8 % and 94.3 % (segment-based) and 97.2 %, 83.3 %, 94.6 %, 90.9 % and 93.8 % (patient-based). Significant differences between the two groups were seen in specificity, PPV and accuracy (92.1 % vs. 97.9 %, 76.0 % vs. 86.7 %, 91.7 % vs. 96.6 %, P?<?0.05; segment-based). The average effective dose was 1.30?±?0.15 mSv.

Conclusion

Low-dose prospective coronary CTA with IR can acquire satisfactory image quality and show high diagnostic accuracy in patients with suspected CAD; however, blooming continues to pose a challenge in severely calcified segments.

Key Points

? Coronary artery disease (CAD) is increasingly investigated using coronary CTA. ? The iterative reconstruction (IR) algorithm is promising in decreasing radiation doses. ? Low-dose prospective coronary CTA with IR can acquire satisfactory image quality. ? Low-dose prospective coronary CTA with IR can show high diagnostic accuracy.     

Prognostic value of atherosclerotic burden and coronary vascular function in patients with suspected coronary artery disease

Purpose

To evaluate the prognostic value of coronary atherosclerotic burden, assessed by coronary artery calcium (CAC) score, and coronary vascular function, assessed by coronary flow reserve (CFR) in patients with suspected coronary artery disease (CAD).

Methods

We studied 436 patients undergoing hybrid ⁸²Rb positron emission tomography/computed tomography imaging. CAC score was measured according to the Agatston method, and patients were categorized into three groups (0, <400, and ≥400). CFR was calculated as the ratio of hyperemic to baseline myocardial blood flow, and it was considered reduced when <2.

Results

Follow-up was 94% complete during a mean period of 47±15 months. During follow-up, 17 events occurred (4% cumulative event rate). Event-free survival decreased with worsening of CAC score category (p < 0.001) and in patients with reduced CFR (p < 0.005). At multivariable analysis, CAC score ≥400 (p < 0.01) and CFR (p < 0.005) were independent predictors of events. Including CFR in the prognostic model, continuous net reclassification improvement was 0.51 (0.14 in patients with events and 0.37 in those without). At classification and regression tree analysis, the initial split was on CAC score. For patients with a CAC score < 400, no further split was performed, while patients with a CAC score ≥400 were further stratified by CFR values. Decision curve analyses indicate that the model including CFR resulted in a higher net benefit across a wide range of decision threshold probabilities.

Conclusions

In patients with suspected CAD, CFR provides significant incremental risk stratification over established cardiac risk factors and CAC score for prediction of adverse cardiac events.

     

Does quantification of myocardial flow reserve using rubidium-82 positron emission tomography facilitate detection of multivessel coronary artery disease?

Background

Relative myocardial perfusion imaging (MPI) is the standard imaging approach for the diagnosis and prognostic work-up of coronary artery disease (CAD). However, this technique may underestimate the extent of disease in patients with 3-vessel CAD. Positron emission tomography (PET) is also able to quantify myocardial blood flow. Rubidium-82 (⁸²Rb) is a valid PET tracer alternative in centers that lack a cyclotron. The aim of this study was to assess whether assessment of myocardial flow reserve (MFR) measured with ⁸²Rb PET is an independent predictor of severe obstructive 3-vessel CAD.

Methods

We enrolled a cohort of 120 consecutive patients referred to a dipyridamole ⁸²Rb PET MPI for evaluation of ischemia neither with prior coronary artery bypass graft nor with recent percutaneous coronary intervention that also underwent coronary angiogram within 6?months of the PET study. Patients with and without 3-vessel CAD were compared.

Results

Among patients with severe 3-vessel CAD, MFR was globally reduced (<2) in 88% (22/25). On the adjusted logistic Cox model, MFR was an independent predictor of 3-vessel CAD [.5 unit decrease, HR: 2.1, 95% CI (1.2-3.8); P?=?.015]. The incremental value of ⁸²Rb MFR over the SSS was also shown by comparing the adjusted SSS models with and without ⁸²Rb MFR (P?=?.005).

Conclusion

⁸²Rb MFR is an independent predictor of 3-vessel CAD and provided added value to relative MPI. Clinical integration of this approach should be considered to enhance detection and risk assessment of patients with known or suspected CAD.     

Incremental value of the CT coronary calcium score for the prediction of coronary artery disease

Objectives:

To validate published prediction models for the presence of obstructive coronary artery disease (CAD) in patients with new onset stable typical or atypical angina pectoris and to assess the incremental value of the CT coronary calcium score (CTCS).

Methods:

We searched the literature for clinical prediction rules for the diagnosis of obstructive CAD, defined as ≥50% stenosis in at least one vessel on conventional coronary angiography. Significant variables were re-analysed in our dataset of 254 patients with logistic regression. CTCS was subsequently included in the models. The area under the receiver operating characteristic curve (AUC) was calculated to assess diagnostic performance.

Results:

Re-analysing the variables used by Diamond & Forrester yielded an AUC of 0.798, which increased to 0.890 by adding CTCS. For Pryor, Morise 1994, Morise 1997 and Shaw the AUC increased from 0.838 to 0.901, 0.831 to 0.899, 0.840 to 0.898 and 0.833 to 0.899. CTCS significantly improved model performance in each model.

Conclusions:

Validation demonstrated good diagnostic performance across all models. CTCS improves the prediction of the presence of obstructive CAD, independent of clinical predictors, and should be considered in its diagnostic work-up.