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.

Impact of heart rate frequency and variability on radiation exposure, image quality, and diagnostic performance in dual-source spiral CT coronary angiography.

PURPOSE: To investigate the effect of heart rate frequency (HRF) and heart rate variability (HRV) on radiation exposure, image quality, and diagnostic performance to help detect significant stenosis (> or =50% lumen diameter reduction) by using adaptive electrocardiographic (ECG) pulsing at dual-source (DS) spiral computed tomographic (CT) coronary angiography. MATERIALS AND METHODS: Institutional review committee approval and informed consent were obtained. No prescan beta-blockers were applied. Unenhanced CT and CT coronary angiography with adaptive ECG pulsing were performed in 927 consecutive patients (600 men, 327 women; mean age, 60.3 years +/- 11.0 [standard deviation]) divided in three HRF groups: low, intermediate, and high (< or =65, 66-79, and > or =80 beats/min, respectively), and four HRV groups given mean interbeat difference (IBD) during CT coronary angiography: normal, minor, moderate, and severe (IBDs of 0-1, 2-3, 4-10, and >10, respectively). Radiation exposure and image quality were also evaluated. In 444 of these, diagnostic performance was presented as sensitivity, specificity, positive predictive values (PPVs), and negative predictive values and likelihood ratios with corresponding 95% confidence intervals by using quantitative coronary angiography as the reference standard. RESULTS: CT coronary angiography yielded good image quality in 98% of patients and no significant differences in image quality were found among HRF and HRV groups. Radiation exposure was significantly higher in patients with low versus high HRF and in patients with severe versus normal HRV. No significant differences among HRF and HRV groups in image quality and diagnostic performance were found. A nonsignificant trend was found toward a lower specificity and PPV in patients with a high HRF or severe HRV when compared with low HRF or normal HRV in patients with a low calcium score (Agatston score <100). CONCLUSION: DS spiral CT coronary angiography performed with adaptive ECG pulsing results in preserved diagnostic image quality and performance independent of HRF or HRV at the cost of limited dose reduction in arrhythmic patients.

Computed tomography in total coronary occlusions (CTTO registry): radiation exposure and predictors of successful percutaneous intervention.

AIMS: There is no mention in the current "appropriateness criteria for CTCA" of the need of CTCA investigation prior to an attempt at recanalisation of a CTO. To define better the role of CTCA in the treatment of patients with CTOs, we performed CTCA in a consecutive cohort of eligible patients who were scheduled for percutaneous recanalisation of a CTO. METHODS AND RESULTS: Symptomatic patients due to a CTO suitable for percutaneous treatment were included. One hundred and thirty-nine (142 CTOs) patients were studied. Overall success rate was 62.7%. By CTCA, the occlusion length was 24.9 +/- 18.3 vs. 30.7 +/- 20.7 mm in successful and failed cases (p = 0.1), but the frequency of patients with an occlusion length >15 mm was different, i.e., 63.2% vs. 82.7%, respectively (p = 0.02). Severe calcification, (> 50% CSA) was more prevalent in failed cases (54.7% vs. 35.9%, p = 0.03). Calcification at the entry of the occlusion was present in 58.5% of the failures vs. 41.6% of the successful cases (p = 0.04), while calcium at the exit was not different. The length of calcification was 8.5 +/- 8.4 vs. 5.5 +/- 6.6 mm in the failed and successful cases respectively (p = 0.027). By multivariable analysis, the only independent predictor of procedural success was the absence of severe calcification as defined by CTCA. The mean effective radiation dose of the PCI was 39.3 +/- 30.1 mSv. The mean effective radiation dose of CT scan was 22.4 mSv: 19.2 +/- 6.5 mSv for contrast-enhanced scan, 3.2 +/- 1.7 mSv for calcium scoring scan. CONCLUSIONS: More severe calcified patterns, as assessed by CTCA, are seen in failed cases. The radiation exposure during a CT scan prior to a CTO PCI is considerable, and further studies are required to determine whether this extra diagnostic study is warranted.

Plaque and shear stress distribution in human coronary bifurcations: a multislice computed tomography study.

AIMS: Early atherosclerosis is located in low wall shear-stress (WSS) regions, however plaques are also found in the high WSS sensing flow divider walls of coronary bifurcations. We assessed the plaque distribution and morphology near bifurcations non-invasively with 64-slice computed tomography in relation to the WSS distribution. METHODS AND RESULTS: We inspected 65 cross-sections near coronary bifurcations for the presence of plaque. Cross-sections were divided into four equal parts, which we numbered according to expected levels of WSS, with part I the lowest WSS (outer wall) and increasing WSS's in part II (inner bend), III (outer bend) and IV (flow divider). Of the cross-sections 88% had plaque. Of all parts I, 72% contained plaque. This was 62%, 38% and 31% in parts II, III and IV. In cross-sections with only 1 or 2 parts inflicted, plaque was found in part I and/or II in 94%. In 93% of the cross-sections with the flow divider inflicted, parts I and/or II were also inflicted. Plaque was never found exclusively in the flow divider part IV. CONCLUSIONS: We demonstrated that plaque is mostly present in low WSS regions, whereas plaque in high WSS regions is accompanied by plaque in adjacent low WSS regions. It is therefore plausible that plaque grows from the outer wall (low WSS) of the bifurcation towards the flow divider (high WSS).

Optimal electrocardiographic pulsing windows and heart rate: effect on image quality and radiation exposure at dual-source coronary CT angiography.

PURPOSE: To determine the optimal width and timing of the electrocardiographic (ECG) pulsing window within the cardiac cycle in relation to heart rate (HR), image quality, and radiation exposure in patients who are suspected of having coronary artery disease. MATERIALS AND METHODS: The institutional review board approved the study, and all patients gave informed consent. Dual-source computed tomography (CT) was performed in 301 patients (mean HR, 70.1 beats per minute +/- 13.3 [standard deviation]; range, 43-112 beats per minute) by using a wide ECG pulsing window (25%-70% of the R-R interval). Data sets were reconstructed in 5% steps from 20%-75% of R-R interval. Image quality was assessed by two observers on a per-segment level and was classified as good or impaired. High-quality data sets were those in which each segment was of good quality. The width and timing of the image reconstruction window was calculated. On the basis of these findings, an optimal HR-dependent ECG pulsing protocol was designed, and the potential dose-saving effect on effective dose (in millisieverts) was calculated. RESULTS: At low HR (< or = 65 beats per minute), high-quality data sets were obtained during end diastole (ED); at high HR (> or = 80 beats per minute), they were obtained during end systole (ES); and at intermediate HR (66-79 beats per minute), they were obtained during both ES and ED. Optimal ECG pulsing windows for low, intermediate, and high HR were at 60%-76%, 30%-77%, and 31%-47% of the R-R interval, respectively, and with these levels, the effective dose was decreased at low HR from 18.7 to 6.8 mSv, at intermediate HR from 14.7 to 13.4 mSv, and at high HR from 11.3 to 4.2 mSv. CONCLUSION: With optimal ECG pulsing, radiation exposure to patients, particularly those with low or high HR, can be reduced with preservation of image quality.

Detection and characterization of coronary bifurcation lesions with 64-slice computed tomography coronary angiography.

AIMS: To compare the performance of 64-slice computed tomography coronary angiography (CTCA) and invasive coronary angiography (ICA) in the detection and classification (according to the Medina system) of bifurcation lesions (BLs). METHODS AND RESULTS: We studied 323 consecutive patients undergoing 64-slice CTCA prior to ICA. All coronary segments >or=2 mm in diameter were evaluated for the presence of a significant (>or=50% diameter reduction on quantitative coronary angiography) BL. Evaluation of BL by CTCA included the assessment of significant lumen obstruction in both main and side branch vessels. Forty-one out of 43 patients (46/48 lesions) with significant BL were identified by CTCA. Excluding coronary segments with non-diagnostic image quality (5%), the sensitivity, specificity, and positive and negative predictive values of CTCA for detecting significant BL were 96, 99, and 85 and 99%, respectively. In 39 of these 41 patients, CTCA assessment was concordant with the Medina lesion classification on ICA. CONCLUSION: Sixty-four-slice CTCA allows accurate assessment of complex BL.

Use of 64-slice CT in symptomatic patients after coronary bypass surgery: evaluation of grafts and coronary arteries.

AIMS: Although previous generations of multislice computed tomography (CT) have demonstrated accurate detection of obstructive bypass graft disease, progression of coronary disease is a more frequent cause for ischaemic symptoms late after bypass graft surgery. We explored the diagnostic performance of 64-slice CT in symptomatic patients after bypass surgery, for the assessment of both grafts and native coronary arteries. METHODS AND RESULTS: The 64-slice CT angiography (Siemens Sensation 64, Germany) was performed in 52 symptomatic patients, 10 +/- 5 years after bypass surgery. Two independent, blinded observers assessed all grafts and coronary arteries for stenosis, using conventional quantitative angiography as a reference. A total of 109 grafts (182 graft segments), 123 distal coronary run-offs, and 116 non-bypassed coronary branches (288 segments) were analysed. Per-segment detection of graft disease yielded a sensitivity of 99% (71/72) and specificity of 96% (106/110). Sensitivity and specificity to detect run-off disease were 89% (8/9) and 93% (106/114), positive predictive value was 50% (8/16). In non-grafted coronary segments, CT detected significant stenosis with a sensitivity and specificity of 97% (62/64) and 86% (192/224). Overestimation occurred more frequently in calcified segments (P = 0.002). CONCLUSION: The 64-slice CT allows angiographic evaluation of grafts and coronary arteries, although overestimation of coronary obstruction occurs, particularly in the presence of calcified disease.

Pre-operative computed tomography coronary angiography to detect significant coronary artery disease in patients referred for cardiac valve surgery.

OBJECTIVES: We studied the diagnostic performance of 64-slice computed tomography coronary angiography (CTCA) to rule out or detect significant coronary stenosis in patients referred for valve surgery. BACKGROUND: Invasive conventional coronary angiography (CCA) is recommended in most patients scheduled for valve surgery. METHODS: During a 6-month period, 145 patients were prospectively identified from a consecutive patient population scheduled for valve surgery. Thirty-five patients were excluded because of CTCA criteria: irregular heart rhythm (n = 26), impaired renal function (n = 5), and known contrast allergy (n = 4). General exclusion criteria were: hospitalization in community hospital (n = 4), no need for CCA (n = 4), previous coronary artery bypass surgery (n = 1), or percutaneous coronary intervention (n = 4). Of the remaining 97 patients, 27 denied written informed consent. Thus, the study population comprised 70 patients (49 male, 21 female; mean age 63 +/- 11 years). RESULTS: Prevalence of significant coronary artery disease, defined as having at least 1 > or =50% stenosis per patient, was 25.7%. Beta-blockers were administered in 71%, and 64% received lorazepam. The mean heart rate dropped from 72.5 +/- 12.4 to 59.5 +/- 7.5 beats/min. The mean scan time was 12.8 +/- 1.3 s. On a per-patient analysis, the sensitivity, specificity, and positive and negative predictive values were: 100% (18 of 18; 95% confidence interval [CI] 78 to 100), 92% (48 of 52; 95% CI 81 to 98), 82% (18 of 22; 95% CI 59 to 94), and 100% (48 of 48; 95% CI 91 to 100), respectively. CONCLUSIONS: The diagnostic accuracy of 64-slice CTCA for ruling out the presence of significant coronary stenoses in patients undergoing valve surgery is excellent and allows CTCA implementation as a gatekeeper for invasive CCA in these patients.

Multislice spiral computed tomography for the evaluation of stent patency after left main coronary artery stenting: a comparison with conventional coronary angiography and intravascular ultrasound.

BACKGROUND: Surveillance conventional coronary angiography (CCA) is recommended 2 to 6 months after stent-supported left main coronary artery (LMCA) percutaneous coronary intervention due to the unpredictable occurrence of in-stent restenosis (ISR), with its attendant risks. Multislice computed tomography (MSCT) is a promising technique for noninvasive coronary evaluation. We evaluated the diagnostic performance of high-resolution MSCT to detect ISR after stenting of the LMCA. METHODS AND RESULTS: Seventy-four patients were prospectively identified from a consecutive patient population scheduled for follow-up CCA after LMCA stenting and underwent MSCT before CCA. Until August 2004, a 16-slice scanner was used (n = 27), but we switched to the 64-slice scanner after that period (n = 43). Patients with initial heart rates > 65 bpm received beta-blockers, which resulted in a mean periscan heart rate of 57 +/- 7 bpm. Among patients with technically adequate scans (n = 70), MSCT correctly identified all patients with ISR (10 of 70) but misclassified 5 patients without ISR (false-positives). Overall, the accuracy of MSCT for detection of angiographic ISR was 93%. The sensitivity, specificity, and positive and negative predictive values were 100%, 91%, 67%, and 100%, respectively. When analysis was restricted to patients with stenting of the LMCA with or without extension into a single major side branch, accuracy was 98%. When both branches of the LMCA bifurcation were stented, accuracy was 83%. For the assessment of stent diameter and area, MSCT showed good correlation with intravascular ultrasound (r = 0.78 and 0.73, respectively). An intravascular ultrasound threshold value > or = 1 mm was identified to reliably detect in-stent neointima hyperplasia with MSCT. CONCLUSIONS: Current MSCT technology, in combination with optimal heart rate control, allows reliable noninvasive evaluation of selected patients after LMCA stenting. MSCT is safe to exclude left main ISR and may therefore be an acceptable first-line alternative to CCA.