Cardiac computed tomography angiography-derived analysis of left atrial appendage morphology and left atrial dimensions for the prediction of atrial fibrillation recurrence after pulmonary vein isolation.

BACKGROUND: Left atrial appendage (LAA) is a potential source of atrial fibrillation (AF) triggers. HYPOTHESIS: LAA morphology and dimensions are associated with AF recurrence after pulmonary vein isolation (PVI). METHODS: From cardiac computed tomography angiography (CCTA), left atrial (LA), pulmonary vein (PV), and LAA anatomy were assessed in cryoballoon ablation (CBA) patients. RESULTS: Among 1103 patients undergoing second-generation CBA, 725 (65.7%) received CCTA with 473 (42.9%) qualifying for detailed LAA analysis (66.3 ± 9.5 years). Symptomatic AF reoccurred in 166 (35.1%) patients during a median follow-up of 19 months. Independent predictors of recurrence were LA volume, female sex, and mitral regurgitation ≥°II. LAA volume and AF-type were dependent predictors of recurrence due to their strong correlations with LA volume. LA volumes ≥122.7 ml (sensitivity 0.53, specificity 0.69, area under the curve [AUC] 0.63) and LAA volumes ≥11.25 ml (sensitivity 0.39, specificity 0.79, AUC 0.59) were associated with recurrence. LA volume was significantly smaller in females. LAA volumes showed no sex-specific difference. LAA morphology, classified as windsock (51.4%), chicken-wing (20.7%), cactus (12.5%), and cauliflower-type (15.2%), did not predict successful PVI (log-rank; p = 0.596). CONCLUSIONS: LAA volume was strongly correlated to LA volume and was a dependent predictor of recurrence after CBA. Main independent predictors were LA volume, female sex, and mitral regurgitation ≥°II. Gender differences in LA volumes were observed. Individual LAA morphology was not associated with AF recurrence after cryo-PVI. Our results indicate that preprocedural CCTA might be a useful imaging modality to evaluate ablation strategies for patients with recurrences despite successful PVI.

Impact of age on the outcome of cryoballoon ablation as the primary approach in the interventional treatment of atrial fibrillation: Insights from a large all-comer study.

INTRODUCTION: The objective was to analyze the impact of patient age on clinical characteristics, procedural results, safety, and outcome of cryoballoon ablation (CBA) as the primary approach in the interventional treatment of symptomatic atrial fibrillation (AF). METHODS AND RESULTS: The single-center prospective observational study investigated consecutive patients who underwent initial left atrial ablation for symptomatic paroxysmal (PAF) or persistent AF (persAF). Age groups (A-F) of less than 40, 40-49, 50-59, 60-69, 70-79 and more than or equal to 80 years were evaluated. Follow-up (FU) included ECG, Holter monitoring and assessment of AF-symptoms. From 2012 to 2016, a total of 786 patients (64 ± 11 years, range 21-85) underwent CBA. With advancing age, more cardiovascular comorbidities and larger LA diameter were observed, more females were included (each p < .001). PAF (57%) and persAF (43%, p = .320) were equally distributed over all age groups. Age was neither related to procedural parameters, nor to the complication rate (3.9%, p = .233). Median FU was 38 months. Two non-procedure related noncardiac deaths occurred late during FU. Freedom from arrhythmia was independent of age at 18 months (p = .210) but decreased for patients more than or equal to 70 years at 24 months (p = .02). At 36 months, freedom from arrhythmia was 66%-74% (groups A-D), 54% (E) and 49% (F), respectively (p = .002). LA diameter and persAF were independent predictors, whereas age was a dependent predictor of recurrence. CONCLUSION: CBA as the primary approach in the initial ablation procedure is safe and highly effective in the young, middle aged, and elderly population. LA diameter and persAF, but not ageing, were independent predictors for arrhythmia recurrence.

Radiation Dose Reduction Using a Novel Fluoroscopy System in Patients Undergoing Diagnostic Invasive Coronary Angiography.

BACKGROUND: Invasive coronary angiography (ICA) still causes a significant amount of radiation exposure for patients and operators. In February 2017, the Azurion system was introduced, a new-generation fluoroscopy image acquisition and processing system. Radiation exposure in patients undergoing ICA was assessed comparing the novel Azurion 7 F12 angiography system to its predecessor Allura Xper in a randomized manner. METHODS: Radiation exposure was prospectively analyzed in 238 patients undergoing diagnostic ICA. Patients were randomly assigned to the novel Azurion system (119 patients) or its predecessor Allura Xper system (119 patients). In each patient, 8 predefined standard projections (5 left coronary artery, 3 right coronary artery) were performed. Image quality was quantified by grading of the images on the basis of a 5-point grading system. RESULTS: Radiation dose area product was significantly lower in the Azurion group 109 (interquartile range [IQR 75-176] cGy cm) compared with the Allura Xper group 208 [IQR 134-301] cGy cm (P<0.001). Body mass index (26.6 [IQR 23.9-29.7] kg/m vs. 26.2 [IQR 24.2-29.4] kg/m; P=0.607), body surface area (1.96 [IQR 1.81-2.11] m vs. 1.90 [IQR 1.77-20.4] m; P=0.092), and procedure duration (1.5 [IQR 1.2-2.3] min vs. 1.6 [IQR 1.2-2.5] min; P=0.419) were similar in both groups. Images from the Azurion system were at least of equal quality compared with Allura Xper (image quality grade 4.82±0.45 vs. 4.75±0.52, P=0.43). CONCLUSION: Use of the novel Azurion 7 F12 angiography system resulted in a significant reduction of dose area product in patients undergoing diagnostic ICA by 56%.

Significant Radiation Dose Reduction Using a Novel Angiography Platform in Patients Undergoing Cryoballoon Pulmonary Vein Isolation.

OBJECTIVES: Cryoballoon pulmonary vein isolation (cPVI) in patients with atrial fibrillation requires fluoroscopic guidance, causing a relevant amount of radiation exposure. Strategies to reduce radiation exposure in electrophysiologic procedures and specifically cPVI are of great importance. The aim of this study was to evaluate a possible reduction of radiation dose using the novel Azurion 7 F12 x-ray system compared with its predecessor Allura FD10. METHODS: In February 2017, the Philips Azurion angiography system was introduced, combining the Allura Clarity radiation dose reduction technology with a more powerful generator, improved image resolution, and a large screen display. In 173 patients undergoing cPVI by a single experienced operator in our institution between December 2016 and April 2018, dose area products (cGy×cm) and image quality were compared using Azurion 7 F12 or Allura FD10 angiography system. RESULTS: A significant reduction in total radiation dose expressed as a dose area products of 524 (332; 821) cGy×cm on the Allura system compared with 309 (224; 432) cGy×cm on the Azurion system was observed (P<0.001). The number of imaging scenes recorded were 14.7 versus 13.9, and mean overall imaging quality scores (grading 4.85±0.4 with Azurion vs. 4.80±0.4 with Allura, P=0.38) and scores based on specific quality parameters were similar in both groups. CONCLUSION: Use of the new Azurion 7 F12 angiography system substantially reduced radiation doses compared with the previous generation reference system, Allura Clarity, without compromising imaging quality in patients undergoing cryoballoon pulmonary vein isolation.

Renal Sympathetic Denervation: Does Reduction of Left Ventricular Mass Improve Functional Myocardial Parameters? A Cardiovascular Magnetic Resonance Imaging Pilot Study.

OBJECTIVES: Left ventricular (LV) hypertrophy in resistant hypertensive patients is associated with a reduced intramyocardial perfusion. Renal sympathetic denervation (RDN) has been shown to reduce blood pressure (BP) and sympathetic tone. We aimed to prospectively investigate the effect of RDN on functional myocardial parameters and myocardial perfusion reserve (MPR) using cardiac magnetic resonance imaging (cMRI) in patients with resistant hypertension. METHODS: A total of 15 resistant hypertensive patients (11 male individuals, mean age 62±13 y) were included. Adenosine stress-induced cMRI was performed at baseline, 3, 6, and 12 months after RDN. RDN was performed using a single soft-tip radiofrequency catheter (Symplicity). cMRI semiquantitative perfusion analysis was performed using the upslope of myocardial signal enhancement to derive the myocardial perfusion reserve index. RESULTS: Both systolic-BP and diastolic-BP significantly decreased from 148±14 to 133±14 mm Hg and 87±14 to 80±10 mm Hg, respectively (P<0.05). LV septal wall thickness was significantly reduced (P<0.001). LV ejection fraction and MPR lacked significant trends 12 months after RDN. CONCLUSIONS: In this pilot study, RDN significantly reduced LV mass and LV septal wall thickness, as diagnosed by cMRI, with no significant changes in MPR. cMRI may help in diagnosing clinically relevant changes of functional myocardial parameters after interventional therapy in resistant hypertensive patients.

Current and future applications of CT coronary calcium assessment.

INTRODUCTION: Computed tomographic (CT) coronary artery calcium scoring (CAC) has been validated as a well-established screening method for cardiovascular risk stratification and treatment management that is used in addition to traditional risk factors. The purpose of this review is to present an update on current and future applications of CAC. Areas covered: The topic of CAC is summarized from its introduction to current application with focus on the validation and clinical integration including cardiovascular risk prediction and outcome, cost-effectiveness, impact on downstream medical testing, and the technical advances in scanner and software technology that are shaping the future of CAC. Furthermore, this review aims to provide guidance for the appropriate clinical use of CAC. Expert commentary: CAC is a well-established screening test in preventive care that is underused in daily clinical practice. The widespread clinical implementation of CAC will be decided by future technical advances in CT image acquisition, cost-effectiveness, and reimbursement status.

CT coronary calcium scoring with tin filtration using iterative beam-hardening calcium correction reconstruction.

OBJECTIVES: To investigate the diagnostic accuracy of CT coronary artery calcium scoring (CACS) with tin pre-filtration (Sn100kVp) using iterative beam-hardening correction (IBHC) calcium material reconstruction compared to the standard 120kVp acquisition. BACKGROUND: Third generation dual-source CT (DSCT) CACS with Sn100kVp acquisition allows significant dose reduction. However, the Sn100kVp spectrum is harder with lower contrast compared to 120kVp, resulting in lower calcium score values. Sn100kVp spectral correction using IBHC-based calcium material reconstruction may restore comparable calcium values. METHODS: Image data of 62 patients (56% male, age 63.9±9.2years) who underwent a clinically-indicated CACS acquisition using the standard 120kVp protocol and an additional Sn100kVp CACS scan as part of a research study were retrospectively analyzed. Datasets of the Sn100kVp scans were reconstructed using a dedicated spectral IBHC CACS reconstruction to restore the spectral response of 120kVp spectra. Agatston scores were derived from 120kVp and IBHC reconstructed Sn100kVp studies. Pearson's correlation coefficient was assessed and Agatston score categories and percentile-based risk categorization were compared. RESULTS: Median Agatston scores derived from IBHC Sn100kVp scans and 120kVp acquisition were 31.7 and 34.1, respectively (p=0.057). Pearson's correlation coefficient showed excellent correlation between the acquisitions (r=0.99, p<0.0001). Agatston score categories and percentile-based cardiac risk categories showed excellent agreement (ĸ=1.00 and ĸ=0.99), resulting in a low cardiac risk reclassification of 1.6% with the use of IBHC CACS reconstruction. Image noise was 24.9±3.6HU in IBHC Sn100kVp and 17.1±3.9HU in 120kVp scans (p<0.0001). The dose-length-product was 13.2±3.4mGycm with IBHC Sn100kVp and 59.1±22.9mGycm with 120kVp scans (p<0.0001), resulting in a significantly lower effective radiation dose (0.19±0.07mSv vs. 0.83±0.33mSv, p<0.0001) for IBHC Sn100kVp scans. CONCLUSION: Low voltage CACS with tin filtration using a dedicated IBHC CACS material reconstruction algorithm shows excellent correlation and agreement with the standard 120kVp acquisition regarding Agatston score and cardiac risk categorization, while radiation dose is significantly reduced by 75% to the level of a chest x-ray.

Lessons from individualized cryoballoon sizing. Is there a role for the small balloon?

BACKGROUND: Cryoablation for paroxysmal atrial fibrillation (PAF) is well established. The single-big-balloon strategy has been preferred for pulmonary vein isolation (PVI) using the second generation cryoballoon (CBG2). Individual PV-morphologies raise the question if an individualized anatomic approach using the 23-mm or 28-mm CB is reasonable. METHODS: Consecutive patients were prospectively enrolled in the non-randomized single-center study. Patients were treated with the 28-mm CB, if any PV was >21mm, the 23-mm CB, if all PV were ≤21mm, or both sizes, if PVI was difficult. The primary endpoint was arrhythmia-free survival. The secondary endpoint considered procedural results and complications. RESULTS: Overall, 197 patients with symptomatic PAF (64±11 years, 36% female) were included. Acute PVI was achieved in 99.9% of PV. Based on preprocedural imaging, the 28-mm CB was applied as the primary catheter in 47% (92/197 patients), the 23-mm CB in 53% (105/197, p=0.23). The 23-mm CB group included more females, patients with short left atrial (LA)-diameters (each p<0.01), and smaller patients (p=0.04). Both CB-sizes were used in 24% (47/197). Additional 23-mm CB usage was necessary in 23% (21/92) of patients, mainly because of insufficient PV-occlusion with the 28-mm CB. Additional 28-mm CB usage was necessary in 25% (26/105, p=0.82), mainly because PV diameters were larger than initially measured. Both CB-sizes were equally safe and effective with a low complication rate and an overall success rate of 86% at 12 and 71% at 18 months (6% on antiarrhythmic drugs). No predictors for AF-recurrence were identified. CONCLUSION: CB ablation can sometimes be challenging. The 28-mm CB is the preferred catheter in all patients. If balloon positioning is difficult, the 23-mm CB is an option to achieve PVI in small veins. Further studies need to investigate if the 23-mm CB could be beneficial as the primary CB in females with small body height and short LA diameter.

Global quantification of left ventricular myocardial perfusion at dynamic CT imaging: Prognostic value.

BACKGROUND: There is no published data on the prognostic value of global myocardial perfusion values at stress dynamic CT myocardial perfusion imaging (CTMPI). METHODS: Data of 144 patients from 6 centers who had undergone coronary CT angiography (coronary CTA) and CTMPI were assessed. Coronary CTA studies were acquired at rest; CTMPI was performed under vasodilator stress. Coronary CTA data were evaluated for coronary artery stenosis (≥50% luminal narrowing) on a per-vessel basis. Volumes-of-interest were placed over the entire left ventricular myocardium to obtain global myocardial blood flow (MBF), myocardial blood volume (MBV), and volume transfer constant (Ktrans). Follow-up was obtained at 6/12/18 months. Major adverse cardiac events (MACE, defined as cardiac death, non-fatal myocardial infarction, unstable angina requiring hospitalization, and revascularization) served as the endpoint. RESULTS: MACE occurred in 40 patients (nonfatal myocardial infarction, n = 1, unstable angina, n = 13, PCI, n = 23, and CABG, n = 3). Patients with global MBF of <121 mL/100 mL/min were at increased risk for MACE (HR 2.07, 95% confidence interval [CI]: 1.12-3.84, p = 0.02). This association remained significant after adjusting for age, gender, and clinical risk factors (HR 2.17, 95%CI: 1.16-4.06, p = 0.02), after further adjusting for presence of ≥50% stenosis at coronary CTA (HR 2.18, 95%CI: 1.16-4.10, p = 0.02) and when excluding early (<6 months) revascularizations (HR 2.34, 95%CI: 1.01-5.43, p = 0.0486). Global MBV and Ktrans were not independent predictors of MACE. CONCLUSION: Global quantification of left ventricular MBF at stress dynamic CTMPI may have incremental predictive value for future MACE over clinical risk factors and assessment of stenosis at coronary CTA.

Accuracy and Radiation Dose Reduction Using Low-Voltage Computed Tomography Coronary Artery Calcium Scoring With Tin Filtration.

This study prospectively investigated the accuracy and radiation dose reduction of CT coronary artery calcium scoring (CACS) using a 100 kVp acquisition protocol with tin filtration (Sn100 kVp) compared with the standard 120 kVp acquisition protocol; 70 patients (59% men, 62.1 ± 10.7 years) who underwent a clinically indicated CACS acquisition using the standard 120 kVp protocol on a third-generation dual-source CT system were enrolled. An additional Sn100 kVp CACS scan was performed. Agatston scores and categories, percentile-based risk categorization, and radiation dose estimates were derived from 120 and Sn100 kVp studies and compared. Median Agatston scores from the Sn100 and 120 kVp acquisitions were 38.2 and 41.2, respectively (p <0.0001). Excellent correlation of Agatston scores was found between the 2 acquisitions (r = 0.99, p <0.0001). Although the Agatston scores were systematically lower with Sn100 than with 120 kVp, the comparison of Agatston score categories and percentile-based cardiac risk categories showed excellent agreement (κ = 0.98 and κ = 0.98). Image noise was 26.3 ± 5.7 Hounsfield units in Sn100 kVp and 17.6 ± 4.1 Hounsfield units in 120 kVP scans (p <0.0001). The dose-length product was 14.1 ± 3.7 mGy·cm with Sn100 kVp and 58.5 ± 23.5 mGy·cm with 120 kVp scans (p <0.0001), resulting in a significantly lower effective radiation dose (0.19 ± 0.05 vs 0.82 ± 0.32 mSv, p <0.0001) for Sn100 kVp scans. CACS using a low-voltage tin filtration protocol shows excellent correlation and agreement with the standard method with regard to the Agatston score and subsequent cardiac risk categorization, while achieving a 75% reduction in radiation dose.

Dynamic CT myocardial perfusion imaging identifies early perfusion abnormalities in diabetes and hypertension: Insights from a multicenter registry.

BACKGROUND: To identify patients with early signs of myocardial perfusion reduction, a reference base for perfusion measures is needed. OBJECTIVE: To analyze perfusion parameters derived from dynamic computed tomography perfusion imaging (CTPI) in patients with suspected coronary artery disease (CAD), and relationship with risk factors. METHODS: In this multicenter study, coronary CT angiography (cCTA) and dynamic CTPI were performed by second-generation dual-source CT in patients suspected of CAD. Risk factors were collected from hospital records. Patients with visual perfusion defects on CTPI, previous coronary intervention, or missing risk factor details were excluded. This analysis included 98 patients (mean age ± standard deviation [SD], 59.0 ± 8.6yrs; 73 male). Global measures of left ventricular myocardial blood flow (MBF), myocardial blood volume (MBV) and volume transfer constant (K(trans)) were calculated. RESULTS: Mean MBF was 139.3 ± 31.4 mL/100 mL/min, MBV 19.1 ± 2.7 mL/100 mL, and Ktrans 85.0 ± 17.5 mL/100 mL/min. No significant differences in perfusion parameters were found by gender or age category. Hypertension and diabetes mellitus resulted in lower perfusion parameters (hypertension vs normotension: MBV 18.5 ± 3.0 vs 19.7 ± 2.3 mL/100 mL and K(trans) 82.0 ± 18.0 vs 89.0 ± 16.0, p < 0.05; diabetes vs no diabetes: MBF 128.5 ± 31.5 vs 144.0 ± 30.5 mL/100 mL/min and MBV 17.9 ± 2.4 vs 19.4 ± 2.8 mL/100 mL, p < 0.05). In patients with hyperlipidemia, MBF was higher (146.8 ± 34.4 vs 130.7 ± 24.3 mL/100 mL/min, p < 0.05). Smoking and family history did not show perfusion parameter differences. CONCLUSIONS: Dynamic CTPI identifies early perfusion disturbances in conditions like diabetes and hypertension. With further standardization, absolute perfusion measures may improve CAD risk stratification in patients without visual perfusion defects.

Cryoballoon ablation for persistent atrial fibrillation - Large single-center experience.

BACKGROUND: Different catheter ablation (CA) strategies have been established in the treatment of persistent atrial fibrillation (persAF). Pulmonary vein isolation (PVI) only might be an option for the initial ablation procedure. There is a paucity of outcome data on second-generation cryoballoon (CBG2) PVI in persAF. METHODS: Patients with symptomatic drug-refractory persAF who underwent initial CA of AF were prospectively enrolled and PVI was performed with CBG2. The primary composite endpoint was freedom from AF, atrial tachycardia, or related symptoms after a 3-month blanking period. The secondary endpoint referred to periprocedural complications. RESULTS: One hundred seventy-three consecutive patients (64±10 years, 29% female) with symptomatic drug-refractory persAF were identified. Acute PVI was achieved in 100% of pulmonary veins with the CB technique. The left atrial procedure time was 112±30min. Major complications occurred in 1.7% (3 of 173 patients) including two phrenic nerve palsies (1%), which resolved until discharge, and one pericardial effusion (0.6%). Follow-up ≥12 months was completed for 157 of 173 patients (91%). Median follow-up was 14 months. At 12 months, the primary composite endpoint was achieved in 129 of 157 patients (82%). However, 22 of 129 patients at risk (17%) were still on antiarrhythmic drugs. A relapse during the blanking period was identified as the only independent predictor for AF recurrence. CONCLUSION: PVI using the second-generation cryoballoon is a reasonable treatment option for patients with symptomatic drug-refractory persAF with a favorable rate of freedom from AF and a low complication rate.

Outcome of paroxysmal atrial fibrillation ablation with the cryoballoon using two different application times: the 4- versus 3-min protocol.

PURPOSE: The second-generation cryoballoon (CBG2) is highly effective for pulmonary vein isolation (PVI) in paroxysmal atrial fibrillation (PAF). One-year outcome data are consistent among different research groups. First results suggest that a shortened application time might be equally effective. The objective of the study was to compare procedural and outcome data for a 240 and 180-s protocol. METHODS: Prospectively, consecutive patients with symptomatic PAF underwent initial PVI with CBG2. In succession, two groups were created: the application time was 240 s in group 1 and 180 s in group 2. In both groups, a bonus application was applied. Periprocedural data, complications, and freedom from atrial fibrillation (AF)/AT/symptoms were compared between the groups. RESULTS: From May 2012 to June 2013, 114 patients (57 per group, 38% female) were included. The mean left atrial dwelling time decreased by 19 min (-16%) in group 2 compared to group 1 (p = 0.005). Intraprocedural pulmonary vein (PV) reconduction occurred infrequently (0.4% in both groups, p = 1.0). One persistent PNP occurred and resolved during the follow-up. Complications were without significant differences. One patient was lost to follow-up. The cumulative rates of freedom from recurrence at 12 months are 76.8% in group 1 and 83.6% in group 2. After a mean follow-up of 491 ± 208 days, the rates of freedom from AF/AT/symptoms at last visit were 38/57 (67%) and 44/56 (78.6%) in groups 1 and 2 (p = 0.14), respectively. Female sex was identified as a predictor for recurrence. CONCLUSIONS: Compared to a protocol with cryoballoon applications of 240 s, a shortened application time to 180 s results in a faster procedure with comparable high rates of freedom from AF at 16 months. Female sex seems to be predictive for recurrences; this finding has to be reconfirmed in a larger population.

Feasibility of dynamic CT-based adenosine stress myocardial perfusion imaging to detect and differentiate ischemic and infarcted myocardium in an large experimental porcine animal model.

The purpose of the study is feasibility of dynamic CT perfusion imaging to detect and differentiate ischemic and infarcted myocardium in a large porcine model. 12 Country pigs completed either implantation of a 75 % luminal coronary stenosis in the left anterior descending coronary artery simulating ischemia or balloon-occlusion inducing infarction. Dynamic CT-perfusion imaging (100 kV, 300 mAs), fluorescent microspheres, and histopathology were performed in all models. CT based myocardial blood flow (MBFCT), blood volume (MBVCT) and transit constant (Ktrans), as well as microsphere's based myocardial blood flow (MBFMic) were derived for each myocardial segment. According to histopathology or microsphere measurements, 20 myocardial segments were classified as infarcted and 23 were ischemic (12 and 14 %, respectively). Across all perfusion states, MBFCT strongly predicted MBFMic (ß 0.88 ± 0.12, p < 0.0001). MBFCT, MBVCT, and Ktrans were significantly lower in ischemic/infarcted when compared to reference myocardium (all p < 0.01). Relative differences of all CT parameters between affected and non-affected myocardium were higher for infarcted when compared to ischemic segments under rest (48.4 vs. 22.6 % and 46.1 vs. 22.9 % for MBFCT, MBVCT, respectively). Under stress, MBFCT was significantly lower in infarcted than in ischemic myocardium (67.8 ± 26 vs. 88.2 ± 22 ml/100 ml/min, p = 0.002). In a large animal model, CT-derived parameters of myocardial perfusion may enable detection and differentiation of ischemic and infarcted myocardium.

Iterative image reconstruction techniques for CT coronary artery calcium quantification: comparison with traditional filtered back projection in vitro and in vivo.

PURPOSE: To investigate in vitro and in vivo the use of image-based and raw data-based iterative reconstruction algorithms for quantification of coronary artery calcium by using the Agatston score and subsequent cardiac risk stratification. MATERIALS AND METHODS: In vitro data were obtained by using a moving anthropomorphic cardiac phantom containing calcium inserts of different concentrations and sizes. With institutional review board approval and HIPAA compliance, coronary calcium imaging data of 110 consecutive patients (mean age ± standard deviation, 58.2 years ± 9.8; 48 men) were reconstructed with filtered back projection (FBP), iterative reconstruction in image space (IRIS), and sinogram-affirmed iterative reconstruction (SAFIRE). Image noise was measured and the Agatston score was obtained for all reconstructions. Assignment to Agatston scores and percentile-based cardiac risk categories was compared. Statistical analysis included the Cohen κ coefficient and Friedman and Wilcoxon testing. RESULTS: In vitro, mean Agatston scores ± standard deviation for FBP (638.9 ± 9.6), IRIS (622.7 ± 15.2), and SAFIRE (631.4 ± 17.6) were comparable (P = .30). The smallest phantom calcifications were more frequently detected when iterative reconstruction techniques were used. The Agatston scores in the patient cohort were not significantly different among FBP, IRIS, and SAFIRE in paired comparisons (median Agatston score [25th and 75th percentiles]: 76.0 [20.6, 243.9], 76.4 [22, 249.3], and 75.7 [21.5, 49.1], respectively; P = .20 each). Comparison of categorization based on Agatston score percentiles showed excellent agreement for both IRIS and SAFIRE with FBP (κ = 0.975 [0.942-1.00] and κ = 0.963 [0.922-1.00], respectively). The mean effective dose was 1.02 mSv ± 0.51. Mean image noise was significantly (P < .001) higher with FBP than that with iterative reconstructions. CONCLUSION: In comparison with FBP, iterative reconstruction techniques do not have a profound effect on the reproducible quantification of coronary calcium according to Agatston score and subsequent cardiac risk classification, although risk reclassification may occur in a small subset of subjects.

Iterative reconstruction to preserve image quality and diagnostic accuracy at reduced radiation dose in coronary CT angiography: an intraindividual comparison.

OBJECTIVES: This study sought to determine whether a 50%-reduced radiation dose protocol using iterative reconstruction (IR) preserves image quality and diagnostic accuracy at coronary computed tomography angiography (CTA) as compared with a routine dose protocol using traditional filtered back projection (FBP). BACKGROUND: IR techniques show promise to decrease radiation requirements at coronary CTA. No study has performed a direct head-to-head, intraindividual comparison of IR algorithms with FBP vis-à-vis diagnostic accuracy and radiation dose at coronary CTA. METHODS: Sixty consecutive subjects (45 men, 53.3 ± 9.4 years of age) prospectively underwent coronary catheter angiography (CCA) and 2 coronary CTA scans. One coronary CTA acquisition used routine radiation dose settings and was reconstructed with FBP. For another scan, the tube current-time product was reduced by 50%, and data were reconstructed with IR. Studies were blindly and randomly interpreted. Image quality, radiation dose, and diagnostic accuracy were compared using CCA as the reference standard. RESULTS: Sensitivity and specificity for diagnosing ≥50% coronary artery stenosis on a per-segment level were 88.5% and 92.1% with FBP and 84.2% and 93.4% with IR, respectively. On a per-patient level, sensitivity and specificity were 100% and 93.1% with FBP and 96.8% and 89.7% with IR, respectively (all p > 0.05). With FBP versus IR, the area under the receiver-operating characteristic curve was 0.903 (95% confidence interval [CI]: 0.881 to 0.922) and 0.888 (95% CI: 0.864 to 0.909) on a per-segment level, and 0.966 (95% CI: 0.883 to 0.996) and 0.932 (95% CI: 0.836 to 0.981) on a per-patient level, respectively (p = 0.290 and 0.330). Compared with FBP, the iterative series showed no significant (p > 0.05) differences in image quality analyses. Median dose-length product was 52% lower for the IR protocol compared with the FBP protocol (109.00 [interquartile range: 82.00 to 172.50] mGy·cm vs. 52.00 [interquartile range: 39.00 to 84.00] mGy·cm, p < 0.001). CONCLUSIONS: Compared with a routine radiation dose FBP protocol, 50% reduced dose acquisition using IR preserves image quality and diagnostic accuracy at coronary CTA.

Magnetic resonance myocardial perfusion imaging at 3.0 Tesla for the identification of myocardial ischaemia: comparison with coronary catheter angiography and fractional flow reserve measurements.

AIMS: To assess image quality and diagnostic performance of 3.0 Tesla (3T) cardiac magnetic resonance (CMR) myocardial perfusion imaging with a dual radiofrequency source to detect functional relevant coronary artery disease (CAD), using coronary angiography and invasive pressure-derived fractional flow reserve (FFR) as reference standard. METHODS AND RESULTS: We included 116 patients with suspected or known CAD, who underwent 3T adenosine myocardial perfusion CMR (resolution 2.97 × 2.97 mm) and coronary angiography plus FFR measurements in intermediate lesions. Image quality of myocardial perfusion CMR was graded on a 4-point scale (1 = poor to 4 = excellent). Diagnostic accuracy was assessed by ROC analyses using a 16-myocardial segment-based summed perfusion score (0 = normal to 3 = transmural perfusion defect) and by determining sensitivity, specificity, positive and negative predictive value on the coronary vessel territory and the patient level. Diagnostic image quality was achieved for all stress myocardial perfusion CMR studies with an average quality score of 2.5, 3.1, and 3.0 for LAD, LCX, and RCA territories. The ability of the myocardial perfusion CMR perfusion score to detect significant coronary artery stenosis yielded an area under the curve of 0.93 on ROC analysis. Values for sensitivity, specificity, positive and negative predictive value on a vessel territory level and the patient level were 89, 95, 87, 96% and 85, 87, 77, 92%, respectively. CONCLUSION: In patients with suspected or known significant CAD, 3T myocardial perfusion CMR with standard perfusion protocols provides consistently high image quality and an excellent diagnostic performance.

Iterative image reconstruction: a realistic dose-saving method in cardiac CT imaging?

Iterative techniques are a valuable computed tomography image reconstruction alternative to filtered back projection. In repetitive cycles, iterative algorithms reduce image noise virtually independently of spatial resolution. In light of substantially decreased image noise, tube voltage or current reductions are enabled, resulting in significant radiation dose savings while preserving image quality. Moreover, iterative reconstruction techniques have the advantage of minimizing calcium blooming and metal artifacts. Iterative reconstruction may therefore lead to more exact coronary artery evaluation at constant x-ray tube settings and appears beneficial in clinically challenging scenarios such as overly obese patients, calcified coronary arteries and presence of iatrogenic hardware. For cardiac computed tomography, iterative reconstruction represents a promising and readily available tool.

CT evaluation of coronary artery stents with iterative image reconstruction: improvements in image quality and potential for radiation dose reduction.

OBJECTIVES: Comparison of coronary artery stent assessment with cardiac CT angiography (cCTA) using traditional filtered back projection (FBP) and sinogram affirmed iterative reconstruction (SAFIRE), in both full- and half-radiation dose image data. METHODS: Dual-source cCTA studies of 37 implanted stents were reconstructed at full- and half-radiation dose with FBP and SAFIRE. Half-dose data were based on projections from one DSCT detector. In-stent noise, signal-to-noise ratio (SNR), and stent-lumen attenuation increase ratio (SAIR) were measured and image quality graded. Stent volumes were measured to gauge severity of beam hardening artefacts. RESULTS: Full-dose SAFIRE reconstructions were superior to full-dose FBP vis-à-vis in-stent noise (21.2 ± 6.6 vs. 35.7 ± 17.5; P < 0.05), SNR (22.1 ± 8.6 vs. 14.3 ± 6.7; P < 0.05), SAIR (19.6 ± 17.6 vs. 33.4 ± 20.4%; P < 0.05), and image quality (4.2 ± 0.86 vs. 3.5 ± 1.0; P < 0.05). Stent volumes were lower measured with SAFIRE (119.9 ± 53.7 vs. 129.8 ± 65.0 mm(3); P > 0.05). Comparing half-dose SAFIRE with full-dose FBP, in-stent noise (26.7 ± 13.0 vs. 35.7 ± 17.5; P < 0.05) and SNR (18.2 ± 6.9 vs. 14.3 ± 6.7; P < 0.05) improved significantly. SAIR (31.6 ± 24.3 vs. 33.4 ± 20.4%; P > 0.05), stent volume (129.6 ± 57.3 vs. 129.8 ± 65.0 mm(3); P > 0.05), and image quality (3.5 ± 1.0 vs. 3.7 ± 1.1; P > 0.05) did not differ. Radiation dose decreased from 8.7 ± 5.2 to 4.3 ± 2.6 mSv. CONCLUSIONS: Iterative reconstruction significantly improves imaging of coronary artery stents by CT compared with FBP, even with half-radiation-dose data.

Cryoballoon in AF ablation: impact of PV ovality on AF recurrence.

INTRODUCTION: Complete occlusion of the pulmonary veins (PV) is crucial for successful PV isolation. While two different sizes of cryoballoons (23 and 28 mm) are available, complete occlusion is not always achieved in any given PV. We investigated the role of PV ostial anatomy during cryoballoon PV occlusion grading and atrial fibrillation (AF) recurrence rate. METHODS: PV ostial diameter was analyzed in 168 consecutive patients (111 men, 61 ± 10 years, 124 paroxysmal (px) and 44 persistent AF) using cardiac computed tomography (CT) prior to procedure. The ovality index at the PV ostial level was calculated in any given PV. During follow-up, 7-day holter monitors were performed at 1, 3, 6, 9, 12, 18 and 24 months post-ablation. RESULTS: The success rate at 12 ± 6 months follow-up was 69% including a 3-month blanking period (px AF: 66%; persistent AF 77%). The ovality index of the left-sided PVs was significantly larger ("more oval") than that of the right-sided PVs (p<0.001). An optimized PV occlusion in all individual PVs (complete occlusion, grading 4/4) was achieved during ablation in 49% of patients with AF recurrence and in 73% of patients without AF recurrence (p=0.004). Patients with AF recurrence had "more oval" left-sided PVs compared to patients free from AF recurrence (LSPV 0.40 ± 0.2 vs. 0.33 ± 0.2; p=0.04 and LIPV 0.41 ± 0.3 vs. 0.32 ± 0.2; p=0.03), whereas no significant association was found for right sided PVs. CONCLUSION: The ostial PV anatomy seems to have an important impact on clinical outcome and should be considered when planning and performing cryoballoon AF ablation procedures.