The Year in Cardiac Imaging
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Archive for 'Invasive Imaging'
Head-to-Head Comparison of Left Ventricular Function Assessment with 64-Row Computed Tomography, Biplane Left Cineventriculography, and Both 2- and 3-Dimensional Transthoracic Echocardiography – Comparison With Magnetic Resonance Imaging as the Reference Standard
OBJECTIVES: This study was designed to compare the accuracy of 64-row contrast computed tomography (CT), invasive cineventriculography (CVG), 2-dimensional echocardiography (2D Echo), and 3-dimensional echocardiography (3D Echo) for left ventricular (LV) function assessment with magnetic resonance imaging (MRI). Cardiac function is an important determinant of therapy and is a major predictor for long-term survival in patients with coronary artery disease. A number of methods are available for assessment of function, but there are limited data on the comparison between these multiple methods in the same patients.
METHODS: A total of 36 patients prospectively underwent 64-row CT, CVG, 2D Echo, 3D Echo, and MRI (as the reference standard). Global and regional LV wall motion and ejection fraction (EF) were measured. In addition, assessment of interobserver agreement was performed.
RESULTS: For the global EF, Bland-Altman analysis showed significantly higher agreement between CT and MRI (p < 0.005, 95% confidence interval: ±14.2%) than for CVG (±20.2%) and 3D Echo (±21.2%). Only CVG (59.5 ± 13.9%, p = 0.03) significantly overestimated EF in comparison with MRI (55.6 ± 16.0%). CT showed significantly better agreement for stroke volume than 2D Echo, 3D Echo, and CVG. In comparison with MRI, CVG—but not CT—significantly overestimated the end-diastolic volume (p < 0.001), whereas 2D Echo and 3D Echo significantly underestimated the EDV (p < 0.05). There was no significant difference in diagnostic accuracy (range: 76% to 88%) for regional LV function assessment between the 4 methods when compared with MRI. Interobserver agreement for EF showed high intraclass correlation for 64-row CT, MRI, 2D Echo, and 3D Echo (intraclass correlation coefficient >0.8), whereas agreement was lower for CVG (intraclass correlation coefficient = 0.58).
CONCLUSIONS: 64-row CT may be more accurate than CVG, 2D Echo, and 3D Echo in comparison with MRI as the reference standard for assessment of global LV function.
Automated Quantification of Coronary Plaque With Computed Tomography: Comparison With Intravascular Ultrasound Using a Dedicated Registration Algorithm for Fusion-Based Quantification
OBJECTIVES: Previous studies have used semi-automated approaches for coronary plaque quantification on multi-detector row computed tomography (CT), while an automated quantitative approach using a dedicated registration algorithm is currently lacking. Accordingly, the study aimed to demonstrate the feasibility and accuracy of automated coronary plaque quantification on cardiac CT using dedicated software with a novel 3D coregistration algorithm of CT and intravascular ultrasound (IVUS) data sets.
METHODS: Patients who had undergone CT and IVUS were enrolled. Automated lumen and vessel wall contour detection was performed for both imaging modalities. Dedicated automated quantitative software (QCT) with a unique registration algorithm was used to fuse a complete IVUS run with a CT angiography volume using true anatomical markers. At the level of the minimal lumen area (MLA), percentage lumen area stenosis, plaque burden, and degree of remodelling were obtained on CT. Additionally, mean plaque burden was assessed for the whole coronary plaque. At the identical level within the coronary artery, the same variables were derived from
RESULTS: IVUS. Fifty-one patients (40 men, 58 ± 11 years, 103 coronary arteries) with 146 lesions were evaluated. Quantitative computed tomography and IVUS showed good correlation for MLA (n = 146, r = 0.75, P < 0.001). At the level of the MLA, both techniques were well-correlated for lumen area stenosis (n = 146, r = 0.79, P < 0.001) and plaque burden (n = 146, r = 0.70, P < 0.001). Mean plaque burden (n = 146, r = 0.64, P < 0.001) and remodelling index (n = 146, r = 0.56, P < 0.001) showed significant correlations between QCT and IVUS.
CONCLUSIONS: Automated quantification of coronary plaque on CT is feasible using dedicated quantitative software with a novel 3D registration algorithm.
PMID: 22285583
RV Dysfunction In Pulmonary Hypertension Is Independently Related To Pulmonary Artery Stiffness
OBJECTIVES: This study investigated whether right ventricular (RV) adaptation to chronic pressure overload is associated with pulmonary artery (PA) stiffness beyond the degree of severity of pulmonary hypertension (PH). Increased PA stiffness has been associated with reduced survival in PH. The mechanisms for this association remain unclear.
METHODS: Right heart catheterization and cardiac magnetic resonance were performed within 1 week in 124 patients with known or suspected chronic PH. Pulmonary vascular resistance index (PVRI) and PA pressures were quantified from right heart catheterization. Cardiac magnetic resonance included standard biventricular cine sequences and main PA flow quantification with phase-contrast imaging. Indexes of PA stiffness (elasticity, distensibility, capacitance, stiffness index beta, and pulse pressure) were quantified combining right heart catheterization and cardiac magnetic resonance data. RV performance and adaptation were measured by RV ejection fraction, right ventricular mass index (RVMI), RV end-systolic volume index, and right ventricular stroke work index (RVSWI).
RESULTS: All indexes of PA stiffness were significantly correlated with measures of RV performance (Spearman rho coefficients ranging from –0.20 to 0.61, p < 0.05). Using multivariate regression analysis, PA elasticity, distensibility, and index beta were independently associated with all measures of RV performance after adjusting PVRI (p 
0.024). PA capacitance was independently associated with RV ejection fraction, RVMI, and RVSWI (p < 0.05), whereas PA pulse pressure was associated with RVMI and RVSWI (p 0.027). Compared with PVRI, PA elasticity, distensibility, capacitance, and index beta explained 15% to 68% of the variability in RV ejection fraction, RVMI, and RV end-systolic volume index. Relative contributions of PA stiffness for RVSWI were 1.2x to 18.0x higher than those of PVRI.
CONCLUSIONS: PA stiffness is independently associated with the degree of RV dysfunction, dilation, and hypertrophy in PH. RV adaptation to chronic pressure overload is related not only to the levels of vascular resistance (steady afterload), but also to PA stiffness (pulsatile load).
Characteristics and Clinical Significance of Angiographically Mild Lesions in Acute Coronary Syndromes
OBJECTIVES: The aim of this study was to assess whether residual nonculprit (NC) lesions, defined as visual diameter stenosis ≥30% after successful percutaneous coronary intervention, affect the rate of future events in patients with acute coronary syndromes. In patients with acute coronary syndromes, approximately one-half of recurrent events after percutaneous coronary intervention arise from untreated lesions.
METHODS: Patients enrolled in PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) were divided into 3 groups: those with no NC lesions, 1 NC lesion, or ≥2 NC lesions. Time to events for major adverse cardiac events was estimated up to 3 years.
RESULTS: Among 697 patients, 13.3% had no NC lesions, 19.7% had 1 NC lesion, and 67.0% had ≥2 NC lesions. The median diameter stenoses of the NC lesions in the latter 2 groups were 36.7% (interquartile range: 31.0% to 43.4%) and 37.4% (interquartile range: 32.0% to 46.5%), respectively (p = 0.22). At least 1 thin-cap fibroatheroma was present in one-half the patients in each group. At 3 years, the incidence of major adverse cardiac events was 8.5%, 15.2%, and 24.3%, respectively (p = 0.0009). NC lesion-related events occurred in 0%, 5.0%, and 15.9% of patients, respectively (p < 0.0001). Of 105 NC lesion-related clinical events occurring during follow-up, 73 (69.5%) originated from angiographically evident baseline NC lesions (of which 36 had diameter stenosis >50%), while the other 32 arose from normal or near normal segments.
CONCLUSIONS: Residual NC lesions are common after percutaneous coronary intervention for acute coronary syndromes and portend a higher rate of recurrent ischemic events within 3 years, especially when angiographically more severe. Conversely, the absence of NC lesions by angiography is highly predictive of freedom from events not related to the originally treated culprit lesion(s).
PMID: 22421235
Consensus Standards for Acquisition, Measurement, and Reporting of Intravascular Optical Coherence Tomography Studies: A Report from the International Working Group for Intravascular Optical Coherence Tomography Standardization and Validation
OBJECTIVES: The purpose of this document is to make the output of the International Working Group for Intravascular Optical Coherence Tomography (IWG-IVOCT) Standardization and Validation available to medical and scientific communities, through a peer-reviewed publication, in the interest of improving the diagnosis and treatment of patients with atherosclerosis, including coronary artery disease. Intravascular optical coherence tomography (IVOCT) is a catheter-based modality that acquires images at a resolution of ∼10 μm, enabling visualization of blood vessel wall microstructure in vivo at an unprecedented level of detail. IVOCT devices are now commercially available worldwide, there is an active user base, and the interest in using this technology is growing. Incorporation of IVOCT in research and daily clinical practice can be facilitated by the development of uniform terminology and consensus-based standards on use of the technology, interpretation of the images, and reporting of IVOCT results.
METHODS: The IWG-IVOCT, comprising more than 260 academic and industry members from Asia, Europe, and the United States, formed in 2008 and convened on the topic of IVOCT standardization through a series of 9 national and international meetings.
RESULTS: Knowledge and recommendations from this group on key areas within the IVOCT field were assembled to generate this consensus document, authored by the Writing Committee, composed of academicians who have participated in meetings and/or writing of the text.
CONCLUSIONS: This document may be broadly used as a standard reference regarding the current state of the IVOCT imaging modality, intended for researchers and clinicians who use IVOCT and analyze IVOCT data.
PMID: 22421299
Cross-Sectional Computed Tomographic Assessment Improves Accuracy of Aortic Annular Sizing for Transcatheter Aortic Valve Replacement and Reduces the Incidence of Paravalvular Aortic Regurgitation
OBJECTIVES: In an effort to define the gold standard for annular sizing for transcatheter aortic valve replacement (TAVR), we sought to critically analyze and compare the predictive value of multiple measures of the aortic annulus for post-TAVR paravalvular (PV) regurgitation and then assess the impact of a novel cross-sectional computed tomographic (CT) approach toannular sizing. Recent studies have shown clear discrepancies between conventional 2-dimensional (2D) echocardiographic and CT measurements. In terms of aortic annular measurement for TAVR, such findings have lacked the outcome analysis required to inform clinical practice.
METHODS: The discriminatory value of multiple CT annular measures for post-TAVR PV aortic regurgitation was compared with 2D echocardiographic measures. TAVR outcomes with device selection according to aortic annular sizing using a traditional 2D transesophageal echocardiography-guided or a novel CT-guided approach were also studied.
RESULTS: In receiver-operating characteristic models, cross-sectional CT parameters had the highest discriminatory value for post-TAVR PV regurgitation: This was with the area under the curve for [maximal cross-sectional diameter minus prosthesis size] of 0.82 (95% confidence interval: 0.69 to 0.94; p < 0.001) and that for [circumference-derived cross-sectional diameter minus prosthesis size] of 0.81 (95% confidence interval: 0.7 to 0.94; p < 0.001). In contrast, traditional echocardiographic measures were nondiscriminatory in relation to post-TAVR PV aortic regurgitation. The prospective application of a CT-guided annular sizing approach resulted in less PV aortic regurgitation of grade worse than mild after TAVR (7.5% vs. 21.9%; p = 0.045).
CONCLUSIONS: Our data lend strong support to 3-dimensional cross-sectional measures, using CT as the new gold standard foraortic annular evaluation for TAVR with the Edwards SAPIEN device.
PMID: 22365424
3-Dimensional Aortic Annular Assessment by Multidetector Computed Tomography Predicts Moderate or Severe Paravalvular Regurgitation After Transcatheter Aortic Valve Replacement A Multicenter Retrospective Analysis
OBJECTIVES: This study sought to analyze multidetector computed tomography (MDCT) 3-dimensional aortic annular dimensions for the prediction of paravalvular aortic regurgitation (PAR) following transcatheter aortic valve replacement (TAVR). Moderate or severe PAR after TAVR is associated with increased morbidity and mortality.
METHODS: A total of 109 consecutive patients underwent MDCT pre-TAVR with a balloon expandable aortic valve. Differences between transcatheter heart valve (THV) size and MDCT measures of annular size (mean diameter, area, and circumference) were analyzed concerning prediction of PAR. Patients with THV malposition (n = 7) were excluded. In 50 patients, MDCT was repeated after TAVR to assess THV eccentricity (1 – short diameter/long diameter) and expansion (MDCT measured THV area/nominal THV area).
RESULTS: Moderate or severe PAR (13 of 102) was associated with THV undersizing (THV diameter – mean diameter = -0.7 ± 1.4 mm vs. 0.9 ± 1.8 mm for trivial to mild PAR, p < 0.01). The difference between THV size and MDCT annular size was predictive of PAR (mean diameter: area under the curve [AUC]: 0.81, 95% confidence interval [CI]: 0.68 to 0.88; area: AUC: 0.80, 95% CI: 0.65 to 0.90; circumference: AUC: 0.76, 95% CI: 0.59 to 0.91). Annular eccentricity was not associated with PAR (AUC: 0.58, 95% CI: 0.46 to 0.75). We found that 35.3% (36 of 102) and 45.1% (46 of 102) of THVs were undersized relative to the MDCT mean diameter and area, respectively. THV oversizing relative to the annular area was not associated with THV eccentricity or underexpansion (oversized vs. undersized THVs; expansion: 102.7 ± 5.3% vs. 106.1 ± 5.6%, p = 0.03; eccentricity: median: 1.7% [interquartile range: 1.4% to 3.0%] vs. 1.7% [interquartile range: 1.1% to 2.7%], p = 0.28).
CONCLUSIONS: MDCT-derived 3-dimensional aortic annular measurements are predictive of moderate or severe PAR following TAVR. Oversizing of THVs may reduce the risk of moderate or severe PAR.
PMID: 22365423
Prediction of Optimal Deployment Projection for Transcatheter Aortic Valve Replacement: Angiographic 3-Dimensional Reconstruction of the Aortic Root Versus Multidetector Computed Tomography
OBJECTIVES: Identifying the optimal fluoroscopic projection of the aortic valve is important for successful transcatheter aortic valve replacement (TAVR). Various imaging modalities, including multidetector computed tomography (MDCT), have been proposed for prediction of the optimal deployment projection. We evaluated a method that provides 3-dimensional angiographic reconstructions (3DA) of the aortic root for prediction of the optimal deployment angle and compared it with MDCT.
METHODS: Forty patients undergoing transfemoral TAVR at St Paul’s Hospital, Vancouver, Canada, were evaluated. All underwent preimplant 3DA and 68% underwent preimplant MDCT. Three-dimensional angiographic reconstructions were generated from images of a C-arm rotational aortic root angiogram during breath-hold, rapid ventricular pacing, and injection of 32 mL contrast medium at 8 mL/s. Two independent operators prospectively predicted perpendicular valve projections. The implant angle was chosen at the discretion of the physician performing TAVR. The angles from 3DA, from MDCT, the implant angle, and the postdeployment perpendicular prosthesis view were compared. The shortest distance from the postdeployment perpendicular prosthesis projection to the regression line of predicted perpendicular projections was calculated. All but 1 patient had adequate image quality for reproducible angle predictions.
RESULTS: There was a significant correlation between 3DA and MDCT for prediction of perpendicular valve projections (r=0.682, P<0.001). Deviation from the regression line of predicted angles to the postdeployment prosthesis view was 5.1±4.6° for 3DA and 7.9±4.9° for MDCT (P=0.01).
CONCLUSIONS: Three-dimensional angiographic reconstructions and MDCT are safe, practical, and accurate imaging modalities for identifying the optimal perpendicular valve deployment projection during TAVR.
PMID: 22438432
Automated Quantification of Coronary Plaque with Computed Tomography: Comparison With Intravascular Ultrasound Using a Dedicated Registration Algorithm for Fusion-Based Quantification
OBJECTIVES: Previous studies have used semi-automated approaches for coronary plaque quantification on multi-detector row computed tomography (CT), while an automated quantitative approach using a dedicated registration algorithm is currently lacking. Accordingly, the study aimed to demonstrate the feasibility and accuracy of automated coronary plaque quantification on cardiac CT using dedicated software with a novel 3D coregistration algorithm of CT and intravascular ultrasound (IVUS) data sets.
METHODS: Patients who had undergone CT and IVUS were enrolled. Automated lumen and vessel wall contour detection was performed for both imaging modalities. Dedicated automated quantitative software (QCT) with a unique registration algorithm was used to fuse a complete IVUS run with a CT angiography volume using true anatomical markers. At the level of the minimal lumen area (MLA), percentage lumen area stenosis, plaque burden, and degree of remodelling were obtained on CT. Additionally, mean plaque burden was assessed for the whole coronary plaque. At the identical level within the coronary artery, the same variables were derived from IVUS.
RESULTS: Fifty-one patients (40 men, 58 ± 11 years, 103 coronary arteries) with 146 lesions were evaluated. Quantitative computed tomography and IVUS showed good correlation for MLA (n = 146, r = 0.75, P < 0.001). At the level of the MLA, both techniques were well-correlated for lumen area stenosis (n = 146, r = 0.79, P < 0.001) and plaque burden (n = 146, r = 0.70, P < 0.001). Mean plaque burden (n = 146, r = 0.64, P < 0.001) and remodelling index (n = 146, r = 0.56, P < 0.001) showed significant correlations between QCT and IVUS.
CONCLUSIONS: Automated quantification of coronary plaque on CT is feasible using dedicated quantitative software with a novel 3D registration algorithm.
PMID: 22285583
Impact of Statin Therapy on Plaque Characteristics as Assessed by Serial OCT, Grayscale and Integrated Backscatter-IVUS
OBJECTIVES: The purpose of this study was to evaluate the effect of statin treatment on coronary plaque composition and morphology by optical coherence tomography (OCT), grayscale and integrated backscatter (IB) intravascular ultrasound (IVUS) imaging. Although previous studies have demonstrated that statins substantially improve cardiac mortality, their precise effect on the lipid content and fibrous cap thickness of atherosclerotic coronary lesions is less clear. While IVUS lacks the spatial resolution to accurately assess fibrous cap thickness, OCT lacks the penetration of IVUS. We used a combination of OCT, grayscale and IB-IVUS to comprehensively assess the impact of pitavastatin on plaque characteristics.
METHODS: Prospective serial OCT, grayscale and IB-IVUS of nontarget lesions was performed in 42 stable angina patients undergoing elective coronary intervention. Of these, 26 received 4 mg pitavastatin after the baseline study; 16 subjects who refused statin treatment were followed with dietary modification alone. Follow-up imaging was performed after a median interval of 9 months.
RESULTS: Grayscale IVUS revealed that in the statin-treated patients, percent plaque volume index was significantly reduced over time (48.5 ± 10.4%, 42.0 ± 11.1%; p = 0.033), whereas no change was observed in the diet-only patients (48.7 ± 10.4%, 50.4 ± 11.8%; p = NS). IB-IVUS identified significant reductions in the percentage lipid volume index over time (34.9 ± 12.2%, 28.2 ± 7.5%; p = 0.020); no change was observed in the diet-treated group (31.0 ± 10.7%, 33.8 ± 12.4%; p = NS). While OCT demonstrated a significant increase in fibrous cap thickness (140 ± 42 μm, 189 ± 46 μm; p = 0.001), such changes were not observed in the diet-only group (140 ± 35 μm, 142 ± 36 μm; p = NS). Differences in the changes in the percentage lipid volume index (-6.8 ± 8.0% vs. 2.8 ± 9.9%, p = 0.031) and fibrous cap thickness (52 ± 32 μm vs. 2 ± 22 μm, p < 0.001) over time between the pitavastatin and diet groups were highly significant.
CONCLUSIONS: Statin treatment induces favorable plaque morphologic changes with an increase in fibrous cap thickness, and decreases in both percentage plaque and lipid volume indexes.
PMID: 22340823
Real-Time Magnetic Resonance Imaging-Guided Transarterial Aortic Valve Implantation In-Vivo Evaluation in Swine
Real-time magnetic resonance imaging (rtMRI) is considered attractive for guiding transarterial aortic valve implantation (TAVI). Compared with X-ray fluoroscopy, rtMRI offers unrestricted scan plane orientation and an unsurpassed soft-tissue contrast with simultaneous device visualization, potentially allowing enhanced positioning accuracy together with online monitoring of cardiac function and immediate detection of complications. Additionally, MRI offers noninvasive assessment of cardiovascular anatomy and function for preinterventional screening as well as immediate morphologic and functional assessment of the implanted prothesis and may, thus, be envisioned as a single comprehensive imaging modality for TAVI. We, therefore, sought to assess the preclinical feasibility of entirely rtMRI-guided TAVI in a swine model (female domestic pigs weighing 70.5 to 86.5 kg) using the original CoreValve (Medtronic, Minneapolis, Minnesota) prosthesis without alterations in conjunction with a modified, MRI-compatible delivery device (1).
rtMRI-guided transfemoral (n = 2) and transsubclavian (n = 6) TAVI was performed in a 1.5-T whole-body MRI scanner (Magnetom Avanto, Siemens Healthcare Sector, Erlangen, Germany). Conventional x-ray fluoroscopy and angiography were performed for comparison. After pre-interventional evaluation using standard steady-state free-precession imaging with electrocardiographic gating and time-resolved retrospective image reconstruction (cine-TrueFISP retro) (TR, 40 ms; TE, 1.1 ms; flip angle, 62°; FOV, 380 x 330 mm2; matrix, 192 x 168; slice thickness, 6 mm; bandwidth, 930 Hz/pixel; image acquisition time, 15 s for a single slice acquired over 20 phases of the cardiac R-R interval) and electrocardiography-triggered, flow-sensitive, phase-contrast sequences (TR, 62 ms; TE, 3.5 ms; flip angle, 30°; FOV, 320 x 220 mm2; matrix, 192 x 132; bandwidth, 555 Hz/pixel; acquisition time, 1 min 52 s; velocity encoding value, 100 cm/s), TAVI was performed using rtMRI fluoroscopy based on a commercially available interactive real-time projection reconstruction TrueFISP sequence with radial k-space filling during free breathing and without cardiac triggering that was modified to achieve a frame rate of 7 frames per second (TR, 3.0 ms; TE, 1.5 ms; flip angle, 70°; FOV, 360 x 360 mm2; matrix, 192 x 192; bandwidth, 1530 Hz/pixel; slice thickness, 6 mm). Images were displayed without delay inside the scanner room and could be adapted interactively according to the operator’s (P.K.) needs while the sequence was running. After TAVI, real-time TrueFISP, cine-TrueFISP retro, and flow-sensitive phase-contrast sequences were used to verify procedural success. Autopsies were performed to validate MRI findings.
Three-point localizer sequences allowed for rapid detection (11 ± 3 min) of all scan planes required for preinterventional evaluation, procedural guidance, and post-procedural validation. High-resolution TrueFISP retro sequences enabled detailed visualization of all procedurally relevant anatomic landmarks and allowed precise measurements (aortic annulus diameter in long axis, 17 ± 3 mm; aortic arch diameter, 21 ± 4 mm; distance from aortic annulus to left and right coronary ostium, 9 ± 3 and 10 ± 2 mm; access vessel diameter, 6.9 ± 1.2 mm) in good accordance with measurements on previous angiographic images (mean error, 0.4 ± 0.3 mm; p = NS) and during autopsy (mean error, 0.5 ± 0.2 mm; p = NS).
Passive device visualization using real-time TrueFISP sequences provided reliable imaging guidance during TAVI superior to fluoroscopy. Mild susceptibility artifacts confined to the loaded stent valve enabled adequate determination of the position of stent valve and delivery system in relation to the surrounding anatomy without undue image distortion, allowing a precise, real-time anatomic orientation during device navigation through the vasculature, aortic valve passage, positioning and deployment of the prosthesis, and catheter withdrawal.
In 6 of 8 animals, an oversized 26-mm CoreValve prosthesis was successfully placed across the aortic annulus without dislocation, coronary artery obstruction, or impairment of the mitral valve, as confirmed by autopsy (rtMRI acquisition time, 4 ± 2 min) (Fig. 1). However, 2 implant failures occurred. The first was a result of unsuccessful aortic arch passage due to insufficient support by the initially used MRI-compatible, soft polymer guidewire and led to a controlled deployment of the stent valve in the thoracic aorta, which is sometimes required in clinical application when the prosthesis dislocates into the ascending aorta during deployment. As a consequence, we continued our experiments without guidewire support and focused on the straighter transsubclavian access route. The second implant failure occurred due to perforation of the left ventricular apex caused by the delivery device, which was inadvertently pushed with too much force, this complication being immediately detected by rtMRI. Both cases indicate that rtMRI might improve both precision and safety of the TAVI procedure.
Postprocedural TrueFISP retro sequences allowed precise structural evaluation of the procedural result in good accordance with autopsy findings. Flow-sensitive, electrocardiography-triggered, phase-contrast sequences with imaging planes placed approximately 1 cm below and above the nitinol stent frame confirmed good systolic transvalvular blood flow without diastolic regurgitation. The current study demonstrates the preclinical feasibility of entirely MRI-guided TAVI. As a single imaging modality, MRI offered comprehensive diagnostic evaluation of the relevant cardiac and vascular anatomy for adequate interventional planning, real-time procedural guidance with excellent anatomic orientation, immediate evaluation of procedure-related complications, and post-interventional validation of treatment success with a total procedure time of 61 ± 13 min. Complementary to reduction of radiation exposure and nephrotoxic contrast media, rtMRI guidance, therefore, provides clinically relevant advantages over conventional X-ray-fluoroscopy and warrants further attention. These advantages should encourage future efforts to translate rtMRI-guided TAVI into clinical application using commercial but modified or entirely novel devices (2,3) and to overcome remaining obstacles such as the development of suitable, MRI-compatible guidewires.
PMID: 22222083
Multicenter Assessment of the Reproducibility of Volumetric Radiofrequency-Based Intravascular Ultrasound Measurements in Coronary Lesions that Were Consecutively Stented
OBJECTIVES: To assess in a multicenter design the between-center reproducibility of volumetric virtual histology intravascular ultrasound (VH-IVUS) measurements with a semi-automated, computer-assisted contour detection system in coronary lesions that were consecutively stented.
METHODS: 4 European IVUS centers performed independent analyses (in total 8,052 cross-sectional analyses) to obtain volumetric data of 40 coronarysegments (length 20.0 ± 0.3 mm) from target lesions prior to percutaneous intervention that were performed in the setting of stable (65%) or unstable angina pectoris (35%).
RESULTS: Geometric and compositional VH-IVUS measurements were highly correlated for the different comparisons. Overall intraclass correlation for vessel, lumen, plaque volume and plaque burden was 0.99, 0.92, 0.96, and 0.83, respectively; for fibrous, fibro-lipidic, necrotic core and calcified volumes overall intraclass correlation was 0.96, 0.94, 0.98, and 0.99, respectively. Nevertheless, significant differences for both geometrical and compositional measurements were seen. Of the plaque components, fibrous tissue and necrotic core showed on average the highest measurement reproducibility.
CONCLUSIONS: A central analysis for VH-IVUS multicenter studies of lesions prior to PCI should be pursued. Moreover, it may be problematical to pool VH-IVUS data of individual trials analyzed by independent centers.
PMID: 22246064
Natural History of Stent Edge Dissection, Tissue Protrusion and Incomplete Stent Apposition Detectable Only on Optical Coherence Tomography After Stent Implantation
OBJECTIVES: The clinical impact of stent edge dissection, tissue protrusion, and incomplete stent apposition (ISA) after stent implantation, detectable only on optical coherence tomography (OCT), is still unknown because the natural course has not been investigated.
METHODS: All consecutive patients with angina pectoris in whom both intravascular ultrasound (IVUS) and OCT were performed immediately after stenting and at follow-up were included in the present study. The natural history of OCT-detected stent edge dissection, tissue protrusion, and ISA during follow-up was investigated.
RESULTS: A total of 36 patients with 39 lesions was analyzed. At baseline, OCT showed 12 stent edge dissections, 25 tissue protrusions, and 8 ISAs, whereas IVUS demonstrated 6 stent edge dissections, 5 tissue protrusions, and 3 ISAs. All IVUS findings were clearly visualized on OCT. The maximum length of dissection flap and depth of ISA visualized on OCT were significantly shorter than those visualized on IVUS. Maximum length of tissue protrusion tended to be smaller on OCT than on IVUS. At follow-up (median 188 days), all findings noted on OCT were healed or resolved without any restenosis or thrombus formation.
CONCLUSIONS: Acute findings after stenting, such as edge dissection, tissue protrusion, and ISA, detectable only on OCT, tended to be smaller than those seen on both OCT and IVUS. The majority of OCT-detected acute findings resolved completely at follow-up.
PMID: 22251751
Long-Term Follow-Up After Fractional Flow Reserve-Guided Treatment Strategy in Patients With an Isolated Proximal Left Anterior Descending Coronary Artery Stenosis
OBJECTIVES: This study sought to evaluate the long-term clinical outcome of patients with an angiographically intermediate left anterior descending coronary artery (LAD) stenosis in whom the revascularization strategy was based on fractional flow reserve (FFR). When revascularization is based mainly on angiographic guidance, a number of hemodynamically nonsignificant stenoses will be revascularized.
METHODS: In 730 patients with a 30% to 70% isolated stenosis in the proximal LAD and no significant valvular disease, FFR measurements were obtained to guide treatment strategy. When FFR was ≥ 0.80, the patients (n = 564) were treated medically (medical group); when FFR was <0.80, the patients (n = 166) underwent a revascularization procedure (revascularization group; 13% coronary artery bypass graft surgery and 87% percutaneous coronary intervention). A 100% long-term clinical follow-up (median follow-up: 40 months) was obtained. The 5-year survival of the medical group was compared with that of a reference population. For each patient, 4 controls were selected from an age- and sex-matched control population.
RESULTS: The 5-year survival estimate was 92.9% in the medical group versus 89.6% in the controls (p = 0.74). The mean diameter stenosis was significantly smaller in the medical than in the revascularization group (39 ± 14% vs. 54 ± 13%, p < 0.0001), but there was a large overlap between both groups. The 5-year event-free survival estimates (death, myocardial infarction, and target vessel revascularization) were 89.7% and 68.5%, respectively (p < 0.0001).
CONCLUSIONS: Medical treatment of patients with a hemodynamically nonsignificant stenosis (FFR ≥ 0.80) in the proximal LAD is associated with an excellent long-term clinical outcome with survival at 5 years similar to an age- and sex-matched control population.
PMID: 22035875
