Incremental prognostic value of coronary CT angiography in patients with suspected coronary artery disease.

BACKGROUND: Multidetector CT coronary angiography (MDCTCA) is capable of detecting coronary artery disease (CAD) with a high diagnostic accuracy. In particular, this technique is credited with having a negative predictive value close to 100%. However, data about the prognostic value of MDCTCA are currently lacking. We sought to determine the prognostic value of MDCTCA in patients with suspected but undocumented CAD and, in particular, the incremental prognostic value as compared with clinical risk and calcium scoring.

METHODS AND RESULTS: A total of 441 patients (age, 59.7+/-11.6 years) with suspected CAD underwent MDCTCA to evaluate the presence and severity of the disease. Patients were followed up as to the occurrence of hard cardiac events (cardiac death, nonfatal myocardial infarction, and unstable angina requiring hospitalization). Coronary lesions were detected in 297 (67.3%) patients. During a mean follow-up of 31.9+/-14.8 months, 44 hard cardiac events occurred in 40 patients. CT calcium scoring showed a statistically significant incremental prognostic value as compared to a baseline clinical risk model (P=0.018), whereas MDCTCA provided an additional incremental prognostic value as compared with a baseline clinical risk model plus calcium scoring if considering both nonobstructive versus obstructive CAD (P=0.016) or, better, plaque composition (calcified versus noncalcified and/or mixed plaques, P=0.0001). During follow-up, an excellent prognosis was noted in patients with normal coronary arteries, with an annualized incidence rate of 0.88% if compared with those with mild CAD (3.89%) and with patients with significant coronary disease (8.09%). The presence of noncalcified or mixed plaques, regardless of lesion severity, was found to be the strongest predictor of events (P<0.0001) as a potential marker of plaque vulnerability.

CONCLUSIONS: MDCTCA provides independent and incremental prognostic information as compared to baseline clinical risk factors and calcium scoring in patients with suspected CAD.

PMID: 20460497

Remodeling of Carotid Arteries Detected with MR Imaging: Atherosclerosis Risk in Communities Carotid MRI Study

OBJECTIVES: To determine the extent of thickening of the carotid arterial walls that may be accommodated by outward remodeling.

METHODS: Institutional review board approval was obtained at each participating site, and informed consent was obtained from each participant. All study sites conducted this study in compliance with HIPAA requirements. A total of 2066 participants (age range, 60-85 years) from the Atherosclerosis Risk in Communities (ARIC) study were enrolled in the ARIC Carotid MRI Study. Maximum wall thickness and luminal area were measured with gadolinium-enhanced magnetic resonance (MR) imaging in both common carotid arteries (CCAs) and in one internal carotid artery (ICA) 2 mm above the flow divider. Complete data were available for 1064 ICAs and 3348 CCAs. The association of maximum wall thickness with lumen area was evaluated with linear regression, and adjustments were made for participant age, sex, race, height, and height squared.

RESULTS: In the ICA, lumen area was relatively constant across patients with a wall thickness of 1.38 mm or less. In patients with a wall thickness of more than 1.38 mm, however, lumen area decreased linearly as wall thickness increased. Wall area represented a median of 61.9% of the area circumscribed by the vessel at a maximum wall thickness of 1.50 mm +/- 0.05 (standard deviation) and 75.4% at a maximum wall thickness of 4.0 mm +/- 0.10. In the CCA, lumen area was preserved across wall thicknesses less than 2.06 mm, representing 99% of vessels.

CONCLUSIONS: Atherosclerotic thickening in the ICA appears to be accommodated for vessels with a maximum wall thickness of less than 1.5 mm. Beyond this threshold, greater thickness is associated with a smaller lumen. The CCA appears to accommodate a wall thickness of less than 2.0 mm. These estimates indicate that the carotid arteries are able to compensate for a greater degree of thickening than are the coronary arteries.

PMID: 20651061

Minimally-Invasive Valve Surgery: STATE-OF-THE-ART PAPER

Minimally-invasive approaches have become increasingly important in cardiac valve surgery. Smaller incisions have become commonplace in many major centers. We reviewed the existing literature and present the current state-of-the-art of minimally-invasive valve operations in this paper.

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Cardiac Computed Tomography and Myocardial Perfusion Scintigraphy for Risk Stratification in Asymptomatic Individuals Without Known Cardiovascular Disease: A Position Statement of The Working Group on Nuclear Cardiology and Cardiac CT of the European Society of Cardiology

OBJECTIVES: Cardiovascular events remain one of the most frequent causes of mortality and morbidity worldwide. The majority of cardiac events occur in individuals without known coronary artery disease (CAD) and in low- to intermediate-risk subjects. Thus, the development of improved preventive strategies may substantially benefit from the identification, among apparently intermediate-risk subjects, of those who have a high probability for developing future cardiac events. Cardiac computed tomography and myocardial perfusion scintigraphy (MPS) by single photon emission computed tomography may play a role in this setting. In fact, absence of coronary calcium in cardiac computed tomography and inducible ischaemia in MPS are associated with a very low rate of major cardiac events in the next 3–5 years.

METHODS: Based on current evidence, the evaluation of coronary calcium in primary prevention subjects should be considered in patients classified as intermediate-risk based on traditional risk factors, since high calcium scores identify subjects at high-risk who may benefit from aggressive secondary prevention strategies. In addition, calcium scoring should be considered for asymptomatic type 2 diabetic patients without known CAD to select those in whom further functional testing by MPS or other stress imaging techniques may be considered to identify patients with significant inducible ischaemia.

RESULTS: From available data, the use of MPS as first line testing modality for risk stratification is not recommended in any category of primary prevention subjects with the possible exception of first-degree relatives of patients with premature CAD in whom MPS may be considered.

CONCLUCIONS: However, the Working Group recognizes that neither the use of computed tomography for calcium imaging nor of MPS have been proven to significantly improve clinical outcomes of primary prevention subjects in prospective controlled studies. This information would be crucial to adequately define the role of imaging approaches in cardiovascular preventive strategies.

PMID: 20630895

Small Coronary Calcifications Are Not Detectable by 64-Slice Contrast Enhanced Computed Tomography

OBJECTIVES: Recently, small calcifications have been associated with unstable plaques. Plaque calcifications are both in intravascular ultrasound (IVUS) and multi-slice computed tomography (MSCT) easily recognized. However, smaller calcifications might be missed on MSCT due to its lower resolution.

METHODS: Because it is unknown to which extent calcifications can be detected with MSCT, we compared calcification detection on contrast enhanced MSCT with IVUS. The coronary arteries of patients with myocardial infarction or unstable angina were imaged by 64-slice MSCT angiography and IVUS. The IVUS and MSCT images were registered and the arteries were inspected on the presence of calcifications on both modalities independently. We measured the length and the maximum circumferential angle of each calcification on IVUS.

RESULTS: In 31 arteries, we found 99 calcifications on IVUS, of which only 47 were also detected on MSCT. The calcifications missed on MSCT (n = 52) were significantly smaller in angle (27° ± 16° vs. 59° ± 31°) and length (1.4 ± 0.8 vs. 3.7 ± 2.2 mm) than those detected on MSCT. Calcifications could only be detected reliably on MSCT if they were larger than 2.1 mm in length or 36° in angle.

CONCLUSIONS: Half of the calcifications seen on the IVUS images cannot be detected on contrast enhanced 64-slice MSCT angiography images because of their size. The limited resolution of MSCT is the main reason for missing small calcifications.

PMID: 20602171

Serial Coronary CT Angiography-Verified Changes in Plaque Characteristics as an End Point: Evaluation of Effect of Statin Intervention

OBJECTIVES: This study sought to assess, by serial computed tomography angiography (CTA), the effect of statin treatment on coronary plaque morphology. In addition to the assessment of luminal stenosis, CTA also allows characterization of plaque morphology. Large, positively remodeled plaques with large necrotic cores have been reported as indicators of plaque instability.

METHODS: CTA was performed in 32 patients (26 men, ages 64.3 ± 8.5 years). Of these, 24 received fluvastatin after the baseline study; 8 subjects who refused statin treatment were followed as the control subjects. Serial imaging was performed after a median interval of 12 months. All vessels were examined in every subject, and a 10-mm-long segment was identified for comparison before and after intervention. Total plaque volume, low attenuation plaque (LAP) volume, lumen volume, and remodeling index were calculated.

RESULTS: In the statin-treated patients, the total plaque volume (92.3 ± 37.7 vs. 76.4 ± 26.5 mm³, p < 0.01) and LAP volume (4.9 ± 7.8 vs. 1.3 ± 2.3 mm³, p = 0.01) were significantly reduced over time; however, there was no change in the lumen volume (63.9 ± 25.3 vs. 65.2 ± 26.2 mm³, p = 0.59). On the other hand, no change was observed in the CTA characteristics in the control subjects, including total plaque volume (94.4 ± 21.2 vs. 98.4 ± 28.6 mm³, p = 0.48), LAP volume (2.1 ± 3.0 vs. 2.3 ± 3.6 mm³, p = 0.91), and lumen volume (80.5 ± 20.7 vs. 75.0 ± 16.3 mm³, p = 0.26). The plaque volume change (–15.9 ± 22.2 vs. 4.0 ± 14.0 mm³, p = 0.01) and LAP volume change (–3.7 ± 7.0 vs. 0.2 ± 1.5 mm³, p < 0.01) were significantly greater in the statin than the control group. The lumen volume (1.3 ± 15.6 vs. –5.5 ± 13.1 mm³, p = 0.24) and remodeling index (–2.4 ± 6.8% vs. –0.3 ± 6.5%, p = 0.53) did not show the significant differences between the 2 groups. The decrease in the plaque volume was due to reduction in the LAP volume (R = 0.83, p < 0.01), and was not related to any changes in the lumen volume (R = 0.21, p = 0.24).

CONCLUSIIONS: This preliminary study suggests that serial CTA evaluation of coronary plaques allows for the assessment of interval change in the plaque morphology. Statin treatment results in decreases in the plaque and necrotic core volume. The features known to be associated with plaque instability.

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Accuracy of Dual-Source Computed Tomography to Identify Significant Coronary Artery Disease in Patients With Atrial Fibrillation: Comparison With Coronary Angiography

OBJECTIVES: It has been previously reported that the sensitivity and specificity of multislice computed tomography (CT) for detecting significant coronary artery disease (CAD) is high. However, regular sinus rhythm has been considered a prerequisite for an adequate examination, even though atrial fibrillation (AF) is common among patients evaluated for the presence of coronary heart disease. In this study, we investigated the sensitivity and specificity of dual-source CT (DSCT) to detect and rule out significant coronary stenoses in patients with AF referred for invasive coronary angiography.

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Cumulative Exposure to Ionizing Radiation from Diagnostic and Therapeutic Cardiac Imaging Procedures: A Population-Based Analysis

OBJECTIVES: The purpose of this study was to describe radiation exposure from cardiac imaging procedures over time in a general population. Cardiac imaging procedures frequently expose patients to ionizing radiation, but their contribution to effective doses of radiation in the general population is unknown.

METHODS: We used administrative claims to identify cardiac imaging procedures performed from 2005 to 2007 in 952,420 nonelderly insured adults in 5 U.S. health care markets. We estimated 3-year cumulative effective doses of radiation in millisieverts from these procedures We then calculated population-based annual rates of radiation exposure to effective doses 3 mSv/year (background level ofradiation from natural sources), >3 to 20 mSv/year, or >20 mSv/year (upper annual limit for occupational exposure averaged over 5 years).

RESULTS: A total of 90,121 (9.5%) individuals underwent at least 1 cardiac imaging procedure using radiation. Among patients who underwent 1 cardiac imaging procedures, the mean cumulative effective dose over 3 years was 16.4 mSv (range 1.5 to 189.5 mSv). Myocardial perfusion imaging accounted for 74% of the cumulative effective dose. Overall, 47.8% of cardiac imaging procedures were performed in physician offices; this proportion was higher for myocardial perfusion imaging (74.8%) and cardiac computed tomography studies (76.5%). The annual population-based rate of receiving an effective dose of >3 to 20 mSv/year was 89.0 per 1,000; and 3.3 per 1,000 for cumulative doses >20 mSv/year. Annual effective doses increased with age and were generally higher among men.

CONCLUSIONS: Cardiac imaging procedures lead to substantial radiation exposure and effective doses for many patients in the U.S.

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Safety and Efficacy of the Subclavian Approach for Transcatheter Aortic Valve Implantation With the CoreValve Revalving System

OBJECTIVES: Transcatheter aortic valve implantation (TAVI) is a new option for patients with severe aortic stenosis at high surgical risk. The standard retrograde approach through the femoral artery is contraindicated in case of unfavorable iliofemoral anatomy or extensive disease. In these patients, a trans-subclavian approach may be feasible.

METHODS: Between June 2007 and July 2009, TAVI with the CoreValve bioprosthesis (Medtronic, Minneapolis, Minn) was performed in 514 consecutive patients at 13 Italian hospitals, using the subclavian approach in 54 cases.

RESULTS: The median logistic EuroSCORE was significantly higher in the subclavian (19.4; interquartile range, 12.5 to 29.8) versus femoral group (25.3; interquartile range, 15.1 to 36.6) (P=0.03), as well as the rate of comorbidities. Procedural success was obtained in 100% versus 98.4% of the subclavian versus femoral groups, respectively (P=0.62), with intraprocedural mortality of 0% versus 0.9% (P=1.00). The most common in-hospital complications were a new left bundle-branch block (22.4%) and the need for pacemaker (16.3%). No specific complications for the subclavian access (vessel rupture, vertebral or internal mammary ischemia) were reported. The learning curve for the subclavian approach led to a wider use of local anesthesia. Thirty-day mortality was 0% versus 6.1% in the subclavian versus femoral groups, respectively (P=0.13). Six-month mortality rate was 9.4% versus 15.8% (P=0.44), whereas valve-related adverse events were 13.6% versus 13.9% (P=0.79). \

CONCLUSIONS: TAVI through the subclavian approach appeared feasible and safe, with excellent procedural success and low in-hospital complication rates. This new technique allows patients with contraindications to the femoral approach to be treated with TAVI.

PMID: 20606135

Dual-Step Prospective ECG-Triggered 128-Slice Dual-Source CT for Evaluation of Coronary Arteries and Cardiac Function Without Heart Rate Control: A Technical Note

PMID: 20407896

Influence of Slice Thickness and Reconstruction Kernel on the Computed Tomographic Attenuation of Coronary Atherosclerotic Plaque

OBJECTIVE: The computed tomographic (CT) attenuation of coronary atherosclerotic plaque has been proposed as a marker for tissue characterization and may thus potentially contribute to the assessment of plaque instability.We analyzed the influence of reconstruction parameters on CT attenuation measured within noncalcified coronary atherosclerotic lesions.

METHODS: Seventy-two patients were studied by contrast-enhanced dual-source CT coronary angiography (330 millisecond rotation time, 2 x 64 x 0.6 mm collimation, 120 kV, 400 mAs, 80 mL contrast agent intravenously at 6 mL/s), and a total of 100 distinct noncalcified coronary atherosclerotic plaques were identified. Image data sets were reconstructed with a soft (B20f), medium soft (B26f), and sharp (B46f) reconstruction kernel. With the medium soft kernel, image data sets were reconstructed with a slice thickness/increment of 0.6/0.3 mm, 0.75/0.4 mm, and 1.0/0.5mm. Within each plaque, CT attenuation was measured.

RESULTS: Mean CT attenuation using the medium soft kernel was 109 +/- 58 HU (range, -16 to 168 HU). Using the soft kernel, mean density was 113 +/- 57 HU (range, -13 to 169 HU), and using a sharp kernel, mean density was 97 +/- 49 HU (range, -23 to 131 HU). Similarly, reconstructed slice thickness had a significant influence on the measured CT attenuation (mean values for medium soft kernel: 102 +/- 52 HU versus 109 +/- 58 HU versus 113 +/- 57 HU for 0.6-mm, 0.75-mm, and 1.0-mm slice thickness). The differences between 0.75-mm and 0.6-mm slice thickness (P = 0.05) and between medium sharp and sharp kernels (P = 0.02) were statistically significant.

CONCLUSIONS: Image reconstruction significantly influences CT attenuation of noncalcified coronary atherosclerotic plaque. With decreasing spatial resolution (softer kernel or thicker slices), CT attenuation increases significantly. Using absolute CT attenuation values for plaque characterization may therefore be problematic.

PMID: 20430341

Aortic Annulus Evaluation in Transcatheter Aortic Valve Implantation

OBJECTIVES: We compared the annulus diameters measured by transthoracic echocardiography (TTE), transesophageal echocardiography (TEE) and dual-source computed tomography (DSCT) prior to transcatheter aortic valve implantation (TAVI). In TAVI correct evaluation of the aortic annulus is mandatory in order to choose the correct prosthesis type and size and to prevent complications. There is no gold standard for the assessment of aortic annulus diameters.

METHODS: Preoperative assessment of the aortic annulus with TTE, TEE and DSCT was performed in 187 consecutive patients referred for TAVI between 06/2007 and 05/2009.

RESULTS: The mean aortic annuli were 22.6+/-2.0mm measured with DSCT, 22.3+/-2.5mm with TTE and 22.9+/-2.2mm with TEE. Despite a strong correlation between the measurement techniques relevant statistical spread occurred with differences up to 3mm in all measurement methods. Inter- and intra-observer variability was good for TEE and less satisfactory for DSCT measurements. TEE measurements taken as decisive parameter for the implantation changed the implantation strategy in 15,5% of patients and did not show an increased rate of procedural complications.

CONCLUSION: Despite a strong correlation, the measurement techniques for the aortic annulus show relevant statistical spread, consequently one measurement technique cannot definitely predict another. TEE measurements show a more satisfactory intra- and inter-observer variability than DSCT. Taking TEE annulus measurements as decisive parameter for the implantation has an impact on the implantation strategy and is safe with a low rate of procedural complications.

PMID: 20518012

Prognostic Value of Absence or Presence of Coronary Artery Disease Determined by 64-Slice Computed Tomography Coronary Angiography: A Systematic Review and Meta-Analysis

OBJECTIVES: To determine via a meta-analysis the prognostic value of 64-slice computed tomography angiography (CTA) by quantifying risk of major adverse cardiac events (MACE) in different patient groups classified according to CT angiographic findings.

METHODS: A systematic literature search and meta-analyses was conducted on 10 studies examining stable, symptomatic and intermediate risk patients by 64-slice CTA. Patients were followed up for a mean of 21 month. Patient groups with CT-angiographic non-obstructive (stenosis <50% of luminal narrowing) or obstructive (stenosis >50% of luminal narrowing) CAD were compared to those having normal angiography without CAD. MACE (cardiac death, non-fatal myocardial infarction and revascularization) numbers were used to calculate odds ratios (OR) with 95% confidence interval (CI) in each group.

RESULTS: Ten studies including 5,675 patients were eligible for meta-analysis. The cumulative MACE rate over 21 months were 0.5% in patients with normal CTA, 3.5% in non-obstructive CAD and 16% in obstructive CAD. Compared to normal CTA, non-obstructive CAD was associated with significant increased risk of MACE with OR = 6.68 (3.01-14.82 CI 95%), P = 0.0001. Obstructive CAD was associated with further significant increased risk of MACE with OR = 41.19 (22.56-75.18, CI 95%), P = 0.0001. The studies were homogenous, P-value >0.05 for heterogeneity.

CONCLUSIONS: 64-slice CTA is able to differentiate low-risk from high-risk patients with suspected or known CAD. Absence of CAD predicts excellent prognosis, while obstructive CAD is associated with markedly increased risk of MACE.

PMID: 20549366

Determination of Infarct Size and Transmurality by Contrast-Enhanced 3D-Echocardiography

OBJECTIVES: Myocardial infarct scars are usually imaged using delayed-enhanced cardiac magnetic resonance (DE-cMR). In this study, we tested the hypothesis that the detection and the quantification of myocardial scars can be evaluated by 3D-Echo.

METHODS: Fifty patients with a healed myocardial infarction (>3 months) and 10 controls underwent 3D-Echo and DE-cMR within 2 weeks. 3D-Echo images were acquired using different settings, in the presence or absence of contrast.

RESULTS: The highest contrast-to-noise ratio was obtained using second harmonic imaging (1.6/3.2 MHz), at an MI of 0.5, in the presence of contrast. Using this modality, the sensitivity and specificity for the 3D-Echo detection of cMR scars on a segmental basis were 78% and 99%, respectively. On a per patient basis, they were of 96% and 90%, respectively. Good correlation and limits of agreement were found between the assessment of scar mass by 3D-Echo and DE-cMR (r=0.93, p<0.001, bias: 1.4±3.6g), and the concordance between both techniques for the assessment of scar transmurality was good. Intraobserver, interobserver and day-to-day reproducibility was comparable between 3D-Echo and DE-cMR for both the detection and the quantification of scars.

CONCLUSIONS: Contrast-enhanced 3D-Echo is a promising new tool for the detection and the quantification of myocardial infarct scars.

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Dyssynchrony By Speckle-Tracking Echocardiography and Response to Cardiac Resynchronization Therapy: Results of the Speckle Tracking and Resynchronization (STAR) Study

OBJECTIVES: The Speckle Tracking and Resynchronization (STAR) study used a prospective multi-centre design to test the hypothesis that speckle-tracking echocardiography can predict response to cardiac resynchronization therapy (CRT).

METHODS: We studied 132 consecutive CRT patients with class III and IV heart failure, ejection fraction (EF) ≤35%, and QRS ≥120 ms from three international centres. Baseline dyssynchrony was evaluated by four speckle tracking strain methods; radial, circumferential, transverse, and longitudinal (≥130 ms opposing wall delay for each). Pre-specified outcome variables were EF response and three serious long-term events: death, transplant, or left ventricular assist device.

RESULTS: Of 120 patients (91%) with baseline dyssynchrony data, both short-axis radial strain and transverse strain from apical views were associated with favourable EF response 7 ± 4 months and long-term outcome over 3.5 years (P < 0.01). Radial strain had the highest sensitivity at 86% for predicting EF response with a specificity of 67%. Serious long-term unfavourable events occurred in 20 patients after CRT, and happened three times more frequently in those who lacked baseline radial or transverse dyssynchrony than in patients with dyssynchrony (P < 0.01). Patients who lacked both radial and transverse dyssynchrony had unfavourable clinical events occur in 53%, in contrast to events occurring in 12% if baseline dyssynchrony was present (P < 0.01). Circumferential and longitudinal strains predicted response when dyssynchrony was detected, but failed to identify dyssynchrony in one-third of patients who responded to CRT.

CONCLUSIONS: Dyssynchrony by speckle-tracking echocardiography using radial and transverse strains is associated with EF response and long-term outcome following CRT.

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