Iterative Reconstruction of Dual-Source Coronary CT Angiography: Assessment of Image Quality and Radiation Dose

OBJECTIVES: To assess the image quality and radiation dose of low-dose dual-source CT (DSCT) coronary angiography reconstructed using iterativereconstruction in image space (IRIS), in comparison with routine-dose CT using filtered back projection (FBP).

METHODS: Eighty-one patients underwent low-dose coronary DSCT using IRIS with two protocols: (a)100 kVp and 200 mAs per rotation for body mass index (BMI) < 25 (group I), (b)100 kVp and 320 mAs for BMI ≥ 25 (II). For comparison, two sex-and BMI-matched groups using standard protocols with FBP were selected: (a)100 kVp and 320 mAs for BMI < 25 (III), (b)120 kVp and 320 mAs for BMI ≥ 25 (IV). Image noise, signal to noise ratio (SNR) and modulation transfer function (MTF) 50% were objectively calculated. Two blinded readers then subjectively graded the image quality. Radiation dose was also measured.

RESULTS: Image noise tended to be lower in IRIS of low-dose protocols: 22.0 ± 4.5 for group I versus 24.8 ± 4.0 for III (P < 0.001); 20.9 ± 4.5 for II versus 21.6 ± 4.9 for IV (P = 0.6). SNR was better with IRIS: 25.8 ± 4.4 for I versus 22.7 ± 4.6 for III (P < 0.001); 24.6 ± 5.4 for II versus 18.7 ± 4.5 for IV (P < 0.001). No differences in MTF 50% or image quality scores were seen between each two groups (P > 0.05). Radiation reduction was 40% for I and 51% for II, compared to standard protocols.

CONCLUSIONS: Compared with routine-dose CT using FBP, low-dose coronary angiography using IRIS provides significant radiation reduction without impairment to image quality.

PMID: 22187198

A High-Risk Period for Cerebrovascular Events Exists After Transcatheter Aortic Valve Implantation

OBJECTIVES: This study assesses if there exists a high-risk period for cerebrovascular events (CeV) after transcatheter aortic valve implantation (TAVI). Even though acute strokes after TAVI have been described, it is uncertain if stroke rates continue to remain high in the early months after TAVI. Furthermore, the optimal dose and duration of thromboprophylaxis is unclear.

METHODS: Patients who underwent TAVI were evaluated at baseline, at discharge, at 1 and 6 months, and yearly. Risk factors for CeV events, procedural details, and antithrombotic therapy were recorded. Outcomes assessed were CeV events and death. The timing of such events, predictors, and impact on survival were analyzed.

RESULTS: A total of 253 patients were assessed. Median age was 85 years. The median Society of Thoracic Surgeons score was 8.1% (interquartile range [IQR]: 5.5% to 12.0%). Risk factors included smoking (47%), hypertension (70%), dyslipidemia (66%), and diabetes mellitus (25%). Twenty-three percent had known cerebrovascular disease and 39% had atrial fibrillation. Median follow-up was 455 days (IQR: 160 to 912 days) at which time 23 patients experienced a CeV event. The incidence was highest in the first 24 h but remained high for 2 months. In-hospital mortality rate after a CeV event was 21%. A prior history of CeV disease was an independent predictor of an event (hazard ratio: 4.23, 95% CI: 1.60 to 11.11, p = 0.004).

CONCLUSIONS: The incidence of CeV events is highest within 24 h of TAVI, but this risk may remain elevated for up to 2 months. A prior history of cerebrovascular disease is an independent predictor. This may have implications for patient selection and antithrombotic strategies.

PMID: 22192370

Anomalous Origin of the Right Coronary Artery from the Left Coronary Sinus With an Interarterial Course: Subtypes and Clinical Importance

OBJECTIVES: To classify anomalous origins of the right coronary artery (RCA) from the left coronary sinus (AORL) with an interarterial course into two subtypes and to evaluate the clinical importance of each.

METHODS: Institutional review board approval was obtained for this retrospective study, and informed consent was waived. Through a retrospective review of 22 925 consecutive cardiac computed tomographic (CT) scans, 124 cases of AORL with an interarterial course were identified. These anomalies were classified into two subtypes according to the location of the anomalous RCA ostium: high interarterial course (between the aorta and the pulmonary artery) and low interarterial course (between the aorta and the right ventricular outflow tract). The clinical records were evaluated, and differences in prevalence of typical angina and major adverse cardiac events (MACEs) between the subtypes were analyzed through the χ(2) contingency tables or Fisher exact test.

RESULTS: After excluding patients with combined cardiac disease, 87 patients (51 [59%] men, 36 [41%] women; mean age, 56.0 years) were enrolled. Of the 87 patients, 53 had a high interarterial course and 34 had a low interarterial course. A significant difference in the prevalence of typical angina (high [43%] vs low [6%], P = .001) and MACE (high [28%] vs low [6%], P = .012) was observed between the two subtypes. For patients with a high interarterial course, the odds ratio for typical angina was 12.3 (95% confidence interval: 2.7, 56.6), and the odds ratio for MACE was 6.3 (95% confidence interval: 1.3, 29.7).

CONCLUSIONS: The prevalence of typical angina and that of MACE were significantly higher in patients with a high interarterial course than in those with a low interarterial course.

PMID: 22056684

Age-and Gender-Specific Differences in the Prognostic Value of CT Coronary Angiography

OBJECTIVES: To evaluate the potential age- and gender-specific differences in the incidence and prognostic value of coronary artery disease (CAD) in patients undergoing CT coronary angiography (CTA).

METHODS: In this multicentre prospective registry study, 2432 patients (mean age 57±12, 56% male) underwent CTA for suspected CAD. Patients were stratified into four groups according to age <60 or ≥60 years and, male or female gender.Main outcome measuresA composite end point of cardiac death and non-fatal myocardial infarction.

RESULTS: CTA results were normal in 991 (41%) patients, showed non-significant CAD in 761 (31%) patients and significant CAD in the remaining 680 (28%) patients. During follow-up (median 819 days, 25-75th centile 482-1142) a cardiovascular event occurred in 59 (2.4%) patients. The annualised event rate was 1.1% in the total population (men=1.3% and women=0.9%). In patients aged <60 years, the annualised event rate of male and female patients was 0.6% and 0.5%, respectively. Among patients aged ≥60 years the annualised event rate was 1.9% in male and 1.1% in female patients. Observations on CTA predicted events in male patients, both age <60 and ≥60 years and in female patients age ≥60 years (log-rank test in all groups, p<0.01). However, CTA provided limited prognostic value in female patients aged <60 years (log-rank test, p=0.45).

CONCLUSIONS: After age and gender stratification, CTA findings were shown to be of limited predictive value in female patients aged <60 years as compared with male patients at any age and female patients aged ≥60 years.

PMID: 21917657

Cardiovascular Magnetic Resonance and Single-Photon Emission Computed Tomography for Diagnosis of Coronary Heart Disease (CE-MARC): A Prospective Trial

PMID:

CT for Evaluation of Myocardial Cell Therapy in Heart Failure A Comparison With CMR Imaging

OBJECTIVES: The aim of this study was to use multidetector computed tomography (MDCT) to assess therapeutic effects of myocardial regenerative cell therapies. Cell transplantation is being widely investigated as a potential therapy in heart failure. Noninvasive imaging techniques are frequently used to investigate therapeutic effects of cell therapies in the preclinical and clinical settings. Previous studies have shown that cardiac MDCT can accurately quantify myocardial scar tissue and determine left ventricular (LV) volumes and ejection fraction (LVEF).

METHODS: Twenty-two minipigs were randomized to intramyocardial injection of phosphate-buffered saline (placebo, n = 9) or 200 million mesenchymal stem cells (MSC, n = 13) 12 weeks after myocardial infarction (MI). Cardiac magnetic resonance and MDCT acquisitions were performed before randomization (12 weeks after MI induction) and at the study endpoint 24 weeks after MI induction. None of the animals received medication to control the intrinsic heart rate during first-pass acquisitions for assessment of LV volumes and LVEF. Delayed-enhancement MDCT imaging was performed 10 min after contrast delivery. Two blinded observers analyzed MDCT acquisitions.

RESULTS: MDCT demonstrated that MSC therapy resulted in a reduction of infarct size from 14.3 ± 1.2% to 10.3 ± 1.5% of LV mass (p = 0.005), whereas infarct size increased in nontreated animals (from 13.8 ± 1.3% to 16.5 ± 1.5%; p = 0.02) (placebo vs. MSC; p = 0.003). Both observers had excellent agreement for infarct size (r = 0.96; p < 0.001). LVEF increased from 32.6 ± 2.2% to 36.9 ± 2.7% in MSC-treated animals (p = 0.03) and decreased in placebo animals (from 33.3 ± 1.4% to 29.1 ± 1.5%; p = 0.01; at week 24: placebo vs. MSC; p = 0.02). Infarct size, end-diastolic LV volume, and LVEF assessed by MDCT compared favorably with those assessed by cardiac magnetic resonance acquisitions (r = 0.70, r = 0.82, and r = 0.902, respectively; p < 0.001).

CONCLUSIONS: This study demonstrated that cardiac MDCT can be used to evaluate infarct size, LV volumes, and LVEF after intramyocardial-delivered MSC therapy. These findings support the use of cardiac MDCT in preclinical and clinical studies for novel myocardial therapies.

PMID: 22172785

Survival After Open Versus Endovascular Thoracic Aortic Aneurysm Repair in an Observational Study of the Medicare Population

OBJECTIVES: The goal of this study was to describe short- and long-term survival of patients with descending thoracic aortic aneurysms (TAAs) after open and endovascular repair (TEVAR).

METHODS: Using Medicare claims from 1998 to 2007, we analyzed patients who underwent repair of intact and ruptured TAA, identified from a combination of procedural and diagnostic International Classification of Disease, ninth revision, codes. Our main outcome measure was mortality, defined as perioperative mortality (death occurring before hospital discharge or within 30 days), and 5-year survival, from life-table analysis. We examined outcomes across repair type (open repair or TEVAR) in crude, adjusted (for age, sex, race, procedure year, and Charlson comorbidity score), and propensity-matched cohorts.

RESULTS: Overall, we studied 12 573 Medicare patients who underwent open repair and 2732 patients who underwent TEVAR. Perioperative mortality was lower in patients undergoing TEVAR compared with open repair for both intact (6.1% versus 7.1%; P=0.07) and ruptured (28% versus 46%; P<0.0001) TAA. However, patients with intact TAA selected for TEVAR had significantly worse survival than open patients at 1 year (87% for open, 82% for TEVAR; P=0.001) and 5 years (72% for open; 62% for TEVAR; P=0.001). Furthermore, in adjusted and propensity-matched cohorts, patients selected for TEVAR had worse 5-year survival than patients selected for open repair.

CONCLUSIONS: Although perioperative mortality is lower with TEVAR, Medicare patients selected for TEVAR have worse long-term survival than patients selected for open repair. The results of this observational study suggest that higher-risk patients are being offered TEVAR and that some do not benefit on the basis of long-term survival. Future work is needed to identify TEVAR candidates unlikely to benefit from repair.

PMID: 22104552

3D Echo Systematically Underestimates Right Ventricular Volumes Compared to Cardiovascular Magnetic Resonance in Adult Congenital Heart Disease Patients With Moderate or Severe RV Dilatation

OBJECTIVES: Three dimensional echo is a relatively new technique which may offer a rapid alternative for the examination of the right heart. However its role in patients with non-standard ventricular size or anatomy is unclear. This study compared volumetric measurements of the right ventricle in 25 patients with adult congenital heart disease using both cardiac magnetic resonance (CMR) and three dimensional echocardiography.

METHODS: Patients were grouped by diagnosis into those expected to have normal or near-normal RV size (patients with repaired coarctation of the aorta) and patients expected to have moderate or worse RV enlargement (patients with repaired tetralogy of Fallot or transposition of the great arteries). Right ventricular end diastolic volume, end systolic volume and ejection fraction were compared using both methods with CMR regarded as the reference standard

RESULTS: Bland-Altman analysis of the 25 patients demonstrated that for both RV EDV and RV ESV, there was a significant and systematic under-estimation of volume by 3D echo compared to CMR. This bias led to a mean underestimation of RV EDV by -34% (95%CI: -91% to + 23%). The degree of underestimation was more marked for RV ESV with a bias of -42% (95%CI: -117% to + 32%). There was also a tendency to overestimate RV EF by 3D echo with a bias of approximately 13% (95% CI -52% to +27%).

CONCLUSIONS: Statistically significant and clinically meaningful differences in volumetric measurements were observed between the two techniques. At the current time, three dimensional echocardiography is not interchangeable with CMR for volumetric assessment of ACHD patients who have more than mild RV dilatation.

PMID:

Image Quality and Radiation Exposure Using Different Low-Dose Scan Protocols in Dual-Source CT Coronary Angiography: Randomized Study

PMID: 21969666

Prognostic Importance of Late Gadolinium Enhancement Cardiovascular Magnetic Resonance in Cardiomyopathy

Cardiovascular magnetic resonance has revolutionised the diagnosis of cardiomyopathy, particularly through the use of late gadolinium enhancement imaging which provides the unique opportunity to assess myocardial fibrosis in vivo. More recently, the prognostic capability of cardiovascular magnetic resonance to predict outcomes has been assessed. Traditional risk markers do not at present adequately predict outcomes in either dilated cardiomyopathy or hypertrophic cardiomyopathy, which are the two most common causes of primary heart muscle disease. Many of these existing markers reflect underlying disease severity. Given the important role fibrosis is thought to play in the pathogenesis and sequelae of these cardiomyopathies, the presence and amount of fibrosis has been proposed as a potential novel risk factor for adverse events. This paper reviews the evidence for late gadolinium enhancement as a prognostic marker in dilated and hypertrophic cardiomyopathy and highlights the challenges ahead.

PMID: 22128204

Prognostic Value of Routine Cardiac Magnetic Resonance Assessment of Left Ventricular Ejection Fraction and Myocardial Damage: An International, Multicenter Study

OBJECTIVES: Cardiac magnetic resonance (CMR) is considered the reference standard for assessment of left ventricular ejection fraction (LVEF) and myocardial damage.  However, few studies have evaluated the relationship between CMR findings and patient outcome, and of these, most are small and none multicenter.  We performed an international, multicenter study to assess the prognostic importance of routine CMR in patients with known or suspected heart disease.

METHODS: From 10 centers in 6 countries, consecutive patients undergoing routine CMR assessment of LVEF and myocardial damage by cine and delayed-enhancement imaging (DE-CMR), respectively, were screened for enrollment.  Clinical data, CMR protocol information, and findings were collected at all sites and submitted to the data coordinating center for verification of completeness and analysis.  The primary end point was all-cause mortality.

RESULTS: A total of 1560 patients (age, 59±14 years; 70% men) were enrolled.  Mean LVEF was 45±18%, and 1049 (67%) patients had hyperenhanced tissue (HE) on DE-CMR indicative of damage.  During a median follow-up time of 2.4 years (interquartile range, 1.2, 2.9 years), 176 (11.3%) patients died.  Patients who died were more likely to be older (P<0.0001), have coronary disease (P=0.004), have lower LVEF (P<0.0001), and have more segments with HE (P<0.0001).  In multivariable analysis, age, LVEF, and number of segments with HE were independent predictors of mortality.  Among patients with near-normal LVEF (≥50%), those with above-median HE (>4 segments) had reduced survival compared to patients with below- or at-median HE (P=0.02).

CONCLUSIONS: Both LVEF and amount of myocardial damage as assessed by routine CMR are independent predictors of all-cause mortality.  Even in patients with near-normal LVEF, significant damage identifies a cohort with a high risk for early mortality.

PMID: 21911738

Exercise-Induced Right Ventricular Dysfunction and Structural Remodelling in Endurance Athletes

PMID:

Effect of Two Intensive Statin Regimens on Progression of Coronary Disease

OBJECTIVES: Statins reduce adverse cardiovascular outcomes and slow the progression of coronary atherosclerosis in proportion to their ability to reduce low-density lipoprotein (LDL) cholesterol. However, few studies have either assessed the ability of intensive statin treatments to achieve disease regression or compared alternative approaches to maximal statin administration.

METHODS: We performed serial intravascular ultrasonography in 1039 patients with coronary disease, at baseline and after 104 weeks of treatment with either atorvastatin, 80 mg daily, or rosuvastatin, 40 mg daily, to compare the effect of these two intensive statin regimens on the progression of coronary atherosclerosis, as well as to assess their safety and side-effect profiles.

RESULTS: After 104 weeks of therapy, the rosuvastatin group had lower levels of LDL cholesterol than the atorvastatin group (62.6 vs. 70.2 mg per deciliter [1.62 vs. 1.82 mmol per liter], P<0.001), and higher levels of high-density lipoprotein (HDL) cholesterol (50.4 vs. 48.6 mg per deciliter [1.30 vs. 1.26 mmol per liter], P=0.01). The primary efficacy end point, percent atheroma volume (PAV), decreased by 0.99% (95% confidence interval [CI], -1.19 to -0.63) with atorvastatin and by 1.22% (95% CI, -1.52 to -0.90) with rosuvastatin (P=0.17). The effect on the secondary efficacy end point, normalized total atheroma volume (TAV), was more favorable with rosuvastatin than with atorvastatin: -6.39 mm(3) (95% CI, -7.52 to -5.12), as compared with -4.42 mm(3) (95% CI, -5.98 to -3.26) (P=0.01). Both agents induced regression in the majority of patients: 63.2% with atorvastatin and 68.5% with rosuvastatin for PAV (P=0.07) and 64.7% and 71.3%, respectively, for TAV (P=0.02). Both agents had acceptable side-effect profiles, with a low incidence of laboratory abnormalities and cardiovascular events.

CONCLUSIONS: Maximal doses of rosuvastatin and atorvastatin resulted in significant regression of coronary atherosclerosis. Despite the lower level of LDL cholesterol and the higher level of HDL cholesterol achieved with rosuvastatin, a similar degree of regression of PAV was observed in the two treatment groups.

PMID: 22085316

Percutaneous Transvenous Melody Valve-in-Ring Procedure for Mitral Valve Replacement

OBJECTIVES: The purpose of this study was to demonstrate the feasibility of percutaneous transvenous mitral valve-in-ring (VIR) implantation using the Melody valve in an ovine model. The recurrence of mitral regurgitation following surgical mitral valve (MV) repair in both adult and pediatric patients remains a significant clinical problem. Mitral annuloplasty rings are commonly used in MV repair procedures and may serve as secure landing zones for percutaneous valves.

METHODS: Five sheep underwent surgical MV annuloplasty (24 mm, n = 2; 26 mm, n = 2; 28 mm, n = 1). Animals underwent cardiac catheterization with VIR implantation via a transfemoral venous, transatrial septal approach 1 week following surgery. Hemodynamic, angiographic, and echocardiographic data were recorded before and after VIR.

RESULTS: VIR was technically successful and required <1 h of procedure time in all animals. Fluoroscopy demonstrated securely positioned Melody valves within the annuloplasty ring in all animals. Angiography revealed no significant MV regurgitation in 4 and moderate central MV regurgitation in the animal with the 28-mm annuloplasty. All animals demonstrated vigorous left ventricular function, no outflow tract obstruction, and no aortic valve insufficiency.

CONCLUSIONS: This study demonstrated the feasibility of a purely percutaneous approach to MV replacement in patients with preexisting annuloplasty rings. This novel approach may be of particular benefit to patients with failed repair of ischemic mitral regurgitation and in pediatric patients with complex structural heart disease.

PMID: 22133846

Health at a Glance 2011: OECD Indicators

This sixth edition of Health at a Glance provides the latest comparable data on different aspects of the performance of health systems in OECD (Organization for Economic Cooperation and Development)countries. It provides striking evidence of large variations across countries in the costs, activities and results of health systems. For the first time, it also features a chapter on long-term care.

This edition presents data for all OECD member countries. Where possible, it also reports data for Brazil, China, India, Indonesia, the Russian Federation and South Africa, as major non-OECD economies.

This publication takes as it main basis OECD Health Data 2011, the most comprehensive set of statistics and indicators for comparing health systems across the 34 OECD member countries.

Download the publication.

http://www.oecd.org/document/11/0,3746,en_2649_33929_16502667_1_1_1_1,00.html

PMID: