Incidental Findings in Imaging Research. Evaluating Incidence, Benefit, and Burden

OBJECTIVES: Little information exists concerning the frequency and medical significance of incidental findings (IFs) in imaging research.

METHODS: Medical records of research participants undergoing a research imaging examination interpreted by a radiologist during January through March 2004 were reviewed, with 3-year clinical follow-up. An expert panel reviewed all IFs generating clinical action to determine medical benefit/burden on the basis of predefined criteria. The frequency of IFs that generated further clinical action was estimated by modality, body part, age, and sex, along with net medical benefit or burden.

RESULTS: Of 1426 research imaging examinations, 567 (39.8%) had at least 1 IF (1055 total). Risk of an IF increased significantly by age (odds ratio [OR], 1.5; 95% confidence interval, 1.4-1.7 per decade increase). Abdominopelvic computed tomography generated more IFs than other examinations (OR, 18.9 vs ultrasonography; 9.2% with subsequent clinical action), with computed tomography of the thorax and magnetic resonance imaging of the head next (OR, 11.9 and 5.9; 2.8% and 2.2% with action, respectively). Of the 567 examinations with an IF, 35 (6.2%) generated clinical action, resulting in clear medical benefit in 1.1% (6 of 567) and clear medical burden in 0.5% (3 of 567). Medical benefit/burden was usually unclear (26 of 567 [4.6%]).

CONCLUSIONS: Frequency of IFs in imaging research examinations varies significantly by imaging modality, body region, and age. Research imaging studies at high risk for generating IFs can be identified. Routine evaluation of research images by radiologists may result in identification of IFs in a high number of cases and subsequent clinical action to address them in a small but significant minority. Such clinical action can result in medical benefit to a small number of patients.

PMID:

Transcatheter Aortic-Valve Implantation for Aortic Stenosis in Patients Who Cannot Undergo Surgery

OBJECTIVES: Many patients with severe aortic stenosis and coexisting conditions are not candidates for surgical replacement of the aortic valve. Recently, transcatheter aortic-valve implantation (TAVI) has been suggested as a less invasive treatment for high-risk patients with aortic stenosis.

METHODS: We randomly assigned patients with severe aortic stenosis, whom surgeons considered not to be suitable candidates for surgery, to standard therapy (including balloon aortic valvuloplasty) or transfemoral transcatheter implantation of a balloon-expandable bovine pericardial valve. The primary end point was the rate of death from any cause.

RESULTS: A total of 358 patients with aortic stenosis who were not considered to be suitable candidates for surgery underwent randomization at 21 centers (17 in the United States). At 1 year, the rate of death from any cause (Kaplan–Meier analysis) was 30.7% with TAVI, as compared with 50.7% with standard therapy (hazard ratio with TAVI, 0.55; 95% confidence interval [CI], 0.40 to 0.74; P<0.001). The rate of the composite end point of death from any cause or repeat hospitalization was 42.5% with TAVI as compared with 71.6% with standard therapy (hazard ratio, 0.46; 95% CI, 0.35 to 0.59; P<0.001). Among survivors at 1 year, the rate of cardiac symptoms (New York Heart Association class III or IV) was lower among patients who had undergone TAVI than among those who had received standard therapy (25.2% vs. 58.0%, P<0.001). At 30 days, TAVI, as compared with standard therapy, was associated with a higher incidence of major strokes (5.0% vs. 1.1%, P=0.06) and major vascular complications (16.2% vs. 1.1%, P<0.001). In the year after TAVI, there was no deterioration in the functioning of the bioprosthetic valve, as assessed by evidence of stenosis or regurgitation on an echocardiogram.

CONCLUSIONS: In patients with severe aortic stenosis who were not suitable candidates for surgery, TAVI, as compared with standard therapy, significantly reduced the rates of death from any cause, the composite end point of death from any cause or repeat hospitalization, and cardiac symptoms, despite the higher incidence of major strokes and major vascular events.

PMID:

Impact of Luminal Density on Plaque Classification by CT Coronary Angiography

OBJECTIVES: Non-invasive coronary CT angiography (CCTA) has the potential to characterize the composition of non-calcified coronary plaques. CT-density values characterized by Hounsfield Units (HU) may classify non-calcified plaques as fibrous or lipid-rich, but the luminal density caused by the applied contrast material influences HU in the plaques in vitro. The influence of luminal density on HU in non-calcified plaques in vivo is unknown. Hence the purpose of this study was to test whether plaque characterization by CCTA in vivo depends on luminal density.

METHODS: Two CCTA-scans using two different contrast protocols were obtained from 14 male patients with coronary artery disease. The two contrast protocols applied resulted in high and low luminal density.

RESULTS: Eleven non- calcified and 13 calcified plaques were identified and confirmed by intravascular ultrasound. Luminal attenuation differed with the two contrast protocols; 326[284;367] vs. 118[103;134] HU (P < 0.00001). In non-calcified plaques mean HU-values was lower 48[28;69] vs. 11[-4;25] HU (P = 0.004) with the low density protocol. As a consequence three out of eleven non-calcified plaques (27%) were reclassified from fibrous (high) to lipid rich (low). For calcified plaques a less pronounced but still significant difference in HU-values was found with the low luminal density. 770[622;919] vs. 675[496;855] HU (P = 0.02).

CONCLUSIONS: Non-calcified plaques can be identified and classified by CCTA. However, the luminal density affects the absolute HU of both non-calcified and calcified plaques. Characterization and classification of non-calcified plaques by absolute CT values therefore requires standardization of contrast protocols.

PMID: 20820922

Prognostic Value of E/E’ Ratio in Patients With Unoperated Severe Aortic Stenosis

OBJECTIVES: The aim of this study was to evaluate the value of clinical and echo-Doppler parameters for the prognosis of unoperated severe aortic stenosis (AS). Approximately one-third of severe, symptomatic AS patients are denied surgery. Risk stratification of unoperated AS is important to determine eligibility for percutaneous aortic valve replacement, an evolving treatment option for AS patients deemed suboptimal for surgical aortic valve replacement.

METHODS: We retrospectively compared clinical and echo-Doppler parameters between survivors and nonsurvivors of 125 patients with unoperated severe AS.

RESULTS: The 1-year survival rate was 62.4%. In univariate analysis, survivors compared with nonsurvivors were younger (80.0 ± 10.9 years vs. 84.9 ± 11.1 years, p = 0.02), had a greater left ventricular ejection fraction (LVEF) (55 ± 15% vs. 50 ± 16%, p = 0.042), a higher left ventricular stroke volume (63 ± 19 ml vs. 56 ± 13 ml, p = 0.015), a lower E/E’ ratio (12.19 ± 5.7 vs. 16.87 ± 7.43, p < 0.001), and a lower prevalence of E/E’ >15 (20% vs. 55%, p < 0.001). Symptomatic status was nonsignificantly different between survivors and nonsurvivors. In patients with an LVEF ≥50%, the subgroup with E/E’ ≤15 and with E/E’ >15 had a 73.8% and 47.8% 1-year survival rate, respectively (p = 0.027). In the patients with an LVEF <50%, the patients with E/E’ ≤15 and those with E/E’ >15 demonstrated a 70.6% and 22.3% 1-year survival rate, respectively (p = 0.003). In multivariate analysis, significant predictors of mortality were E/E’ >15 and a combination of E/E’ >15 and B-type natriuretic peptide >300 ng/ml: adjusted mortality risk 2.34 (95% confidence interval (CI) 1.27 to 4.33, p = 0.0072) and 2.59 (95% CI 1.21 to 5.55, p = 0.014), respectively.

CONCLUSIONS: The E/E’ ratio is the single most predictive clinical and echo-Doppler parameter in the assessment of overall prognosis in patients with unoperated severe AS. LVEF was a significant predictor of survival only in the univariate analysis. B-type natriuretic peptide alone was not a predictor of prognosis in the study population. However, the combination of E/E’ and B-type natriuretic peptide is even more predictive of the 1-year prognosis.

PMID: 20846623

Quantification of Diffuse Myocardial Fibrosis and its Association with Myocardial Dysfunction in Congenital Heart Disease

OBJECTIVES: The etiology of ventricular dysfunction in adult congenital heart disease (ACHD) is not well understood. Diffuse fibrosis is a likely common final pathway and is quantifiable using magnetic resonance imaging (MRI).

METHODS: ACHD patients (N=50) were studied with cardiac MRI to quantify systemic ventricular volume and function, and diffuse fibrosis. The fibrosis index for a single mid-ventricular plane of the systemic ventricle was quantified by measuring T1 values for blood pool and myocardium before and after administration of gadolinium (0.15 mmol/kg), then adjusted for hematocrit.

RESULTS: Results were compared to healthy volunteers (normal controls, N=14) and patients with acquired heart failure (positive controls, N=4). Patients studied (age 37±12 years, 40% female) included 11 with a systemic right ventricle (RV), 17 with tetralogy of Fallot, 10 with cyanosis and 12 with other lesions. The fibrosis index was significantly elevated in ACHD patients compared to normal controls (31.9±4.9% vs. 24.8±2.0%, p=0.001). Values were highest in systemic RV patients (35.0±5.8%, p<0.001) and cyanotic patients (33.7±5.6%, p<0.001). The fibrosis index correlated with end-diastolic volume index (r=0.60, p<0.001) and ventricular ejection fraction (r=-0.53, p<0.001), but not with age, nor oxygen saturation in cyanotic patients. Late gadolinium enhancement did not account for the differences seen.

CONCLUSIONS: ACHD patients have evidence of diffuse, extracellular matrix remodeling, similar to patients with acquired heart failure. The fibrosis index may facilitate studies on the mechanisms and treatment of myocardial fibrosis and heart failure in these patients.

PMID: 20855860

Transcatheter Aortic Valve Implantation: Durability of Clinical and Hemodynamic Outcomes Beyond 3 Years in a Large Patient Cohort

OBJECTIVES: Although short- and medium-term outcomes after transcatheter aortic valve implantation are encouraging, long-term data on valve function and clinical outcomes are limited.

METHODS: Consecutive high-risk patients who had been declined as surgical candidates because of comorbidities but who underwent successful transcatheter aortic valve implantation with a balloon-expandable valve between January 2005 and December 2006 and survived past 30 days were assessed. Clinical, echocardiographic, and computed tomographic follow-up examinations were performed. Seventy patients who underwent successful procedures and survived longer than 30 days were evaluated at a minimum follow-up of 3 years.

RESULTS: At a median follow-up of 3.7 years (interquartile range 3.4 to 4.3 years), survival was 57%. Survival at 1, 2, and 3 years was 81%, 74%, and 61%, respectively. Freedom from reoperation was 98.5% (1 patient with endocarditis). During this early procedural experience, 11 patients died within 30 days, and 8 procedures were unsuccessful. When these patients were included, overall survival was 51%. Transaortic pressure gradients increased from 10.0 mm Hg (interquartile range 8.0 to 12.0 mm Hg) immediately after the procedure to 12.1 mm Hg (interquartile range 8.6 to 16.0 mm Hg) after 3 years (P=0.03). Bioprosthetic valve area decreased from a mean of 1.7±0.4 cm(2) after the procedure to 1.4±0.3 cm(2) after 3 years (P<0.01). Aortic incompetence after implantation was trivial or mild in 84% of cases and remained unchanged or improved over time. There were no cases of structural valvular deterioration, stent fracture, deformation, or valve migration.

CONCLUSIONS: Transcatheter aortic valve implantation demonstrates good medium- to long-term durability and preserved hemodynamic function, with no evidence of structural failure. The procedure appears to offer an adequate and lasting resolution of aortic stenosis in selected patients.

PMID: 20837893

Transcatheter Device Closure of Perimembranous Ventricular Septal Defects: Mid-Term Outcomes

OBJECTIVES: The aim of this study was to evaluate the safety and efficacy of transcatheter closure for perimembranous ventricular septal defect (pmVSD) and its long-term results. The most common congenital heart condition is pmVSD. Transcatheter closure of pmVSD is a recently described technique with limited results for mid- to long-term follow-up.

METHODS: Between June 2002 and June 2008, 848 patients with pmVSD were enrolled in our study and treated percutaneously with pmVSD occluders. All patients were followed up until December 2008, an average of 37 months.

RESULTS: According to colour Doppler transthoracic echocardiography before the intervention and ventriculography, the average end-diastolic pmVSD size was 5.1 and 5.4 mm, respectively. Placement of the device was successful in 832 patients (98.1%) and the median device size was 8.6 mm. During follow-up, 103 adverse events (12.4%) were reported. Most adverse events were categorized as minor and there were nine major adverse events (8.7%), including two complete atrioventricular block requiring pacemaker implantation. Kaplan-Meier estimates showed >85% freedom from major or minor adverse events during a maximal follow-up of 79 months.

CONCLUSIONS: In experienced hands, transcatheter pmVSD closure can be performed safely and successfully with low morbidity and mortality. Long-term prognostic results are favourable, and the transcatheter approach provides a less-invasive alternative that may become the first choice in selected pmVSD patients.

PMID: 20801925

Impact of New Development of Ulcer-Like Projection on Clinical Outcomes in Patients With Type B Aortic Dissection With Closed and Thrombosed False Lumen

 OBJECTIVES: The purpose of this study was to investigate the clinical importance of newly developed ulcer-like projection (ULP) in patients with type B aortic dissection with closed and thrombosed false lumen (AD with CTFL), which is better known as aortic intramural hematoma.

METHODS: A total of 170 patients with acute type B AD with CTFL were admitted to our institution from 1986 to 2008 and treated initially with medical therapy. There were 31 late deaths, including 9 cases of aortic rupture. The actuarial survival rates of all patients were 99%, 89%, 83% at 1, 5, and 10 years, respectively.

RESULTS: A total of 62 (36%) patients showed new ULP development within 30 days from the onset. Patients who had ULP showed significantly poorer survival rates than patients who did not have ULP (P=0.037). Development of ULP was also associated with a significant increase in adverse aorta-related events (P<0.001). In addition, patients with ULP in the proximal descending thoracic aorta (PD) showed significantly higher aorta-related event rates than patients without ULP in the PD (P<0.001). Initial aortic diameter (hazard ratio, 3.55; P<0.001) and development of ULP in PD (hazard ratio, 3.79; P=0.003) were the strongest predictors of adverse aorta-related events.

CONCLUSIONS: Initial aortic diameter and development of ULP in the PD are both strong predictors of adverse aorta-related events in patients with type B AD with CTFL. Patients with newly developed ULP should be more carefully followed up with close surveillance imaging than those without ULP.

PMID: 20837929

The Impact of Cardiovascular Risk Factors on Aortic Stiffness and Wave Reflections Depends on Age: The Anglo-Cardiff Collaborative Trial (ACCT III)

Ageing exerts differential effects on arterial stiffness and wave reflections. However, the impact of cardiovascular risk factors on arterial stiffness and wave reflections and, particularly, how such effects are influenced by ageing has not been assessed within a single large population, covering a sufficiently wide age range. Therefore, we determined the extent to which age alters the impact of traditional cardiovascular risk factors on arterial stiffness and wave reflections. Aortic stiffness and wave reflections were assessed in 4421 individuals (age range 18 to 92 years). When treated as continuous variables, clinic systolic, diastolic, and pulse pressures and glucose levels were independently associated with stiffness, and, with the exception of diastolic pressure, these associations were more marked in older individuals. In contrast, clinic systolic and diastolic pressures and smoking were independently associated with wave reflections, with stronger associations observed in younger individuals. The impact of traditional cardiovascular risk factors on arterial stiffness and wave reflections is strongly dependent on age and is largely driven by blood pressure. Additional studies are required to assess the impact of these arterial measures on cardiovascular outcome within a single population.

PMID: 20696989

Impaired Aortic Distensibility Measured by Computed Tomography is Associated With the Severity of Coronary Artery Disease

OBJECTIVES: Impaired aortic distensibility index (ADI) is associated with cardiovascular risk factors. This study evaluates the relation of ADI measured by computed tomographic angiography (CTA) with the severity of coronary atherosclerosis in subjects with suspected coronary artery disease (CAD).

METHODS: Two hundred and twenty-nine subjects,age 63 +/- 9 years, 42% female, underwent coronary artery calcium (CAC) scanning and CTA, and their ADI and Framingham risk score (FRS) were measured. End-systolic and end-diastolic (ED) cross-sectional-area(CSA) of ascending-aorta (AAo) was measured 15-mm above the left-main coronary ostium. ADI was defined as: [(Deltalumen-CSA)/(lumen-CSA in ED x systemic-pulse-pressure) x 10(3)]. ADI measured by 2D-trans-thoracic echocardiography (TTE) was compared with CTA-measured ADI in 26 subjects without CAC. CAC was defined as 0, 1-100, 101-400 and 400+. CAD was defined as luminal stenosis 0, 1-49% and 50%.

RESULTS: There was an excellent correlation between CTA- and TTE-measured ADI (r (2) = 0.94, P = 0.0001). ADI decreased from CAC 0 to CAC 400+; similarly from FRS 1-9% to FRS 20% + (P < 0.05). After adjustment for risk factors, the relative risk for each standard deviation decrease in ADI was 1.66 for CAC 1-100, 2.26 for CAC 101-400 and 2.32 for CAC 400+ as compared to CAC 0; similarly, 2.36 for non-obstructive CAD and 2.67 for obstructive CAD as compared to normal coronaries. The area under the ROC-curve to predict significant CAD was 0.68 for FRS, 0.75 for ADI, 0.81 for CAC and 0.86 for the combination (P < 0.05).

CONCLUSIONS: Impaired aortic distensibility strongly correlates with the severity of coronary atherosclerosis. Addition of ADI to CAC and traditional risk factors provides incremental value to predict at-risk individuals.

PMID: 20711815

Effective Radiation Dose, Time, and Contrast Medium to Measure Fractional Flow Reserve

OBJECTIVES: This study sought to define the additional effective radiation dose, procedural time, and contrast medium needed to obtain fractional flow reserve (FFR) measurements after a diagnostic coronary angiogram. The FFR measurements performed at the end of a diagnostic angiogram allow the obtaining of functional information that complements the anatomic findings.

METHODS: In 200 patients (mean age 66 +/- 10 years) undergoing diagnostic coronary angiography, FFR was measured in at least 1 intermediate coronary artery stenosis. Hyperemia was achieved by intracoronary (n = 180) or intravenous (n = 20) adenosine. The radiation dose (mSv), procedural time (min), and contrast medium (ml) needed for diagnostic angiography and FFR were recorded.

RESULTS: A total of 296 stenoses (1.5 +/- 0.7 stenoses per patient) were assessed. The additional mean radiation dose, procedural time, and contrast medium needed to obtain FFR expressed as a percentage of the entire procedure were 30 +/- 16% (median 4 mSv, range 2.4 to 6.7 mSv), 26 +/- 13% (median 9 min, range 7 to 13 min), and 31 +/- 16% (median 50 ml, range 30 to 90 ml), respectively. The radiation dose and contrast medium during FFR were similar after intravenous and intracoronary adenosine, though the procedural time was slightly longer with intravenous adenosine (median 11 min, range 10 to 17 min, p = 0.04) than with intracoronary adenosine (median 9 min, range 7 to 13 min). When FFR was measured in 3 or more lesions, radiation dose, procedural time, and contrast medium increased.

CONCLUSIONS: The additional radiation dose, procedural time, and contrast medium to obtain FFR measurement are low as compared to other cardiovascular imaging modalities. Therefore, the combination of diagnostic angiography and FFR measurements is warranted to provide simultaneously anatomic and functional information in patients with coronary artery disease.

PMID: 20723854

Myocardial scar visualized by cardiovascular magnetic resonance imaging predicts major adverse events in patients with hypertrophic cardiomyopathy.

OBJECTIVES: We sought to establish the prognostic value of a comprehensive cardiovascular magnetic resonance (CMR) examination in risk stratification of hypertrophic cardiomyopathy (HCM) patients.

BACKGROUND: With annual mortality rates ranging between 1% and 5%, depending on patient selection, a small but significant number of HCM patients are at risk for an adverse event. Therefore, the identification of and prophylactic therapy (i.e., defibrillator placement) in patients with HCM who are at risk of dying are imperative.

METHODS: Two-hundred forty-three consecutive patients with HCM were prospectively enrolled. All patients underwent initial CMR, and 220 were available for clinical follow-up. The mean follow-up time was 1,090 days after CMR. End points were all-cause and cardiac mortality.

RESULTS: During follow-up 20 of the 220 patients died, and 2 patients survived sudden cardiac death due to adequate implantable cardioverter-defibrillator discharge. Most events (n = 16) occurred for cardiac reasons; the remaining 6 events were related to cancer and accidents. Our data indicate that the presence of scar visualized by CMR yields an odds ratio of 5.47 for all-cause mortality and of 8.01 for cardiac mortality. This might be superior to classic clinical risk factors, because in our dataset the presence of 2 risk factors yields an odds ratio of 3.86 for all-cause and of 2.20 for cardiac mortality, respectively. Multivariable analysis also revealed the presence of late gadolinium enhancement as a good independent predictor of death in HCM patients.

CONCLUSIONS: Among our population of largely low or asymptomatic HCM patients, the presence of scar indicated by CMR is a good independent predictor of all-cause and cardiac mortality.

PMID: 20667520

Prognostic significance of myocardial fibrosis in hypertrophic cardiomyopathy.

OBJECTIVES: We investigated the significance of fibrosis detected by late gadolinium enhancement cardiovascular magnetic resonance for the prediction of major clinical events in hypertrophic cardiomyopathy (HCM).

BACKGROUND: The role of myocardial fibrosis in the prediction of sudden death and heart failure in HCM is unclear with a lack of prospective data.

METHODS: We assessed the presence and amount of myocardial fibrosis in HCM patients and prospectively followed them for the development of morbidity and mortality in patients over 3.1 +/- 1.7 years.

RESULTS: Of 217 consecutive HCM patients, 136 (63%) showed fibrosis. Thirty-four of the 136 patients (25%) in the fibrosis group but only 6 of 81 (7.4%) patients without fibrosis reached the combined primary end point of cardiovascular death, unplanned cardiovascular admission, sustained ventricular tachycardia or ventricular fibrillation, or appropriate implantable cardioverter-defibrillator discharge (hazard ratio [HR]: 3.4, p = 0.006). In the fibrosis group, overall risk increased with the extent of fibrosis (HR: 1.18/5% increase, p = 0.008). The risk of unplanned heart failure admissions, deterioration to New York Heart Association functional class III or IV, or heart failure-related death was greater in the fibrosis group (HR: 2.5, p = 0.021), and this risk increased as the extent of fibrosis increased (HR: 1.16/5% increase, p = 0.017). All relationships remained significant after multivariate analysis. The extent of fibrosis and nonsustained ventricular tachycardia were univariate predictors for arrhythmic end points (sustained ventricular tachycardia or ventricular fibrillation, appropriate implantable cardioverter-defibrillator discharge, sudden cardiac death) (HR: 1.30, p = 0.014). Nonsustained ventricular tachycardia remained an independent predictor of arrhythmic end points after multivariate analysis, but the extent of fibrosis did not.

CONCLUSIONS: In patients with HCM, myocardial fibrosis as measured by late gadolinium enhancement cardiovascular magnetic resonance is an independent predictor of adverse outcome.

PMID: 20688032

Assessment of Coronary Artery Disease Using Magnetic Resonance Coronary Angiography A National Multicenter Trial

OBJECTIVES: This national multicenter study determined the diagnostic performance of 1.5-T whole-heart coronary magnetic resonance angiography (MRA) in patients with suspected coronary artery disease (CAD). Whole-heart coronary MRA using steady-state free precession allows noninvasive detection of CAD without the administration of contrast medium. However, the accuracy of this approach has not been determined in a multicenter trial.

METHODS: Using a 1.5-T magnetic resonance imaging unit, free-breathing steady-state free precession whole-heart coronary MRA images were acquired for 138 patients with suspected CAD at 7 hospitals. The accuracy of MRA for detecting a ≥50% reduction in diameter was determined using X-ray coronary angiography as the reference method.

RESULTS: Acquisition of whole-heart coronary MRA images was performed in 127 (92%) of 138 patients with an average imaging time of 9.5 ± 3.5 min. The areas under the receiver-operator characteristic curve from MRA images according to vessel- and patient-based analyses were 0.91 (95% confidence interval [CI]: 0.87 to 0.95) and 0.87 (95% CI: 0.81 to 0.93), respectively. The sensitivity, specificity, positive and negative predictive values, and accuracy of MRA according to a patient-based analysis were 88% (49 of 56, 95% CI: 75% to 94%), 72% (51 of 71, 95% CI: 60% to 82%), 71% (49 of 69, 95% CI: 59% to 81%), 88% (51 of 58, 95% CI: 76% to 95%), and 79% (100 of 127, 95% CI: 72% to 86%), respectively.

CONCLUSIONS: Non–contrast-enhanced whole-heart coronary MRA at 1.5-T can noninvasively detect significant CAD with high sensitivity and moderate specificity. A negative predictive value of 88% indicates that whole-heart coronary MRA can rule out CAD.

PMID:

ECG-Gated Dual-Source CT for Detection of Left Atrial Appendage Thrombus in Patients Undergoing Catheter Ablation for Atrial Fibrillation

OBJECTIVES: Left atrial ablation is increasingly used to treat patients with symptomatic atrial fibrillation (AF). Prior to ablation, exclusion of left atrial appendage (LAA) thrombus is important. Whether ECG-gated dual-source computed tomography (DSCT) provides a sensitive means of detecting LAA thrombus in patients undergoing percutaneous AF ablation is unknown. Thus, we sought to determine the utility of ECG-gated DSCT in detecting LAA thrombus in patients with AF.

METHODS: A total of 255 patients (age 58 +/- 11 years, 78% male, ejection fraction 58 +/- 9%) who underwent ECG-gated DSCT and transesophageal echocardiography (TEE) prior to AF ablation between February 2006 and October 2007 were included. CHADS2 score and demographic data were obtained prospectively. Gated DSCT images were independently reviewed by two cardiac imagers blinded to TEE findings. The LAA was either defined as normal (fully opacified) or abnormal (under-filled) by DSCT.

RESULTS: An under-filled LAA was identified in 33 patients (12.9%), of whom four had thrombus confirmed by TEE. All patients diagnosed with LAA thrombus using TEE also had an abnormal LAA by gated DSCT. Thus, sensitivity and specificity for gated DSCT were 100% and 88%, respectively. No cases of LAA filling defects were observed in patients <51 years old with a CHADS2 of 0.

CONCLUSIONS: In patients referred for AF ablation, thrombus is uncommon in the absence of additional risk factors. Gated DSCT provides excellent sensitivity for the detection of thrombus. Thus, in AF patients with a CHADS2 of 0, gated DSCT may provide a useful stand-alone imaging modality.

PMID: 20809409