Troy M Labounty

Cedars-Sinai Medical Center, Los Angeles, California, United States

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Publications (84)449.8 Total impact

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    ABSTRACT: Prior studies examining coronary atherosclerosis in the young have been limited by retrospective analyses in small cohorts. We examined the relationship between cardiovascular risk factors (RFs) and prevalence and severity of coronary atherosclerosis in a large, prospective, multinational registry of consecutive young individuals undergoing coronary computerized tomographic angiography (CCTA). Of 27 125 patients undergoing CCTA, 1635 young (<45 years) individuals without known coronary artery disease (CAD) or coronary anomalies were identified. Coronary plaque was assessed for any CAD, obstructive CAD (≥50% stenosis), and presence of calcified plaque (CP) and non-calcified plaque (NCP). Among 1635 subjects (70% men, age 38 ± 6 years), any CAD, obstructive CAD, CP, and NCP were observed in 19, 4, 5, and 8%, respectively. Compared with women, men demonstrated higher rates of any CAD (21 vs. 12%, P < 0.001), CP (6 vs. 3%, P = 0.01), and NCP (9 vs. 5%, P = 0.008), although no difference was observed for rates of obstructive CAD (5 vs. 4%, P = 0.46). Any CAD, obstructive CAD, and NCP were higher for young individuals with diabetes, hypertension, dyslipidaemia, current smoking, or family history of CAD; while only diabetes and dyslipidaemia were associated with CP. Increasing cardiovascular RFs was associated with a greater prevalence and extent and severity of CAD, with individuals with 0, 1, 2, ≥3 RFs manifesting a dose-response increase in any CAD (P < 0.001, for trend), obstructive CAD (P < 0.001, for trend), NCP (P < 0.001, for trend), and CP (P < 0.001, for trend). In multivariable analysis adjusting for sex and cardiovascular RFs, male sex was the strongest predictor for any CAD (odds ratio [OR] = 1.95, 95% confidence interval [CI] = 1.43-2.66, P < 0.001), CP (OR = 1.46, 95% CI = 1.08-1.98, P = 0.01), and NCP (OR = 1.33, 95% CI = 1.06-1.67, P = 0.01); family history of CAD was the strongest predictor for obstructive CAD (OR = 2.71, 95% CI = 1.65-4.45, P < 0.001). Any and obstructive CAD is present in 1 in 5 and 1 in 20 young individuals, respectively, with family history associated with the greatest risk of obstructive CAD. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email:
    European Heart Journal – Cardiovascular Imaging 12/2014; · 2.65 Impact Factor
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    JACC Cardiovascular Imaging 11/2014; · 6.99 Impact Factor
  • JACC Cardiovascular Imaging 10/2014; 7(10):1065–1066. · 6.99 Impact Factor
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    ABSTRACT: Purpose To assess whether gradations of left ventricular (LV) ejection fraction (LVEF) and volumes measured with coronary computed tomography (CT) would augment risk stratification and discrimination for incident mortality. Materials and Methods This study was approved by the institutional review board, and informed consent was obtained when required. Subjects without known coronary artery disease (CAD) who underwent cardiac CT angiography with quantitative LV measurements were categorized according to LVEF (≥55%, 45%-54.9%, 35%-44.9%, or <35%). LV end-systolic volume (LVESV) and LV end-diastolic volume (LVEDV) were classified as normal (≥90 mL) or abnormal (≥200 mL). CAD extent and severity was categorized as none, nonobstructive, obstructive (≥50%), one-vessel, two-vessel, and three-vessel or left main disease. LVEF and volumes were assessed for risk prediction and discrimination of future mortality by using Cox hazards model and receiver operating characteristic curve analysis, respectively. Results During a follow-up of 2.0 years ± 0.9, 7758 patients (mean age, 58.5 years ± 13.0; 4220 male patients [54.4%]) were studied. At multivariable analysis, worsening LVEF was independently associated with mortality for moderately (hazard ratio = 3.14, P < .001) and severely (hazard ratio = 5.19, P < .001) abnormal ejection fraction. LVEF demonstrated improved discrimination for mortality (Az = 0.816) when compared with CAD risk factors alone (Az = 0.781) or CAD risk factors plus extent and severity. At multivariable analysis of a subgroup of 3706 individuals, abnormal LVEDV (hazard ratio = 4.02) and LVESV (hazard ratio = 6.46) helped predict mortality (P < .001). Similarly, LVESV and LVEDV demonstrated improved discrimination when compared with CAD risk factors or CAD extent and severity (P < .05). Conclusion LV dysfunction and volumes measured with cardiac CT angiography augment risk prediction and discrimination for future mortality. © RSNA, 2014.
    Radiology 07/2014; · 6.21 Impact Factor
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    JACC Cardiovascular Imaging 04/2014; · 6.99 Impact Factor
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    ABSTRACT: Background Coronary artery disease (CAD) diagnosis by coronary computed tomographic angiography (CCTA) is useful for identification of symptomatic diabetic individuals at heightened risk for death. Whether CCTA-detected CAD enables improved risk assessment of asymptomatic diabetic individuals beyond clinical risk factors and coronary artery calcium scoring (CACS) remains unexplored. Methods From a prospective 12-center international registry of 27,125 individuals undergoing CCTA, we identified 400 asymptomatic diabetic individuals without known CAD. Coronary stenosis by CCTA was graded as 0%, 1–49%, 50–69%, and ≥70%. CAD was judged on a per-patient, per-vessel and per-segment basis as maximal stenosis severity, number of vessels with ≥50% stenosis, and coronary segments weighted for stenosis severity (segment stenosis score), respectively. We assessed major adverse cardiovascular events (MACE) – inclusive of mortality, nonfatal myocardial infarction (MI), and late target vessel revascularization ≥90 days (REV) – and evaluated the incremental utility of CCTA for risk prediction, discrimination and reclassification. Results Mean age was 60.4 ± 9.9 years; 65.0% were male. At a mean follow-up 2.4 ± 1.1 years, 33 MACE occurred (13 deaths, 8 MI, 12 REV) [8.25%; annualized rate 3.4%]. By univariate analysis, per-patient maximal stenosis [hazards ratio (HR) 2.24 per stenosis grade, 95% confidence interval (CI) 1.61–3.10, p < 0.001], increasing numbers of obstructive vessels (HR 2.30 per vessel, 95% CI 1.75–3.03, p < 0.001) and segment stenosis score (HR 1.14 per segment, 95% CI 1.09–1.19, p < 0.001) were associated with increased MACE. After adjustment for CAD risk factors and CACS, maximal stenosis (HR 1.80 per grade, 95% CI 1.18–2.75, p = 0.006), number of obstructive vessels (HR 1.85 per vessel, 95% CI 1.29–2.65, p < 0.001) and segment stenosis score (HR 1.11 per segment, 95% CI 1.05–1.18, p < 0.001) were associated with increased risk of MACE. Beyond age, gender and CACS (C-index 0.64), CCTA improved discrimination by maximal stenosis, number of obstructive vessels and segment stenosis score (C-index 0.77, 0.77 and 0.78, respectively). Similarly, CCTA findings improved risk reclassification by per-patient maximal stenosis [integrated discrimination improvement (IDI) index 0.03, p = 0.03] and number of obstructive vessels (IDI index 0.06, p = 0.002), and by trend for segment stenosis score (IDI 0.03, p = 0.06). Conclusion For asymptomatic diabetic individuals, CCTA measures of CAD severity confer incremental risk prediction, discrimination and reclassification on a per-patient, per-vessel and per-segment basis.
    Atherosclerosis 02/2014; 232(2):298–304. · 3.71 Impact Factor
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    ABSTRACT: Background: Approximately 55,000 persons become infected with the human immunodeficiency virus (HIV) in the United States annually. Early HAART regimens have commonly been associated with the lipodystrophy syndrome including hyperlipidemia and fat redistribution. The purpose of this study is to quantitate intramyocardial lipid accumulation in a group of HIV (+) patients receiving HAART using cardiac magnetic resonance spectroscopy (cMR Spec). Methods: This is a prospective pilot study of 25 asymptomatic HIV (+) subjects and 25 HIV (-) controls. For cases, inclusion criteria: 35-55 years of age; HAART for ≥ 3 years. Exclusion criteria: known cardiovascular disease, current smoking, diabetes history, IV drug use, GFR < 60 ml/min, or prior AIDS-defining illness. For controls: confirmed negative HIV EIA; matched to cases for age (+/- 3 years), sexual orientation and medical history. Subjects underwent cMR Spec, along with detailed medical history, HIV and HAART history, physical exam including hip/waist ratio, lipid testing, and inflammatory lab tests. Results: Among HIV(+) subjects, mean duration of HIV infection was 17 years (range 5-28 years); mean duration of antiretroviral therapy was -13 years (range 3-26 years). Preliminary results: Intramyocardial lipid accumulation was found to be- HIV (+) subjects (n=19), Median = 0.87% (range = 0 to 4.28 %) versus HIV (-) controls (n=17), Median = 0.25% (range = 0 to 3.87%). Correlations of these data with biomarkers of lipodystrophy, including lipid levels, hip/waist ratio, and antiretroviral history are currently under investigation and will be presented. Conclusion: Our study, using cMR Spec, demonstrates a higher percentage of intracardiac lipid accumulation, as well as a higher volume of epidcardial fat, among HIV+ subjects on HAART compared to HIV(-) controls. This increase in cardiac lipid may contribute to or be associated with an increased risk of cardiovascular disease, including end-stage heart failure in this patient population. Further investigation is needed in order to determine the impact and long-term sequelae of myocardial lipid accumulation in HIV+ patients on HAART.
    IDWeek 2013 Meeting of the Infectious Diseases Society of America; 10/2013
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    ABSTRACT: Subendocardial dark-rim artifacts (DRAs) remain a major concern in first-pass perfusion (FPP) myocardial MRI and may lower the diagnostic accuracy for detection of ischemia. A major source of DRAs is the "Gibbs ringing" effect. We propose an optimized radial acquisition strategy aimed at eliminating ringing-induced DRAs in FPP. By studying the underlying point spread function (PSF), we show that optimized radial sampling with a simple reconstruction method can eliminate the oscillations in the PSF that cause ringing artifacts. We conducted realistic MRI phantom experiments and in vivo studies (n = 12 healthy humans) to evaluate the artifact behavior of the proposed imaging scheme in comparison to a conventional Cartesian imaging protocol. Simulations and phantom experiments verified our theoretical expectations. The in vivo studies showed that optimized radial imaging is capable of significantly reducing DRAs in the early myocardial enhancement phase (during which the ringing effect is most prominent and may obscure perfusion defects) while providing similar resolution and image quality compared with conventional Cartesian imaging. The developed technical framework and results demonstrate that, in comparison to conventional Cartesian techniques, optimized radial imaging with the proposed optimizations significantly reduces the prevalence and spatial extent of DRAs in FPP imaging. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc.
    Magnetic Resonance in Medicine 09/2013; · 3.40 Impact Factor
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    ABSTRACT: Patients with flow-limiting coronary stenoses exhibit elevated left ventricular end-diastolic pressure (LVEDP) and abnormal left ventricular (LV) relaxation. We investigated the relationship of extent and severity of coronary artery disease (CAD) by coronary CT angiography (CTA) to LVEDP and measures of LV diastolic dysfunction. We identified consecutive patients undergoing coronary CTA and transthoracic echocardiography who were assessed for diastolic function. CAD was evaluated on a per-patient, per-vessel, and per-segment basis for intraluminal diameter stenosis by using an 18-segment model (0 = none, 1 = 1%-49%, 2 = 50%-69%, and 3 = 70%-100%) and summed over segments to obtain overall coronary plaque burden (segment stenosis score [SSS]; maximum = 54). Transthoracic echocardiography evaluated mitral inflow E wave-to-A wave ratio, tissue Doppler early mitral annual tissue velocity axial excursion, stage of diastolic dysfunction, and LV dimensions and estimated LVEDP from the ratio of mitral inflow velocity to early mitral annular (medial) tissue velocity. Four hundred seventy-eight patients (57% women; mean age, 57.9 ± 14.6 years; 24.9% prior CAD) comprised the study population. Increasing per-patient maximal coronary stenosis, number of vessels with obstructive stenosis, and SSS were associated with increased LVEDP. The prevalence of advanced diastolic dysfunction increased with greater number of obstructive vessels. In multivariable analyses, SSS was associated with increased LVEDP (0.8 mm Hg per tertile increase in SSS, 0.5-1.1; P < .001); reduced E' axial excursion (-0.3; 95% confidence interval [CI], -0.5 to -0.1; P = .001), increased LV mass index (1.6 g/m(2) per tertile increase in SSS; P = .04), and increased relative wall thickness (0.005; 95% CI, 0.004-0.009; P = .03), with consistent relationships persisting even among persons with per-patient maximal stenosis <50% and LV ejection fraction ≥55%. Extent and severity of obstructive as well as nonobstructive CAD by coronary CTA are associated with increased LVEDP and measures of diastolic dysfunction.
    Journal of cardiovascular computed tomography 09/2013; 7(5):289-296.e1. · 2.55 Impact Factor
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    ABSTRACT: Purpose:To evaluate beam-hardening (BH) artifact reduction in coronary computed tomography (CT) angiography with dual-energy CT, to define the optimal monochromatic-energy levels for coronary and myocardial signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in dual-energy CT, and to compare these levels with single-energy CT.Materials and Methods:The study was approved by the institutional review board and/or ethics committee at each site. Patients provided informed consent. Thirty-nine patients were prospectively enrolled to undergo dual-energy CT, and 25 also underwent single-energy CT. Myocardial and coronary SNR, CNR, and iodine concentration were measured across multiple segments at varying monochromatic energy levels (40-140 keV). BH was defined as signal decrease in basal inferior wall versus midinferior wall, and signal increase in midseptum versus midinferior wall. Generalized estimating equation was used to identify optimal monochromatic-energy levels and compare them with single-energy CT.Results:BH was noted at single-energy CT with basal inferior wall mean reduction of 19.7 HU ± 29.2 (standard deviation) and midseptum increase of 46.3 HU ± 36.3. There was reduction in this artifact at 90 keV or greater (1.7 HU ± 18.4 in basal inferior wall and 20.1 HU ± 37.5 in midseptum at 90 keV; P < .05). SNR and CNR were higher in the myocardium and coronary arteries at 60-80 keV than single-energy CT (myocardium: SNR, 3.02 vs 2.39, and CNR, 6.73 vs 5.16; coronary arteries: SNR, 10.83 vs 7.75, and CNR, 13.31 vs 9.54; P < .01). Mean iodine concentration in resting myocardium was 2.19 mg/mL ± 0.57.Conclusion:Rapid kilovolt peak-switching dual-energy CT resulted in significant BH reduction and improvements in SNR and CNR in the myocardium and coronary arteries.© RSNA, 2013Supplemental material:
    Radiology 04/2013; · 6.21 Impact Factor
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    ABSTRACT: Patients with chronic kidney disease have a worse cardiovascular prognosis than those without. The aim of this study was to determine the incremental prognostic value of coronary computed tomographic angiography in predicting mortality across the entire spectrum of renal function in patients with known or suspected coronary artery disease (CAD). A large international multicenter registry was queried, and patients with left ventricular ejection fraction (LVEF) and creatinine data were screened. National Cholesterol Education Program Adult Treatment Panel III risk was calculated. Coronary computed tomographic angiographic results were evaluated for CAD severity (normal, nonobstructive, or obstructive) and an LVEF <50%. Patients were followed for the end point of all-cause mortality. Among 5,655 patients meeting the study criteria, follow-up was available for 5,572 (98.9%; median follow-up duration 18.6 months). All-cause mortality (66 deaths) significantly increased with every 10-unit decrease in renal function (hazard ratio [HR] 1.23, 95% confidence interval [CI] 1.07 to 1.41). All-cause mortality occurred in 0.33% of patients without coronary atherosclerosis, 1.82% of patients with nonobstructive CAD, and 2.43% of patients with obstructive CAD. Multivariate Cox proportional-hazards models revealed that impaired renal function (HR 2.29, 95% CI 1.65 to 3.18), CAD severity (HR 1.81, 95% CI 1.31 to 2.51), and an abnormal LVEF (HR 4.16, 95% CI 2.45 to 7.08) were independent predictors of all-cause mortality. In conclusion, coronary computed tomographic angiographic measures of CAD severity and the LVEF provide effective risk stratification across a wide spectrum of renal function. Furthermore, renal dysfunction, CAD severity, and the LVEF have additive value for predicting all-cause death in patients with suspected obstructive CAD.
    The American journal of cardiology 03/2013; · 3.58 Impact Factor
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    ABSTRACT: Although an increased pulmonary trunk (PT) diameter to ascending aorta (AA) diameter ratio (PT/AA ratio) is associated with pulmonary hypertension, the prognostic utility of this metric remains unexamined. We investigated whether an increase in the PT/AA ratio, as measured using coronary computed tomographic angiography, is associated with the risk of all-cause death. We identified 1,326 consecutive patients (mean age 61 ± 13 years; 60% men) without known coronary artery disease who underwent coronary computed tomographic angiography. Patients with a history of congenital or valvular heart disease or aortic enlargement (≥4 cm) were excluded. The PT and AA diameters were measured at the PT bifurcation level. The patients were categorized by PT/AA deciles, with the ≥90th percentile (PT/AA ratio 0.9) considered elevated. All-cause death associated with a PT/AA ratio <0.9 versus ≥0.9 was evaluated using multivariate Cox proportional hazard models. During 2.9 ± 1.0 years of follow-up, 58 patients died. Patients with a PT/AA ratio ≥0.9 experienced 2.5-fold greater annualized mortality compared to those with <0.9 (3.1% vs 1.3%, p = 0.004). Adjusting for age, gender, heart rate, dyslipidemia, smoking, and coronary artery disease extent, the patients with a PT/AA ratio ≥0.9 experienced a greater mortality risk compared to patients with PT/AA ratio <0.9 (hazard ratio 3.2, 95% confidence interval 1.6 to 6.6, p = 0.001). In the 1,059 patients with left ventricular ejection fraction measurements, a lower left ventricular ejection fraction was observed in the PT/AA ratio ≥0.9 group (p <0.05). In conclusion, incrementally and independent of the traditional coronary artery disease risk factors, an elevated PT/AA ratio was associated with increased mortality risk in patients without known coronary artery disease undergoing coronary computed tomographic angiography.
    The American journal of cardiology 02/2013; · 3.58 Impact Factor
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    ABSTRACT: PURPOSE: To develop a three-dimensional retrospective image-based motion correction technique for whole-heart coronary MRA with self-navigation that eliminates both the need to setup a diaphragm navigator and gate the acquisition. METHODS: The proposed technique uses one-dimensional self-navigation to track the superior-inferior translation of the heart, with which the acquired three-dimensional radial k-space data is segmented into different respiratory bins. Respiratory motion is then estimated in image space using an affine transform model and subsequently this information is used to perform efficient motion correction in k-space. The performance of the proposed technique on healthy volunteers is compared with the conventional navigator gating approach as well as data binning using diaphragm navigator. RESULTS: The proposed method is able to reduce the imaging time to 7.1±0.5 min from 13.9±2.6 min with conventional navigator gating. The scan setup time is reduced as well due to the elimination of the navigator. The proposed method yields excellent image quality comparable with either conventional navigator gating or the navigator binning approach. CONCLUSION: We have developed a new respiratory motion correction technique for coronary MRA that enables 1 mm(3) isotropic resolution and whole-heart coverage with 7 min of scan time. Further tests on patient population are needed to determine its clinical usage. Magn Reson Med, 2013. © 2013 Wiley Periodicals, Inc.
    Magnetic Resonance in Medicine 02/2013; 71(1). · 3.40 Impact Factor
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    Journal of Cardiovascular Magnetic Resonance 01/2013; 15(1). · 4.44 Impact Factor
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    ABSTRACT: Prospectively triggered coronary computed tomography angiography (CTA) is commonly performed with a widened acquisition window to provide flexibility in image reconstruction. We conducted a randomized controlled trial to determine whether the use of a narrow acquisition window in prospectively triggered coronary CTA would allow lower radiation dose while preserving image quality and interpretability. Prospective 2-center 2- platform randomized trial that evaluated 205 consecutive patients 96 with widened acquisition (WA) and 109 narrow acquisition (NA) referred for coronary CTA in sinus rhythm and heart rate <65 beats/min. Patients scanned with WA had phases reconstructed at 5% intervals, and each phase was assigned an individual study ID. Images were reviewed with individual phase reconstructions interpreted randomly by 2 level 3 readers with a third for consensus. Images were evaluated with a 5-point Likert scale on a per-vessel basis (best score on any phase). Scores were then dichotomized into diagnostic (score 3-5) compared with nondiagnostic (score 1-2). Readers also reported obstructive coronary artery disease on a per-patient basis. Agreement for the diagnosis of obstructive disease and per-artery interpretability was performed. Signal and noise measurements were also performed. No difference in demographics between groups (P = NS). The signal-to-noise ratio was comparable 12.99 ± 3.4 NA and 12.53 ± 4.13 for the WA (P = 0.45). The median effective dose was 1.78 mSv for NA compared with 3.26 mSv for WA (P < 0.001). Image quality, diagnostic interpretability, interreader agreement, and downstream testing were not significantly different between the 2 groups (P= NS for all). Coronary CTA with NA resulted in a 47% lower radiation dose without significant difference in study interpretability or image quality or increased downstream resource use or testing.
    Journal of cardiovascular computed tomography 01/2013; 7(1):18-24. · 2.55 Impact Factor
  • Anesthesia and analgesia 12/2012; · 3.42 Impact Factor
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    ABSTRACT: Studies examining coronary computed tomographic angiography (CCTA) have demonstrated increased mortality related to coronary artery disease (CAD) severity but are limited to relatively nondiverse ethnic populations. The aim of this study was to evaluate the prognostic significance of CAD on CCTA according to ethnicity for patients without previous CAD in a prospective international CCTA registry of 11 sites (7 countries) who underwent 64-slice CCTA from 2005 to 2010. CAD was defined as any coronary artery atherosclerosis and obstructive CAD as ≥50% stenosis. All-cause mortality and nonfatal myocardial infarction (MI) were assessed by ethnicity using Kaplan-Meier and Cox proportional hazards, controlling for baseline risk factors, medications, and revascularization. A total of 16,451 patients of mean age 58 years (55% men) were followed over a median of 2.0 years (interquartile range 1.4 to 3.2). Patients were 60.1% Caucasian, 34.4% East Asian, and 5.5% African. Death or MI occurred in 0.5% (38 of 7,109) among patients with no CAD, 1.6% (91 of 5,600) among those with nonobstructive CAD, and 3.8% (142 of 3,742) among those with ≥50% stenosis (p <0.001 among all groups). The annualized incidence of death or MI comparing obstructive to no obstructive CAD among Caucasians was 2.2% versus 0.7% (adjusted hazard ratio [aHR] 2.77, 95% confidence interval [CI] 1.73 to 4.43, p <0.001), among Africans 4.8% versus 1.1% (aHR 6.25, 95% CI 1.12 to 34.97, p = 0.037), and among East Asians 0.8% versus 0.1% (aHR 4.84, 95% CI 2.24 to 10.9, p <0.001). Compared to other ethnicities, East Asians had fewer than expected events (aHR 0.25, 95% CI 0.16 to 0.38, p <0.001). In conclusion, the presence and severity of CAD visualized by CCTA predict death or MI across 3 large ethnicities, whereas normal results on CCTA identify patients at very low risk.
    The American journal of cardiology 12/2012; · 3.58 Impact Factor
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    ABSTRACT: AimsTo date, the therapeutic benefit of revascularization vs. medical therapy for stable individuals undergoing invasive coronary angiography (ICA) based upon coronary computed tomographic angiography (CCTA) findings has not been examined.Methods and resultsWe examined 15 223 patients without known coronary artery disease (CAD) undergoing CCTA from eight sites and six countries who were followed for median 2.1 years (interquartile range 1.4-3.3 years) for an endpoint of all-cause mortality. Obstructive CAD by CCTA was defined as a ≥50% luminal diameter stenosis in a major coronary artery. Patients were categorized as having high-risk CAD vs. non-high-risk CAD, with the former including patients with at least obstructive two-vessel CAD with proximal left anterior descending artery involvement, three-vessel CAD, and left main CAD. Death occurred in 185 (1.2%) patients. Patients were categorized into two treatment groups: revascularization (n = 1103; 2.2% mortality) and medical therapy (n = 14 120, 1.1% mortality). To account for non-randomized referral to revascularization, we created a propensity score developed by logistic regression to identify variables that influenced the decision to refer to revascularization. Within this model (C index 0.92, χ2 = 1248, P < 0.0001), obstructive CAD was the most influential factor for referral, followed by an interaction of obstructive CAD with pre-test likelihood of CAD (P = 0.0344). Within CCTA CAD groups, rates of revascularization increased from 3.8% for non-high-risk CAD to 51.2% high-risk CAD. In multivariable models, when compared with medical therapy, revascularization was associated with a survival advantage for patients with high-risk CAD [hazards ratio (HR) 0.38, 95% confidence interval 0.18-0.83], with no difference in survival for patients with non-high-risk CAD (HR 3.24, 95% CI 0.76-13.89) (P-value for interaction = 0.03).Conclusion In an intermediate-term follow-up, coronary revascularization is associated with a survival benefit in patients with high-risk CAD by CCTA, with no apparent benefit of revascularization in patients with lesser forms of CAD.
    European Heart Journal 10/2012; · 14.72 Impact Factor
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    ABSTRACT: OBJECTIVES: Our objective was to examine patterns of follow-up invasive coronary angiography (ICA) and revascularization (REV) after coronary computed tomography angiography (CCTA). BACKGROUND: CCTA is a noninvasive test that permits direct visualization of the extent and severity of coronary artery disease (CAD). Post-CCTA patterns of follow-up ICA and REV are incompletely defined. METHODS: We examined 15,207 intermediate likelihood patients from 8 sites in 6 countries; these patients were without known CAD, underwent CCTA, and were followed up for 2.3 ± 1.2 years for all-cause mortality. Coronary artery stenosis was judged as obstructive when ≥50% stenosis was present. A multivariable logistic regression was used to estimate ICA use. A Cox proportional hazards model was used to estimate all-cause mortality. RESULTS: During follow-up, ICA rates for patients with no CAD to mild CAD according to CCTA were low (2.5% and 8.3%), with similarly low rates of REV (0.3% and 2.5%). Most ICA procedures (79%) occurred ≤3 months of CCTA. Obstructive CAD was associated with higher rates of ICA and REV for 1-vessel (44.3% and 28.0%), 2-vessel (53.3% and 43.6%), and 3-vessel (69.4% and 66.8%) CAD, respectively. For patients with <50% stenosis, early ICA rates were elevated; over the entirety of follow-up, predictors of ICA were mild left main, mild proximal CAD, respectively, or higher coronary calcium scores. In patients with <50% stenosis, the relative hazard for death was 2.2 (p = 0.011) for ICA versus no ICA. Conversely, for patients with CAD, the relative hazard for death was 0.61 for ICA versus no ICA (p = 0.047). CONCLUSIONS: These findings support the concept that CCTA may be used effectively as a gatekeeper to ICA.
    Journal of the American College of Cardiology 10/2012; · 15.34 Impact Factor
  • Ryo Nakazato, Damini Dey, Troy M. LaBounty
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    ABSTRACT: While coronary computed tomographic angiography (CCTA) has high diagnostic performance to identify and exclude obstructive coronary artery disease, it is susceptible to false-positive results and non-interpretable studies, and requires the use of ionizing radiation. New methods of image reconstruction and post-processing have the potential to significantly improve image quality, reduce the number of non-interpretable studies, and improve the diagnostic accuracy of CCTA. In this manuscript, we will review current and novel technologies for image reconstruction and post-processing that may improve the image quality of CCTA.
    Current Cardiovascular Imaging Reports 10/2012; 5(5).

Publication Stats

908 Citations
449.80 Total Impact Points


  • 2011–2014
    • Cedars-Sinai Medical Center
      • Cedars Sinai Medical Center
      Los Angeles, California, United States
  • 2012–2013
    • Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center
      • Department of Medicine
      Torrance, California, United States
    • Emory University
      • School of Medicine
      Atlanta, GA, United States
    • Brigham and Women's Hospital
      • Center for Brain Mind Medicine
      Boston, MA, United States
    • Robarts Research Institute
      • Imaging Research Laboratories
      London, Ontario, Canada
  • 2006–2013
    • University of Michigan
      • • Cardiovascular Center (CVC)
      • • Division of Cardiovascular Medicine
      Ann Arbor, Michigan, United States
  • 2010–2012
    • University of British Columbia - Vancouver
      • Division of Cardiology
      Vancouver, British Columbia, Canada
  • 2009–2012
    • Weill Cornell Medical College
      • Division of Cardiology
      New York City, New York, United States
  • 2010–2011
    • New York Presbyterian Hospital
      • Department of Cardiology
      New York City, New York, United States