Kendrick A Shunk

San Francisco VA Medical Center, San Francisco, California, United States

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Publications (65)631.96 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Limited data exist on long-term outcomes of patients with stent thrombosis (ST). Our aim was to describe the long-term outcomes after angiographically confirmed ST. In this multicentre registry, consecutive cases of definite ST were identified between 2005 and 2013. Clinical and procedural characteristics, in-hospital outcomes and long-term survival up to five years were compared between those with and those without adverse cardiovascular and cerebrovascular events (MACCE), defined as all-cause mortality, myocardial infarction and stroke. Two hundred and twenty-one patients with 239 stent thrombosis events were identified. Patients who developed MACCE were older, less likely to be men, and less likely to have hypertension. Angiographic characteristics were similar. Patients who had a MACCE event showed a trend towards a lower likelihood of procedural success (86% vs. 91%, p=0.05). MACCE rates were 22% at one year and 41% at five years. All-cause mortality was 13% at one year and 24% at five years. On multivariable analysis, age, diabetes mellitus, active smoking and ST at a bifurcation were independently associated with the occurrence of MACCE up to five years. Age, active smoking, diabetes mellitus and bifurcation disease are independently associated with long-term MACCE over a five-year follow-up period.
    EuroIntervention: journal of EuroPCR in collaboration with the Working Group on Interventional Cardiology of the European Society of Cardiology 06/2015; 11(2):188-195. DOI:10.4244/EIJV11I2A33 · 3.77 Impact Factor
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    ABSTRACT: Abstract Objectives This study sought to determine whether pre-percutaneous coronary intervention (PCI) plaque characterization using near-infrared spectroscopy identifies lipid-rich plaques at risk of periprocedural myonecrosis and whether these events may be prevented by the use of a distal protection filter during PCI. Background Lipid-rich plaques may be prone to distal embolization and periprocedural myocardial infarction (MI) in patients undergoing PCI. Methods Patients undergoing stent implantation of a single native coronary lesion were enrolled in a multicenter, prospective trial. Near-infrared spectroscopy and intravascular ultrasound were performed at baseline, and lesions with a maximal lipid core burden index over any 4-mm length (maxLCBI4mm) ≥600 were randomized to PCI with versus without a distal protection filter. The primary endpoint was periprocedural MI, defined as troponin or a creatine kinase-myocardial band increase to 3 or more times the upper limit of normal. Results Eighty-five patients were enrolled at 9 U.S. sites. The median (interquartile range) maxLCBI4mm was 448.4 (274.8 to 654.4) pre-PCI and decreased to 156.0 (75.6 to 312.6) post-PCI (p < 0.0001). Periprocedural MI developed in 21 patients (24.7%). The maxLCBI4mm was higher in patients with versus without MI (481.5 [425.6 to 679.6] vs. 371.5 [228.9 to 611.6], p = 0.05). Among 31 randomized lesions with maxLCBI4mm ≥600, there was no difference in the rates of periprocedural MI with versus without the use of a distal protection filter (35.7% vs. 23.5%, respectively; relative risk: 1.52; 95% confidence interval: 0.50 to 4.60, p = 0.69). Conclusions Plaque characterization by near-infrared spectroscopy identifies lipid-rich lesions with an increased likelihood of periprocedural MI after stent implantation, presumably due to distal embolization. However, in this pilot randomized trial, the use of a distal protection filter did not prevent myonecrosis after PCI of lipid-rich plaques.
    JACC. Cardiovascular Interventions 05/2015; DOI:10.1016/j.jcin.2015.01.032 · 7.35 Impact Factor
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    ABSTRACT: Objectives The aim of this study was to describe contemporary frequency, predictors, and outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI) in the United States. Background CTO PCI can provide significant clinical benefits, yet there is limited information on its success and safety in unselected patient populations. Methods We analyzed the frequency and outcomes of CTO PCI compared with non-CTO PCI in elective patients, and of successful versus failed CTO PCI between July 1, 2009, and March 31, 2013, in the National Cardiovascular Data Registry CathPCI Registry. Generalized estimating equations logistic regression modeling was used to generate independent variables associated with procedural success and procedural complications. Results During the study period, CTO PCI represented 3.8% of the total PCI volume for stable coronary artery disease (22,365 of 594,510). Overall, patients undergoing CTO PCI required greater contrast volume and longer fluoroscopy time and had lower procedural success (59% vs. 96%, p < 0.001) and higher major adverse cardiac event (1.6% vs. 0.8%, p < 0.001) rates than non-CTO PCI patients. On multivariable analysis, several parameters (including older age, current smoking, previous myocardial infarction, previous coronary artery bypass graft, previous peripheral arterial disease, previous cardiac arrest, right coronary artery CTO target vessel, and less operator experience) were associated with a lower likelihood of CTO PCI procedural success, whereas operators' annual CTO PCI volume was associated with improved success without a significant increase in major complications. Conclusions CTO PCI is currently performed infrequently in the United States for stable coronary artery disease and is associated with lower procedural success and higher complication rates compared with non-CTO PCI. Procedural success was associated with several patient factors and operator experience.
    JACC Cardiovascular Interventions 02/2015; 8(2):245-53. DOI:10.1016/j.jcin.2014.08.014 · 7.35 Impact Factor
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    ABSTRACT: Transcatheter aortic valve replacement (TAVR) revolutionized the treatment of aortic stenosis. Developing a TAVR program with a custom-built hybrid operating room (HOR) outside the surgical operating room area poses unique challenges in Veterans Affairs (VA) institutions. To present the process by which the San Francisco VA Medical Center developed a VA-approved TAVR program, in which an HOR exists in a cardiac catheterization laboratory, as a guideline for future programs. Retrospective review of each required approval process for developing an HOR in a cardiac catheterization laboratory in a VA designated for complex surgery. Participants included San Francisco VA Medical Center health care professionals and individuals responsible for new program initiation in VA institutions. External reviews by industry vendors, the VA Central Office, and the Office for Construction, Facilities, and Management and an internal Healthcare Failure Mode and Effect Analysis. The timeline for each process. Developing a TAVR program required vetting and approval from industry vendors, who provided training and expertise. Architectural plans for construction of the HOR began in 2010-2011, followed by approval from Edwards Lifesciences, Inc, in 2012 and fundamentals training on February 8 and 9, 2013. Following a pilot launch of the first VA TAVR program at the Houston VA Medical Center, subsequent programs were required to submit a plan to the VA Central Office for proposed restructuring of their clinical programs. After the San Francisco VA Medical Center proposal submission on February 3, 2013, a site visit consisting of a National Chief of Catheterization Laboratory Managers, a cardiac surgeon, and an interventional cardiologist with TAVR experience was conducted on April 12, 2013. During construction, HOR plans were inspected by the Office for Construction, Facilities, and Management followed by on-site inspection on August 8, 2013, to assess the adequacy of the HOR, newly built restricted corridors, equipment storage areas, and altered staff and patient flow patterns. Last, a Healthcare Failure Mode and Effect Analysis was performed to mitigate any negative effects of the HOR not being colocated in the surgical operating room area. Approval was then granted on November 13, 2013. Our first 10 TAVR cases were successfully completed as of April 2, 2014. The primary factor for development of a successful TAVR program is integration of the heart valve team. Particular adaptations to the cardiac catheterization laboratory environment are required to accommodate an uncompromised HOR in which cardiac and vascular surgeons can be as comfortable as their interventional cardiology colleagues.
    01/2015; 150(3). DOI:10.1001/jamasurg.2014.1404
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    ABSTRACT: Objectives To characterize the prevalence of thrombus burden, collateral vessels to the infarct-related artery, epicardial coronary artery flow, and myocardial perfusion in patients with angiographically confirmed definite stent thrombosis (ST), and to define their relationship with associated treatments and outcomes. Background Angiographic characteristics of ST are not well defined. Methods All cases of angiographically determined ST at five academic hospitals from 2005 to 2012 were reviewed. Demographic, procedural, and angiographic characteristics were recorded. In-hospital and 1-year follow-up data were obtained. ResultsAmong 205 cases of angiographic definite ST (608 years; 87% male), the majority presented with late/very late ST (69%) and STEMI (66%). High-risk angiographic findings at presentation included thrombus grade 4-5 (87%), absence of collateral vessels (76%), and reduced initial TIMI 3 flow (90%). Final TIMI 3 flow was achieved in 90% of patients and was associated with greater use of aspiration thrombectomy (60% vs. 25%; P=0.003), glycoprotein IIb/IIIa inhibitors (80% vs. 30%, P<0.001), and repeat stenting (67% vs. 10%, P<0.001). A final myocardial perfusion grade of 2-3 was achieved in 79% of patients and was associated with greater use of aspiration thrombectomy (61% vs. 36%, P=0.003). After multivariable logistic regression, aspiration thrombectomy (AOR 2.6, 95% CI 1.3-5.2) and implantation of a new stent (AOR 2.1, 95% CI 1.1-4.3) were associated with optimal combined epicardial flow and myocardial perfusion. At 1-year follow-up, significantly lower risk of repeat ST (HR 0.1; 95% CI 0.1,0.2; P<0.001) among patients with initial TIMI 3 flow at index ST was observed. Conclusions The majority of ST patients present with late/very late ST with high thrombus burden and STEMI. Presence of collateral vessels and low thrombus burden is cardioprotective, while reduced initial TIMI flow is associated with larger infarct size and recurrent ST. Aspiration thrombectomy and repeat stenting are associated with improved epicardial coronary artery flow and myocardial perfusion among patients treated for ST. (c) 2014 Wiley Periodicals, Inc.
    Catheterization and Cardiovascular Interventions 01/2015; 85(1). DOI:10.1002/ccd.25519 · 2.11 Impact Factor
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    ABSTRACT: The risk of mortality for patients presenting to the cardiac catheterization laboratory with stent thrombosis (ST) may differ as a function of the timing from initial stent implantation. We hypothesized that the 30-day mortality would differ for angiographically defined early ST (EST), late ST (LST), and very late ST (VLST). Methods All patients undergoing angiography for diagnosis and treatment of ST were identified by the Department of Veterans Affairs (VA) Clinical Assessment, Reporting, and Tracking (CART) Program from 2006 to 2012. Stent thrombosis occurring ≤30 days after stent implantation were defined as EST; 31 to 365 days as LST; and >365 days as VLST. Log-rank test and Cox proportional hazard regression modeling were used to describe unadjusted and adjusted differences in mortality between groups. Results A total of 656 patients were diagnosed with angiographic definite ST with known timing. This cohort consisted of 129 (20%), 138 (21%), and 389 (59%) patients with EST, LST, and VLST, respectively. Over three fourths (76%) of VLST cases occurred >2 years after stent implantation. Stent thrombosis timing was significantly associated with 30-day mortality risk in unadjusted (P < .001) and adjusted (P = .04) analyses. Unadjusted mortality risk was 3% in VLST, 6% in LST, and 13% in EST. After multivariable adjustment, patients with LST had nonsignificantly lower 30-day mortality (hazard ratio [HR] for LST, 0.5; 95% CI, 0.2-1.2), whereas VLST had significantly lower 30-day mortality (HR for VLST, 0.38; 95% CI, 0.18-0.82) when compared with patients with EST. Conclusions Thirty-day mortality after an angiographic definite ST presentation is associated with time from index percutaneous coronary intervention to ST. This relationship potentially reflects the differing mechanisms of ST that are postulated to predominate at different timeframes.
    American Heart Journal 10/2014; 168(4). DOI:10.1016/j.ahj.2014.07.020 · 4.46 Impact Factor
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    ABSTRACT: Objectives: The aim of this study was to determine the incidence, predictors, and outcomes of recurrent stent thrombosis (rST). Background: Patients who had an initial stent thrombosis (ST) develop may be at high risk of rST. Methods: We analyzed a multicenter California registry of angiographic definite ST at 5 academic hospitals from 2005 to 2013. A detailed review of the angiogram and procedure was performed of patients with and without rST. Results: Among 221 patients with a median follow-up of 3.3 years, definite or probable rST developed in 29, including 19 with angiographic definite rST. The cumulative hazard ratio (HR) of definite or probable rST was 16% at 1 year and 24% at 5 years, whereas the cumulative HR of angiographic definite rST was 11% at 1 year and 20% at 5 years. Despite similar angiographic results, patients who had rST develop had significantly greater peak creatine kinase at the time of initial ST (mean, 2,655 mg/dl vs. 1,654 mg/dl; p = 0.05) than those without rST. The 3-year rate of major adverse cardiovascular events was 50% for patients with rST compared with 22% for patients with a single ST (p = 0.01). After multivariable adjustment, independent predictors of definite/probable rST were age (HR: 1.4; 95 confidence interval [CI]: 1.1 to 1.8 per 10 years), bifurcation ST (HR: 4.4; 95% CI: 1.8 to 10.9), and proximal vessel diameter (HR: 1.8; 95% CI: 1.1 to 3.2 per millimeter). Conclusions: rST represents an important cause of long-term morbidity and mortality after an initial ST. Bifurcation ST and a larger proximal reference vessel diameter are independently associated with an increased risk of rST.
    JACC. Cardiovascular Interventions 10/2014; 7(10):1105-13. DOI:10.1016/j.jcin.2014.05.017 · 7.35 Impact Factor
  • Jeffrey Zimmet · Erhard Kaiser · Elaine Tseng · Kendrick Shunk
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    ABSTRACT: This is the first reported case of partial aortic valve and annulus rupture during transcatheter aortic valve replacement, and its successful management through percutaneous means. It stresses the fact that even severe procedural complications can often be treated by a heart team endovascularly, without requiring sternotomy.
    The Journal of invasive cardiology 10/2014; 26(10):E137-40. · 0.95 Impact Factor
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    ABSTRACT: The rate of concurrent right-heart catheterization (RHC) in patients undergoing left-heart catheterization (LHC) for coronary artery disease (CAD) indications or bilateral heart catheterization (BHC) is recommended as a measure of hospital quality, with higher rates suggesting over utilization. Our aim was to describe the prevalence of BHC and abnormal RHC findings in patients undergoing BHC with a primary indication for LHC. A retrospective analysis was performed for patients undergoing cardiac catheterization for CAD indications using the Department of Veterans Affairs Clinical Assessment Reporting and Tracking Program. Patients undergoing catheterization from October 2007 to September 2011 in 76 Veterans Affairs hospitals were included. Among 95,656 patients undergoing catheterization for CAD, 6,611 (6.9%) underwent BHC and 88,929 (93.0%) LHC. Among the patients undergoing BHC, 61.3% had at least 1 of the following abnormal RHC values: mean pulmonary artery (PA) pressure >25 mm Hg, pulmonary capillary wedge pressure (PCWP) >15 mm Hg, or pulmonary vascular resistance (PVR) >3 Woods units. A total of 37.5% of patients had mean PA pressures of 26 to 40 mm Hg and 11.1% had mean PA pressures >40 mm Hg. A total of 34.4% of patients had mean PCWP of 16 to 25 mm Hg and 13.6% had mean PAWP >25 mm Hg. A total of 16.5% of patients had PVR between 3 and 6 WU and 2.9% had PVR >6 WU. A total of 4.3% of patients met formal criteria for pulmonary arterial hypertension (defined as the combination of PA mean >25 mm Hg, PCWP ≤15 mm Hg, and PVR >3). In conclusion, these findings suggest that most BHC were performed for appropriate clinical reasons. Future studies should further explore BHC rate as an effective quality indicator.
    The American Journal of Cardiology 09/2014; 114(11). DOI:10.1016/j.amjcard.2014.08.047 · 3.28 Impact Factor
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    ABSTRACT: Recent advances in technology have led to an increase in the use of bilateral femoral artery access and the requirement for large-bore access. Optimal access is in the common femoral artery (CFA), rather than higher (in the external iliac artery) or lower (in one of the branches of the CFA). However, there is a paucity of data in the literature about the relationship between bifurcation level of one CFA and the contralateral CFA. To define the prevalence of high bifurcation of the CFA and the relationship between bifurcation level on both sides, we performed a retrospective analysis of all patients with bilateral femoral angiography. From 4880 femoral angiograms performed at UCSF cardiac catheterization laboratory between 2005-2013, a total of 273 patients had bilateral femoral angiograms. The prevalence of low/normal, high, and very-high femoral bifurcations was 70%, 26%, and 4%, respectively, with no difference between sides. A high or very-high bifurcation significantly increased the likelihood of a high bifurcation on the contralateral side (odds ratio >3.0). Multivariable logistic regression analysis revealed age, gender, self-reported race, height, weight, and body mass index were not predictive of high or very-high bifurcations on either side. In conclusion, high femoral artery bifurcations are common and increase the likelihood of a high bifurcation of the contralateral femoral artery.
    The Journal of invasive cardiology 09/2014; 26(9):409-412. · 0.95 Impact Factor
  • Journal of the American College of Cardiology 09/2014; 64(11):B56-B57. DOI:10.1016/j.jacc.2014.07.233 · 16.50 Impact Factor
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    Journal of the American College of Cardiology 04/2014; 63(12):A1769. DOI:10.1016/S0735-1097(14)61772-1 · 16.50 Impact Factor
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    Journal of the American College of Cardiology 04/2014; 63(12):A158. DOI:10.1016/S0735-1097(14)60158-3 · 16.50 Impact Factor
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    Journal of the American College of Cardiology 04/2014; 63(12):A1788. DOI:10.1016/S0735-1097(14)61791-5 · 16.50 Impact Factor
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    Journal of the American College of Cardiology 04/2014; 63(12):A148. DOI:10.1016/S0735-1097(14)60148-0 · 16.50 Impact Factor
  • Journal of the American College of Cardiology 12/2013; 63(7). DOI:10.1016/j.jacc.2013.12.003 · 16.50 Impact Factor
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    ABSTRACT: Background: Stent thrombosis (ST) is associated with a significant burden of coronary thrombus and potential microvascular obstruction. Aspiration thrombectomy may decrease the extent of microvascular obstruction in patients with acute myocardial infarction but its role in the treatment of ST is uncertain. The present study sought to evaluate the association between aspiration thrombectomy, procedural success and long-term outcomes among patients presenting with ST. Methods: In a multicenter cohort of patients with definite ST, procedural success, long-term mortality and major adverse cardiovascular events (death, stroke, re-infarction, revascularization) were ascertained. Propensity weighting was used to determine the association between aspiration thrombectomy and long-term outcomes. Results: A total of 205 patients with ST were identified. Among these, 115 (56%) patients underwent adjunctive aspiration thrombectomy during percutaneous coronary intervention. Patients undergoing aspiration thrombectomy were more likely to present with ST-elevation myocardial infarction (75% vs. 52%, P<0.003) and require hemodynamic support (19% vs. 10%, P=0.07). Aspiration thrombectomy was associated with improved procedural outcomes including post-procedural TIMI 3 flow, resulting in higher angiographic and procedural success (each 96% vs. 83%, P<0.001). Despite improved angiographic outcomes, the use of aspiration thrombectomy was not associated with a difference in long-term mortality (adjusted HR 0.99, 95% CI 0.44-2.24) or major adverse cardiovascular events (adjusted HR 1.06, 95% CI 0.45-2.48). Conclusions: Aspiration thrombectomy is associated with improved coronary flow and procedural success but is not associated with improved long-term outcomes among patients undergoing percutaneous intervention for definite ST. © 2013 Wiley Periodicals, Inc.
    Catheterization and Cardiovascular Interventions 12/2013; 82(7). DOI:10.1002/ccd.25007 · 2.11 Impact Factor
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    Journal of the American College of Cardiology 10/2013; 62(18). DOI:10.1016/j.jacc.2013.08.986 · 16.50 Impact Factor
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    ABSTRACT: Transradial access (TRA) offers advantages including decreased vascular complications, reduced length of hospital stay, and reduced cost. The size of the radial artery (RA) limits the equipment that can be used via TRA. Intra-arterial (IA) vasodilators prevent and treat RA spasm, yet are not uniformly used in TRA and their effect on the absolute size of the RA remains unknown. 121 patients undergoing TRA for cardiac catheterization were included. 78 patients underwent RA angiography prior to administration of IA vasodilators ('no vasodilator' group), 43 patients underwent radial angiography after administration of an IA verapamil and nitroglycerin cocktail ('vasodilator' group). Quantitative angiography was used to compare the RA diameters. Clinical characteristics were similar between the groups, except that patients in the 'no vasodilator' cohort were taller (1.67±0.1m vs. 1.73±0.1m, p=0.002), and heavier (84.9±18.2kg vs. 75±17.1kg, p=0.003). In the 'vasodilator' group the proximal RA diameter was larger (2.29±0.47mm vs. 2.09±0.41mm, p=0.02) as was the narrowest segment (1.83±0.56mm vs 1.39±0.43, p<0.0001) compared to the 'no vasodilator' group. At the RA origin, 79.4% of those in the 'vasodilator' group were larger than a 6Fr guide catheter, compared to 51.4% in the 'no vasodilator' group (p=0.004). At the narrowest segment a higher percentage of RAs in the 'vasodilator' group were larger than a 5Fr guide catheter (65.1% vs 26.9%, p<0.001) and a 6Fr catheter (34.9% vs 10.3%, p=0.001). IA vasodilators increase pre-procedural RA diameter in patients undergoing cardiac catheterization via TRA. This increase in diameter has important implications for procedural planning. Boyer et al. performed a blinded controlled clinical trial investigating the effects of intra-arterial vasodilators on radial artery size and spasm during cardiac catheterization. The study demonstrates that intra-arterial vasodilators significantly increased the radial artery size throughout the entire course of the vessel and significantly decreased the amount of radial artery spasm. The authors conclude that these findings support the use of intra-arterial vasodilators during cardiac catheterization and have important implications for emerging technologies such as larger bore sheathless radial procedures.
    Cardiovascular revascularization medicine: including molecular interventions 10/2013; 14(6). DOI:10.1016/j.carrev.2013.08.009
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    ABSTRACT: This study sought to describe near-infrared spectroscopy (NIRS) findings of culprit lesions in ST-segment elevation myocardial infarction (STEMI). Although autopsy studies demonstrate that most STEMI are caused by rupture of pre-existing lipid core plaque (LCP), it has not been possible to identify LCP in vivo. A novel intracoronary NIRS catheter has made it possible to detect LCP in patients. We performed NIRS within the culprit vessels of 20 patients with acute STEMI and compared the STEMI culprit findings to findings in nonculprit segments of the artery and to findings in autopsy control segments. Culprit and control segments were analyzed for the maximum lipid core burden index in a 4-mm length of artery (maxLCBI4mm). MaxLCBI4mm was 5.8-fold higher in STEMI culprit segments than in 87 nonculprit segments of the STEMI culprit vessel (median [interquartile range (IQR)]: 523 [445, 821] vs. 90 [6, 265]; p < 0.001) and 87-fold higher than in 279 coronary autopsy segments free of large LCP by histology (median [IQR]: 523 [445, 821] vs. 6 [0, 88]; p < 0.001).Within the STEMI culprit artery, NIRS accurately distinguished culprit from nonculprit segments (receiver-operating characteristic analysis area under the curve = 0.90). A threshold of maxLCBI4mm >400 distinguished STEMI culprit segments from specimens free of large LCP by histology (sensitivity: 85%, specificity: 98%). The present study has demonstrated in vivo that a maxLCBI4mm >400, as detected by NIRS, is a signature of plaques causing STEMI.
    JACC. Cardiovascular Interventions 07/2013; 6(8). DOI:10.1016/j.jcin.2013.04.012 · 7.35 Impact Factor

Publication Stats

1k Citations
631.96 Total Impact Points


  • 2010–2015
    • San Francisco VA Medical Center
      San Francisco, California, United States
  • 2003–2015
    • University of California, San Francisco
      • • Department of Medicine
      • • Veterans Affairs Medical Center
      • • Department of Radiology and Biomedical Imaging
      • • Division of Hospital Medicine
      San Francisco, California, United States
  • 2013
    • U.S. Department of Veterans Affairs
      Washington, Washington, D.C., United States
  • 2008
    • Spokane VA Medical Center
      Spokane, Washington, United States