Persistent enhancement of exciton diffusivity in CsPbBr3 nanocrystal solids.

In semiconductors, exciton or charge carrier diffusivity is typically described as an inherent material property. Here, we show that the transport of excitons among CsPbBr3 perovskite nanocrystals (NCs) depends markedly on how recently those NCs were occupied by a previous exciton. Using transient photoluminescence microscopy, we observe a striking dependence of the apparent exciton diffusivity on excitation laser power that does not arise from nonlinear exciton-exciton interactions or thermal heating. We interpret our observations with a model in which excitons cause NCs to transition to a long-lived metastable configuration that markedly increases exciton transport. The exciton diffusivity observed here (>0.15 square centimeters per second) is considerably higher than that observed in other NC systems, revealing unusually strong excitonic coupling between NCs. The finding of a persistent enhancement in excitonic coupling may help explain other photophysical behaviors observed in CsPbBr3 NCs, such as superfluorescence, and inform the design of optoelectronic devices.

Alcohol septal ablation for obstructive hypertrophic cardiomyopathy: outcomes in young, middle-aged, and elderly patients.

OBJECTIVES: We compared the efficacy and safety of alcohol septal ablation (ASA) for obstructive hypertrophic cardiomyopathy (HCM) in young, middle-aged, and elderly patients. BACKGROUND: Intersociety guidelines suggest based on limited evidence that young patients with medically refractory symptoms of obstructive HCM should undergo surgical myectomy while elderly patients may be more appropriate for ASA. METHODS: Data for 360 patients undergoing 389 ASAs were prospectively collected and retrospectively analyzed according to age. RESULTS: Young (<45 years), middle-aged (45-64 years), and elderly (≥65 years) patients comprised 28, 40, and 32% of the study population, respectively. Young patients had thicker left ventricular septal walls at baseline, and elderly patients had more comorbidity and dyspnea. Resting, mean left ventricular outflow tract gradients (LVOTGs) were similar across the age groups at baseline (62, 66, and 68 mm Hg, respectively; P = NS for all comparisons). LVOTGs and dyspnea were significantly and similarly improved in all age groups immediately after ASA and through 12 months of follow-up (P < 0.001 for before and after comparisons; P = NS for intergroup comparisons). Complication rates were similar for young and middle-aged patients but higher for elderly patients (9.1 and 6.3% vs. 20.8%, respectively; P ≤ 0.016 for elderly vs. others). Mortality rates for young and middle-aged patients were lower than for elderly patients, but the differences were not statistically significant. CONCLUSIONS: Patients undergoing ASA had significant and similar improvements in LVOTGs and symptoms regardless of age. Procedural complications were increased in elderly patients, who had numerically but not statistically significantly higher mortality rates.

Light Emission in 2D Silver Phenylchalcogenolates.

Silver phenylselenolate (AgSePh, also known as "mithrene") and silver phenyltellurolate (AgTePh, also known as "tethrene") are two-dimensional (2D) van der Waals semiconductors belonging to an emerging class of hybrid organic-inorganic materials called metal-organic chalcogenolates. Despite having the same crystal structure, AgSePh and AgTePh exhibit a strikingly different excitonic behavior. Whereas AgSePh exhibits narrow, fast luminescence with a minimal Stokes shift, AgTePh exhibits comparatively slow luminescence that is significantly broadened and red-shifted from its absorption minimum. Using time-resolved and temperature-dependent absorption and emission microspectroscopy, combined with subgap photoexcitation studies, we show that exciton dynamics in AgTePh films are dominated by an intrinsic self-trapping behavior, whereas dynamics in AgSePh films are dominated by the interaction of band-edge excitons with a finite number of extrinsic defect/trap states. Density functional theory calculations reveal that AgSePh has simple parabolic band edges with a direct gap at Γ, whereas AgTePh has a saddle point at Γ with a horizontal splitting along the Γ-N1 direction. The correlation between the unique band structure of AgTePh and exciton self-trapping behavior is unclear, prompting further exploration of excitonic phenomena in this emerging class of hybrid 2D semiconductors.

Power-Dependent Photoluminescence Efficiency in Manganese-Doped 2D Hybrid Perovskite Nanoplatelets.

Substitutional metal doping is a powerful strategy for manipulating the emission spectra and excited state dynamics of semiconductor nanomaterials. Here, we demonstrate the synthesis of colloidal manganese (Mn2+)-doped organic-inorganic hybrid perovskite nanoplatelets (chemical formula: L2[APb1-xMnxBr3]n-1Pb1-xMnxBr4; L, butylammonium; A, methylammonium or formamidinium; n (= 1 or 2), number of Pb1-xMnxBr64- octahedral layers in thickness) via a ligand-assisted reprecipitation method. Substitutional doping of manganese for lead introduces bright (approaching 100% efficiency) and long-lived (>500 µs) midgap Mn2+ atomic states, and the doped nanoplatelets exhibit dual emission from both the band edge and the dopant state. Photoluminescence quantum yields and band-edge-to-Mn intensity ratios exhibit strong excitation power dependence, even at a very low incident intensity (<100 µW/cm2). Surprisingly, we find that the saturation of long-lived Mn2+ dopant sites cannot explain our observation. Instead, we propose an alternative mechanism involving the cross-relaxation of long-lived Mn-site excitations by freely diffusing band-edge excitons. We formulate a kinetic model based on this cross-relaxation mechanism that quantitatively reproduces all of the experimental observations and validate the model using time-resolved absorption and emission spectroscopy. Finally, we extract a concentration-normalized microscopic rate constant for band edge-to-dopant excitation transfer that is ∼10× faster in methylammonium-containing nanoplatelets than in formamidinium-containing nanoplatelets. This work provides fundamental insight into the interaction of mobile band edge excitons with localized dopant sites in 2D semiconductors and expands the toolbox for manipulating light emission in perovskite nanomaterials.

Two Origins of Broadband Emission in Multilayered 2D Lead Iodide Perovskites.

Broadband emission in lead iodide 2D perovskites has been alternately attributed to self-trapped excitons (STEs) or permanent structural defects and/or impurities. Here, we investigate six different multilayered (n > 1) 2D lead iodide perovskites as a function of sample temperature from 5 to 300 K. We distinguish shallow defect-associated emission from a broad near-infrared (NIR) spectral feature, which we assign to an STE through subgap photoexcitation experiments. When we varied the thickness (n = 2, 3, 4), A-site cation (methylammonium vs formamidinium), and organic spacer (butylammonium vs hexylammonium vs phenylethylammonium), we found that the temperature dependence of broad NIR emission was strongly correlated with both the strength of electron-phonon coupling and the extent of structural deformation of the ground-state lattice, strongly supporting the assignment of this spectral feature to an STE. However, the extent to which formation of these STEs is intrinsic versus defect-assisted remains open to debate.

2-Year Outcomes After Stenting of Lipid-Rich and Nonrich Coronary Plaques.

BACKGROUND: Autopsy studies suggest that implanting stents in lipid-rich plaque (LRP) may be associated with adverse outcomes. OBJECTIVES: The purpose of this study was to evaluate the association between LRP detected by near-infrared spectroscopy (NIRS) and clinical outcomes in patients with coronary artery disease treated with contemporary drug-eluting stents. METHODS: In this prospective, multicenter registry, NIRS was performed in patients undergoing coronary angiography and possible percutaneous coronary intervention (PCI). Lipid core burden index (LCBI) was calculated as the fraction of pixels with the probability of LRP >0.6 within a region of interest. MaxLCBI4mm was defined as the maximum LCBI within any 4-mm-long segment. Major adverse cardiac events (MACE) included cardiac death, myocardial infarction, definite or probable stent thrombosis, or unplanned revascularization or rehospitalization for progressive angina or unstable angina. Events were subcategorized as culprit (treated) lesion-related, nonculprit (untreated) lesion-related, or indeterminate. RESULTS: Among 1,999 patients who were enrolled in the COLOR (Chemometric Observations of Lipid Core Plaques of Interest in Native Coronary Arteries Registry), PCI was performed in 1,621 patients and MACE occurred in 18.0% of patients, of which 8.3% were culprit lesion-related, 10.7% were nonculprit lesion-related, and 3.1% were indeterminate during 2-year follow-up. Complications from NIRS imaging occurred in 9 patients (0.45%), which resulted in 1 peri-procedural myocardial infarction and 1 emergent coronary bypass. Pre-PCI NIRS imaging was obtained in 1,189 patients, and the 2-year rate of culprit lesion-related MACE was not significantly associated with maxLCBI4mm (hazard ratio of maxLCBI4mm per 100: 1.06; 95% confidence interval: 0.96 to 1.17; p = 0.28) after adjusting clinical and procedural factors. CONCLUSIONS: Following PCI with contemporary drug-eluting stents, stent implantation in NIRS-defined LRPs was not associated with increased periprocedural or late adverse outcomes compared with those without significant lipid.

Barriers to clopidogrel adherence following placement of drug-eluting stents.

BACKGROUND: Nonadherence to clopidogrel after drug-eluting stent (DES) placement is associated with in-stent thrombosis and adverse cardiac events. OBJECTIVE: To identify the incidence of and barriers associated with nonadherence to clopidogrel in patients receiving DES. METHODS: Patients who received a DES between March 1, 2004, and August 31, 2005, from a single academic medical center were eligible. Telephone interviews were conducted 6 or more months following discharge. Nonadherence was defined as premature discontinuation of or less than 80% adherence to clopidogrel. Patients were asked to identify barriers to adherence. Differences between adherent and nonadherent patients were analyzed using chi(2) and t-test analysis. RESULTS: Of the 674 patients identified, 257 (38%) participated. The nonadherence rate was 20%. The majority (58%) of nonadherent patients discontinued therapy prematurely. Patients identified the main reason for discontinuation as medical barriers (18.56%), including perceived adverse effects (9.28%). The incidence of rash was higher in patients who were nonadherent (12% vs 4%; p = 0.049). Overall, 49% of patients recalled receiving discharge counseling regarding adverse effects. A financial barrier was identified by 22 (42%) patients in the nonadherent and 73 (36%) in the adherent group, of whom 64% and 52%, respectively, reported having insurance coverage for medications. Adherent patients reported higher copays ($29.69 vs $18.14; p = 0.01). CONCLUSIONS: Prospective studies should be conducted to aid in identifying patients at risk for nonadherence and possible in-stent thrombosis in order to identify interventions to improve adherence.

Relation of Lymphangiogenic Factor Vascular Endothelial Growth Factor-D to Elevated Pulmonary Artery Wedge Pressure.

Lymphatic flow is augmented in states of chronic heart failure (cHF). However, the biological mechanism driving increased lymphatic flow capacity (lymphangiogenesis) in cHF is unknown. Recent studies have indicated that vascular endothelial growth factors (VEGF-A, -C, and -D) are involved in lymphangiogenesis. This study examined the association between VEGF-A, -C, and -D levels, invasively measured hemodynamics, and heart failure symptoms. Subjects who underwent clinically indicated right heart catheterization at Medical University of South Carolina between 12/2016 and 7/2018 were eligible for inclusion. These subjects underwent clinical assessment of cHF severity (including 6MWT and KCCQ), hemodynamic assessment with right heart catheterization, laboratory studies including B-type natriuretic peptide, and concomitant measurement of VEGF-A, -C, and -D. Fifty-six patients were included for analysis. Subjects with elevated pulmonary artery wedge pressure (PAWP) had significantly higher VEGF-D levels (263 ± 415 pg/ml vs 65 ± 101 pg/ml; p = 0.02). PAWP was not associated with VEGF-A or VEGF-C levels. When stratified by VEGF-D, subjects with elevated VEGF-D had clinical and hemodynamic characteristics associated with worse HF severity (lower ejection fraction, higher b-type natriuretic peptide, higher PAWP, lower cardiac output), but were not more symptomatic by Kansas City Cardiomyopathy Questionnaire scores and had similar 6-minute walk test distance compared with subjects with lower VEGF-D. Subjects with an elevated VEGF-D were more likely to have a diagnosis of heart failure for >3 years. In conclusion, VEGF-D is associated with elevated PAWP in cHF, and elevated VEGF-D may mitigate cHF symptoms.

Comparison between angiography and fractional flow reserve versus single-photon emission computed tomographic myocardial perfusion imaging for determining lesion significance in patients with multivessel coronary disease.

We hypothesized that myocardial perfusion imaging (MPI) would fail to identify all vascular zones with the potential for myocardial ischemia in patients with multivessel coronary disease (MVD). MPI is based on the concept of relative flow reserve. The ability of these techniques to determine the significance of a particular stenosis in the setting of MVD is questionable. Fractional flow reserve (FFR) can determine the significance of individual stenoses. Thirty-six patients with disease involving 88 arteries underwent angiography, FFR, and MPI. FFR was performed using a pressure wire with hyperemia from intracoronary adenosine. Myocardial perfusion images were analyzed quantitatively and segments assigned to a specific coronary artery. The relation between FFR and perfusion was determined for each vascular zone. Of the 88 vessels, the artery was occluded (n=20) or had an abnormal FFR

Transmyocardial revascularization ameliorates ischemia by attenuating paradoxical catecholamine-induced vasoconstriction.

BACKGROUND: The mechanism by which transmyocardial revascularization (TMR) offers clinical benefit is controversial. We hypothesized that TMR ameliorates ischemia by reversing paradoxical catecholamine-induced vasoconstriction. METHODS AND RESULTS: Chronic ischemic cardiomyopathy was created in 11 dogs by placing ameroid constrictors on the proximal coronary arteries and their major branches. Six weeks later, 35 channels were created percutaneously in the left circumflex artery region, with the left anterior descending artery region serving as control. At rest, wall thickening and myocardial blood flow did not change in the treated region, whereas they deteriorated in the control bed. Contractile and myocardial blood flow reserve increased in the treated region but deteriorated in the control region. There was diminished iodine 123 metaiodobenzylguanidine uptake and a significant reduction in noradrenergic nerves in the treated region compared with the control region, with a corresponding reduction in tissue tyrosine hydroxylase activity. CONCLUSIONS: We conclude that the absence of a catecholamine-induced reduction in MBF reserve and contractile reserve in the TMR-treated region with associated evidence of neuronal injury indicates that the relief of exercise-induced ischemia after TMR most likely results from reversal of paradoxical catecholamine-induced vasoconstriction. These findings may have implications in selecting patients who would benefit from TMR.

Higher Maximum Doses and Infusion Rates Compared with Standard Unfractionated Heparin Therapy Are Associated with Adequate Anticoagulation without Increased Bleeding in Both Obese and Nonobese Patients with Cardiovascular Indications.

STUDY OBJECTIVE: To evaluate the time to achieve therapeutic activated partial thromboplastin time (aPTT) values and occurrence of bleeding based on standard unfractionated heparin (UFH) weight-based dosing recommendations compared with an aggressive weight-based UFH dosing strategy using higher maximum doses and infusion rates in both obese and nonobese patients who presented with non-ST-segment elevation myocardial infarction or unstable angina (NSTEMI/UA) or atrial fibrillation. DESIGN: Retrospective cohort study. SETTING: Academic medical center. PATIENTS: A total of 197 adults were included who were admitted for NSTEMI/UA, atrial fibrillation, or other cardiac indications and received at least 6 hours of a continuous UFH infusion. Of those patients, 71 were treated with standard UFH dosing (60-unit/kg bolus [or maximum 4000 units] followed by an infusion of 12 units/kg/hour [or maximum 1000 units/hr]) between September 2013 and February 2014, and 126 patients received an aggressive UFH dosing strategy (60-unit/kg bolus [or maximum 10,000 units] followed by an infusion of 12 units/kg/hr [or maximum 2250 units/hr]) between October 2014 and March 2015. Patients in the standard dosing and aggressive strategy cohorts were further classified by body mass index status (normal, overweight, obese, and morbidly obese) and weight status. MEASUREMENTS AND MAIN RESULTS: A time-to-event analysis for achievement of therapeutic aPTT range (60-80 sec) was assessed. A significantly higher proportion of patients treated with the aggressive strategy achieved a therapeutic aPTT within 6 hours (23% vs 11%, p=0.043). The delay or failure to achieve therapeutic anticoagulation was particularly evident in obese patients in the standard dosing group. The mean ± SD initial infusion rate was 10.8 ± 1.4 units/kg/hour in the standard dosing group versus 12 ± 0.02 units/kg/hour in the aggressive strategy group (p=<0.0005). The occurrence of supratherapeutic aPTT values and the highest aPTT achieved were similar between the two dosing groups (p=0.817 and p=0.348, respectively). No bleeding events were reported in either group. CONCLUSION: Patients who had higher UFH maximum bolus doses and infusion rates achieved therapeutic anticoagulation more rapidly, without increased bleeding, and these doses can be adjusted for obese as well as nonobese patients. However, despite use of the higher doses, only 23% of patients achieved therapeutic aPTT values within 6 hours, suggesting that an even higher bolus dose and infusion rate may still be warranted.

Electromechanical mapping identifies improvement in function and retention of contractile reserve after revascularization in ischemic cardiomyopathy.

BACKGROUND: We hypothesized that (1) a significant proportion of ischemic dysfunctional segments that do not improve function will demonstrate postrevascularization contractile reserve and (2) electromechanical mapping (EMM) can identify segments that improve function as well as those with postrevascularization contractile reserve, a potential indicator of delayed functional improvement. METHODS AND RESULTS: Eighteen patients with severe ischemic left ventricular dysfunction underwent EMM and dobutamine (D) cardiac magnetic resonance imaging (CMR) followed by revascularization. Four months after revascularization, all patients underwent a repeated D-CMR, and at 35 months, a subgroup (n=6) underwent a third CMR. Of 120 dysfunctional segments, 60 segments had improved rest function (IRF) and 60 did not. Twenty-eight of 60 segments (47%) that did not improve RF demonstrated postrevascularization contractile reserve (CR), and 32 of 60 segments (53%) that demonstrated neither IRF nor CR were persistently dysfunctional (PD). CR segments recovered significantly greater late function compared with IRF or PD: 14+/-12% vs 2+/-5% and 4+/-7%, respectively; P<0.05. EMM ratio, defined as the unipolar voltage divided by linear shortening, was significantly higher in IRF segments compared with segments that did not improve RF: 2.4+/-4.5 vs 0.7+/-3.5, P<0.05. Unipolar voltage was stepwise lower in normal, IRF, CR, and PD segments (10.5+/-4.7, 9.3+/-3.9, 8.8+/-3.2, and 7.4+/-2.3 mV, respectively; P<0.01 for trend). CONCLUSIONS: Almost half of dysfunctional myocardial segments in chronic ischemic heart disease that do not improve RF early after revascularization demonstrate early CR and delayed functional recovery. EMM parameters can identify segments that improve RF and retain CR early after revascularization.

Impact of different platelet glycoprotein IIb/IIIa receptor inhibitors among diabetic patients undergoing percutaneous coronary intervention: : Do Tirofiban and ReoPro Give Similar Efficacy Outcomes Trial (TARGET) 1-year follow-up.

BACKGROUND: The platelet glycoprotein IIb/IIIa receptor inhibitor abciximab, a monoclonal antibody, has been shown to improve early and late outcomes among diabetic patients undergoing percutaneous coronary intervention (PCI). It is unknown whether small-molecule agents confer similar benefits. METHODS AND RESULTS: In 18 countries, 4809 patients undergoing PCI with stent implantation were randomized to tirofiban or abciximab. At the time of enrollment, patients were stratified according to diabetes status. As compared with non-diabetic patients, patients with diabetes (n=1117) showed similar 30-day ischemic outcomes, an increased incidence of any target vessel revascularization (TVR) at 6 months (10.3% versus 7.8%; P= 0.008), and a trend toward higher 1-year mortality (2.5% versus 1.6%; P=0.056). Among diabetic patients randomized to tirofiban (n=560), the incidence of death, myocardial infarction (MI), or urgent TVR at 30 days was 6.2%, and among those randomized to abciximab (n=557) it was 5.4% (hazard ratio [HR] 1.16; P=0.540). At 6 months, the composite of death, MI, or any TVR occurred in 15.7% and in 16.9% of tirofiban and abciximab patients, respectively (HR 0.93; P=0.610). Any TVR occurred in 9.5% and 11.1%, respectively (HR 0.84; P= 0.366). The 1-year mortality was 2.1% in the tirofiban group and 2.9% in the abciximab group (HR 0.74; P= 0.436). CONCLUSIONS: Among diabetic patients undergoing PCI, tirofiban and abciximab were associated with comparable event rates, including similar rates of 6-month TVR and 1-year mortality. These findings suggest that the non-glycoprotein IIb/IIIa properties of abciximab do not translate into a discernible long-term clinical benefit among diabetic patients.

Impact of clinical syndrome acuity on the differential response to 2 glycoprotein IIb/IIIa inhibitors in patients undergoing coronary stenting: the TARGET Trial.

BACKGROUND: Although glycoprotein IIb/IIIa inhibitors have been shown to reduce periprocedural and late ischemic events in patients undergoing stent implantation, the relative safety and efficacy of different agents in this class is less established. Also unknown is whether the acuity of the presenting clinical syndrome, which may affect the degree of platelet inhibition required or achieved, influences the response to different antiplatelet agents. METHODS AND RESULTS: A prospective, multicenter, double-blind, randomized trial was performed in which 4809 patients undergoing planned stenting were randomized to receive abciximab or tirofiban. In patients with acute coronary syndromes (ACS; n=3025), abciximab resulted in lower rates of myocardial infarction at 30 days (5.8% versus 8.5%; P=0.004) and 6 months (7.2% versus 9.8%; P=0.013), although 6-month mortality rates were identical (1.39% in both groups; P=0.99). Conversely, in patients without ACS (n=1784), myocardial infarction rates were not significantly lower with tirofiban, survival was similar, and target vessel revascularization was reduced, which translated into a trend toward enhanced 6-month event-free survival with tirofiban (89.7% versus 86.6%; P=0.056). CONCLUSIONS: In patients with ACS undergoing stent implantation, abciximab use compared with tirofiban results in greater suppression of periprocedural myonecrosis, although a survival benefit has not been demonstrated. Patients with stable coronary syndromes may have equivalent or better outcomes with tirofiban relative to abciximab, with fewer adverse hematologic and hemorrhagic events. These data raise important issues regarding the relative pharmacodynamic inhibition of platelet function required in varying clinical scenarios and have important implications for the cost-effective utilization of glycoprotein IIb/IIIa inhibitors.

Detection of myocardial viability by contrast echocardiography in acute infarction predicts recovery of resting function and contractile reserve.

OBJECTIVES: We sought to determine whether myocardial contrast echocardiography (MCE) performed before and early after primary coronary stenting (PCS) in patients with acute myocardial infarction (AMI) could predict recovery of resting left ventricular systolic function and contractile reserve. BACKGROUND: Myocardial contrast echocardiography can be used to assess perfusion within the risk area before PCS and the extent of necrosis soon after PCS. METHODS: In 30 patients with AMI, MCE and two-dimensional echocardiography were performed before PCS and 3 to 5 days and 4 weeks after PCS. Contractile reserve was assessed by dobutamine echocardiography at four weeks in patients with persistent severe wall-motion abnormalities. RESULTS: Of segments without perfusion at 3 to 5 days, 95% had severe hypokinesis to akinesis at 4 weeks. Of segments with normal perfusion at 3 to 5 days, 90% had normal wall motion or mild hypokinesis at 4 weeks, whereas those with partial perfusion at 3 to 5 days were evenly divided between normal wall motion, hypokinesis, and akinesis. In segments with persistent severe wall-motion abnormalities at four weeks, contractile reserve was found in >80% of segments with perfusion, compared with only 10% of segments without detectable perfusion (p < 0.01). The presence of myocardial perfusion by MCE before PCS was associated with maintained or improved perfusion at 3 to 5 days and eventual recovery of resting wall motion. CONCLUSIONS: Myocardial contrast echocardiography performed early after PCS provides information on the extent of infarction, and hence the likelihood for recovery of resting systolic function or contractile reserve. The presence of perfusion before PCS, from either collateral or antegrade flow, predicts the maintenance of perfusion and recovery of systolic function.

Coronary flow reserve abnormalities in patients with diabetes mellitus who have end-stage renal disease and normal epicardial coronary arteries.

BACKGROUND: Diabetic nephropathy is associated with increased cardiovascular events. Coronary atherosclerosis is responsible for many of these events, but other mechanisms such as impaired flow reserve may be involved. The purpose of this study was to define the prevalence and mechanism of abnormal coronary velocity reserve (CVR) in patients with diabetes mellitus who have nephropathy and a normal coronary artery. METHODS: Patients undergoing catheterization for clinical purposes were enrolled. CVR was measured with a Doppler ultrasound scanning wire in a normal coronary in 32 patients without diabetes mellitus, 11 patients with diabetes mellitus who did not have renal failure, and 21 patients with diabetes mellitus who had nephropathy. A CVR <2.0 was considered to be abnormal. RESULTS: Patients with diabetes mellitus who had renal failure had a higher incidence of hypertension and left ventricular hypertrophy. The average peak velocity (APV) at baseline was higher in patients with diabetes mellitus who had renal failure. At peak hyperemia, APV increased in all 3 groups, with no difference between groups. The mean CVR for patients without diabetes was 2.8 +/- 0.8 and was not different from that in patients with diabetes mellitus who did not have renal failure (2.7 +/- 0.7), but was lower than that in patients with diabetes mellitus who had renal failure (1.6 +/- 0.5; P < 0.001). Abnormal CVR was observed in 9% of patients without diabetes mellitus, 18% of patients with diabetes mellitus who did not have renal failure, and 57% of patients with diabetes mellitus who had renal failure, and abnormal CVR was caused by an elevation of baseline APV in 66% of these cases. The baseline heart rate and the presence of diabetes mellitus with renal failure were independent predictors of abnormal CVR by multivariable analysis. CONCLUSIONS: Patients with diabetic nephropathy have abnormalities in CVR in the absence of angiographically evident coronary disease.

Comparison between visual assessment and quantitative angiography versus fractional flow reserve for native coronary narrowings of moderate severity.

We tested the hypothesis that experienced interventional cardiologists can identify patients with fractional flow reserve (FFR) <0.75 either by visual assessment of the angiogram or by quantitative coronary angiography (QCA). Estimation of the significance of moderate lesions is difficult. FFR can determine the physiologic significance of a stenosis. Data comparing visual assessment and QCA of moderate lesions with FFR are limited. FFR was measured in 83 moderate lesions defined as having a 40% to 70% stenosis by visual inspection. An FFR <0.75 was considered "significant." Lesions were visually assessed by 3 experienced interventional cardiologists and their significance estimated. QCA was performed. Both analyses were compared with FFR. FFR averaged 0.82 +/- 0.11 and was <0.75 in 15 of 83 lesions (18%). The reviewers' classification was concordant with the FFR in about half the lesions. Concordance between reviewers was poor (Spearman's rho = 0.36). Visual assessment resulted in good sensitivity (80%) and negative predictive value (91%), but poor specificity (47%) and positive predictive value (25%) compared with FFR. By QCA, no patient with stenosis <60% or minimal luminal diameter >1.4 mm had FFR <0.75. QCA did not discriminate the significance of lesions outside of these parameters. Thus, neither visual assessment of an angiogram by experienced interventional cardiologists nor QCA can accurately predict the significance of most moderate narrowings.