Faculty Bibliography

Background: Observation of the kinetics of tissue enhancement after the injection of a bolus of tracer has been used for the analysis of perfusion and related variables. In general, a gradient of concentration in the exchanging vascular compartment between the arterial and venous ends is represented in models via focus on maintaining the detailed balance between the advective and diffusive exchange processes. Conventionally, this is by considering the exchange in an Eulerian framework, based on considering the exchange within each compartment as a separate unit (e.g., tissue homogeneity (TH) model [1]). Herein, we present a Lagrangian approach to the exchange modeling, such that the blood flowing between compartments is considered as the primary unit, and, thereby, allowing for coarser discretization and more efficient calculations (Figure 1a). Methods: Eight patients (age 63 + 12 years) underwent first-pass perfusion (FPP) rest and regadenoson stress cardiac MRI (CMR) (3T scanner, Tim Trio, Siemens), followed by invasive coronary angiography. Images were obtained at 4 slice locations (the aortic root for the arterial input function (AIF) and 3 short-axis slices of the left ventricle for the wall) using a TurboFLASH readout with centric k-space reordering [2]. A proton density-weighted image was acquired for normalization [3]. Myocardial blood flow (MBF) (mL/g/min) and perfusion reserve index (MPRI) were calculated in endocardial and epicardial areas (total 32 segments) using our method by an expert in the field of MRI blinded to coronary angiography results. Results: The results of a representative patient (66 year old man) with history of hypertension, hyperlipidemia, Diabetes Mellitus and known coronary artery disease with prior stents on maximal medical therapy are shown in Figure 1b-f. Coronary angiography was performed via the right femoral artery and demonstrated severe triple-vessel disease with left to right collaterals (Figure 1b). First-pass CMR perfusion imaging demonstrates a delay!

Numerous definitions have been proposed for the diagnosis of myocardial infarction (MI) after coronary revascularization. The universal definition for MI designates post procedural biomarker thresholds for defining percutaneous coronary intervention (PCI)-related MI (type 4a) and coronary artery bypass grafting (CABG)-related MI (type 5) which are of uncertain prognostic importance. In addition, for both MI types cTn is recommended as the biomarker of choice, the prognostic significance of which is less well validated than CK-MB. Widespread adoption of a MI definition not clearly linked to subsequent adverse events such as mortality or heart failure may have serious consequences for the appropriate assessment of devices and therapies, may affect clinical care pathways, and may result in misinterpretation of physician competence. Rather than employing an MI definition sensitive for small degrees of myonecrosis (the occurrence of which, based on contemporary large-scale studies, are unlikely to have important clinical consequences), it is instead recommended that a threshold level of biomarker elevation which has been strongly linked to subsequent adverse events in clinical studies be used to define a "clinically relevant MI." The present document introduces a new definition for "clinically relevant MI" after coronary revascularization (PCI or CABG) which is applicable for use in clinical trials, patient care, and quality outcomes assessment. (c) 2013 Wiley Periodicals, Inc.

Abstract Some studies suggest that mean platelet volume (MPV) correlates with increased risk for cardiovascular morbidity and mortality. In this study, we aim to assess reproducibility, need for standardized measurements, effect of aspirin, and association with other established markers of platelet activity. Following an overnight fast, 48 healthy volunteers had weekly assessment of platelet activity and were administered aspirin 81 mg daily for 7 d between weeks 3 and 4. We investigated the influence of time between phlebotomy and MPV measurement (n = 10). Reproducibility was assessed by coefficient of variation (CV) and intraclass correlation coefficient (ICC). MPV measurements were reproducible (Week 1: 10.6 fL [9.9-11], Week 2: 10.6 fL [10.0-10.9], Week 3: 10.6 fL [9.8-11]). CV was 0.85 (p < 0.001) for each comparison, indicating excellent reproducibility. There was no effect of aspirin on MPV (10.6 fL [9.8-11] versus 10.5 fL [9.9-11]; p = 0.81). MPV significantly increased as time between phlebotomy and MPV measurement increased (Spearman's rho = 0.94, p = 0.001). Increasing MPV tertiles was associated with collagen- and thrombin receptor-activated peptide-induced platelet aggregation but not with ADP- or arachidonic acid-induced or spontaneous platelet aggregation. In conclusion, when standardized, MPV is a reproducible marker of platelet size and not affected by low-dose aspirin. MPV is modestly associated with some, but not all, markers of platelet activity.

Numerous definitions have been proposed for the diagnosis of myocardial infarction (MI) after coronary revascularization. The universal definition for MI designates post procedural biomarker thresholds for defining percutaneous coronary intervention (PCI)-related MI (type 4a) and coronary artery bypass grafting (CABG)-related MI (type 5), which are of uncertain prognostic importance. In addition, for both the MI types, cTn is recommended as the biomarker of choice, the prognostic significance of which is less well validated than CK-MB. Widespread adoption of a MI definition not clearly linked to subsequent adverse events such as mortality or heart failure may have serious consequences for the appropriate assessment of devices and therapies, may affect clinical care pathways, and may result in misinterpretation of physician competence. Rather than using an MI definition sensitive for small degrees of myonecrosis (the occurrence of which, based on contemporary large-scale studies, are unlikely to have important clinical consequences), it is instead recommended that a threshold level of biomarker elevation which has been strongly linked to subsequent adverse events in clinical studies be used to define a "clinically relevant MI." The present document introduces a new definition for "clinically relevant MI" after coronary revascularization (PCI or CABG), which is applicable for use in clinical trials, patient care, and quality outcomes assessment.

BACKGROUND: In the BARI 2D trial, patients with type 2 diabetes and stable coronary artery disease were randomized to prompt revascularization versus intensive medical therapy (IMT). This analysis sought to evaluate how the availability of drug-eluting stents (DESs) has changed practice and outcomes. METHODS: In BARI 2D, 1,605 patients were in the percutaneous coronary intervention (PCI)-intended stratum. As DES became available midway through recruitment, we report clinical outcomes among patients who underwent IMT versus prompt PCI with bare-metal stents (BMSs) or DES up to 4 years. RESULTS: In North America, after DES became available, selection for the PCI-intended stratum increased from 73% to 79% (P = .003). Fewer BMS than DES patients had total occlusions treated or underwent rotational atherectomy (5.6% vs 9.7%, P = .02, and 1.2% vs 3.7%, P < .01, respectively). Subsequent revascularization (IMT 39%, BMS 29%, DES 21%, P < .01) and target vessel revascularization (BMS 16.1% vs DES 9.6%, P = .03) were lower with DES. Angina at 2 years tended to be less common with DES (IMT 39%, BMS 37%, DES 29%, P = .04, for 3 groups, P = .07 for DES vs BMS). The composite of death, myocardial infarction, or stroke was IMT 16.0%, BMS 20.5%, DES 17.5%; P = .80. CONCLUSIONS: When DES became available in North America, patients were more likely to be selected into the PCI-intended stratum. Compared with patients receiving BMS, those receiving DES tended to have less target vessel revascularization and angina.

BACKGROUND: Studies demonstrate an increase in radiation exposure with transradial approach (TRA) when compared with transfemoral approach (TFA) for coronary angiography. Given the learning curve associated with TRA, it is not known if this increased radiation exposure to patients is seen when procedures are performed by experienced operators. METHODS: We retrospectively evaluated 1,696 patients who underwent coronary angiography with or without percutaneous coronary intervention (PCI) by experienced operators at a tertiary center from October 2010 to June 2011. Experienced operators were defined as those that perform >75 PCIs/year with >95% of cases performed using the TRA or TFA approach for >/=5 years. The outcomes of interest were dose area product (DAP) and fluoroscopy time (FT). RESULTS: Of the 1,696 patients, 1,382 (81.5%) were performed by experienced femoral operators using TFA and 314 (18.5%) were performed by experienced radial operators using TRA. Most of these cases (65.4%) were diagnostic only (870 TFA and 240 TRA) with both DAP (6040 [3210-8786] vs 5019 [3377-6869] muGy.m, P = .003] and FT [6.2 [4.0-10.3] vs 3.3 [2.6-5.0] minutes, P < .001) significantly higher using TRA versus TFA. For procedures involving PCI, despite similar baseline patient, procedural and lesion characteristics, DAP and FT remained significantly higher using TRA versus TFA (19,649 [11,996-25,929] vs 15,395 [10,078-21,617] muGy.m, P = .02 and 22.1 [13.3-31.0] vs. 13.8 [9.8-20.3] minutes, P < .001). CONCLUSIONS: In a contemporary cohort of patients undergoing coronary angiography by experienced operators, TRA was associated with higher radiation exposure when compared with TFA.