Clinical outcomes after implantation of a centrifugal flow left ventricular assist device and concurrent cardiac valve procedures.

BACKGROUND: Cardiac valve procedures are commonly performed concurrently during implantation of left ventricular assist devices, but the added procedural risk has not been studied in detail. METHODS AND RESULTS: Data from patients receiving the HeartWare Ventricular Assist Device in the ADVANCE bridge to transplant (BTT) trial and continued access protocol were reviewed. Of 382 consecutive patients who completed follow-up between August 2008 and June 2013 (mean time on support 389 days, median 271 days), 262 (68.6%) underwent isolated HeartWare Ventricular Assist Device implantation, 75 (19.6%) a concurrent valve procedure, and 45 (11.8%) concurrent nonvalvular procedures. Of the concurrent valve procedures, 56 were tricuspid, 13 aortic, and 6 mitral. Survival was similar between groups (79% for concurrent valve procedures and 85% for HeartWare Ventricular Assist Device only at 1 year; P=0.33). Concurrent valve procedures were also associated with increased unadjusted early right heart failure (RHF). A multivariable analysis for death and RHF (121 total events) identified female sex (odds ratio=2.0 [95% confidence interval, 1.2-3.3; P=0.0053]) and preimplant tricuspid regurgitation severity (odds ratio=2.9 [95% confidence interval, 1.8-4.8, P<0.0001]) as independent predictors while concurrent tricuspid valve procedures (TVP) were not predictors. Furthermore, patients with significant preimplant tricuspid regurgitation who did not receive a TVP experienced an increased rate of late RHF compared with those who received TVP (0.19 versus 0.05 events per patient-year, respectively; P=0.024). CONCLUSIONS: Compared with HeartWare Ventricular Assist Device alone, survival was equivalent for the concurrent valve procedure group. Tricuspid regurgitation severity was the most important predictor of increased postoperative RHF, and concurrent TVP was not an independent predictor of RHF overall. Concurrent TVP may reduce the rate of late RHF for patients with significant preimplant tricuspid insufficiency. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00751972.

Pharmacodynamic effects of clopidogrel in pediatric cardiac patients: a comparative study of platelet aggregation response.

Little data on pediatric percent platelet aggregation (%PA) exist in the literature, particularly in cardiac patients and in response to clopidogrel. The objectives were to estimate the %PA range expected in pediatric patients and to measure the clopidogrel effect on %PA in the PICOLO (Platelet Inhibition in Children on Clopidogrel) trial. To estimate a neonatal/infant %PA response range, %PA induced by 5 µM adenosine diphosphate (ADP) was assessed using light transmission aggregometry in 16 cord and 11 normal adult blood samples and prior to clopidogrel therapy in 49 neonatal and 49 infant/toddler cardiac patients enrolled in PICOLO. The %PA induced by 5 µM thrombin receptor-activating peptide (TRAP) was also assessed for 10 neonates and 21 infants/toddlers enrolled in PICOLO and compared with 11 adult samples. Percent inhibition of platelet aggregation (%IPA) induced by 5 µM ADP at steady-state clopidogrel levels was assessed in 33 neonates and 39 infants/toddlers. ADP-induced %PA was lowest in cord blood samples, intermediate in study neonates and infants/toddlers, and highest in adults. Similarly, TRAP-induced platelet aggregation was lower in neonates and infants/toddlers than adults. For all groups, %PA and %IPA were highly variable, with 11% of neonates and 13% of infants/toddlers showing <10% IPA. In conclusion, ADP- and TRAP-induced %PA is lower in pediatric cardiac patients than normal adults, but highly variable in both. The lower baseline %PA may explain why the pediatric clopidogrel dose providing 30-50% IPA (0.20 mg/kg/day) is lower than a simple weight-based extrapolation of the adult dose (75 mg/day) providing similar inhibition.

Advances in Large Volume Subcutaneous Injections: A Pilot Tolerability Study of an Innovative Needle-Free Injection Platform.

Many medical conditions require chronic treatment with subcutaneous injectable biologics often exceeding 1.0 mL. However, subcutaneous administration of volumes of 2.0 mL or greater using a standard needle and syringe or auto-injector proves challenging, and patients often must administer two separate injections to achieve their full dose or endure injection times in excess of 10 s if using a mechanical autoinjector. In addition, needle-based injections often cause patient anxiety and discomfort. In this article, we describe an approach to meet these needs with a needle-free medication delivery device capable of rapidly delivering up to 2.0 mL with minimal discomfort. A pilot study was conducted with this needle-free injection system to evaluate the delivery of a 2.0 mL volume in human subjects. The results demonstrated that injections of up to 2.0 mL were well tolerated and often preferred over two separate 1.0 mL injections using the needle-free injection system.

Advances in subcutaneous injections: PRECISE II: a study of safety and subject preference for an innovative needle-free injection system.

Needle-free injection is a desirable goal for many reasons, including reducing pain, anxiety, and eliminating safety risks associated with needle-stick injuries. However, development of a safe, reliable needle-free device optimized for at-home use has been met with many challenges. Portal Instruments Inc. has been developing needle-free medication delivery using a well-designed hand-held device, PRIME, that is safe, intuitive to use, and utilizes advanced electronic control of a focused, high velocity, pressurized liquid injection stream. The PRECISE II human study demonstrated that the PRIME needle-free injection system was safe, well tolerated, and strongly preferred by participants for self-injections over a standard needle and syringe. In addition, the study was able to be completed early for superiority following the success of the pre-defined interim analysis.

Machine Learning Approaches to Analyzing Adverse Events Following Durable LVAD Implantation.

BACKGROUND: This study employed machine learning approaches to analyze sequences of adverse events (AEs) after left ventricular assist device (LVAD) implantation. METHODS: Data on patients implanted with the HeartWare HVAD durable LVAD were extracted from the ENDURANCE and ENDURANCE Supplemental clinical trials, with follow-up through 5 years. Major AEs included device malfunction, major bleeding, major infection, neurological dysfunction, renal dysfunction, respiratory dysfunction, and right heart failure (RHF). Time interval and transition probability analyses were performed. We created a Sankey diagram to visualize transitions between AEs. Hierarchical clustering was applied to dissimilarity matrices based on the longest common subsequence to identify clusters of patients with similar AE profiles. RESULTS: A total of 568 patients underwent HVAD implantation with 3590 AEs. Bleeding and RHF comprised the highest proportion of early AEs after surgery whereas infection and bleeding accounted for most AEs occurring after 3 months. The highest transition probabilities were observed with infection to infection (0.34), bleeding to bleeding (0.31), RHF to bleeding (0.31), RHF to infection (0.28), and bleeding to infection (0.26). Five distinct clusters of patients were generated, each with different patterns of time intervals between AEs, transition rates between AEs, and clinical outcomes. CONCLUSIONS: Machine learning approaches allow for improved visualization and understanding of AE burden after LVAD implantation. Distinct patterns and relationships provide insights that may be important for quality improvement efforts.

Interpreting Neurologic Outcomes in a Changing Trial Design Landscape: An Analysis of HeartWare Left Ventricular Assist Device Using a Hybrid Intention to Treat Population.

Randomized controlled trials can provide optimal clinical evidence to assess the benefits of new devices, and it is these data that often shape device usage in real-world practice. However, individual clinical trial results sometimes appear discordant for the same device, and alternative devices are sometimes not employed in similar patient populations. To make sound evidence-based decisions, clinicians routinely rely on cross-trial comparisons from different trials of similar but not identical patient populations to assess competing technology when head-to-head randomized comparisons are unavailable.

A clinical risk score for prediction of stent thrombosis.

The aim was to develop a clinically useful patient risk score predictive for stent thrombosis (ST). Using readily available baseline clinical and angiographic characteristics, a Cox proportional hazards multivariate model was used to identify significant (p <0.10) predictors of ST through 1 year in 2,487 patients receiving a TAXUS Express (Boston Scientific Corp., Natick, Massachusetts) drug-eluting stent (DES) in the ARRIVE 1 registry. Hazard ratios of significant predictors were rounded to an integer value ranging from 2 to 5. These values were summed for a maximum possible score of 24. The model was validated using 1-year data from a similar DES data set (ARRIVE 2, n = 4,820 patients). The 8 significant predictors found were thienopyridine therapy discontinuation before 6 months, insulin-requiring diabetes, smoker at baseline, left main stent placement, multiple stent placement, lesion length >28 mm, moderate to severe lesion calcification, and reference vessel diameter <3 mm. Model discrimination was high, indicated by an area under the receiver-operator characteristic curve of 0.819. Stratification of patients into low-, medium-, and high-risk groups showed that ST developed in 0.8% of patients with a score <6, 3.6% of patients with a score of 7 to 13, and 12.6% of patients with a score >or=14. In conclusion, using 8 readily available clinical and angiographic characteristics, we defined an ST risk score for patients receiving a DES during the first year. Analysis of patients from ARRIVE 1 and 2 showed that most (73%) were in the lowest risk category, with 25% in the moderate risk category. Less than 2% were at highest risk of developing ST.

An examination of survival by sex and race in the HeartWare Ventricular Assist Device for the Treatment of Advanced Heart Failure (ADVANCE) Bridge to Transplant (BTT) and continued access protocol trials.

BACKGROUND: The Ventricular Assist Device for the Treatment of Advanced Heart Failure (ADVANCE) Bridge to Transplant (BTT) trial was a multicenter, prospective trial of the HeartWare Ventricular Assist Device (HVAD). The performance of the HVAD in various demographic sub-groups was evaluated. METHODS: Baseline characteristics, adverse events, and survival were compared for men vs. women and whites vs. non-whites in the combined ADVANCE BTT and continued access protocol trial. Of 332 patients enrolled in these trials, 236 were men and 96 women, with 228 whites and 104 non-whites. RESULTS: At baseline, women had a smaller body surface area (1.8 ± 0.2 vs. 2.1 ± 0.3 m2, p < 0.0001), less hypertension (50.0% vs. 61.9%, p = 0.05), and less ischemic cardiomyopathy (15.6% vs. 45.3%, p < 0.0001). Differences in Kaplan-Meier survival were not significant at 180 days (men, 91.8%; women, 91.7%) and 1 year (men, 85.3%; women, 85.1%) despite adjustment for baseline differences. Men had a lower incidence of early right heart failure and renal and respiratory dysfunction, and a shorter length of stay. In the analysis by race, non-whites were younger than whites and had less ischemic heart failure, more hypertension, and lower creatinine levels at baseline. Non-whites had lower rates of arrhythmia, bleeding requiring rehospitalization, and device malfunctions than whites. Survival was high in non-whites and whites, at 94.1% vs. 90.4% at 180 days and 89.2% vs. 82.8% at 1 year, respectively, despite adjustment for baseline differences. CONCLUSIONS: Although heart failure etiology differed between men and women and between whites and non-whites, sex and race were not factors that affected survival in patients receiving the HVAD as BTT, which was high in all sub-groups.

Comparative pharmacodynamic evaluation of eptifibatide and tirofiban HCl in patients undergoing percutaneous coronary intervention (the TAM1 Study).

We performed a comparative analysis of platelet aggregation inhibition achieved with the glycoprotein IIb/IIIa inhibitors eptifibatide and tirofiban HCl in patients who underwent percutaneous coronary intervention and used light transmission aggregometric assays with D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone as an anticoagulant and 20 micromol of adenosine diphosphate as an agonist. Taking into account the differences in clinical efficacy of these 2 drugs in large trials investigating percutaneous coronary intervention, we hypothesized that the variable clinical effects might be related to variability in the magnitude and consistency of platelet aggregation inhibition achieved with dosing regimens of these glycoprotein IIb/IIIa inhibitors.

A clinical risk score for the prediction of very late stent thrombosis in drug eluting stent patients.

AIMS: Very late stent thrombosis (VLST; >1 year) is an infrequent but potentially serious complication, whose risk factors have not been fully elucidated. This investigation sought to develop a clinically useful risk stratification score for VLST following drug eluting stent (DES) placement. METHODS AND RESULTS: A Cox proportional hazards multivariate model of VLST was developed based on follow-up into a second year of patients enrolled in the ARRIVE registries, utilising readily available baseline clinical and angiographic characteristics. ST predictors between one and two years were identified among 7,459 consecutively enrolled patients who received a TAXUS® Express2™ (Boston Scientific, Natick, MA, USA) DES. Six significant predictors were found: presence of renal disease, prior myocardial infarction, multiple stenting, bifurcation lesions, prior CABG, and smoking at baseline. Each predictor was assigned a score, then summed for a maximum possible score of 10. Stratification into low and high risk groups revealed that VLST developed in 0.5% of 6,759 patients with scores<5, and 2.6% of 700 patients with scores≥5. CONCLUSIONS: We defined a VLST risk score for patients during the second year post DES-placement that provides a useful tool for risk stratification.

The pharmacodynamics of parenteral glycoprotein IIb/IIIa inhibitors.

Glycoprotein (GP) IIb/IIIa antagonists are a unique class of antiplatelet agents introduced for the management of patients undergoing percutaneous coronary intervention (PCI) and those presenting with unstable angina or non-ST segment elevation (NSTE) myocardial infarction (MI), collectively recognized as acute coronary syndromes (ACS). Eptifibatide, abciximab, and tirofiban HCl are three GPIIb/IIIa antagonists approved for use by the Food and Drug Administration. Of the three agents, eptifibatide is approved for use in both PCI and NSTE ACS patient populations, whereas abciximab is indicated for patients undergoing PCI, and tirofiban is approved for patients with NSTE ACS. Dose selection for the initial trials using the three parenteral antagonists was based on in vitro and ex vivo pharmacodynamic assays conducted under different blood collection and platelet function assay conditions. Recent comparative pharmacodynamics studies, which used newly defined and standardized assay conditions, indicate that the platelet aggregation inhibition achieved with these dosing regimens is variable. Therefore, the differences in clinical efficacy as evidenced in the more recent clinical studies (e.g., Enhanced Suppression of the Platelet Receptor GPIIb/IIIa using Integrilin Therapy [ESPRIT], Global Use of Strategies to Open Occluded Coronary Arteries IV Acute Coronary Syndromes [GUSTO-IV ACS], and Do Tirofiban HCl and ReoPro Give Similar Efficacy Outcomes Trial [TARGET]) may be related to the variable antiplatelet effects of the approved dose regimens.

The use of the point of care Helena ICHOR/Plateletworks and the Accumetrics Ultegra RPFA for assessment of platelet function with GPIIB-IIIa antagonists.

OBJECTIVE: To evaluate a newly modified rapid platelet function analysis system (ICHOR/ Plateletworks) and to compare the results obtained with those of traditional light transmission aggregometry (LTA), and the Ultegra/RPFA system. BACKGROUND: Anti-platelet therapy is standard of care for patients as an adjunct to percutaneous coronary intervention (PCI) or for medical management of non-ST elevation acute coronary syndromes (NSTE ACS). Recent clinical trial results suggest that the three currently approved platelet GPIIb-IIIa receptor antagonists, eptifibatide, tirofiban and abciximab, may vary in extent of inhibition of platelet aggregation (IPA) at the approved doses. Thus, pharmacodynamic evaluations of these agents to determine the extent of platelet function inhibition, especially during the periprocedural time of a cardiac intervention, are necessary. A rapid measurement method as a surrogate for LTA, the current gold standard, would be ideal in order to have the option for dose monitoring or adjustment prior to or during an intervention. The Helena ICHOR/ Plateletworks may be useful for point of care testing. METHODS: Blood samples collected in D-Phe-Pro-Arg-chloromethyl ketone dihydrochloride (PPACK) anticoagulant were treated with increasing concentrations of eptifibatide, tirofiban or abciximab. LTA was carried out in conjunction with the ICHOR/Plateletworks, using a modified method, and Accumetrics Ultegra with RPFA cartridges. RESULTS: This study demonstrated that platelet inhibition measured by the ICHOR/Plateletworks mirrored the level of IPA obtained with LTA. In contrast, the Ultegra system had less correlation when compared to LTA at inhibition levels < 90%. CONCLUSIONS: Based on these data, the ICHOR/ Plateletworks utilized under modified guidelines may serve as a surrogate for LTA when rapid measurements are necessary.A rapid platelet function measurement method as a surrogate for light transmission aggregometry (LTA), the current gold standard, is ideal in order to have the option for GPIIb-IIIa antagonist dose monitoring or adjustment prior to or during a coronary intervention. A newly modified rapid platelet function analysis system (ICHOR/Plateletworks was evaluated and compared to the results obtained with traditional light transmission aggregometry (LTA), and the Ultegra/RPFA system. Blood samples collected in D-Phe-Pro-Arg-chloromethyl ketone dihydrochloride (PPACK) anticoagulant were treated with increasing concentrations of eptifibatide, tirofiban or abciximab. LTA was carried out in conjunction with the ICHOR/Plateletworks, using a modified method, and Accumetrics Ultegra with RPFA cartridges. Based on these data, the ICHOR/Plateletworks utilized under modified guidelines may serve as a surrogate for LTA when rapid measurements are necessary.

Comparative pharmacodynamic evaluation of eptifibatide and abciximab in patients with non-ST-segment elevation acute coronary syndromes: the TAM2 study.

BACKGROUND: The importance of the relationship between clinical outcome and degree of platelet aggregation inhibition (PAI) achieved with the dosing regimens of GPIIb-IIIa inhibitors used in large trials in patients with non-ST segment elevation (NSTE) acute coronary syndromes (ACS) is increasingly appreciated. In the PURSUIT trial, eptifibatide treatment that consistently provided >80% PAI was associated with clinical benefit at 30 days and 6 months. The GUSTO IV ACS trial, however, did not show any effect of abciximab on 30-day outcomes. This difference might be due to variability of antiplatelet effects of these drugs. As previous studies found, a 12 hr abciximab infusion had <80% PAI, particularly at 6 and 12 hr. These studies did not evaluate PAI with a longer, 24-hour infusion as used in GUSTO IV ACS. METHODS: We conducted a prospective study in 40 patients with NSTE ACS prior to catheterization or coronary intervention at 3 centers using the PURSUIT dose of eptifibatide (180/2.0) [DOSAGE ERROR CORRECTED] and the GUSTO IV dose of abciximab (0.25, 0.125). Blood samples were collected at baseline, and during the infusion at 10 min, 1 hr, 6 hr, 8 hr, 12 hr, 18 hr, and 24 hr. Measurements of ex vivo light transmission aggregometry (LTA) were performed using PPACK anticoagulant and 20 microM ADP agonist. Receptor Occupancy (RO) was also determined in a subset of patients. RESULTS: Eptifibatide achieves higher PAI during the entire infusion period than abciximab (p<0.01). At 10 min, average PAI with eptifibatide and abciximab was 88% and 80%, respectively, 95% and 79% at 6 hr, and 97% and 79% at 24 hr. There was also more variability in individual patient response to abciximab. Although average RO for eptifibatide was similar to that of abciximab at 10 min, 67% versus 69%, respectively, average RO was higher in the eptifibatide cohort at all subsequent timepoints. By 24 hr, average RO for eptifibatide was 86%, whereas abciximab averaged 67%. CONCLUSION: These data support the hypothesis that differences in clinical outcomes of large GPIIb-IIIa trials in patients with NSTE ACS may be related to the consistency and potency of antiplatelet effects of the dosing regimens used.