Michael Amann

High-sensitivity cardiac troponin for risk prediction in patients with and without coronary heart disease☆ , ☆☆

BACKGROUND In stable patients with unknown coronary anatomy, higher levels of cardiac troponin are associated with an increased risk of cardiovascular events. It was supposed that this association might be explained by the ability of cardiac troponin to detect minor myocardial necrosis which might be caused by subclinical coronary atherosclerosis. Thus, this analysis tested if the predictive value of high-sensitivity troponin T (hsTnT) in stable patients is dependent of the presence or absence of angiographically documented coronary heart disease. METHODS Stable patients undergoing elective coronary angiography were enrolled (n=2046). HsTnT was determined before diagnostic procedures. The patients were followed for up to seven years. Primary endpoint was all-cause mortality or non-fatal myocardial infarction. All endpoints were adjudicated by independent physicians. Results were adjusted to a clinical model including independent clinical predictors of the primary endpoint. RESULTS Out of the 2046 patients enrolled, 1236 (60%) had a diagnosis of obstructive coronary heart disease. HsTnT predicted independently the primary endpoint (adjusted HR 1.33, 95%-CI 1.21-1.46, P<0.001). The use of hsTnT in addition to the clinical model significantly improved discrimination (c-statistic: 0.751 to 0.773, P<0.001) as well as reclassification of the primary endpoint (NRI=0.362, P<0.001). This significant improvement persisted across various subsets and was independent of the presence of clinically detectable coronary heart disease and other variables. CONCLUSION The use of hsTnT in addition to clinical variables significantly improves discrimination and reclassification of patients with respect to all-cause mortality or non-fatal myocardial infarction irrespective of the presence of clinically detectable coronary heart disease. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov (Identifier: NCT00457236).

Randomized Comparison of Different Thienopyridine Loading Strategies in Patients Undergoing Elective Coronary Intervention: The ExcelsiorLOAD Trial.

OBJECTIVES This randomized trial investigated to what extent loading with prasugrel can provide a more rapid peri-interventional antiplatelet effect than clopidogrel 600 mg. BACKGROUND Effective platelet inhibition at the start of a percutaneous coronary intervention (PCI) reduces the risk of ischemic complications. With clopidogrel administered immediately before a PCI, effective platelet inhibition is delayed by 2 h. Prasugrel has the potential of shortening this period. METHODS We randomly assigned 300 P2Y12 receptor blocker-naive patients undergoing an elective PCI to loading with clopidogrel 600 mg, prasugrel 30 mg, or prasugrel 60 mg immediately before the PCI. Platelet function was assessed serially by impedance aggregometry. The primary endpoint was the proportion of patients with high on-treatment platelet reactivity at 60 min after loading defined as ≥468 aggregation units × minute (Multiplate Analyzer, Roche Diagnostics, Mannheim, Germany). RESULTS The 3 groups were well balanced with respect to clinical and angiographic characteristics. At 60 min, 33% of the patients assigned to prasugrel 60 mg, 37% of patients assigned to prasugrel 30 mg, but 55% of those assigned to clopidogrel had high on-treatment platelet reactivity (p < 0.001). At any time point starting from 30 min, prasugrel 60 mg achieved significantly lower platelet reactivity than clopidogrel. Platelet reactivity at 60 min after prasugrel was not significantly different from that at 120 min after clopidogrel (p = 0.18). Prasugrel 30 mg had an intermediate effect. The 30-day incidence of bleeding events was not different among the 3 groups. CONCLUSIONS From 30 min onward, prasugrel 60 mg achieved a stronger platelet inhibition than clopidogrel loading in stable patients undergoing a PCI. Compared with clopidogrel, prasugrel 60 mg was associated with a twice as fast onset of platelet inhibition. (Impact of Extent of Clopidogrel-Induced Platelet Inhibition during Elective Stent Implantation on Clinical Event Rate-Advanced Loading Strategies [ExcelsiorLOAD]; DRKS00006102).

Clopidogrel pretreatment of patients with ST-elevation myocardial infarction does not affect platelet reactivity after subsequent prasugrel-loading: Platelet reactivity in an observational study

Current guidelines recommend prasugrel or ticagrelor for patients undergoing percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction (STEMI). Whereas available data support ticagrelor independent of pretreatment with clopidogrel, corresponding data for prasugrel are missing. Here, we investigated platelet reactivity after loading with prasugrel in clopidogrel-naïve vs. clopidogrel-pretreated patients. Forty-seven consecutive patients with STEMI referred for primary PCI were enrolled. Use of GPIIb/IIIa inhibitors and known contraindications to prasugrel served as exclusion criteria. A total of 31 patients were already treated with a loading dose of clopidogrel 600 mg by the emergency medical system before admission, while 16 patients were P2Y12 antagonist naïve. All patients received a loading dose of prasugrel 60 mg immediately before PCI. Adenosine diphosphate (ADP) induced platelet reactivity was determined by VerifyNow™ P2Y12 assay, by light transmission aggregometry (LTA) and by multiple electrode impedance aggregometry (MEIA; Multiplate™ analyser). No differences in platelet reactivity were observed at day 1 after PCI between the bolus-on-bolus treatment regimen and single prasugrel loading. Platelet reactivity was profoundly decreased to 10 [8–31] platelet reactivity unit (PRU; median [interquartile range]) in patients on clopidogrel + prasugrel vs. 9 [6–60] PRU in patients on prasugrel only (p = 0.916). Consistent results were obtained by LTA and MEIA. The proportion of patients reaching a MEIA associated with increased risk bleeding (<188 AU*min) was also similar between the two study groups. The level of platelet reactivity at day 1 after the 60 mg loading dose of prasugrel was independent of pretreatment with clopidogrel. Our results do not support withholding prasugrel in patients pretreated with clopidogrel who undergo PCI for STEMI.

Controlled type II diabetes mellitus has no major influence on platelet micro-RNA expression. Results from micro-array profiling in a cohort of 60 patients.

Diabetes mellitus as a major contributor to cardiovascular disease burden induces dysfunctional platelets. Platelets contain abundant miRNAs, which are linked to inflammatory responses and, thus, may play a role in atherogenesis. While diabetes mellitus affects plasma miRNAs, no data exist on platelet miRNA profiles in this disease. Therefore, this study sought to explore the miRNA profile of platelets in patients with diabetes mellitus that is unrelated to the presence or absence of coronary artery disease (CAD). Platelet miRNA profiles were assessed in stable diabetic and non-diabetic patients (each n=30); 15 patients in each group had CAD. Platelet miRNA was isolated from leucocyte-depleted platelet-rich plasma, and miRNA profiling was performed using LNA micro-array technology (miRBase18.0, containing 1,917 human miRNAs). Effects of diabetes mellitus were explored by univariate statistical tests for each miRNA, adjusted for potential confounders, and by developing a multivariable signature; evaluated by resampling techniques. Platelets in non-diabetic patients demonstrated miRNA expression profiles comparable to previous data. The miRNA profiles of platelets in diabetics were similar. Statistical analysis unveiled three miRNAs (miR-377-5p, miR-628-3p, miR-3137) with high reselection probabilities in resampling techniques, corresponding to signatures with modest discriminatory performance. Functional annotation of predicted targets for these miRNAs pointed towards an influence of diabetes mellitus on mRNA processing. We did not find major differences in platelet miRNA profiles between diabetics and non-diabetics. Minor differences pertained to miRNAs associated with mRNA processing. Thus, described differences in plasma miRNAs between diabetic and non-diabetic patients cannot be explained by plain changes in platelet miRNA profile.

Transanal endoscopic microsurgery in treatment of rectal adenomas and T1 low-risk carcinomas

BackgroundTransanal endoscopic microsurgery as a local therapy option for rectal neoplasms is a tissue-sparing technique that protects the anal sphincter. The present retrospective analysis reports the course of observation after local excision of adenomas and T1 low-risk carcinomas using transanal endoscopic microsurgery.MethodsIn a retrospective analysis we examined data on 279 patients for local recurrence. A total of 144 patients had a rectal adenoma (n = 103) or a R0 resection of low-risk T1 carcinomas (n = 41). In this collective, we also examined parameters concerning perioperative management, complications, intraoperative blood loss and duration of hospital stay.ResultsPatients with adenoma were on average 64.9 (range 37 to 90) years old; 83.5% of the adenomas were located 3 to 11 cm from the anocutaneous line. In adenoma patients the recurrence rate was 2.9% for an observation period of 21.8 months. The postoperative course was without any complications in 98.1% of patients.Patients with T1 low-risk carcinoma were 64.6 (range 30 to 89) years old. In all cases, an R0 resection could be performed. The recurrence rate was 9.8% for an observation period of 34.4 months. In this group the postoperative course was free of complications in 97.6% of patients.ConclusionsThe high efficacy of transanal endoscopic microsurgery ensures minimally invasive treatment of adenomas and low-risk T1 carcinomas with low complication rates and a low rate of therapeutic failure.

Impact of reticulated platelets on antiplatelet response to thienopyridines is independent of platelet turnover

Reticulated platelets are associated with impaired antiplatelet response to thienopyridines. It is uncertain whether this interaction is caused by a decreased drug exposure due to high platelet turnover reflected by elevated levels of reticulated platelets or by intrinsic properties of reticulated platelets. This study sought to investigate if the impact of reticulated platelets on early antiplatelet response to thienopyridines is mainly caused by platelet turnover as previously suggested. Elective patients undergoing coronary intervention were randomised to loading with clopidogrel 600 mg or prasugrel 60 mg (n=200). Adenosine diphosphate (ADP)-induced platelet reactivity was determined by impedance aggregometry before, at 30, 60, 90, and 120 minutes and at day 1 after loading. Immature platelet count was assessed as marker of reticulated platelets by flow cytometry. Platelet reactivity increased with rising levels of immature platelet count in both groups. This effect was more distinctive in patients on clopidogrel as compared to patients on prasugrel. Overall, immature platelet count correlated well with on-treatment platelet reactivity at all time-points (p < 0.001). These correlations did not change over time in the entire cohort as well as in patients treated with clopidogrel or prasugrel indicating an effect independent of platelet turnover (comparison of correlations 120 minutes/day 1: p = 0.64). In conclusion, the association of immature platelet count with impaired antiplatelet response to thienopyridines is similar early and late after loading. This finding suggests as main underlying mechanism another effect of reticulated platelets on thienopyridines than platelet turnover.

Novel biomarkers in cardiovascular disease: research tools or ready for personalized medicine?

In recent years, a wide range of novel biomarkers have been evaluated for different cardiovascular disease states (eg, ischemia, congestion, and physiological stress), and many have shown promising results for the prediction of cardiovascular end points. However, to become useful for clinicians and to allow for personalized medicine, each novel biomarker must fulfill 3 fundamental criteria: (1) it must be easy to measure; (2) it must provide new information; and (3) it must help the clinician to manage patients. Although many biomarkers may be useful for prognostication, very few have been shown to improve the treatment of patients with cardiovascular disease when implemented in a clinical setting.

Intrinsic platelet reactivity before start with clopidogrel as predictor for on-clopidogrel platelet function and long-term clinical outcome

High on-clopidogrel platelet reactivity is associated with worse clinical outcome. Previous data suggest that intrinsic platelet reactivity before initiation of clopidogrel contributes significantly to on-clopidogrel platelet reactivity. It is unknown whether intrinsic reactivity can sufficiently predict on-clopidogrel reactivity and therefore identify patients with insufficient response to clopidogrel before initiation of treatment and at risk for worse clinical outcome. This analysis included 765 consecutive patients undergoing elective coronary stent implantation. Platelet reactivity was assessed by light transmission aggregometry (5 µM ADP) before administration of clopidogrel 600mg and after intake of first maintenance dose of clopidogrel on day 1 following coronary stenting. Patients were followed for up to seven years. The combined primary endpoint was death of any cause or non-fatal myocardial infarction. Intrinsic and on-clopidogrel platelet reactivity were significant correlated (r=0.31; p < 0.001). Among all tested clinical and genetic factors including the cytochrome P450 2C19*2 polymorphism, intrinsic platelet reactivity was the strongest predictor for on-clopidogrel platelet reactivity. However, intrinsic platelet reactivity could only explain 8 % of variability of on-clopidogrel platelet function. Only on-treatment platelet reactivity was predictive for long-term clinical outcome (HR 1.47, 95 % CI 1.05-2.05; p = 0.02) whereas intrinsic platelet reactivity was not (HR 1.03, 95 % CI 0.74-1.43; p = 0.86). In conclusion, intrinsic platelet reactivity before initiation of clopidogrel is the strongest predictor of early on-clopidogrel platelet reactivity but can only explain a minor proportion of its variability and is not significantly associated with clinical outcome. Thus, baseline testing cannot substitute on-clopidogrel platelet function testing.

Predictors of high-sensitivity cardiac troponin in stable patients undergoing coronary angiography.

AIMS Elevated levels of high-sensitivity troponin are seen in a significant proportion of stable patients undergoing elective coronary assessment. Multiple variables have been associated with troponin levels. The present analysis sought to identify variables independently associated with elevations of troponin and their relative strength of association with this biomarker. METHODS AND RESULTS Stable patients undergoing elective coronary angiography and echocardiographic assessment were enrolled. High-sensitivity troponin T (hsTnT) was determined before any diagnostic procedures. Multivariable linear regression models including angiographic and echocardiographic parameters were used to identify independent predictors of levels of troponin and to determine their relative contribution to levels of troponin. Out of 2,046 patients, 15% presented with levels of troponin above the upper reference limit of normal. In a combined analysis, gender followed by renal function, age, left ventricular ejection fraction, diabetes, and left ventricular mass showed the strongest association with levels of troponin. Coronary obstruction was also an independent predictor, but strength of association weakened following adjustment. CONCLUSIONS Up to 15% of patients undergoing coronary assessment outside the setting of acute coronary syndromes present with elevated levels of cardiac troponin. These changes are independently associated with multiple clinical, laboratory, and imaging variables.

On-clopidogrel platelet reactivity as predictor for long-term clinical outcome in patients after planned discontinuation of clopidogrel

It is unknown whether the known association of high on-treatment platelet reactivity (HTPR) with worse clinical outcome in patients on clopidogrel following coronary stent implantation persists after planned discontinuation of clopidogrel. This study investigated the association of HTPR with major ischaemic events after planned discontinuation of clopidogrel. Consecutive patients undergoing elective coronary stent implantation after loading with clopidogrel 600 mg were followed for up to seven years (n=765). Platelet reactivity was tested on day 1 after coronary intervention. Clopidogrel was continued for six months after implantation of drug-eluting stents and for one month if only bare-metal stents were used. The combined primary endpoint was death of any cause or non-fatal myocardial infarction (MACE). HTPR was found in 217 of 765 patients (28 %). During a median follow-up of 5.7 years, the primary endpoint occurred in 145 subjects after planned discontinuation of clopidogrel. Patients with HTPR showed a higher incidence of MACE after discontinuation of clopidogrel. There was a significant interaction of HTPR and time following discontinuation of clopidogrel beyond one year (p for interaction 0.08). Landmark analyses confirmed that the association of HTPR and MACE was only significant within the first year (HR: 2.93, 95 %-CI 1.13-7.60, p=0.03), but not beyond the first year following discontinuation of clopidogrel (HR: 1.19, 95 %-CI 0.82-1.72, p=0.37). In conclusion, patients with HTPR persist to be at high risk for death or myocardial infarction even following planned discontinuation of clopidogrel. However, this association was only significant for the first year following discontinuation of clopidogrel.