A comprehensive validation of very early rule-out strategies for non-ST-segment elevation myocardial infarction in emergency departments:protocol for a multicentre prospective cohort study

Introduction: Recent advances in troponin sensitivity enabled early and accurate judgement of ruling-out myocardial infarction, especially non-ST elevation myocardial infarction (NSTEMI) in emergency departments (EDs) with development of various prediction-rules and high-sensitive-troponin-based strategies (hs-troponin). Reliance on clinical impression, however, is still common, and it remains unknown which of these strategies is superior. Therefore, our objective in this prospective cohort study is to comprehensively validate the diagnostic accuracy of clinical impression-based strategies, prediction-rules and hs-troponin-based strategies for ruling-out NSTEMIs. Methods and analysis: In total, 1500 consecutive adult patients with symptoms suggestive of acute coronary syndrome will be prospectively recruited from five EDs in two tertiary-level, two secondary-level community hospitals and one university hospital in Japan. The study has begun in July 2018, and recruitment period will be about 1 year. A board-certified emergency physician will complete standardised case report forms, and independently perform a clinical impression-based risk estimation of NSTEMI. Index strategies to be compared will include the clinical impression-based strategy; prediction rules and hs-troponin-based strategies for the following types of troponin (Roche Elecsys hs-troponin T; Abbott ARCHITECT hs-troponin I; Siemens ADVIA Centaur hs-troponin I; Siemens ADVIA Centaur sensitive-troponin I). The reference standard will be the composite of type 1 MI and cardiac death within 30 days after admission to the ED. Outcome measures will be negative predictive value, sensitivity and effectiveness, defined as the proportion of patients categorised as low risk for NSTEMI. We will also evaluate inter-rater reliability of the clinical impression-based risk estimation. Ethics and dissemination: The study is approved by the Ethics Committees of the Kyoto University Graduate School and Faculty of Medicine and of the five hospitals where we will recruit patients. We will disseminate the study results through conference presentations and peer-reviewed journals

Angiotensin converting enzyme inhibitors attenuated the expression of G-protein coupled receptor kinases in heart failure patients

Background: There are few biological markers, which strictly show the severity of congestive heart failure (CHF). Methods and Results: Lymphocyte G-protein coupled receptor kinase (GRK) mRNA expression was measured by quantitative reverse transcription-polymerase chain reaction in 15 CHF patients: 5 patients classified as New York Heart Association class-II treated with angiotensin converting enzyme inhibitor (ACEI) (IIA), 5 patients in class-II without ACEI (IIC), and 5 patients in class-III treated with ACEI (IIIA). GRK mRNA level in IIIA was significantly higher than those in IIA (p<0.05). GRK mRNA level in IIA were significantly lower than those in IIC (p<0.05). Conclusions: The expression level of lymphocyte GRK might show the severity of CHF, and ACEI treatment could reduce the level of GRK in CHF patients. (Circ J 2006; 70: 362 - 363

Chronic beta-adrenergic receptor stimulation enhances the expression of G-Protein coupled receptor kinases, GRK2 and GRK5, in both the heart and peripheral lymphocytes

Background: Enhanced expression of G protein-coupled receptor kinase (GRK) has been reported in failing hearts and in the present study the stability of enhanced GRK mRNA expression, and the correlation between the expression level of GRK mRNA in peripheral lymphocytes and in the heart were both evaluated. Methods and Results: Isoproterenol was injected into rats for 2 weeks, and then GRK5 mRNA was assessed by quantitative reverse transcriptase-palymerase chain reaction. An enhanced expression of cardiac GRK5 mRNA was observed even after 4 weeks of recovery. The isoproterenol-induced increased expression of GRK2 and GRK5 mRNA was equally observed in the heart and lymphocytes, and there was a close correlation between the heart and lymphocytes in the level of expression of each GRK mRNA. Conclusions: The GRK mRNA level is maintained at a high level for a long period without continuous β-adrenergic receptor stimulation. The level in circulating lymphocytes could be used as a surrogate marker to estimate the level of cardiac GRK expression and, presumably, the β-adrenergic receptor function of cardiomyocytes. (Circ J 2005; 69: 987-990