Activation of prothrombin accompanying thrombolysis with recombinant tissue-type plasminogen activator

AbstractIncreases in thrombin activity in patients given fibrinolytic agents for acute myocardial infarction have been shown to be important in limiting the ultimate success of coronary thrombolysis. The present study was designed to determine whether increases in thrombin activity reflect, in part, activation of prothrombin accompanying thrombolysis. Plasma concentrations of prothrombin fragment 1.2, a polypeptide released when prothrombin is activated by factor Xa, were measured in 22 patients with acute myocardial infarction before and after treatment with 100 mg of recombinant tissue-type plasminogen activator (rt-PA). Concentrations of prothrombin fragment 1.2 increased from 0.83 ± 1.1 nM(mean ± SD) before rt-PA infusion to 1.5 ± 1.5 nM2 h after initiation of the infusion (p < 0.05). After a 5,000-U intravenous dose of heparin given at the end of the infusion of rt-PA, concentrations of prothrombin fragment 1.2 decreased from 1.8 ± 1.5 to 1.1 ± 0.9 nM(n = 20, p < 0.05), although values were still increased compared with concentrations before rt-PA.These results indicate that thrombin activity increases in patients given rt-PA at least in part because of activation of the coagulation system leading to activation of prothrombin. Thus, inhibition of the reactions involving coagulant proteins that lead to activation of prothrombin may be of value as conjunctive treatment to potentiate the efficacy of pharmacologic thrombolysis

High-sensitive troponin T measurements: what do we gain and what are the challenges?

Cardiac troponin (cTn) I and T are structural proteins unique to the heart. Detection of cTn in peripheral blood indicates cardiomyocyte damage. As acute myocardial infarction (AMI) is the most important cause of cardiomyocyte damage, cTns have become an integral part in the diagnosis of AMI. For this indication, cTns are superior to all other biomarkers and therefore are the preferred marker for the diagnosis of AMI. However, cTn indicates and provides an estimate of cardiomyocyte damage irrespective of its cause. The major limitation of contemporary cTn assays is that they are often not elevated during the initial hours of AMI. Recent advances in assay technology have led to more sensitive and precise cTn assays that will have a profound impact on clinical practice. High-sensitive cTn (hs-cTn) assays have two differentiating features from contemporary cTn assays: (i) detection of cTn in a majority of healthy persons and (ii) precise definition of what is ‘normal' (=the 99th percentile). Recent multicentre studies have shown that hs-cTn assays improve the early diagnosis of patients with suspected AMI, particularly the early rule-out. To achieve best clinical use, cTn has to be interpreted as a quantitative variable. Rising and/or falling levels differentiate acute from chronic cardiomyocyte damage. The terms ‘troponin-positive' and ‘troponin negative' should therefore be avoided. ‘Detectable' levels will become the norm and will have to be differentiated from ‘elevated' levels. The differential diagnosis of a small amount of cardiomyocyte damage and therefore minor elevations of cTn is broad and includes acute and chronic cardiac disorders. The differential diagnosis of larger amount of injury and therefore more substantial elevations of cTn is largely restricted to AMI, myocarditis, and a rare patient with tako-tsubo cardiomyopath

Biochemical Validation of Patient-Reported Symptom Onset Time in Patients With ST-Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention

AbstractObjectivesThis study evaluated a biochemical validation of patient-reported symptom onset time in patients with ST-segment elevation myocardial infarction (STEMI).BackgroundSymptom onset time is an important metric but has never been formally validated.MethodsThe Mayo Clinic Percutaneous Coronary Intervention (PCI) Registry was interrogated to obtain baseline, procedural, and outcome data on 607 STEMI patients undergoing primary PCI. Biochemical onset time was determined by backward extrapolation of serial increasing cardiac troponin T (cTnT) measurements.ResultsThe median patient-reported onset time was 12 min later than the calculated time of first cTnT increase and was therefore estimated to be 4.2 h later than the biochemical onset time (interquartile range: 1.9 to 11.1 h; p < 0.001), assuming a 4-h interval between coronary occlusion and first cTnT increase. Conventional ischemic time showed no association with infarct size (correlation with peak cTnT: r = 0.023; p = 0.61) or 1-year mortality (hazard ratio: 0.97 per doubling; 95% confidence interval: 0.68 to 1.40; p = 0.88). However, after recalculation of ischemic time with biochemical onset time, significant associations with infarct size (r = 0.14; p = 0.001) and 1-year mortality (hazard ratio: 1.70 per doubling; 95% confidence interval: 1.20 to 2.40; p = 0.003) were found. When underestimation of ischemic time by patient-reported onset time increased, so did the risk of mortality.ConclusionsAlthough our point estimate should be interpreted with caution, our study indicates that the actual onset of STEMI is likely to be earlier than the patient-reported onset time. Recalculation of ischemic time with biochemical onset time greatly enhanced its prognostic value. Underestimation of ischemic time by patient-reported onset time occurred more often in high-risk patients

Profiles of Serial Changes in Cardiac Troponin T Concentrations and Outcome in Ambulatory Patients With Chronic Heart Failure

ObjectivesThe purpose of this study was to determine whether different profiles of cardiac troponin T (cTnT) values assessed over time would yield incremental prognostic information on clinically stable outpatients with heart failure (HF).BackgroundcTnT levels were used to estimate prognosis in HF; however, most studies evaluated hospitalized patients using single measurements.MethodsA cohort of 172 New York Heart Association functional class III to IV outpatients was prospectively studied with serial cTnT measurements collected every 3 months over a 2-year period. The primary end point was death or cardiac transplantation, and secondary end points included HF hospitalization.ResultsOf the 172 patients, 22 (13%) died or underwent transplantation during the first year. Therefore, 150 patients were included in the second-year analysis of 3 pre-determined groups: 1) no serial cTnT elevations (defined as <0.01 ng/ml); 2) 1 or more, but not all cTnT values elevated ≥0.01 ng/ml; and 3) all cTnT values elevated during the first year. During the second year, 30 events occurred: 53 patients had persistently normal cTnT levels (<0.01 ng/ml) with 6 primary events (11%); 57 patients had 1 or more but not all cTnT levels elevated with 11 events (19%); 40 patients demonstrated persistently elevated cTnT levels with 13 (33%) primary events (odds ratio: 3.77; 95% confidence interval: 1.28 to 11.07, p = 0.02).ConclusionsElevations in cTnT, even using a low threshold of 0.01 ng/ml, detected during routine clinical follow-up of ambulatory patients with HF, are highly associated with an increased risk of events, particularly with frequent or persistent cTnT elevations of ≥0.01 ng/ml. Therefore, the ability to monitor clinical change through serial cTnT measurements may add to risk assessment in the ambulatory HF population