Cardiac biomarkers

Apple FS, Quist HE, Otto AP, Mathews WE, Murakami MM. Release characteristics of cardiac biomarkers and ischemia-modified albumin as measured by the albumin cobaltbinding test after a marathon race. Clin Chem 2002 48 1097-1100. 

Prognostic significance of cardiac biomarker release after percutaneous coronary intervention and the impact of glycoprotein Ilb/IIIa inhibitor treatment... 

Wiviott SD, Cannon CR Morrow DA, et al. Differential expression of cardiac biomarkers by gender in patients with unstable angina/non-ST elevation myocardial infarction. Circulation 2004 109 580-586. 

The second patient group presents 4 to 48 hours after the onset of chest pain but without diagnostic evidence of AMI by ECG. This group of patients also requires serial monitoring of cardiac biomarkers and ECG changes. 

The ideal marker of myocardial injury should (1) provide early detection of injury, (2) allow rapid diagnosis of cardiac injury, (3) serve as a risk stratification tool in patients with ACS, (4) assess the success of reperfusion after thrombolytic therapy, (5) detect reocclusion and reinfarction, (6) determine the timing of an infarction as well as infarct size, and (7) detect procedural-related perioperative MI during cardiac or noncardiac surgery. At present, the perfect biomarker to satisfy all these needs does not exist. It is the function of the laboratory to provide advice to physicians about cardiac biomarker characteristics. 

Review the role of cardiac biomarkers for infarct sizing and monitoring the success of reperfusion following therapy. 

Recommendations for Use of Cardiac Biomarkers for Detection of Myocardial Injury and Myocardi... 

The analytical techniques used to measure the most commonly used cardiac biomarkers are reviewed here. All of the initial cardiac markers were enzymes, so the earfiest techniques measured the catalytic activity of the marker. Immunoassay techniques measure the mass of a marker and they are the predommant methodology used in clinical laboratory practice today. Analytically, they offer lower limits of detection, improved precision, and faster assay times, on both highly automated central laboratory platforms and POCT. 

Figure 44-12 Classic rise and falling pattern of cardiac biomarkers from onset of acute myocardial infarction ...

The clinical utility of cardiac biomarkers for monitoring reperfusion following thrombolytic therapy has not gained favor as a routine form of testing for determining the success or failure of reperfusion therapy It is accepted that... 

Andersson H, Steel D, Asp J et al (2010) Assaying cardiac biomarkers for toxicity testing... 

Interim blood sampling of rats may not be necessary when the dose levels are similar in the short- and longer-duration studies. The sample timings in the guidelines refer to the core tests, but some specialized tests require samples to be collected at times in relation to the toxic injury in acute studies (e.g., cardiac biomarkers) or to expected peaks in the circadian or reproductive cycle rhythms. Additional times for blood sampling should be avoided if the procedures could compromise the health of the animals. In all procedures, consideration should be given to the possible stress effects of the sample collection procedures and the amount of blood collected in relation to the total blood volume. 

The timing of the urine collections is a critical factor in detecting renal injury. Tubular necrosis is an event more likely to occur early in a study, and therefore urine samples are best taken during this early period, whereas renal papillary necrosis is more likely to occur in a later part of a study (Heywood 1981). In some acute cardiac toxic events, the cardiac biomarkers increase within a few hours of injury, so sampling needs to be timed within this window because later samples may not show elevations of these biomarkers. 

Whereas CK and LD isozymes have been quite successful as cardiac biomarkers in humans, their use in animals has been limited by the need to exclude muscle injury (O Brien et al. 1997a). This is clearly more difficult in animals because symptoms of myopathy are more difficult to detect and because of a greater background incidence of effects on skeletal muscle associated with handling and stress. The mildly greater concentration of specific isoenzymes in cardiac versus skeletal muscle that confers diagnostic relevance may be offset by the much larger amount of muscle mass. 

Fatty acid binding protein (FABP3) is a cytosolic protein recently reported to be more sensitive for detection of cardiac injury in humans with myocardial infarct or congestive heart failure (Mion et al. 2007 Niizeki et al. 2007). Flowever, FABP3 is also found, although in much lower concentrations, in muscle, brain, and kidney. As for CK and LD, its occurrence in skeletal muscle substantially diminishes its value as a cardiac biomarker because of the higher and variable background of mild skeletal muscle injury in laboratory animals. Its use as a cardiac biomarker would require exclusion of muscle injury and renal disease. 

---