From the Guidelines
NSTEMI is distinct from elevated troponin levels, as it requires both elevated cardiac troponin and clinical evidence of acute myocardial ischemia, whereas troponin elevations can occur in various other conditions. The diagnosis of NSTEMI involves a comprehensive clinical assessment, including symptoms like chest pain, ECG changes such as ST-segment depression or T-wave inversions, and a rising and/or falling pattern of troponin levels 1. According to the 2015 ESC guidelines, measurement of a biomarker of cardiomyocyte injury, preferably high-sensitivity cardiac troponin, is mandatory in all patients with suspected NSTE-ACS, and a dynamic elevation of cardiac troponin above the 99th percentile of healthy individuals indicates MI 1.
Key differences between NSTEMI and elevated troponin include:
- Clinical presentation: NSTEMI typically presents with symptoms of acute myocardial ischemia, such as chest pain, whereas elevated troponin can occur in various conditions, including heart failure, pulmonary embolism, sepsis, renal failure, myocarditis, and after strenuous exercise 1.
- ECG changes: NSTEMI is characterized by the absence of ST-segment elevation on an ECG, whereas other conditions may have different ECG findings 1.
- Troponin pattern: NSTEMI requires a rising and/or falling pattern of troponin levels, whereas isolated troponin elevation without evidence of acute coronary syndrome would be managed based on the underlying cause 1.
Treatment for NSTEMI typically includes antiplatelet therapy, anticoagulation, and often early cardiac catheterization, whereas isolated troponin elevation without evidence of acute coronary syndrome would be managed based on the underlying cause 1. It is essential to note that high-sensitivity cardiac troponin assays are recommended over less sensitive ones, as they increase diagnostic accuracy for MI at the time of presentation, especially in patients presenting early after chest pain onset 1.
From the Research
NSTEMI and Elevated Troponin
- NSTEMI (Non-ST-Elevation Myocardial Infarction) is a type of heart attack that is diagnosed based on the presence of elevated cardiac troponin levels, ECG changes, and clinical presentation 2.
- Elevated troponin levels can be caused by various medical conditions, not just ACS (Acute Coronary Syndrome) 2.
- A study found that 51% of patients with elevated troponin levels had true ACS, while the remaining 49% had non-ACS-related elevation in troponins 2.
- The presence of chest pain, tobacco smoking, and wall motion abnormalities on echocardiogram were associated with increased risk of true ACS in patients with elevated troponins 2.
Diagnosis and Treatment
- The diagnosis of ACS should not be solely based on elevated troponin levels, as it can lead to expensive workup and utilization of hospital resources 2.
- Antithrombotic therapy with aspirin, clopidogrel, and enoxaparin has been shown to be effective in reducing the combined endpoint of death and non-fatal reinfarctions in patients with NSTEMI 3.
- Enoxaparin has been found to be more effective than unfractionated heparin in preventing the combined endpoint of death and myocardial infarction in patients with NSTEMI 4, 5.
- The use of clopidogrel, aspirin, and enoxaparin has been associated with a reduction in major adverse cardiovascular events in patients with NSTEMI 3, 5.
Patient Management
- Elderly patients with unstable angina pectoris/non-ST-segment elevation myocardial infarction should be hospitalized and treated with aspirin, clopidogrel, and beta blockers 6.
- Patients whose symptoms are not fully relieved with medical therapy should be treated with continuous intravenous nitroglycerin and considered for cardiac catheterization and PCI 6.
- High-risk patients should have an early invasive strategy with CABGS or PCI performed depending on the coronary artery anatomy, left ventricular function, and presence or absence of diabetes 6.