Troponin

Troponin is a protein component of the actin filament and acts as a regulator protein and contractile unit of the muscle. The determination of the values of troponin I and T is used for the diagnosis and monitoring of acute myocardial infarction and the prognosis of unstable angina pectoris

Standard value: The reference range for troponin I is < 99th percentile, for troponin T < 14 ng/l

Pathologically increased: acute myocardial infarction (together with CK-MB), pulmonary embolism, myocarditis, endocarditis, pericarditis, cardiomyopathy, coronary heart disease, heart failure, tachycardia, hypertrophic cardiomyopathy, renal failure, heavy physical load, hypertensive crisis.

Acute cardiotoxicity: Cardiac adverse events during cancer therapy or up to one year thereafter are referred to as acute cardiotoxicity. Risk factors include cumulative dose, age over 65 years, female gender, prior cardiac disease, cardiovascular risk factors, and combination therapy.

Chemotherapy is particularly potent in releasing the cardiac biomarker troponin, and troponin elevation has been shown to be associated with the expression of left ventricular dysfunction. An association of troponin with worsening left ventricular ejection fraction (LVEF) has also been demonstrated for immune checkpoint inhibitor therapy of melanoma.

Preventive Therapy: A meta-analysis indicates that preventive therapy with ACE inhibitors and beta-blockers may reduce not only troponin release but also the decrease in left ventricular ejection fraction. Often, orgasm compensates for acute cardiotoxicity by cardiac hypertrophy. In the longer term, acute coronary syndromes, stroke, and heart failure may occur.

Cardiotoxicity with immunotherapy: Therapy with immune checkpoint inhibitors may also lead to myocarditis. The prevalence of this side effect is 1-2%. Affected individuals show changes in troponin, which is also an important biomarker in this case. nt-ProBNP, on the other hand, is abnormal in only two-thirds of affected individuals, and LVEF is abnormal in only about half.

Cardiac monitoring of cancer therapy with checkpoint inhibitors: A consensus paper recommends determination of troponin, 24-hour ECG, and examination of cardiac function with cMRI or echocardiography before initiation of therapy with immune checkpoint inhibitors . During therapy, troponin should be determined every two weeks along with clinical assessment and ECG, and creatine kinase (CK) should also be determined because of the increased risk of myositis. If the biomarkers increase and clinical symptoms occur at the same time, the therapy must be stopped and a clarification must be made.