This consensus statement from the International Cardio-Oncology Society (IC-OS) seeks to provide a structure for defining cardiovascular toxicities of cancer therapy commonly reported in clinical studies including cardiomyopathy/heart failure and myocarditis, vascular toxicity, hypertension, as well as arrhythmias and QTc prolongation. The following are 10 key points to remember:

1. Asymptomatic cardiac dysfunction or symptomatic heart failure (HF) attributed to cancer therapy is collectively termed cancer therapy-related cardiac dysfunction (CTRCD).
2. Symptomatic CTRCD is characterized by an HF syndrome including typical symptoms with signs of volume overload and/or inadequate perfusion, that are caused by structural and/or functional abnormalities of the heart consistent with American Heart Association/American College of Cardiology (AHA/ACC) Stage C/D.
3. Asymptomatic CTRCD is graded based on the change in left ventricular ejection fraction (EF) in the absence of signs or symptoms of HF. A decrease in EF to <40% is graded as severe, while 40-49% is graded as moderate. Mild asymptomatic CTRCD is defined as preserved EF (≥50%) with >15% reduction in global longitudinal strain relative to baseline or new rise in troponins/natriuretic peptides.
4. Myocarditis is defined using a combination of clinical, electrocardiographic, biomarker, imaging, and tissue pathology findings; using major (definite cardiac magnetic resonance imaging findings) and minor (clinical syndrome, arrhythmias, decrease in EF, regional wall motion abnormalities, abnormal troponin) criteria for a clinical diagnosis.
5. Vascular toxicities encompass a wide variety of subclinical and clinical presentations involving both cardiac and the peripheral vasculature and extending from abnormal vasoreactivity of vessels to acute coronary syndrome. This statement emphasizes characterizing the mode of presentation and defining the specific entity according to established guidelines.
6. The diagnostic and therapeutic thresholds for hypertension in cancer patients are the same as established guidelines. Cancer therapy causing hypertension should be suspended in patients with blood pressures >180 mm Hg systolic or 110 mm Hg diastolic until blood pressures are <160 mm Hg.
7. Arrhythmias are defined according to the standard guidelines.
8. Prolongation of the QT interval is a common effect of various cancer therapies. The Fridericia formula is preferred for the calculation of the QTc: QT_c = QT x RR^-1/3. If the corrected QT interval is <500 ms, the risk of torsades de pointes is very low.
9. A review of the medication regimen for QT-prolonging drugs and a change in cancer therapy should be considered if the QTc is >500 ms.
10. Overall, this statement supports the use of standard definitions established by the various American and European cardiovascular societies rather than the Common Terminology Criteria for Adverse Events (CTCAE) typically used in cancer clinical trials.

Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Cardio-Oncology, Congenital Heart Disease and Pediatric Cardiology, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Prevention, ACS and Cardiac Biomarkers, Implantable Devices, Genetic Arrhythmic Conditions, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Congenital Heart Disease, CHD and Pediatrics and Arrhythmias, CHD and Pediatrics and Imaging, CHD and Pediatrics and Prevention, Acute Heart Failure, Heart Failure and Cardiac Biomarkers, Magnetic Resonance Imaging, Hypertension

Keywords: Acute Coronary Syndrome, Arrhythmias, Cardiac, Biomarkers, Blood Pressure, Cardiomyopathies, Cardiotoxicity, Electrocardiography, Heart Failure, Hypertension, Long QT Syndrome, Magnetic Resonance Imaging, Myocarditis, Natriuretic Peptides, Neoplasms, Perfusion, Pharmaceutical Preparations, Secondary Prevention, Stroke Volume, Torsades de Pointes, Troponin, Vascular Diseases, Ventricular Function, Left

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