Placebo starting prior to the first scheduled anthracycline infusion

LVEF is a measure of contractility of the heart (strength of contraction). Normal values are between 55-65%. It is the most widely used parameter by physicians worldwide to measure cardiac contractility.

LV volumes measure how enlarged the heart is. Chemotherapy destroys cardiac muscle and enlarges the heart (ie. increases LV volumes). The higher the LV volumes, the more damage by chemotherapy.

LV mass measures the amount of cardiac muscle. Chemotherapy destroys cardiac muscle. The lower the LV mass, the more damage by chemotherapy.

Longitudinal strain is the deformation of a material per unit length, defined as the ratio of change in length to the original length in the direction of an applied load. It measures how much an object stretches (tensile) or compresses (compressive) along its axis Longitudinal strain is an echocardiographic technique that quantifies the percentage of systolic shortening of the heart muscle from base to apex. It is a highly sensitive indicator of left ventricular function, detecting subclinical, early myocardial dysfunction (e.g., in cardio-oncology) often before the ejection fraction (LVEF) drops. Normal GLS values are typically >18%.

The 6MWT assesses endurance and ability to walk over longer distances. The 6MWT was first described as a field test for physical fitness in 1963 and then as a 12-minute walk test in people with chronic bronchitis. The 6MWT was found to perform as well as the 12-minute walk, and is now used to assess the submaximal level of functional performance at a similar level required for daily physical activities.

NT-ProBNP is a plasma biomarker of cardiac stress, cardiac tension and severity of heart failure. The higher the NT-ProBNP level, the more severe the heart failure induced by chemotherapy.

Troponin I is a plasma biomarker of cardiac injury and cardiac damage. The higher the troponin levels, the more cardiac damage induced by chemotherapy.