Consecutive patients with a first diagnosis of breast cancer will be identified at the Tom Baker Cancer Centre (TBCC) and included into the study, if they are going to receive chemotherapy with anthracyclines and / or Trastuzumab and do not have contra-indications for the CMR study. Besides the usual clinical care for these patients (e.g. blood samples before each cycle of chemotherapy; MUGA scans to follow cardiac size and function), the patients will undergo serial contrast-enhanced CMR studies (before, during and 9-12 months after completion of the chemotherapy); patients will be seen at an outpatient clinic in the Dept. of Cardiac Sciences / Heart Function Clinic for a clinical assessment (including ECG, additional blood test like Troponin-T, BNP, 6-minute-walk-test) and recommendations will be made to medical treatment in patients with evidence for heart failure.

Time points for the CMR and clinic assessments will be co-coordinated with regularly scheduled test by the TBCC to avoid unnecessary burden for the patients. The oncologists at the TBCC will be blinded to the results of the CMR studies and to laboratory results, unless the participating cardiologists identify a clinical need for communication.

Standardized CMR protocols will be employed and all interpretations will be blinded to the time course of the chemotherapy and cardiotoxic side effects.

We will test the hypothesis, whether CMR can be useful in patients with potentially cardiotoxic chemotherapy to:

• Identify patients at risk for the development of grade 2-4 cardiotoxic side effects as classified by the NCI guidelines (common toxicity criteria, 2001, 1-12)
• Identify imaging parameters to predict early or late Cardiotoxicity
• Provide additional clinical information to optimize medical treatment for heart failure