Prevention of Anthracycline or Trastuzumab Induced Cardiomyopathy by Metoprolol

This is a randomized, controlled exploration. Consent will be obtained from patients receiving care for cancer with anthracycline or trastuzumab at the University Of Maryland Greenebaum Cancer Center prior to initiation of anthracycline or trastuzumab treatment during the initial oncology visit. Patients will be evaluated in the initial consultation in the oncology clinic during which time consent will be obtained, and any patient with bradycardia (HR less than 50) or other contraindication will be excluded from the study. The patients will be randomly assigned to metoprolol vs. control groups during this initial visit. Individuals in the control group will not receive any study drug where as those in the metoprolol group will be given prophylactic metoprolol prior to initiation of anthracycline or trastuzumab treatment. Metoprolol tartrate will be provided to each patient randomized to the metoprolol group. Also at the time of the initial consultation, a baseline MUGA will be obtained for evaluation of left ventricular ejection fraction. Additionally, a post-treatment MUGA will be obtained after the final course of chemotherapy. Lastly, also at the initial visit, one vial of blood will be obtained from each patient to test for genetic polymorphisms, as described in the background section, which may contribute to the response to beta blockade in the prevention of anthracycline or trastuzumab induced cardiomyopathy. Each participant in the metoprolol group will be started on 25 mg of metoprolol tartrate twice a day prior to initiation of the anthracycline or trastuzumab. After one week, this dose will be increased to 50 mg twice daily, if tolerated. Prior to increasing the dose, the patients will be seen in the cardiology research clinic by the study doctor and evaluated for side effects. After another week the dose will again be increased to 100 mg twice daily. The dose can be decreased at any time if side effects occur such as bradycardia with HR less than 50 or hypotension with SBP less than 90. The beta blocker will be held for two days prior to the post-treatment MUGA so as not to acutely affect heart rate, as a decrease in heart rate would be expected to increase EF14. Abrupt cessation of metoprolol tartrate will not lead to withdrawal of beta-blockade. This study will end with the post-treatment MUGA. The primary end point of this study will be the change in EF before and after anthracycline or trastuzumab treatment. A pill diary will be maintained to document compliance of study medication.