questions about echo

My onc took me off my herceptin because my exho showed an ejection fraction of ony 40-45%. my last one was 60- the rest of the report seemed ok-said the ventricles were ok and no hypertrphy but LV systolic function midly reduced.All other valves normal What does this all mean. He said I may or may not be able to resume herceptin xxometime but did not say for sure, Any info would be helpful. Thanks.