Methods and pharmaceutical compositions for treatment of amyloid deposition diseases using chimeric (e.g., mouse-human) antibody are disclosed, including a method for treating amyloid deposition diseases with cardiac involvement by administering pharmaceutical compositions comprising a chimeric anti-amyloid fibril antibody. The methods herein can improve myocardial function in patients diagnosed with light chain amyloid light chain amyloidosis (ALA) having a cardiac involvement in as little as three weeks after treatment.