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In the remaining three patients , procainamide was administered orally for treatment of chronic premature ventricular contractions or atrial flutter .
 procainamide, premature ventricular contractions, atrial flutter
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: Disease, Chemical 
Text: {0} 
Answer:
 procainamide, premature ventricular contractions, atrial flutter