847
Multiple syncopal episodes started to occur during thalidomide treatment, and a Holter electrocardiogram showed multiple abnormalities, with an episode of sustained ventricular tachycardia.
 adverse event: occur 
Please tell me event type and its trigger word from given type options. Output format is "type: trigger".  Option: adverse event, potential therapeutic event 
Text: {0} 
Answer:
 adverse event: occur 