Only two Swedish runners have run faster than Bengtström in history.
Johan Wissman in Italy in 2009 when he ran 45.89 and the Swedish record holder Jimisola Laursen who ran 45.59 in Vienna in 2002.
21-year-old Carl Bengtström has previously won gold in the distance in the U20 WC 2019 and is the reigning Swedish indoor champion in the 200 meters.
Bengtström's previous personal record of 400 meters indoors, was 47.17 from competitions in Norway 2019.
The competitions in Växjö, Quality Hotel Games, are in progress.