tokens: After exercise , ejection fraction was reduced at 15 and 30 minutes compared with baseline ( mean ( SEM ) , - 5 . 6 ( 1 . 5 ) % , p < 0 . 05 ; and - 6 . 1 ( 2 . 2 ) % , p < 0 . 01 ) , and at 30 and 45 minutes after dobutamine ( - 10 . 8 ( 1 . 8 ) % and - 5 . 5 ( 1 . 8 ) % , both p < 0 . 01 ) .