procainamide had a more pronounced effect on qrs duration than amiodarone during sinus rhythm ( +18 vs. +8 msec , p less than 0.01 ) and during paced cycle lengths of 600-550 msec ( +32 vs. +23 msec , p less than 0.01 ) and 400 msec ( +37 vs. +28 msec , p less than 0.1 ) but a similar effect on the qrs duration during vt ( +32 vs. +29 msec ) .
C0033216
procainamide
C0042514
vt