A new piperidine compound is pharmacologically effective for treatment of the arrythmia and is defined by the formula:
in which R 1 is a lower alkyl or a tolyl, R 2 is hydrogen, hydroxyl, a lower alkoxy or a lower alkyl, R 3 is hydrogen, a lower alkyl, a lower alkenyl, a cycloalkyl or a cycloalkylalkyl, X is -CO-, -CH 2 - or -CHOH-, g is an integer of 1 to 3, h is an integer of 1 to 3, Y is hydrogen, a lower alkyl, a lower alkenyl, cyano, -CH 2 COOR, R being hydrogen or a lower alkyl, a cycloalkyl, a cycloalkylalkyl,
1 being 1 or 2, -A-B, A being -(CH 2 )n-, n being an integer of 1 to 5,

a straight-chain alkylene group having 1 to 5 carbon atoms which is a divalent group derived from a straight-chain alkane having lower alkyl, phenyl or hydroxyl. group(s) bonded directly to one or more carbon atoms constituting said alkane by removing a hydrogen atom bonded to each of the carbon atoms placed at both ends thereof,
a straight-chain alkylene group having 1 to 5 carbon atoms which is a divalent group derived from a straight-chain alkene having a double bond formed between carbon atoms adjacent to each other by removing a hydrogen atom bonded to each of the carbon atoms placed at both ends thereof,
k being an integer of 2 to 5, - (CH 2 )p-CO-, p being an integer of 1 to 4, B being cyano, - NR 4 R 5 , a heterocyclic ring or a condensed aromatic ring. A pharmaceutical composition containing said compounds as active ingredient, and the use of said compound in the preparation of a medicament for the treatment of arrhythmia are also disclosed.