Pharmaceutical compositions comprised of aryloxy-N-(aminoalkyl)-1-pyrrolidine and piperidine carboxamides and carbothioamides are provided of the formula: ##STR1## wherein Ar is selected from the group consisting of 1-naphthyl, 2-naphthyl, 2,3-dihydro-1H-inden-4-yl, 2,3-dihydro-1H-inden-5-yl, phenyl, substituted phenyl wherein the substituents are selected from lower alkyl of from 1 to 8 carbon atoms, lower alkyloxy of from 1 to 8 carbon atoms, halogen and trifluoromethyl; m and n are 1 or 2 but are never 2 at the same time; p is 1, 2, 3 or 4; R is selected from hydrogen or lower alkyl of from 1 to 3 carbon atoms; R.sup.1 and R.sup.2 are selected from hydrogen, lower alkyl of from 1 to 8 carbon atoms, phenyl, phenyl lower alkyl of from 7 to 9 carbon atoms, and cycloalkyl of from 3 to 8 carbon atoms, and R.sup.1 and R.sup.2 taken together with the adjacent atom may form a heterocyclic residue selected from 4-morpholino, 1-pyrrolidino, 1-piperidino, 1-piperazino and 4-lower alkyl piperazin-1-yl; X is oxygen or sulfur; and the pharmaceutically acceptable acid addition salts thereof having antiarrhythmic activity.