Novel 1-[(aminoalkyl and aminoalkylamino)carbonyl and thiocarbonyl-.alpha.,.alpha.-diaryl-pyrrolidine, piperidine and homopiperidineacetamides and acetonitriles having the formula: ##STR1## wherein; n is zero, one or two;X is oxygen or sulfur;Z is ##STR2## 10 or --(CH.sub.2); p is 0 to 5 inclusive with the proviso that when Z is ##STR3## p is at least one; Y is aminocarbonyl or cyano;Ar.sup.1 and Ar.sup.2 are 2, 3 or 4-pyrido, phenyl or substituted phenyl;R is hydrogen or loweralkyl;R.sup.1, R.sup.2 and R.sup.3 are hydrogen, cycloalkyl, loweralkyl, phenyl, substituted phenyl, phenylloweralkyl, and R.sup.2 and R.sup.3 taken with the adjacent nitrogen may form a heterocyclic residue, and diastereoisomers when possible and pharmaceutical salts; and the method and pharmaceutical compositions for treating cardiac arrhythmias therewith are disclosed.