As heroin addicts sometimes faint while using illicit drugs , doctors might attribute too many episodes of syncope to illicit drug use and thereby underestimate the incidence of TdP in this special population , and the high mortality in this population may , in part , be caused by the proarrhythmic effect of methadone .
O B-DiseaseOrPhenotypicFeature I-DiseaseOrPhenotypicFeature O O O O O O O O O O O O O O B-DiseaseOrPhenotypicFeature O O O O O O O O O O B-DiseaseOrPhenotypicFeature O O O O O O O O O O O O O O O O O O O O O O O O B-ChemicalEntity O