tell me the number of times patient 13054 had received a ck-mb index lab test since 81 months ago.
select count(*) from labevents where labevents.itemid in ( select d_labitems.itemid from d_labitems where d_labitems.label = 'ck-mb index' ) and labevents.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 13054 ) and datetime(labevents.charttime) >= datetime(current_time,'-81 month')