tell me patient 26772's average value of heart rate on the last icu visit?
select avg(chartevents.valuenum) from chartevents where chartevents.icustay_id in ( select icustays.icustay_id from icustays where icustays.hadm_id in ( select admissions.hadm_id from admissions where admissions.subject_id = 26772 ) and icustays.outtime is not null order by icustays.intime desc limit 1 ) and chartevents.itemid in ( select d_items.itemid from d_items where d_items.label = 'heart rate' and d_items.linksto = 'chartevents' )