what is patient 28966's minimum heart rate, until 169 days ago?
select min(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 = 28966 ) ) and chartevents.itemid in ( select d_items.itemid from d_items where d_items.label = 'heart rate' and d_items.linksto = 'chartevents' ) and datetime(chartevents.charttime) <= datetime(current_time,'-169 day')