when was the last time patient 4718 was having greater than 90.0 heart rate until 770 days ago?
select chartevents.charttime 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 = 4718 ) ) and chartevents.itemid in ( select d_items.itemid from d_items where d_items.label = 'heart rate' and d_items.linksto = 'chartevents' ) and chartevents.valuenum > 90.0 and datetime(chartevents.charttime) <= datetime(current_time,'-770 day') order by chartevents.charttime desc limit 1