in this month, has patient 18866's heart rate been ever less than 88.0?
select count(*)>0 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 = 18866 ) ) 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 < 88.0 and datetime(chartevents.charttime,'start of month') = datetime(current_time,'start of month','-0 month')