- Other contraindications to regadenoson (heart rate < 40 bpm, 2nd or 3rd degree heart block, sick sinus syndrome without a pacemaker, severe asthma or COPD with ongoing wheezing or hospitalization within the past 6 months, systolic blood pressure <90mmHg, recent use of dipyridamole, methylxanthine (such as aminophylline) or dipyridamole use within the past 48 hours, or caffeine within 12 hours)