Introduction Vasodilator stress as part of MPS has existed for decades. There is wide national variation in procedural protocols with many centres advocating physician presence during stress MPS. The suggested safety profile of the adenosine-2A agonist Regadenoson lends itself to physiologist-led stress MPS without the need for physician presence. We investigated the safety of stress MPS with a physiologist-led protocol using Regadenoson as the primary vasodilator agent, compared with an earlier physician-led protocol.

Methods Our centre prefers dynamic stress and will combine it with vasodilator stress as required. Earlier local audit data suggested Regadenoson was safer than other pharmacological stressors in keeping with published data. This resulted in the introduction of physiologist-led stress MPS in September 2011 and replacement of the previous physician-led protocol. Data were prospectively stored on a database. We reviewed all documented serious adverse events (AE) (VF/VT, cardiac arrest, unplanned admission, death) associated with dynamic and vasodilator stress MPS between 1 September 2008 and 30 August 2014. Outcome data between the two periods were analysed: physician-led (September 2008 to August 2011) and physiologist-led (September 2011 to August 2014).

Results In all, 11297 patients underwent stress MPS (physician-led, 5321; physiologist-led, 5976). Compared to the physician-led period, there were fewer patients in sinus rhythm in the physiologist-led period (86.4% vs 91.4%, P < 0.01) and more patients deemed to have a high prognostic cardiovascular risk post-scan (11.7% vs 9.2%, P < 0.01) (Table 1). Vasodilator stress was used more often in the physiologist-led period (43.9% vs 27.9%, P < 0.01). Regadenoson was the main vasodilator in physiologist-led period (64.9%); Dipyridamole in physician-led period (83.9%) (Table 1). There were 8 cases of serious AE (4 in each period) (0.07%): VF/VT (1 and 3 cases in physician and physiologist-led periods respectively), cardiac arrest (2, 2), admission (2, 3) and one death (1, 0). Relative risk of serious AE was 0.89 (95% CI: 0.2–3.6) for patients in the physiologist-led period, relative to those in the physician-led period (Table 2).

Conclusions This retrospective study compared physiologist-led stress MPS using regadenoson as the primary vasodilator agent with a previous physician-led protocol. Physiologist-led stress MPS was not associated with an increased rate of serious AE, with no deaths. Regadenoson stress MPS may be used safely in a physiologist-led setting without immediate physician presence.