A rise in systolic blood pressure during adenosine stress myocardial perfusion imaging does not increase the likelihood of an abnormal scan

Abstract

Background: The normal physiologic response to vasodilators, such as adenosine, is a fall in systolic blood pressure (SBP). However, in some cases, a patient's SBP rises rather than falls during adenosine stress myocardial perfusion imaging (MPI). It has been anecdotally suggested that this paradoxical response may result from a heightened adrenergic state due to adenosine-induced ischemia. We sought to assess whether ischemia is more common among patients whose SBP rises during adenosine stress MPI. Methods: Scan findings and SBP responses for 866 consecutive patients (age = 65.7±12.6 years; 356 men) undergoing adenosine stress MPI were assessed. Adenosine (140 μg/kg/min) was infused for six minutes (no concomitant exercise). MPI was performed using either a 201Tl stress / redistribution or a dual isotope ( 201Tl rest / 99mTc stress) protocol. Scans were interpreted by experienced readers. Results: A rise in SBP ≥10 mmHg was seen in 61 (7%) patients, while 227 (26%) had a flat response (ΔSBP <10 mmHg) and 578 (67%) had a drop in SBP ≥10 mmHg. The ratio of ischemic to non-ischemic scans in women was the same, irrespective of SBP response. In men there was a trend toward fewer ischemic scans among patients whose SBP rose compared with those whose SBP fell during testing (p = 0.08). Men with a flat SBP response had an intermediate scan ratio. MPI Result SBP Decreased SBP Flat SBP Increased Male Female Male Female Male Female % with any ischemia 42 29 34 25 29 27 % with no ischemia 58 71 66 75 71 73 Conclusion: A rise in SBP during adenosine infusion is not associated with a higher likelihood of ischemia in patients undergoing adenosine stress MPI. In fact, there is a trend toward less ischemia among men who demonstrate such a paradoxical response. It is unlikely that a rise in SBP during adenosine stress MPI is due to an adrenergic surge in response to ischemia. The finding of more ischemia in men with a fall in SBP may help to account for the observation that men with exaggerated SBP responses to adenosine have a higher risk of cardiac death.