Adverse reactions to pharmacological agents used in stress myocardial perfusion imaging studies: differences in older and younger patients in a South African population cohort

Abstract

Myocardial perfusion imaging (MPI) is a non-invasive nuclear medicine technique that plays a valuable role in the evaluation of coronary artery disease (CAD). In patients who are unable to tolerate exercise, pharmacological stress MPI with coronary vasodilators is widely used as an alternative to achieve coronary hyperemia. This study aimed to assess age-related differences in patient tolerance to coronary vasodilators (adenosine and dipyridamole), as well as compare their side effect profiles in a South African population cohort. In addition, other factors that may influence tolerability to coronary vasodilators were identified. Two hundred and sixty-four patients undergoing pharmacological stress MPI between August 2018 and November 2019 were prospectively observed for the development of adverse effects during or immediately after the intravenous vasodilator infusion. One hundred and forty seven patients (55.7%) received adenosine while 117 patients (44.3%) received dipyridamole. An age threshold of 60 years was used to divide the study population into two groups; <60 years (Group A) and > 60 years (Group B). Adverse effects occurred in 62.1% of the study population, majority of which were mild and moderate adverse effects and required no intervention. Only 3 patients (1%) developed severe adverse effects which required reversal with intravenous aminophylline. Older study participants (Group B) were 42% less likely to develop adverse effects compared to younger study participants (Group A) (OR = 0.58; 95% CI= 0.35-0.97; p=0.036). For adenosine, chest pain and dyspnea were the most common adverse effects in Group A and B, respectively. For dipyridamole, headache was the most common adverse effect in both age groups. Adenosine was three times as likely to cause adverse effects compared to dipyridamole (OR = 3.23; 95% CI= 1.93-5.43) (p<0.001). However, dipyridamole showed a higher propensity to cause higher grade adverse effects despite more participants receiving adenosine (p<0.001). Pharmacological stress MPI with intravenous vasodilators is an overall safe method for assessing CAD. Side effects are more common in younger patients but are largely tolerable and resolve spontaneously after termination of the vasodilator infusion.