Adenosine-induced transient septal hyperperfusion on myocardial perfusion imaging

Adenosine might evoke transient septal hyperperfusion during myocardial perfusion imaging (MPI). Here, we attempted to prove that adenosine-induced transient septal hyperperfusion is a normal variation on MPI by retrospective and prospective analysis. Inter-ventricular septum (IVS) and left ventricular free wall (LV) perfusions were evaluated by quantitative perfusion SPECT (QPS) and count profile analysis (CPA). IVS: LV perfusion ratios were calculated. In a retrospective analysis, 30 consecutive dual isotope MPI (TI-201 rest/adenosine stress Tc-99m MIBI) cases (M: F = 21: 9, age: means.e. = 65.61.4y), which had been reported to have no significant perfusion defect, were re-evaluated for IVS: LV ratio between stress and rest. In a prospective analysis, 29 patients (M: F = 17: 12, age = 51.48.8y) underwent the dual isotope MPI on day 1 and IVS: LV perfusion ratios were calculated at stress and rest. On day 2 these 29 patients were re-stressed by adenosine infusion and post-stress IVS: LV ratios were obtained by injecting Tc-99m MIBI 15 minutes after completing adenosine infusion. IVS: LV ratios were compared among stress, post-stress and rest phases. In the retrospective analysis, IVS: LV ratios significantly reduced from stress to rest (p<0.001) by QPS (means.e., 0.950.01 vs. 0.900.01) and by CPA (0.930.02 vs. 0.850.01). In the prospective analysis, IVS: LV ratios significantly reduced between stress and post-stress (p<0.001) by QPS (0.980.01 vs. 0.940.01) and by CPA (0.920.01 vs. 0.850.02). In addition, IVS: LV ratios further significantly reduced between post-stress and rest (p<0.01) by QPS (0.940.01 vs. 0.910.01). Adenosine evokes transient septal hyperperfusion, and this generates different distributions of normal perfusion between stress and rest during MPI