Comparison of hemodynamic and stress testing variables in patients undergoing regadenoson stress myocardial perfusion imaging to regadenoson with adjunctive low level exercise myocardial perfusion imaging

Objectives The hemodynamic and stress SPECT variables,aminophylline use and immediate safety when using the new vasodilator regadenoson with adjunctive exercise(REGWALK)compared to REGSPECT has not been well studied and formed the basis of our study.

Methods Retrospective evaluation of 887 patients undergoing REGSPECT(Grp 1)compared to 485 patients undergoing REGWALK SPECT using modified Bruce Protocol stage1(Grp 2)between Jan-Nov 2009.Heart rate(HR),blood pressure(BP)differences, EKG,stress perfusion and gated variables were evaluated.Patient symptoms,documented immediate major clinical events(arrythmias,severe hypotension,syncope,pre-syncope)and use of aminophylline were noted.Continuous variables were expressed as mean +/- SD,and univariate differences were tested using Student t test.

Results Grp 2 patients were younger,male, with higher BSA with less prevalence of prior MI or COPD(all p value <0.001 vs Grp1).Grp 2 had higher stress HR(Grp1 84+19 vs 103+20.5 Grp 2)and HR reserve(stress -rest HR,Grp 1 14.7+15.5 vs 36.3+19,both p=0.001 vs Grp 1).A significant rise in systolic BP(-8.9+19.8 in Grp1 vs 4.8+21.3 mmhg(p<0.001), less fall in diastolic BP(-7.3+10.3 Grp1 vs -3.9+10.7 mmhg Grp2)was also noted.Ischemic EKG changes were significantly more in Grp2 vs Grp1(4.5% Grp1 vs 8%Grp2, OR 1.97,p=0.006).Although summed stress scores and TID ratio were lower in Grp2,total ischemic burden was non-significant between both groups.Finally aminophylline use was significantly lower in Grp2(11.4% Grp1 vs 5.6% Grp2, OR 0.46,p=0.001).No differences in headache,muscle aches or arrythmias were noted between both groups.There were no major adverse events in the immediate post stress period in the Grp2 patients.

Conclusions This study shows that REGWALK SPECT gives more favorable HR, BP response with less use of aminophylline and no increase in adverse events when compared to REGSPECT and can be safely employed in suitable patients.

Research Support Astella