Increase in LV end-systolic volume during vasodilator stress gated SPECT myocardial perfusion imaging is predictive of all-cause mortality

Objectives Although post-stress myocardial stunning by SPECT myocardial perfusion imaging (MPI) is a marker for severe coronary artery disease, associations between rest/stress changes of LV ejection fraction (EF) and volumes with all-cause mortality (ACM) have not been fully studied.

Methods We followed 6395 consecutive patients (pts) (65±14years, 59% men) who underwent adenosine/regadenoson stress gated 99mTc-sestamibi and rest 99mTc-sestamibi/Tl-201 MPI. Perfusion was scored visually in 17 segments (0=normal; 4=absent uptake). Ischemia was defined as summed difference score (SDS) ≥4. EF, end-systolic volume (ESV) and end-diastolic volume (EDV) were measured by QPS. Change (Δ) in EF was calculated as the stress/rest EF difference. ΔESV and ΔEDV were calculated as the difference between stress and rest LV volumes and were indexed by body surface area as ΔESVi and ΔEDVi. Low rest EF was defined as <40%. Wilcoxon rank-sum test and Cox proportional hazards analysis were used to compare groups and to assess predictors of ACM. Multiple cut-points for ΔESVi for ACM were assessed.

Results At follow-up of 4±1years, 1183 all-cause deaths occurred. Compared to alive pts, pts who died had higher frequency of SDS ≥4 (14% in alive vs. 24% in death; p<0.001). Pts who died had higher ΔESVi [(median, interquartile range): 2, 0-5 ml/m2 in alive vs. 4, 1-8 ml/m2 in death; p<0.0001], higher ΔEDVi (6, 2-11 ml/m2 in alive vs. 9, 4-14 ml/m2 in death; p<0.0001) and lower ΔEF (0, -4 to 3% in alive vs. -1, -4 to 3% in death; p<0.0001). In Cox proportional hazards analysis adjusting for age, men, risk factors, SDS ≥4 and low rest EF, ΔESVi (HR=1.01, 95%CI 1.00-1.02, p=0.02) was significantly associated with ACM; however, ΔEDVi (HR=1.00, 95%CI 1.00-1.01, p=0.31) and ΔEF (HR=0.99, 95%CI 0.98-1.00, p=0.09) were not. ΔESV >0 ml/m2 was most predictive of ACM.

Conclusions Increase in ESVi during vasodilator stress provides incremental information over SDS and EF for ACM.