Differences in left ventricular ejection fraction and volumes measured at rest and poststress by gated sestamibi SPECT

Background: Some studies suggested that the poststress left ventricle ejection fraction (LV EF) is lower than rest LV EF in patients with stress-induced ischemia. Methods and Results: By using a 2-day protocol and 30 mCi Tc-99m sestamibi, LV EF, end-systolic volume (ESV), and end-diastolic volume (EDV) were measured with gated SPECT. Of 99 eligible patients, 91 had technically adequate studies. Poststress LV EF minus rest LV EF was defined as ΔLV EF. ΔEDV and ΔESV were similarly defined. Rest and poststress LV EF (r = 0.89), EDV (r = 0.78), and ESV (r = 0.93) were highly correlated (P <.001). Rest LV EF, EDV, and ESV were not significantly different between patients with and without stress-induced ischemia. ΔLV EF was significantly lower in patients with stress-induced ischemia (-3.5% ± 4.5% vs -1.1% ± 4.7%, P = .02). Mean LV EF poststress in ischemic patients was 55.0% ± 10.5% vs 61.2% ± 10.0% in nonischemic patients (P = .008). However, only 1 patient (3%) with ischemia had ΔLV EF that exceeded the 95% confidence limit of ΔLV EF for normal patients. Ischemia was significantly associated with increased ΔEDV and ΔESV (P <.01). Conclusions: Stress-induced ischemia is associated with poststress reduction in LV EF and increased poststress EDV and ESV. However, the effect of ischemia on the difference between poststress and rest EF measurements is modest and rarely exceeds the confidence limits in normal patients undergoing 2-day protocols. In most patients, poststress LV EF is an accurate reflection of rest LV EF.