Short exercise-rest versus long myocardial perfusion gated SPECT protocols in patients with ischemic cardiomyopathy

Abstract

Objective

The purpose of this study was to analyze left systolic ventricular function and myocardial perfusion characteristics between short one day exercise-rest and long two days gated SPECT (Single Photon Emission Computed Tomography) protocols in patients with ischemic cardiomyopathy (ICM).

Methods

A prospective study of 40 patients (59.6 ± 8.9 years, 3 women) with IHD (left ventricular ejection fraction (EF) ≤ 40%) was performed with myocardial perfusion gated SPECT. From 5 to 10 days after a one-day exercise-rest study (gated SPECT-1), patients were called back for a second rest study (gated SPECT-2) in order to compare EF and differences in perfusion summed rest score (ΔSRS=SRS1-SRS2) and summed difference score (ΔSDS=SDS1-SDS2) between both protocols.

Results

Between rest-gated SPECT-1 (short protocol) and rest-gated SPECT-2 (long protocol) EF increased (34% vs 37%, P = 0.008) in 26 patients (65%), and in 11 patients (27.5%) the increase was ≥ 5%. There were no significant differences in clinical and coronary angiography variables between patients with and without increase of the EF ≥ 5%. In the multivariate analysis, ΔSRS (95% CI: −1.1 to −29.2) and ΔSDS (0.179–1.236) were predictors for this EF increase between both studies.

Conclusions

Exercise-rest short protocol can underestimate EF in patients with ICM. Stunning but also contamination of rest images by previous exercise images in a short protocol could explain these results.