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

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 CM. Stunning but also contamination of rest images by previous exercise images in a short protocol could explain these results. © 2009 Elsevier España, S.L. y SEMNIM.