Assessment of the influence of atrial fibrillation on gated SPECT perfusion data by comparison with simultaneously acquired nongated SPECT data.

The impact of arrhythmias on the evaluation of perfusion data from myocardial gated SPECT has been assessed by comparing arrhythmic patients with nonarrhythmic patients or by simulating rhythm disturbances. Whether gating-related artifacts may have a clinically relevant influence on the evaluation of perfusion in atrial fibrillation (AF) patients is still uncertain. Recently, collection of nongated and gated datasets during the same SPECT acquisition has become possible. The aim of this study was to examine the difference in myocardial perfusion between simultaneously acquired gated and nongated SPECT data in AF patients. METHODS: In 44 consecutive AF patients who underwent myocardial perfusion SPECT for standard clinical indications, both a gated and a nongated study were simultaneously acquired. Perfusion was estimated in a masked manner on a 20-segment model using an established scoring scheme. RESULTS: Agreement was good between the gated and nongated perfusion scores on a segment basis; the agreement for resting scores was the highest, with those for stress and difference scores being lower (Spearman rho = 0.82, 0.74, and 0.55, respectively). On a patient basis, a similar trend was seen in summed resting scores (rho = 0.911), summed stress scores (rho = 0.779), and summed difference scores (rho = 0.596). When summed stress and summed difference data were grouped by severity class (normal, mild abnormality, moderate abnormality, and severe abnormality), agreement decreased from rho = 0.818, kappa = 0.639, for summed stress score to rho = 0.549, kappa = 0.367, for summed difference score. The severity class of inducible ischemia changed in 17 patients (39%) if a (summed) gated image was used instead of a standard nongated perfusion image. CONCLUSION: AF may have a clinically relevant impact on summed gated perfusion images, compared with images simultaneously obtained without gating in the same patients. Therefore, acquisition of a nongated SPECT study is mandatory for accurate assessment of myocardial perfusion in AF patients.