Usefulness of distinct activity thresholds according to baseline regional asynergy for predicting functional recovery in patients with chronic coronary artery disease and left ventricular dysfunction: A study with nitrate-enhanced sestamibi gated SPECT

Background. The role of gated single photon emission computed tomography (S PECT) in improving viability detection with the use of perfusion imaging is uncertain. This study aimed to verify whether the classification of baseli ne regional dysfunction with gated SPECT helps to predict functional recove ry with the use of quantitative perfusion imaging. Methods and Results. Resting nitrate-enhanced sestamibi gated SPECT was per formed in 31 patients with left ventricular dysfunction, who later underwen t coronary revascularization. With the use of a 16-segment model, tracer ac tivity was quantified, and wall motion and thickening were estimated with a 4-point scoring scheme. Reversible dysfunction was assessed with followup gated SPECT. According to receiver operating characteristic curve analysis, the best overall cutoff for predicting reversible dysfunction in asynergic segments was 50% of peak activity or greater, with 83% sensitivity, 54% sp ecificity, and 64% accuracy. When the segments were divided according to wa ll motion in resting gated SPECT, the optimal activity cutoff was greater t han 68% for hypokinetic and 50% or greater for adyskinetic segments. With t he use of 2 thresholds, the overall sensitivity remained good (76%), wherea s specificity increased to 73% (P<.0005) and accuracy to 74% (P<.02). Conclusions. Regional dysfunction assessment directly on perfusion images p ermits use of different activity thresholds with an improvement over a sing le cutoff for all asynergic segments. Therefore combining perfusion and fun ctional data with nitrate-enhanced gated SPECT at rest appears to be a prom ising approach for viability detection.