Presence of Postsystolic Shortening Increases the Likelihood of Coronary Artery Disease: A Rest Electrocardiography-Gated Myocardial Perfusion SPECT Study

Postsystolic shortening (PSS), which is a delayed myocardial contraction that occurs after end-systole, has been considered an important diagnostic index of myocardial ischemia. Recent technological advancements in quantitative gated SPECT (QGS) software enables the left ventricular (LV) regional analysis and may be useful for PSS measurement. The purpose of this study was to evaluate whether PSS at the resting condition determined by QGS is useful to identify patients with coronary artery disease. The study comprised 146 patients (mean age ± SD, 71 ± 8 y; 98 men) with normal LV wall motion (mean LV ejection fraction ± SD, 72% ± 9%) who underwent both coronary angiography and resting (99m)Tc-tetrofosmin myocardial perfusion SPECT. The sum of the difference between post-end-systolic maximal LV thickening and end-systolic LV thickening, designated PSS index, was calculated from 17 LV myocardial segments using QGS. The PSS index was significantly higher in patients with significant stenosis of the coronary artery than in the other patients (9.8 ± 10.2 vs. 5.6 ± 5.1; P < 0.01). A cutoff point of 6.0 of the PSS index had sensitivity, specificity, positive predictive value, and negative predictive values of 55%, 70%, 76%, and 47%, respectively, for the diagnosis of coronary artery disease. Multivariate logistic regression analysis demonstrated that a PSS index greater than 6.0 was an independent predictor for the presence of coronary artery disease (odds ratio, 2.46; 95% confidence interval, 1.1-5.4; P < 0.05). Among subjects with normal LV function, PSS index even in the resting condition determined using QGS may help to identify patients with coronary artery disease.