Dipyridamole-induced worsening of mechanical synchrony on Tl-201 gated myocardial perfusion SPECT predicts severe and extensive coronary artery disease

Objectives Our previous work had found that stress-induced myocardial ischemia was associated with early post-stress left ventricular (LV) mechanical dyssynchrony as assessed by phase analysis of Tl-201 gated myocardial perfusion SPECT. In this study, we aimed to evaluate the significance of stress-induced worsening of mechanical synchrony of LV in the diagnosis of coronary artery disease (CAD) on dipyridamole Tl-201 gated SPECT.

Methods The study included 150 patients (107 males, mean age: 64±11), who underwent dipyridamole Tl-201 gated SPECT and invasive coronary angiography within 3 months. The early post-stress scan was started at 5 minutes after injection, and followed by the rest scan 4 hours later. LV dyssynchrony parameters were calculated by phase analysis (Emory Cardiac Toolbox) and compared between the stress and rest images. Increase of phase standard deviation (PSD) ≥ 10 degree from rest to post-stress was considered to have significant stress-induced worsening of LV mechanical synchrony (based on our previous study of repeatability of phase analysis).

Results In the total of 150 patients, 62 were found to have severe and extensive CAD (diameter stenosis ≥ 70% in two or more major coronary arteries). The patients with severe and extensive CAD had worsening LV mechanical synchrony (mean difference of stress/rest PSD: 1.3±8.2), whereas, those without severe and extensive CAD had improved synchrony (mean difference of PSD: -2.9±7.1, p<0.005). Ten patients were found to have significant stress-induced worsening of mechanical synchrony. 9 of the 10 patients (90%) had severe and extensive CAD.

Conclusions Dipyridamole-induced worsening of LV mechanical synchrony shown on early post-stress and rest Tl-201 gated SPECT was highly predictive of severe and extensive CAD.

Research Support 1. Hung GU, Lee KW, Chen CP, et al. Worsening of left ventricular ejection fraction induced by dipyridamole on Tl-201 gated myocardial perfusion imaging predicts significant coronary artery disease. J Nucl Cardiol 2006; 13:225-232. 2. Dorbala S, Vangala D, Sampson U, et al. Value of vasodilator left ventricular ejection fraction reserve in evaluating the magnitude of myocardium at risk and the extent of angiographic coronary artery disease: a 82Rb PET/CT study. J Nucl Med 2007;48:349 -358. 3. Chen CC, Shen TY, Chang MC, Hung GU, Chen WC, Kao CH, Chen J. Stress-induced Myocardial Ischemia is Associated with Early Post-stress Left Ventricular Mechanical Dyssynchrony as Assessed by Phase Analysis of Tl-201 Gated SPECT Myocardial Perfusion Imaging. Eur J Nucl Med Mol Imaging. 2012;39:1904-1909.