Gated-spect imaging using vasodilating stressor for risk stratification of subjects with or without coronary artery disease

Abstract

Dipiridamole stress myocardial SPECT is known to be able to stratify the risk of cardiovascular disease, but there are not data about the additional value of post-stress and rest left ventricular ejection fraction (LVEF), by gated-SPECT (gS) analysis, in the same exam. Aim of our study was to evaluate the stratification of risk matching parameters of perfusion and LV function using stress-dipyridamole/rest gS. Methods: 1008 consecutive patients (pts) (715 males, mean age 69 years) performed stress-dipyridamole Tc-99 tetrofosmin gS (0.56 mg/Kg of dypiridamole in 4 minutes). For the imaging study we adopted a dual-day stress/rest protocol. Both post-exercise and resting images were gated and acquired 20–30 minutes after injection of technetium 99m-tetrofosmin (after 3 minutes from finish of infusion of dypiridamole) using a dual-head camera. Perfusion quantitation (SSS, SRS, SDS), and LVEF were automatically calculated with the use of Autoquant™ software package. The perfusion was normal when SSS < 4 and the LVEF > 45%. The follow-up for hard cardiac events (cardiac death or myocardial infarction) was 18,5 ± 7.5 months and completated in 902 pts (89.4%). Results: The frequency of cardiac events/year was major in pts with SSS > 4 (14/393, 3.7%) vs pts with normal perfusion (4/615, 0.7%) and in pts with post-stress LVEF < 45% (11/191, 5.9%) vs pts with normal LVEF (7/817, 0.9%). The crossing analysis demostreted a major rate of cardiac events in pts with significative reduction of left ventricular function (LVEF < 45%) and perfusion defects (SSS > 4). (see table). Conclusions: The evalutation of perfusion and LV function in the same exam (Gated-SPECT) even using dipyridamole stressor provides an additional value for statification of cardiovascular risk in pts with or without suspected CAD. LVEF normal LVEF < 45% P SSS < 4 (4/584, 0.8%) (1/31, 3.2%) 0.035 SSS > 4 (4/212, 1.8%) (11/181, 6.1%) 0.0001