Enhanced prognostic stratification of CAD patients with low ejection fraction by stress-rest Tc99m tetrofosmin gated-spect

Abstract

Objective — This study was performed to assess whether post-stress and rest functional parameters, as measured by gated-SPECT, provide additional predictive value for long-term prognosis, over clinical and perfusion data in patients (pts.) with low left ventricular ejection fraction (LVEF).

Methods — 647 consecutive pts. underwent stress/rest gated-SPECT, and 497 were followed for a mean period of 516 ± 264 days. Segmental perfusion and motion/thickening (post-stress and rest) were analysed visually, while EF and LV volumes were calculated using an automatic algorithm (QGS).The post-stress and rest ratio were determined for both end-diastolic (EDV) and end-systolic volume (ESV), while the post-stress LVEF change was calculated subtracting rest-EF from stress-EF.

Results — 84/497 pts. showed rest EF < 40%, and 15/84 (18%) experienced a cardiac event (3 cardiac deaths, 1 infarction, 3 hospitalized angina and 9 late revascularizations).The perfusion and functional parameters were not significantly more compromised in pts. with cardiac events compared with pts. without events. Post-stress ESV was the only index significantly higher in pts. with low EF and events compared with pts. with low EF without events (150 ± 72 ml vs. 123 ± 53 ml, P = 0.02). Univariate Cox analysis of clinical, perfusion and functional data showed that the best predictor of cardiac events was stress-ESV (score 6.5, P = 0.01), followed by rest-ESV, rest-EDV, stress-EDV and stress-LVEF. Multivariate analysis demonstrated that the addition of stress-ESV to stress-EF, yielded a significant increase in the global χ2 in the prediction of hard events (cardiac death/infarction) (score 4.634, P = 0.03).

Conclusion — In patients with depressed LVEF, stress-ESV was the only independent predictor of long-term outcome.

Key Words:

• gated SPECT
• 99mTc-tetrofosmin
• dilated ventricle
• low ejection fraction