Independent and incremental prognostic value of left ventricular ejection fraction determined by stress gated rubidium 82 PET imaging in patients with known or suspected coronary artery disease

Abstract

Whether left ventricular ejection fraction (EF) obtained by gated rubidium 82 positron emission tomography (PET) myocardial imaging can identify patients at risk for future cardiac events is unclear. Consecutive patients with known or suspected coronary artery disease who underwent dipyridamole stress gated Rb-82 PET imaging were evaluated. Scoring of perfusion was accomplished by use of a 17-segment model. EF was automatically generated. Patients were stratified based on summed stress scores (SSSs) (0-3, 4-8, or >8) and stress EF (>50%, 40%-49%, or <40%). All-cause mortality was determined by use of the Social Security Death Index. Of 1,441 patients, 132 (9.2%) died during mean follow-up of 2.7 +/- 0.8 years. Annualized mortality rates across SSS groups were 2.4% for SSS of 0 to 3, 4.1% for SSS of 4 to 8, and 6.9% for SSS greater than 8 (P < .001). Similarly, annualized mortality rates were 2.4%, 6.2%, and 9.2% for the group with EF greater than 50%, group with EF of 40% to 49%, and group with EF lower than 40%, respectively (P < .001). On multivariate analysis, the addition of EF to clinical and perfusion variables significantly increased the global chi(2) (73.3 to 107.7, P < .001). Integration of EF with SSS significantly enhanced risk stratification. EF assessed by stress gated Rb-82 PET imaging provides independent and incremental prognostic information and, hence, should be routinely incorporated in risk assessment.