Incremental Prognostic Value of Gated Rb-82 Positron Emission Tomography Myocardial Perfusion Imaging Over Clinical Variables and Rest LVEF

Abstract

OBJECTIVES This investigation sought to study the incremental value of gated rubidium (Rb)-82 positron emission tomography (PET) myocardial perfusion imaging (MPI) over clinical variables for predicting survival and future cardiac events. BACKGROUND The prognostic value of Rb-82 PET-MPI and left ventricular ejection fraction (LVEF) reserve (stress minus rest LVEF) is not well defined. METHODS 1,432 consecutive patients undergoing gated rest/vasodilator stress rubidium-82 PET were followed up for at least 1 year. Of these, rest and peak stress LVEF and LVEF reserve were available in 985 patients. Cardiac events (CE) including cardiac death or nonfatal myocardial infarction and all-cause death were assessed. RESULTS Over a mean follow-up of 1.7 ± 0.7 years, 83 (5.8%) CE and 140 (9.7%) all-cause death were observed. There was an increase in risk for both end points with an increasing percentage of abnormal and ischemic myocardium. With normal, mild, moderate, or severely ischemic scans, the observed annualized rates of CE were 0.7%, 5.5%, 5%, and 11% and of all-cause death were 3.3%, 7.2%, 6.9%, and 12.5%, respectively. In 985 patients with peak stress gated data, the observed annualized rates of CE (2.1% vs. 5.3%, p < 0.001) and all-cause death (4.3% vs. 9.2%, p < 0.001) were higher in patients with an LVEF reserve <0% compared with those with an LVEF reserve ≥0%. On Cox proportional hazards analysis, after consideration of clinical, historical, and rest LVEF information, stress PET results and LVEF reserve yielded incremental prognostic value with respect to both CE and all-cause death. CONCLUSIONS Vasodilator stress Rb-82 PET-MPI provides incremental prognostic value to historical/clinical variables and rest LVEF to predict survival free of CE and all-cause death. An increasing percentage of ischemia on PET-MPI is associated with an increase in the risk of CE and all-cause death. Left ventricular ejection fraction reserve provides significant independent and incremental value to Rb-82 MPI for predicting the risk of future adverse events.

Vasodilator stress and left ventricular asynchrony

“…18 The present study supports the notion that an improvement in LVEF is likely preceded by a reduction in LVAS or 'synchrony reserve'. Studies have shown EF reserve to be inversely related to the severity of ischemia or infarction.…”

“…Studies have shown EF reserve to be inversely related to the severity of ischemia or infarction. 12,19 Contrary to the systematic evaluation LVEF reserve and its prognostic value, 18 the presence of a synchrony reserve is hypothetical and its clinical value is unknown. A prospective and more structured evaluation of LVAS in patients with CAD will be needed to determine whether it has a diagnostic and prognostic role in patient management when global LV function is relatively preserved.…”

Cardiac Imaging Modalities in the Diagnosis of Coronary Artery Disease

“…PET images provide incremental prognostic information to the clinical and angiographic findings with regard to event-free survival. An increased extent and severity of perfusion defects with stress PET were reported to be associated with increased frequency of adverse cardiac events, thus, this indicates PET can be used to predict cardiac mortality [41,42].…”

ASNC imaging guidelines for nuclear cardiology procedures

“…An LVEF reserve \0%, indicating a drop in LVEF with stress, has diagnostic and prognostic significance and can be optionally reported. 38 SPECT and PET MPI also allow interpretation of the perfusion, size, and global and segmental function of the right ventricle (RV). Data elements for this assessment are provided in Table 16.…”