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Stress Rb-82 PET provided effective risk stratification for CAD
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Results from a multicenter registry indicate that stress myocardial perfusion rubidum-82 PET provides effective risk stratification of men and women with suspected cardiac symptoms.
This finding “supports this modality as an alternative to comparative imaging modalities,” researchers wrote.
Stress myocardial perfusion rubidum-82 (Rb-82) PET was accurate in women as well as men and was particularly accurate for women aged at least 55 years. Previously, prognostic accuracy of the technology in women had not been established, according to the report.
Jenna Kay, MD, of Emory University School of Medicine, and colleagues enrolled 6,037 patients (2,904 women) in the PET Prognosis Multicenter Registry. After Rb-82 PET imaging, patients were followed for a median of 2.2 years for the occurrence of CAD mortality. A secondary outcome was all-cause mortality.
Researchers calculated net reclassification improvement (NRI) index. Patients were stratified by the following percentages of abnormal stress myocardium: 0%; 0.1% to 4.9%; 5% to 9.9%; 10% to 14.9%; and ≥15%.
The cumulative 5-year CAD mortality rate was 3.7% for women and 6% for men (P<.0001). Unadjusted CAD mortality for women was 0.9% for those with 0% abnormal stress myocardium vs. 12.9% for those with at least 15% abnormal stress myocardium (P<.0001). Unadjusted CAD mortality for men was 1.5% for those with 0% abnormal stress myocardium vs. 17.4% for those with at least 15% abnormal stress myocardium (P<.0001).
In both unadjusted and adjusted models, percentage of abnormal stress myocardium as measured by Rb-82 PET was a significant predictor of time to CAD mortality for women and men, the researchers wrote.
Categorical NRI was 0.12 for women and 0.17 for men when the researchers added Rb-82 PET data to a clinical risk model.
Because only two cardiac deaths were observed in women younger than 55 years, percentage of abnormal stress myocardium was not significant for that age group (P=.063). However, it was significant for women aged at least 55 years (P<.0001). In that cohort, there was an increased NRI of 0.21 (95% CI, 0.09-0.34), with 17% of CAD deaths and 3.9% of CAD survivors being correctly reclassified.
Percentage of abnormal stress myocardium also was predictive of all-cause mortality in adjusted models for women (P<.0001) and men (P<.0001). For women, there was a 2.9% increase in risk for all-cause death with every 1% increase in percentage of abnormal stress myocardium (HR=1.03; 95% CI, 1.02-1.04). For men, there was a 2.2% increase in risk for all-cause death with every 1% increase in percentage of abnormal stress myocardium (HR=1.022; 95% CI, 1.01-1.03).
“PET has several advantages when compared to [single photon-emission CT], including excellent image quality, sizable reductions in attenuation artifact and, importantly, an improved safety profile with an estimated effective radiation exposure dose of [approximately] 3 mSv with Rb-82, which may proffer a significant advantage in the evaluation of women with suspected myocardial ischemia,” Kay and colleagues wrote.
Disclosure: See the full study for a list of the researchers’ relevant financial disclosures.
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