Influence of Gender on Risk Stratification With Stress Myocardial Perfusion Rb-82 Positron Emission Tomography: Results From the PET Prognosis Multicenter Registry

Study Questions:

Are there gender differences in the prognostic accuracy of stress myocardial perfusion Rubidum-82 positron emission tomography (Rb-82 PET)?

Methods:

A total of 6,037 women and men were enrolled in the PET Prognosis Registry, for stress myocardial perfusion Rb-82 PET, who were clinically followed for the occurrence of death related to coronary artery disease (CAD) (n = 6,037). An additional endpoint of death from all causes was also ascertained. For each of the four centers, all consecutive patients were enrolled prospectively. The representation of women from each site was 44% to 55% of their entire patient series, reflecting similar representation of women across participating sites. Patients were followed for the occurrence of CAD mortality, with a median follow-up of 2.2 years.

Results:

The enrolled 2,904 women were generally older and more often obese, whereas men had a greater prevalence of known CAD including more often prior revascularization. More than one half of the 3,133 men had a high pretest CAD likelihood, whereas approximately one third of women were at low pretest CAD likelihood. Five-year CAD mortality was 3.7% for women and 6.0% for men (p < 0.0001). Unadjusted CAD mortality ranged from 0.9% to 12.9% for women (p < 0.0001) and from to 1.5% to 17.4% for men (p < 0.0001) for 0% to ≥15% abnormal myocardium at stress. In multivariable models, the % abnormal stress myocardium was independently predictive of CAD mortality in women and men. An interaction term of gender by % abnormal stress myocardium was nonsignificant (p = 0.39). The categorical net reclassification improvement index (NRI) when Rb-82 PET data were added to a clinical risk model was 0.12 for women and 0.17 for men. Only two cardiac deaths were reported in women <55 years of age; accordingly, the % abnormal myocardium at stress was of borderline significance (p = 0.063), but was highly significant for women ≥55 years of age (p < 0.0001) with an increased NRI of 0.21 (0.09-0.34), including 17% of CAD deaths and 3.9% of CAD survivors correctly reclassified.

Conclusions:

The investigators concluded that stress Rb-82 PET provides significant and clinically meaningful effective risk stratification of women and men, supporting this modality as an alternative to comparative imaging modalities. Rb-82 PET findings were particularly helpful at identifying high-risk, older women.

Perspective:

These data suggest that Rb-82 PET provides clinically useful risk factor stratification for women.

Clinical Topics: Noninvasive Imaging, Atherosclerotic Disease (CAD/PAD), Computed Tomography, Nuclear Imaging

Keywords: Prognosis, Coronary Artery Disease, Myocardium, Rubidium Radioisotopes, Positron-Emission Tomography


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