Long-Term Prognostic Value of 13N-ammonia Myocardial Perfusion Emission Tomography: Added Value of Coronary Flow Reserve

Objectives: The goal of this study was to assess the predictive value of myocardial perfusion imaging with 13N-ammonia positron emission tomography (PET) and coronary flow reserve (CFR) on long-term prognosis in patients with suspected myocardial ischemia.

Background: No prognostic data exist on the predictive value of CFR and 13N-ammonia PET.
Methods Perfusion and CFR were assessed in 256 patients using 13N-ammonia PET, and follow-up was obtained in 245 (96%) patients. Sixteen early revascularized patients were excluded and 229 were assigned to normal versus abnormal perfusion or normal versus abnormal CFR (2.0). Major adverse cardiac events (MACE) (cardiac death, nonfatal myocardial infarction, late revascularization, or hospitalization for cardiac reasons) were assessed using the Kaplan-Meier method. Cox proportional hazard regression was used to identify independent predictors for cardiac events.

Results: During follow-up (5.4  2.2 years), 78 patients had at least 1 cardiac event, including 29 cardiac deaths. Abnormal perfusion (n  126) was associated with a higher incidence of MACE (p  0.001) and cardiac death (p  0.05). In patients with normal perfusion, abnormal CFR was independently associated with a higher annual event rate over 3 years compared with normal CFR for MACE (1.4% vs. 6.3%; p  0.05) and cardiac death (0.5% vs. 3.1%; p  0.05). In abnormal perfusion, CFR remained predictive throughout the 10-year follow-up (p  0.001).

Conclusions: Perfusion findings in 13N-ammonia PET and CFR are strong outcome predictors. CFR allows further risk stratification, suggesting a “warranty” period of 3 years if normal CFR is associated with normal perfusion. Conversely, in patients with abnormal perfusion, an impaired CFR has added value for predicting adverse outcomes.

Herzog et al, J. Am. Coll. Cardiol. 2009;54:150-156
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