Study Suggests ¹⁸F-FDG PET May Aid Decision Making for Ischemic Cardiomyopathy

April 1, 2010—Arun Abraham, MD, et al have published findings from the Ottawa-FIVE substudy of the PARR 2 (Positron Emission Tomography [PET] and Recovery Following Revascularization) trial in the Journal of Nuclear Medicine (2010;51:567–574). The Ottawa-FIVE substudy was a post hoc analysis to determine the benefit of PET in a center with experience, ready access to fluorodeoxyglucose (¹⁸F-FDG), and integration with clinical teams. The background of the analysis is that the PARR 2 trial demonstrated a trend toward beneficial outcomes with PET-assisted management; the Ottawa-FIVE investigators therefore sought to determine if ¹⁸F-FDG PET may assist decision making in ischemic cardiomyopathy. The study was conducted by Canada's National Cardiac PET Center at the University of Ottawa Heart Institute under the direction of Rob S. B. Beanlands, MD, for the PARR 2 investigators.

According to the investigators, the analysis included patients with left ventricular dysfunction and suspected coronary artery disease who were being considered for revascularization. In PARR 2, the patients had been randomized to PET-assisted management (group 1) or standard care (group 2) and had been enrolled in Ottawa after August 1, 2002, the date that on-site ¹⁸F-FDG was initiated (n = 111). The primary outcome was the composite endpoint of cardiac death, myocardial infarction, or cardiac rehospitalization within 1 year. Data were compared with the remaining PARR 2 patients (PET-assisted management [group 3] or standard care [group 4]).

The investigators reported that in the Ottawa-FIVE subgroup of PARR 2, the cumulative proportion of patients experiencing the composite event was 19% (group 1) versus 41% (group 2). Multivariable Cox proportional hazards regression showed a benefit for the PET-assisted strategy (hazard ratio, 0.34; 95% confidence interval, 0.16–0.72; P = .005). Ottawa-FIVE patients had a lower ejection fraction compared with other patients in PARR 2 (25% ± 7% vs 27% ± 8%; P = .04), were more often women (24% vs 13%; P = .006), tended to be older (64 ± 10 y vs 62 ± 10 y; P = .07), and had less previous coronary artery bypass graft surgery (13% vs 21%; P = .07). For patients in the rest of PARR 2, there was no significant difference in events between groups 3 and 4.

The investigators found that the observed effect of 18F-FDG PET-assisted management in the four groups in the context of adjusted survival curves demonstrated a significant interaction (P = .016). Comparisons of the two arms in Ottawa-FIVE to the two arms in the rest of PARR 2 demonstrated a trend toward significance (standard care, P = .145; PET-assisted management, P = .057).

In this post hoc group analysis, a significant reduction in cardiac events was observed in patients with ¹⁸F-FDG PET-assisted management compared with patients who received standard care. The results suggest that outcome may be benefited using ¹⁸F-FDG PET in an experienced center with ready access to ¹⁸F-FDG and integration with imaging, heart failure, and revascularization teams, the investigators concluded.