Prognostic utility of myocardial blood flow assessed by N-13 ammonia positron emission tomography in patients with idiopathic dilated cardiomyopathy

Previous studies in patients with idiopathic dilated cardiomyopathy (IDC) have suggested that myocardial perfusion is impaired and spatially heterogeneous in such cases. Our objective was to identify any association between an abnormality in myocardial perfusion and the prognosis of patients with IDC. We collected data on N-13 ammonia positron emission tomography (PET) studies performed in 26 patients with IDC (9 nonsurvivors, 17 survivors) and in 8 normal control subjects. Regional myocardial blood flow (rMBF) was quantified using N-13 ammonia positron emission tomography and the Simple flow model. The spatial heterogeneity of myocardial perfusion was assessed by calculating the coefficient of variance of rMBF. Mean rMBF of the survivors was significantly lower (0.54 ± 0.13 ml/min/g) than that of control subjects (0.66 ± 0.06 ml/min/g) (p = 0.03 vs control), but did not differ significantly between nonsurvivors (0.58 ± 0.15 ml/min/g) and control subjects. The coefficient of variance of rMBF was significantly higher in nonsurvivors than in either survivors or control subjects (0.24 ± 0.08 vs 0.15 ± 0.08, p = 0.007, and 0.16 ± 0.05, p = 0.03, respectively). The probability of 3-year survival (Kaplan-Meier method) was 33.0% in subjects whose coefficient of variance of rMBF was above the median compared with 90.0% in subjects whose coefficient of variance of rMBF was below the median (p = 0.01). The probability of 3-year survival did not differ among subjects whose mean rMBF was above versus below the median (61.5% vs 62.9%, respectively). The results suggest that the prognosis of patients with IDC is associated with the spatial heterogeneity of myocardial perfusion, not with initial absolute rMBF.