Predicting the effect of beta-blockade
therapy on the clinical outcome of patients with
dilated cardiomyopathy (DCM) is difficult prior to the initiation of
therapy. Myocardial
fatty acid metabolism has been shown to be impaired in patients with DCM. We examined whether the extent of myocardial injury, as assessed by
iodine-123 15-( p-iodophenyl)-3- R, S-methylpentadecanoic
acid (
BMIPP) myocardial scintigraphy, is related to the response of patients with DCM to beta-blockade
therapy. Thirty-seven patients with DCM were examined using
BMIPP myocardial scintigraphy before and after 6 months of treatment with
metoprolol. Myocardial
BMIPP uptake (%BM uptake) was estimated quantitatively as a percentage of the total injected count ratio. The left ventricular end-diastolic and end-systolic dimensions (LVDd, LVDs) and ejection fraction (LVEF) were also evaluated. The patients were divided into two groups according to their functional improvement (>10% elevation of LVEF) after 6 months of
metoprolol therapy. Twenty-eight patients responded to the
therapy, while nine did not. Prior to the
therapy, no significant differences in LVDd, LVDs or LVEF were observed between the responders and non-responders. However, the %BM uptake was significantly lower in the non-responders than in the responders (1.0%+/-0.2% vs 2.1%+/-0.5%, P<0.001). The %BM uptake could be used to distinguish the responders from the non-responders with a sensitivity of 0.93 and a specificity of 1.00 at a threshold value of 1.4. After the
metoprolol therapy, the %BM uptake improved significantly in the responders (2.5%+/-0.5%, P<0.01) but did not change in the non-responders. These results indicate that myocardial
BMIPP uptake could predict the response of DCM patients to beta-blockade
therapy.