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Differences in myocardial fluoro-18 2-deoxyglucose uptake in young versus older patients with hypertrophic
Y Kagaya1, N Ishide, D Takeyama
1First Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Insights
Younger patients with hypertrophic cardiomyopathy (HC) exhibit more nonhomogeneous myocardial glucose metabolism than older patients. This suggests distinct metabolic characteristics in early-onset HC, impacting disease understanding and treatment strategies.
Area of Science:
- Cardiology
- Nuclear Medicine
- Biomedical Imaging
Background:
- Hypertrophic cardiomyopathy (HC) is a complex cardiac disease.
- Understanding metabolic differences in HC based on age of diagnosis is crucial.
- Myocardial glucose utilization is a key metabolic indicator.
Purpose of the Study:
- To investigate regional myocardial glucose utilization in younger versus middle-aged/older HC patients.
- To determine if metabolic characteristics differ based on the age of HC diagnosis.
Main Methods:
- Positron emission tomography (PET) with fluoro-18 2-deoxyglucose (FDG) was used.
- Regional % FDG fractional uptake and interregional coefficient of variation were calculated.
- Two groups were studied: HC patients <40 years and HC patients >40 years.
Main Results:
- No significant difference in overall left ventricular % FDG uptake between groups.
- Significantly increased interregional coefficient of variation in FDG uptake in younger HC patients (p < 0.02).
- Septal/posterior wall thickness and image counts did not differ between groups.
Conclusions:
- Younger HC patients demonstrate more nonhomogeneous myocardial metabolic activity.
- These findings support the hypothesis that early-onset HC may have distinct metabolic profiles.
- Metabolic nonhomogeneity could be a marker differentiating HC in younger individuals.
Abstract:
The purpose of this study was to determine whether regional myocardial glucose use in patients diagnosed as having hypertrophic cardiomyopathy (HC) at a younger age differs from that in those diagnosed at middle to old age. Sixteen patients with HC (group 1 aged less than 40 years (n = 8); group 2 aged greater than 40 (n = 8) were studied using positron emission tomography and fluoro-18 2-deoxyglucose (FDG). All patients were diagnosed as having HC within 6 years of the study. Contiguous regions of interest were selected circumferentially on each cross-sectional image of the left ventricular wall. In each region of interest, % FDG fractional uptake was calculated. In each patient, % left ventricular FDG fractional uptake was determined as a mean value of % FDG fractional uptake in each region of interest. Moreover, as a measure of nonhomogeneity, the % interregional coefficient of variation in FDG fractional uptake was calculated in each patient. Whereas % left ventricular FDG fractional uptake did not differ between the 2 groups, the % interregional coefficient of variation in FDG fractional uptake was increased in group 1 compared with that in group 2 (11.5 +/- 3.6 vs 7.4 +/- 1.6%; p less than 0.02). Interventricular septum/left ventricular posterior wall thickness ratio and total counts in cross-sectional image did not differ between the 2 groups. These data suggest that patients diagnosed as having HC at a younger age have more nonhomogeneous myocardial metabolic characteristics than do patients diagnosed at middle or old age, and support the notion that HC in the young may be different from that in the middle-aged or elderly.