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Published on: June 28, 2019
Significant regional heterogeneity of coronary flow reserve in paediatric hypertrophic cardiomyopathy
E Tadamura1, M Yoshibayashi, T Yonemura
1Department of Nuclear Medicine, Kyoto University Graduate School of Medicine, Japan.
Insights
Paediatric hypertrophic cardiomyopathy (HCM) patients show reduced coronary flow reserve in specific heart regions, suggesting intrinsic ischemia potential. This contrasts with adult HCM, highlighting age-related differences in cardiac event causes.
Area of Science:
- Cardiology
- Pediatric Cardiology
- Cardiovascular Imaging
Background:
- Cardiac events in young hypertrophic cardiomyopathy (HCM) patients are often linked to ischemia, not arrhythmia.
- Understanding coronary blood flow is crucial for managing pediatric HCM.
- Previous research focused on adult HCM, leaving pediatric aspects less understood.
Purpose of the Study:
- To measure and compare coronary flow reserve (CFR) in pediatric HCM patients versus adult HCM patients and healthy controls.
- To investigate regional differences in CFR within the hypertrophied heart muscle of pediatric HCM.
- To determine if pediatric HCM patients exhibit intrinsic potential for regional ischemia.
Main Methods:
- Studied 12 HCM patients (6 pediatric, 6 adult) and 6 healthy adults.
- Utilized magnetic resonance imaging (MRI) for anatomical assessment.
- Employed dynamic nitrogen-13 ammonia positron emission tomography (PET) to measure myocardial blood flow at rest and after dipyridamole infusion, with partial volume effect correction.
Main Results:
- Adult HCM patients showed no significant CFR difference between septal and lateral walls.
- Pediatric HCM patients exhibited significantly lower CFR in the hypertrophied septal wall compared to the lateral wall (P<0.01).
- Adults had lower CFR than controls in both septal and lateral walls (P<0.0001, P<0.05), while pediatric CFR in the lateral wall was similar to controls, but with reduced flow in the septal region post-vasodilation.
Conclusions:
- Significant regional differences in coronary flow reserve are present in pediatric HCM patients.
- Pediatric HCM patients possess an intrinsic potential for significant regional myocardial ischemia, even without coronary stenosis.
- Findings suggest ischemia, rather than arrhythmia, is a key concern for cardiac events in pediatric HCM.
Abstract:
Previous studies have indicated that cardiac events in young patients with hypertrophic cardiomyopathy (HCM) are related to ischaemia rather than to arrhythmia. We measured coronary flow reserve in paediatric HCM and compared the values with those in adult HCM. We studied 12 patients with HCM including six paediatric (<20 years old; mean 13 years) and six adult patients (>20 years old: mean 62 years), and six healthy young adults (mean 29 years) as controls. Every patient underwent magnetic resonance imaging (MRI) for anatomical assessment. Myocardial blood flow at rest and after dipyridamole infusion was measured with dynamic nitrogen-13 ammonia positron emission tomography (PET). Partial volume effect was corrected for using the anatomical data obtained with MRI. In adult patients with HCM, coronary flow reserve in the hypertrophied septal region was not significantly different from that in the non-hypertrophied lateral wall (1.38+/-0.29 vs 1.77+/-0.39, respectively). In the paediatric patients, coronary flow reserve in the hypertrophied septal region was significantly lower than in the non-hypertrophied lateral wall (0.84+/-0.33 vs 2.74+/-0.90, respectively, P<0.01). In addition, coronary flow reserve in adult patients was lower than in control subjects both in the septal wall (1.38+/-0.29 vs 2.94+/-0.35, respectively, P<0.0001) and in the lateral wall (1.77+/-0.39 vs 2.85+/-0.69, respectively, P<0.05). In contrast, coronary flow reserve in paediatric patients was not significantly different from that in control subjects in the lateral wall (2.74+/-0.90 vs 2.85+/-0.69, respectively), while absolute reduction of myocardial blood flow was noted after pharmacological vasodilatation in the hypertrophied septal region. In conclusion, significant regional differences of coronary flow reserve were present in the paediatric patients with HCM. These results suggest that paediatric patients with HCM intrinsically have the potential to experience significant regional ischaemia even in the absence of coronary stenosis.
