PT  - JOURNAL ARTICLE
AU  - Petri Sipola
AU  - Esko Vanninen
AU  - Hannu J. Aronen
AU  - Kirsi Lauerma
AU  - Sakari Simula
AU  - Pertti Jääskeläinen
AU  - Markku Laakso
AU  - Keijo Peuhkurinen
AU  - Johanna Kuusisto
AU  - Jyrki T. Kuikka
TI  - Cardiac Adrenergic Activity Is Associated with Left Ventricular Hypertrophy in Genetically Homogeneous Subjects with Hypertrophic Cardiomyopathy
DP  - 2003 Apr 01
TA  - Journal of Nuclear Medicine
PG  - 487--493
VI  - 44
IP  - 4
4099  - http://jnm.snmjournals.org/content/44/4/487.short
4100  - http://jnm.snmjournals.org/content/44/4/487.full
SO  - J Nucl Med2003 Apr 01; 44
AB  - Hypertrophic cardiomyopathy (HCM) is a genetic disease caused by mutations in genes encoding sarcomeric proteins. However, other genetic and possibly also environmental factors modify the phenotypic expression of left ventricular (LV) hypertrophy. The present study investigated whether cardiac adrenergic activity affects the severity of LV hypertrophy in genetically identical patients with HCM. Methods: The study population consisted of 21 patients with HCM caused by the Asp175Asn substitution of the α-tropomyosin gene (TPM1-Asp175Asn) and 9 healthy volunteers. LV mass and segmental wall thickness were measured with MRI. Presynaptic cardiac adrenergic activity was measured with 123I-metaiodobenzylguanidine (MIBG) SPECT. Global and segmental washouts of 123I-MIBG were calculated. Results: Global myocardial 123I-MIBG washout was faster in patients with TPM1-Asp175Asn than in healthy volunteers (50% ± 9% vs. 37% ± 8%, P = 0.001). In linear regression analysis, global 123I-MIBG washout was associated with the LV mass index and LV maximal wall thickness index in HCM patients (r = 0.512, P = 0.018, and r = 0.478, P = 0.028, respectively). The mean 123I-MIBG washout was higher in LV segments ≥ 15 mm thick than in LV segments < 15 mm thick (56 ± 10 vs. 49% ± 10%, P = 0.002). Conclusion: In patients with HCM sharing the same causal gene defect, the degree of LV hypertrophy is related to 123I-MIBG washout, suggesting that cardiac adrenergic activity modifies phenotypic expression in HCM.