Key result
Positive sarcomere mutations in HCM link to ~59% greater myocardial fibrosis burden.
Why the study?
Sarcomere gene mutations and myocardial fibrosis are both linked to poorer outcomes in HCM, but their relationship measured by both histopathology and CMR remained to be determined.
Does the presence of a sarcomere gene mutation associate with increased myocardial fibrosis in patients with hypertrophic cardiomyopathy?
Does the presence of a sarcomere gene mutation associate with increased myocardial fibrosis in patients with hypertrophic cardiomyopathy?
In patients with hypertrophic cardiomyopathy, the presence of a sarcomere gene mutation is associated with a greater extent of myocardial fibrosis as measured by both histopathology and CMR.
Answers are grounded in this paper and cite their sources.
May signal higher fibrosis risk in sarcomere-positive HCM; hypothesis-generating and needs prospective validation before informing care.
Background Sarcomere gene mutation and myocardial fibrosis are both associated with poorer clinical outcomes in patients with hypertrophic cardiomyopathy (HCM). The aim of this study was to determine the relationship between sarcomere gene mutation and myocardial fibrosis measured by both histopathology and cardiac magnetic resonance (CMR). Methods and Results Two hundred twenty‐seven patients with HCM who underwent surgical treatment, genetic testing, and CMR were enrolled. We retrospectively analyzed basic characteristics, sarcomere gene mutation, and myocardial fibrosis measured by CMR and histopathology. In our study, the mean age was 43 years, and 152 patients (67.0%) were men. A total of 107 patients (47.1%) carried a positive sarcomere gene mutation. The myocardial fibrosis ratio was significantly higher in the late gadolinium enhancement (LGE)+ group (LGE+ 14.3±7.5% versus LGE− 9.0±4.3%; P =0.001). Patients with HCM with SARC+ showed a high probability of fibrosis both in histopathology (myocardial fibrosis ratio 15.3±8.0% versus 12.4±6.5%; P =0.003) and CMR examination (LGE+ 98.1% versus 84.2%; P <0.001; LGE quantification 8.3% versus 5.8%; P <0.001). Linear regression analysis showed that sarcomere gene mutation (B=2.661; P =0.005) and left atrial diameter (B=0.240; P =0.001) were related factors for histopathological myocardial fibrosis. Also, the myocardial fibrosis ratio was significantly higher in the MYH7 (myosin heavy chain) group ( MYH7 18.1±9.6% versus MYBPC3 [myosin binding protein C] 13.1±5.2%; P =0.019). Conclusions Patients with HCM with positive sarcomere gene mutation had a higher myocardial fibrosis extent than patients without mutation, and a significant difference in myocardial fibrosis was also observed between the MYBPC3 and MYH7 groups. In addition, a high consistency was found between CMR–LGE and histopathological myocardial fibrosis in patients with HCM.
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Huang et al. (2023) studied this question. Patients with hypertrophic cardiomyopathy and positive sarcomere gene mutation had 14.3% myocardial fibrosis compared to 9.0% in those without mutation (P=0.001).
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