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Objective: Elevated levels of N-terminal pro-brain natriuretic peptide (NT-proBNP) are associated with heart failure-related death in hypertrophic cardiomyopathy (HCM), but the relationship between NT-proBNP level and sudden cardiac death (SCD) in HCM remains undefined.Methods: The study prospectively enrolled 977 unrelated patients with HCM with available NT-proBNP results who were prospectively enrolled and followed for 3.0±2.1 years. The Harrell's C-statistic under the receiver operating characteristic curve was calculated to evaluate discrimination performance. A combination model was constructed by adding NT-proBNP tertiles to the HCM Risk-SCD model. The correlation between log NT-proBNP level and cardiac fibrosis as measured by late gadolinium enhancement (LGE) or Masson's staining was analysed.Results: During follow-up, 29 patients had SCD. Increased log NT-proBNP levels were associated with an increased risk of SCD events (adjusted HR 22.27, 95% CI 10.93 to 65.63, p<0.001). The C-statistic of NT-proBNP in predicting SCD events was 0.80 (p<0.001). The combined model significantly improved the predictive efficiency of the HCM Risk-SCD model from 0.72 to 0.81 (p<0.05), with a relative integrated discrimination improvement of 0.002 (p<0.001) and net reclassification improvement of 0.67 (p<0.001). Furthermore, log NT-proBNP levels were significantly correlated with cardiac fibrosis as detected either by LGE (r=0.257, p<0.001) or by Masson's trichrome staining in the myocardium (r=0.198, p<0.05).Conclusion: NT-proBNP is an independent predictor of SCD in patients with HCM and may help with risk stratification of this disease. [ABSTRACT FROM AUTHOR]

Background: The association of metabolic syndrome (MS) with left ventricular (LV) hypertrophy is controversial. The objective of our study was to investigate the influence of MS on LV mass and geometry in community-based hypertensive patients among Han Chinese. Materials and Methods: This study included 1733 metabolic syndrome patients according to the International Diabetes Federation (IDF) definition and 2373 non-MS hypertension patients. LV hypertrophy was diagnosed by the criteria of LV mass >49.2 g/m27 for men and 46.7 g/m27 for women. LV geometric patterns (normal, concentric remodeling, concentric or eccentric hypertrophy) were calculated according to LV hypertrophy and relative wall thickness. Logistic regression analysis was used to determine odds ratio (OR) and 95% confidence interval (CI) of MS for LV hypertrophy and LV geometry abnormality. Results: The LV mass and LV mass index were higher in the MS group than in the non-MS group. In multiple adjusted models. LV mass index, LV mass, interventricular septum, and post wall were raised with the increased number of MS disorders. MS was associated with increased LV hypertrophy risk (unadjusted OR 1.38; 95% CI 1.21-1.57); age, sex, and blood pressure (BP; adjusted OR 1.39; 95% CI 1.22-1.59). MS was also associated with increased risk of eccentric hypertrophy in male and female patients. MS was only associated with increased risk of concentric hypertrophy in female patients; and MS was not associated with concentric remodeling. Conclusion: LV mass and LV mass index were associated with the increased number of MS disorders in the Chinese community-based hypertensive population. MS was not only associated with increased LV hypertrophy risk, but also associated with concentric and eccentric LV geometry abnormality, especially in females. [ABSTRACT FROM AUTHOR]

The molecular mechanisms that drive the development of cardiac hypertrophy in hypertrophic cardiomyopathy (HCM) remain elusive. Accumulated evidence suggests that microRNAs are essential regulators of cardiac remodelling. We have been suggested that microRNAs could play a role in the process of HCM. To uncover which microRNAs were changed in their expression, microRNA microarrays were performed on heart tissue from HCM patients (n = 7) and from healthy donors (n = 5). Among the 13 microRNAs that were differentially expressed in HCM, miR-451 was the most down-regulated. Ectopic overexpression of miR-451 in neonatal rat cardiomyocytes (NRCM) decreased the cell size, whereas knockdown of endogenous miR-451 increased the cell surface area. Luciferase reporter assay analyses demonstrated that tuberous sclerosis complex 1 (TSC1) was a direct target of miR-451. Overexpression of miR-451 in both HeLa cells and NRCM suppressed the expression of TSC1. Furthermore, TSC1 was significantly up-regulated in HCM myocardia, which correlated with the decreased levels of miR-451. As TSC1 is a known positive regulator of autophagy, we examined the role of miR-451 in the regulation of autophagy. Overexpression of miR-451 in vitro inhibited the formation of the autophagosome. Conversely, miR-451 knockdown accelerated autophagosome formation. Consistently, an increased number of autophagosomes was observed in HCM myocardia, accompanied by up-regulated autophagy markers, and the lipidated form of LC3 and Beclin-1. Taken together, our findings indicate that miR-451 regulates cardiac hypertrophy and cardiac autophagy by targeting TSC1. The down-regulation of miR-451 may contribute to the development of HCM and may be a potential therapeutic target for this disease. [ABSTRACT FROM AUTHOR]

Modifier genes contribute to the diverse clinical manifestations of hypertrophic cardiomyopathy (HCM), but are still largely unknown. Muscle ring finger (MuRF) proteins are a class of muscle-specific ubiquitin E3-ligases that appear to modulate cardiac mass and function by regulating the ubiquitin-proteasome system. In this study we screened all the three members of the MuRF family, MuRF1, MuRF2 and MuRF3, in 594 unrelated HCM patients and 307 healthy controls by targeted resequencing. Identified rare variants were confirmed by capillary Sanger sequencing. The prevalence of rare variants in both MuRF1 and MuRF2 in HCM patients was higher than that in control subjects (MuRF1 13/594 (2.2%) vs. 1/307 (0.3%), p = 0.04; MuRF2 22/594 (3.7%) vs. 2/307 (0.7%); p = 0.007). Patients with rare variants in MuRF1 or MuRF2 were younger (p = 0.04) and had greater maximum left ventricular wall thickness (p = 0.006) than those without such variants. Mutations in genes encoding sarcomere proteins were present in 19 (55.9%) of the 34 HCM patients with rare variants in MuRF1 and MuRF2. These data strongly supported that rare variants in MuRF1 and MuRF2 are associated with higher penetrance and more severe clinical manifestations of HCM. The findings suggest that dysregulation of the ubiquitin-proteasome system contributes to the pathogenesis of HCM. [ABSTRACT FROM AUTHOR]