Involvement of the -420C>G RETN polymorphism in myocardial fibrosis in patients with hypertrophic cardiomyopathy

Prediction of cardiac death in patients with hypertrophic cardiomyopathy using plasma adipokine levels

BACKGROUNDS AND AIMS

Hypertrophic cardiomyopathy (HCM) causes cardiac death through both sudden cardiac death (SCD) and death due to heart failure (HF). Although adipokines lead to adverse cardiac remodeling in HCM, the prognostic value of plasma adipokines in HCM remains unknown. We aimed to predict cardiac death in patients with HCM using plasma adipokines.

METHODS AND RESULTS

We performed a multicenter prospective cohort study of patients with HCM. The outcome was cardiac death including heart transplant, death due to HF, and SCD. With data from 1 institution (training set), a prediction model was developed using random forest classification algorithm based on 10 plasma adipokines. The performance of the prediction model adjusted for 8 clinical parameters was examined in samples from another institution (test set). Time-to-event analysis was performed in the test set to compare the rate of outcome events between the low-risk and high-risk groups determined by the prediction model. In total, 389 (267 in the training set; 122 in the test set) patients with HCM were included. During the median follow-up of 2.7 years, 21 patients experienced the outcome event. The area under the covariates-adjusted receiver-operating characteristics curve was 0.89 (95 % confidence interval [CI] 0.71-0.99) in the test set. revealed the high-risk group had a significantly higher risk of cardiac death (hazard ratio 17.8, 95 % CI 2.1-148.3, P = 0.008).

CONCLUSION

The present multicenter prospective study demonstrated that a panel of plasma adipokines predicts cardiac death in patients with HCM.

Biomarkers in patients with myocardial fibrosis

Myocardial fibrosis is observed in many cardiovascular diseases including hypertension, heart failure and cardiomyopathy. Myocardial fibrosis has been proved to be reversible and treatable only under timely intervention, which makes early detection and assessment of fibrosis crucial. Aside from tissue biopsy as the gold standard for the diagnosis of myocardial fibrosis, circulating biomarkers have been adopted as noninvasive assessment of this lesion. Dysregulated collagen deposition is thought to be the major cause of myocardial fibrosis. Collagens, procollagens, TGF-β, TIMP, galectin-3, and microRNAs are thought to be indicators of myocardial fibrosis. In this review, we summarize the molecules that are frequently used as biomarkers in diagnosis of cardiac fibrosis. Mechanisms of fibrosis that they take part in are also introduced.

Clinical implications of nonsarcomeric gene polymorphisms in hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is characterized by cardiomyocyte hypertrophy and fibrosis. Although is an autosomal dominant trait, a group of nonsarcomeric genes have been postulated as modifiers of the phenotypic heterogeneity.

MATERIAL AND METHODS

We prospectively recruited 168 HCM patients and 136 healthy controls from three referral centres. Patients and controls were clinically stable at entry in the study. Nine polymorphisms previously associated with ventricular remodelling were determined: I/D ACE, AGTR1(A1666C), CYP11B2(C344T), PGC1-α(G482S), COLIA1(G2046T), ADRB1(R389G), NOS3(G894T), RETN(-420C>G) and CALM3(-34T>A). Their potential influence on prognosis, assessed by hospital admissions, and their cause were recorded.

RESULTS

The median follow-up time was 49·5 months. Allele and genotype frequencies did not differ between patients and controls. Thirty-six patients (21·5%) required urgent hospitalization (18·5% for heart failure, 22·2% for atrial arrhythmias, 11·1% for ventricular arrhythmias, 29·6% for ischaemic heart disease, 14·8% for stroke and 3·7% for other reasons) with a hospitalization rate of 8·75% per year. Multivariate analysis showed an independent predictive value for noncarriers of polymorphic COL1A1 allele [HR: 2·76(1·26-6·05), P = 0·011] and a trend in homozygous carriers of ADRB1 Arg389 variant [HR: 1·98(0·99-4·02); P = 0·057].

CONCLUSION

Our study suggests that COL1A1 polymorphism (2046G>T) is an independent predictor of prognosis in HCM patients supporting the importance of nonsarcomeric genes on clinical prognosis in HCM.

Increased Transforming Growth Factor-β Levels Associated With Cardiac Adverse Events in Hypertrophic Cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a common genetic heart disease characterized by ventricular hypertrophy, myocardial fibrosis, and impaired ventricular relaxation. The exact mechanisms by which fibrosis is caused remain unknown.

HYPOTHESIS

Circulating TGF-β is related to poor prognosis in HCM.

METHODS

We compared TGF-β levels of 49 HCM patients with those of 40 non-HCM patients. We followed the patients with HCM for 18 months and divided them into 2 groups: low TGF-β (≤ 4877 pg/mL) and high TGF-β (> 4877 pg/mL). We compared the 2 groups in terms of brain natriuretic peptide (BNP), echocardiographic parameters, and clinical outcomes including myocardial infarction, arrhythmias, implantable cardioverter-defibrillator implantation, hospitalization, New York Heart Association (NYHA) class, acute heart failure, and mortality.

RESULTS

The HCM patients had higher TGF-β levels than those in the control group (P = 0.005). In the follow-up, those in the high TGF-β group had higher BNP levels, larger left-atrial size, thicker interventricular septum, NYHA class, more hospitalizations, and a greater number of clinical adverse events (P < 0.001, P = 0.01, P < 0.001, P = 0.002, P < 0.001 and P = 0.003, respectively). TGF-β level of > 4877 pg/mL can predict adverse events with a specificity of 75% and a sensitivity of 72% (P = 0.014). In multivariate regression analysis, TGF-β, BNP, and interventricular septum thickness were significantly associated with adverse events (P = 0.028, P = 0.030, and P = 0.034, respectively).

CONCLUSIONS

The TGF-β level is higher in HCM patients and associated with a poor prognosis in HCM.