Kátia G. Santos

Impact of β1-Adrenergic Receptor Polymorphisms on Susceptibility to Heart Failure, Arrhythmogenesis, Prognosis, and Response to Beta-Blocker Therapy

Beta1-adrenergic receptor polymorphisms have been implicated with inconsistent results in the pathogenesis, clinical presentation, and prognosis of patients with heart failure (HF). The impact of 2 functional polymorphisms (beta1-Arg389Gly and beta1-Ser49Gly) on HF susceptibility, arrhythmogenesis, and prognosis was evaluated in Brazilian outpatients. Genotyping at codons 389 and 49 was performed using polymerase chain reaction with restriction fragment length polymorphism analysis in 201 outpatients with systolic HF and 141 apparently healthy controls. Enrolled patients were followed up at the HF clinic, and vital status was evaluated using electronic hospital records, telephone contact, and a local death certificate database. Allele frequencies were similar between patients with HF and controls, with neither polymorphism related to HF susceptibility. The beta1-389Gly homozygotes had significantly less nonsustained ventricular tachycardia on Holter monitoring (17% vs 48% for Arg/Arg patients; p = 0.015) and improved HF-related survival, with no events after a median follow-up of 40 months (log-rank statistics = 0.025). The negative impact of beta1-389Arg allele on HF-related survival was substantially reduced using high-dose beta-blocker therapy (80% survival for high-dose vs 42% for low-dose beta blockers or nonusers; log-rank statistics = 0.0003). The beta1-Ser49Gly polymorphism was not associated with nonsustained ventricular tachycardia or HF prognosis. In conclusion, beta1-Arg389Gly and beta1-Ser49Gly polymorphisms had no influence on HF susceptibility. However, the Gly389 allele was associated with a lower prevalence of ventricular arrhythmias and better HF-related survival. A pharmacogenetic interaction is suggested because beta blockers were more effective in beta1-389Arg allele carriers.

Diabetic retinopathy in Euro-Brazilian type 2 diabetic patients: relationship with polymorphisms in the aldose reductase, the plasminogen activator inhibitor-1 and the methylenetetrahydrofolate reductase genes

We investigated the relationship between diabetic retinopathy (DR) and three polymorphisms, C(-106)T in the aldose reductase (ALR2) gene, 4G/5G in the plasminogen activator inhibitor-1 (PAI-1) gene and C677T in the methylenetetrahydrofolate reductase (MTHFR) gene, in 210 Euro-Brazilian type 2 diabetic patients. Retinopathy was evaluated by funduscopic examination and genotype analysis was performed using the polymerase chain reaction and allele-specific restriction. Retinopathy was detected in 47% of the patients. There were no significant differences in allele or genotype distributions between patients with or without retinopathy for all polymorphisms. Thus, the three polymorphisms are not related to the presence of DR in Euro-Brazilian type 2 diabetic patients.

Genetic polymorphisms of the adrenergic system and implantable cardioverter-defibrillator therapies in patients with heart failure

AIMSnWe investigated whether the combination of beta(1)-Gly389Arg and GNB3 C825T, two genetic polymorphisms strictly related to adrenergic system modulation, could act as predictors of appropriate therapies in patients with heart failure (HF) using implantable cardioverter-defibrillators (ICDs).nnnMETHODS AND RESULTSnPatients with HF and ICD implantation for primary and secondary prevention were studied. All ICD therapies were registered and classified as appropriate (secondary to ventricular tachycardia) or inappropriate (others). Genetic analysis was performed by polymerase chain reaction and restriction fragment length polymorphism methods. Seventy-three patients with mean left ventricular ejection fraction of 35 +/- 11% were evaluated. Overall, 35 ICD therapies occurred during follow-up in 31 (42.5%) patients. Twenty-four therapies (33%) were appropriate, and 11 (15%) were inappropriate. Individual analysis of each polymorphism only identified T825 carriers of GNB3 C825T as predictor of appropriate shocks. The combined presence of risk genotypes (Arg389 of the beta(1)-Gly389Arg and T825 of the GNB3 C825T) identified patients with higher risk of appropriate shocks. Patients with two at-risk genotypes had a survival rate free of appropriate shocks lower than those with none or only one of these markers (87 vs. 54%, respectively; log-rank statistic = 0.006). Using a Cox regression model, each at-risk genotype was associated with an increment of risk of appropriate ICD shocks (odds ratio = 3.9, 95% confidence interval of 1.3-12.0; P = 0.02).nnnCONCLUSIONnGenetic polymorphisms of the adrenergic system may help to identify HF patients who are more likely to receive appropriate ICD therapies. Further studies are necessary to determine the clinical applicability of these polymorphisms as predictors of arrhythmias.

Prevalence of retinopathy in Caucasian type 2 diabetic patients from the south of Brazil and relationship with clinical and metabolic factors

Diabetic retinopathy (DR) is a sight-threatening chronic complication of diabetes mellitus and is the leading cause of acquired blindness in adults. In this cross-sectional study, we investigated the prevalence of and the factors associated with DR in an analysis of 210 consecutive and unrelated Brazilian Caucasians with type 2 diabetes mellitus. Retinopathy was evaluated by ophthalmoscopy and/or biomicroscopy through dilated pupils. The relationship between clinical and metabolic variables and the presence of DR was assessed by logistic regression analysis. DR was detected in 99 of the 210 patients (47%). In the univariate logistic regression analyses, male sex, duration of diabetes, body mass index, glycated hemoglobin, C-peptide, LDL cholesterol, smoking, and albumin excretion rate were found to be associated with the presence of DR. However, the multiple logistic regression analysis showed that only duration of diabetes (odds ratio (OR) = 1.15, 95% CI = 1.09-1.22; P < 0.001), glycated hemoglobin (OR = 1.21, 95% CI = 1.01-1.46; P = 0.047) and albumin excretion rate > 100 microg/min (OR = 12.72, 95% CI = 3.89-41.56; P < 0.001) were independently associated with DR. Although DR was found to be frequent among Brazilian type 2 diabetic patients, its prevalence was within the range observed in other Caucasian populations. Our findings emphasize the need for good glycemic control in order to prevent or delay the onset of DR, since the most well-known risk factors for the development of this complication in type 2 diabetes mellitus, such as duration of diabetes, glycated hemoglobin and albumin excretion rate were independently related to DR.

Polymorphisms of Matrix Metalloproteinases in Systolic Heart Failure: Role on Disease Susceptibility, Phenotypic Characteristics, and Prognosis

BACKGROUNDnThe role of matrix metalloproteinases (MMPs) polymorphisms on heart failure (HF) susceptibility,xa0phenotypic characteristics, and prognosis has been poorly explored.nnnMETHODS AND RESULTSnWe studied 313 HF patients with left ventricular systolic dysfunction and 367 healthy control subjects. Genotyping of MMP-1 (-1607 1G/2G), MMP-3 (-1171 5A/6A), and MMP-9 (-1562 C/T) polymorphisms was performed by polymerase chain reaction. Allelic and genotypic frequencies of MMP-1, -3, and -9 were similar in HF patients and controls. MMP1 2G allele carriers were positively associated to ischemic etiology and history of myocardial infarction (all P values <.05). Patients were followed-up for a median of 40 months and 58 HF-related deaths occurred during this period. HF-related survival was significantly better in MMP1 2G allele carriers (71% versus 42% for 1G/1G patients,xa0P = .002) and in MMP-3 6A allele carriers (70% versus 61% for 5A/5A patients, P = .064), particularly in non-ischemic patients (P = .039). MMP1 2G allele was independently associated to HF survival after adjustment for several other predictors of risk (hazard ratio 0.47, 95% confidence interval 0.27 to 0.82; P = .008).nnnCONCLUSIONSnMMP-1, -3, and -9 polymorphisms were not associated to HF susceptibility. However, MMP1 2G allele carriers were related to a higher prevalence of ischemic etiology among patients with systolic HF and better HF-related prognosis.

Polymorphisms of endothelial nitric oxide synthase gene in systolic heart failure: An haplotype analysis

BACKGROUNDnEndothelial nitric oxide synthase (eNOS) gene polymorphisms have been associated with the pathogenesis of cardiovascular diseases, but few studies have evaluated the role of eNOS haplotypes on the risk and prognosis of heart failure (HF). This prospective study was designed to analyze the impact of three eNOS polymorphisms (T-786C, VNTR4a/b and Glu298Asp) and their haplotypes on the susceptibility and clinical outcomes in HF outpatients with systolic dysfunction.nnnMETHODS AND RESULTSnWe conducted a case-control and a cohort study in which 316 HF patients and 360 healthy controls were recruited from a tertiary care university hospital. DNA was extracted from peripheral blood and eNOS polymorphisms were detected by PCR or PCR-RFLP. Patients were predominantly men, had a mean left ventricular ejection fraction of 31% and were followed-up for a median of 41months; there were 96 deaths, including 58 HF-related deaths. Genotype distribution of the eNOS T-786C, VNTR 4a/b and Glu298Asp was similar between HF patients and controls. Haplotype frequencies differed between HF patients and controls only in African-Brazilians (p=0.043). African-Brazilian patients that carried the haplotype -786C/4b/Asp298 had a better prognosis than patients that carried other haplotypes (log rank p value=0.016 for all-cause mortality). In a Cox proportional hazard model adjusted for clinical variables of risk, the -786C/4b/Asp298 haplotype remained as an independent genetic predictor of survival (adjusted HR=0.11; 95% CI=0.01-0.83; p=0.03).nnnCONCLUSIONSnThe -786C/4b/Asp298 eNOS haplotype had a significant impact on HF susceptibility and prognosis, particularly in African-Brazilian patients.

Influence of VKORC1 gene polymorphisms on the effect of oral vitamin K supplementation in over-anticoagulated patients

Significant inter-individual variability on the effect of vitamin K to reverse overanticoagulation has been identified. Genetic polymorphisms of the vitamin K epoxide reductase complex subunit 1 (VKORC1) gene might explain in part this variability. The objective of this study was to evaluate the influence of VKORC1 −1639G>A and 3730G>A polymorphisms on the effect of oral vitamin K supplementation in overanticoagulated patients. We performed an interventional trial of oral vitamin K supplementation in over-anticoagulated outpatients (international normalized ratio [INR]xa0≥xa04). Subjects received vitamin K (2.5–5.0xa0mg) according to baseline INR and were genotyped by real time polymerase chain reaction (PCR). INR values were determined at 3, 6, 24 and 72xa0h after supplementation. We evaluated 33 outpatients, 61xa0% were males, with a mean age of 62xa0±xa012xa0years old. There was a significant decrease in INR values over time for both polymorphisms after oral vitamin K. At 3xa0h after supplementation, patients carrying the G allele for the −1639G>A polymorphism had a greater decrease in INR values compared to AA patients (pxa0<xa00.05 for difference among groups; pxa0<xa00.001 for time variation; pxa0=xa00.001 for timexa0×xa0group interaction), with differences of −1.01 for GG versus AA (pxa0=xa00.003) and −0.84 for GA versus AA (pxa0=xa00.024). Mean INR value at 24xa0h was 1.9xa0±xa00.6 and at 72xa0h was 2.1xa0±xa00.7, with no differences among genotypes. No significant interaction was identified between the 3730G>A polymorphism and vitamin K supplementation. Our study indicated that the VKORC1 −1639G>A polymorphism plays a role in the response to acute vitamin K supplementation in over-anticoagulated patients, with faster decrease of INR value in patients carrying the G allele.

Impact of β-2 Thr164Ile and combined β-adrenergic receptor polymorphisms on prognosis in a cohort of heart failure outpatients

Genetic polymorphisms of adrenergic receptors (ARs) have been associated with the development, progression, and prognosis of patients with heart failure (HF), with few data for the Brazilian population. We evaluated the role of the β2-AR Thr164Ile polymorphism at codon 164 on prognosis in a prospective study on 315 adult Brazilian HF patients, predominantly middleaged Caucasian men in functional class I-II, with severe left ventricular systolic dysfunction. Genomic DNA was extracted from peripheral blood and β2-AR164 genotypes were detected by PCR followed by restriction fragment length analysis. During a median follow-up of 3 years, 95 deaths occurred and 57 (60%) were HF-related. Unexpectedly, Ile164 carriers (N = 12) had no HF-related events (log-rank P value = 0.13). Analysis using genotype combination with β1-AR polymorphisms at codons 49 and 389 identified patients with favorable genotypes (Thr164Ile of β2-AR, Gly49Gly of β1-AR and/or Gly389Gly of β1-AR), who had lower HF-related mortality (P = 0.01). In a Cox proportional hazard model adjusted for other clinical characteristics, having any of the favorable genotypes remained as independent predictor of all-cause (hazard ratio (HR): 0.41, 95%CI: 0.17-0.95) and HF-related mortality (HR: 0.12, 95%CI: 0.02-0.90). These data show that the β2-AR Thr164Ile polymorphism had an impact on prognosis in a Brazilian cohort of HF patients. When combined with common β1-AR polymorphisms, a group of patients with a combination of favorable genotypes could be identified.

QRS Widening Rates and Genetic Polymorphisms of Matrix Metalloproteinases in a Cohort of Patients With Chronic Heart Failure

BACKGROUNDnQRS duration is considered to be an indicator of adverse outcome in patients with heart failure (HF), and genetic polymorphisms may be involved in this conductivity impairment. We studied the prognostic impact of the QRS widening rate (QRS-WR) on patients with HF and the influence of the matrix metalloproteinases gene polymorphisms on the QRS-WR.nnnMETHODSnThis prospective cohort study included 184 patients with left ventricular (LV) systolic dysfunction (LV ejection fraction [LVEF] < 45%). The QRS-WR was calculated as the difference between 2 electrocardiogram assessments (in ms) divided by the time elapsed between each evaluation (months). The MMP-1 -1607 1G/2G, MMP-2 -790G/T and -1575G/A, MMP-3 -1171 5A/6A, MMP-9 -1562 C/T and R279Q, and MMP-12 -82A/G polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism.nnnRESULTSnPatients were predominantly white (68%) men (67%) in New York Heart Association functional classes I and II (77%). Patients with HF with a QRS-WR ≥ 0.5 ms/month had more HF-related deaths and more combined clinical events than those with a QRS-WR < 0.5 ms/month (P = 0.03 and P = 0.01, respectively). After adjusting for other covariates, the QRS-WR remained an independent predictor of combined clinical events (hazard ratio, 1.6; 95% confidence interval, 1.1-2.5; P = 0.02). The MMP-1 2G2G genotype was associated with nearly a 2-fold increase in QRS-WR (P = 0.03). Conversely, patients with the MMP-3 5A5A genotype and a nonischemic cause of HF were protected against QRS enlargement (P = 0.03).nnnCONCLUSIONSnQRS-WR retains prognostic value in patients with chronic HF receiving guideline-based pharmacologic treatment. MMP gene polymorphisms can influence the rate of QRS enlargement over time.