ABC | Volume 114, Nº4, April 2020

Original Article Albuquerque et al. Ser49Gly Polymorphism in heart failure Arq Bras Cardiol. 2020; 114(4):613-615 with the Ser allele. 6,7 Because of the continuous exposure to adrenaline, this dysfunction could be clinically relevant in HF. In practice, this genetic mutation would determine desensitization with a relevant intrinsic adrenergic block. 8 Accordingly, in the context of HF, some publications analyzed GPR β 1-Ser49Gly in scenarios that included: risk of HF, 3,9-11 beta-blocker response, 6,12 echocardiographic outcomes, 13 functional capacity, 14 cardiac arrhythmia 10,15 and clinical outcomes. 7,16,17 These studies include a small number of patients and present some inconsistent findings. In general, the Gly allele was associated with better clinical outcome; 7,17 however, a potential influence of ethnicity on these genotypes was observed, inverting this benign behavior in some populations. 9 For these reasons, the role of this genotype is still unknown. Therefore, it is of paramount importance to analyze the behavior of this GP in a Brazilian population with its own ethnic characteristics, in order to establish the pattern of this GP for our population, increasing our (small) current genetic database. 10,16 The objective of this study is to evaluate the association between the Ser49Gly genotypes and major clinical outcomes, such as hospital admissions due to HF and death in individuals with HF with reduced ejection fraction. Methods Study design Longitudinal study of a cohort of patients. Information was collected from medical records dated between January 2015 and April 2018, since the beginning of follow-up. All patients were seen at the same HF clinic of a university hospital. Study population This is a series of cases followed for 6.7 years, which consecutively included 178 patients (113 men and 65 women) diagnosed with HF with reduced ejection fraction, being characterized as a convenience sampling. Inclusion criteria Patients aged 18 or older, with symptomatic HF (defined by the Framingham criteria), systolic ventricular dysfunction and left ventricular ejection fraction (LVEF) ≤ 50% on two‑dimensional echocardiography. Exclusion criteria Patients with unknown clinical status at the end of the study. Method Statistical analysis Statistical analysis was performed using SPSS for Mac, version 25. For all of the tests, 0.05 or 5% (p < 0.05) was defined as the rejection level of the null hypothesis and 95% confidence interval (CI). The measures of central tendency were expressed as mean ± standard deviation. Categorical variables were expressed in absolute and relative frequencies n(%). The following statistical tests were used: One-way ANOVA complemented by Tukey’s test, chi-square test and logistic regression. To evaluate the homogeneity of variances, Levene’s test was used. When there was no homogeneity of variances, the Kruskal-Wallis test was used to compare the means of three or more independent samples and Mann-Whitney test was used for up to two independent samples. Binary logistic regression was used to evaluate the clinical outcomes studied. Initially, the variables were evaluated separately in order to identify which ones were statistically relevant. Subsequently, they were evaluated together as covariables. A 95% significance level was considered for entry in the model and 90% for the removal of variables in the stepwise method of choice. Heart failure etiology The etiologies were classified into five groups: ischemic, idiopathic, hypertensive, alcoholic and others. The attending physician at the HF service was in charge of defining the etiology according to previously established criteria. 18 Clinical, laboratory and echocardiographic parameters Skin color was determined by the attending physician and classified as white, black or other. Functional class was determined according to the New York Heart Association (NYHA) at the beginning and at the end of follow-up. Death registries were taken from the medical records and, if no records were available, an active search was conducted on the electronic medical records, by phone call or on death certificate databases available on the Internet. The most recent laboratory tests were considered for statistical analysis. All individuals had their electrocardiograms (ECG) analyzed for QRS duration, presence of left bundle branch block and atrial fibrillation. Echocardiographic variables The parameters evaluated were: LV systolic diameter, LV diastolic diameter and LV ejection fraction. Two tests were used: one at the beginning and another at the end of follow-up. Genotyping Genotyping was performed using polymerase chain reaction and restriction fragment length polymorphism (PCR‑RFLP) for the R β 1 gene: 49Ser>Gly polymorphism. The details of these procedures followed specific literature. 19 All individuals were tested for the presence of Ser (wild and most common) and Gly (recessive) alleles. Based on the presence of these alleles, the individuals were classified into Ser-Ser, Ser-Gly and Gly-Gly. 617