Estratificação de risco na prevenção primária de morte súbita na cardiomiopatia hipertrófica: desenvolvimento de um escore prognóstico

Abstract

Hypertrophic cardiomyopathy (HCM) is a genetic disease characterized by ventricular hypertrophy in the absence of conditions that lead to heart overload. It is the main cause of sudden death (SD) in young adults, with annual incidence = 1%. Among the risk markers (RM) is highlighted the presence of a family history of SD; severe left ventricular hypertrophy (LVH); unexplained syncope; non-sustained ventricular tachycardia (NSVT); abnormal blood pressure response to exercise (ABPRE) and left ventricular outflow tract obstruction (LVOTO). The RM can define the need for implantable cardioverter defibrillator to prevent SD, however, there is still controversy about how to make this risk stratification. Among the tools recently studied in order to improve this evaluation, the presence of myocardial fibrosis by cardiac magnetic resonance is the one that most call attention. Some studies suggest its correlation with SD, but it is not a consensus. The objectives of the present study were: (1) To develop a new prognostic score based on meta-analyzes of the literature, adding myocardial fibrosis to classic RM (2) update the role of RM in HCM. A systematic review of observational studies was performed. We search in 3 databases (Medline, Lilacs and SciELO) for HCM studies addressing severe arrhythmic outcomes and the following RM: family history of SD, severe LVH, unexplained syncope, NSVT, ABPRE, LVOTO and myocardial fibrosis. For each marker, meta-analysis was performed by DerSimonian and Laird method, in case of heterogeneity, and Mantel-Haenszel method, in case of homogeneity. We use relative risk (RR) as a measure of effect, and random models for analysis. From the meta-analysis of each marker, the prognostic score was derived based on scoring system. Twenty-one studies were selected (14901 patients, 45 ± 16 years, 62.8% male). The meta-analysis showed that the myocardial fibrosis is a major risk marker (RR 3.43, 95% CI 1.95-6.03). Other RM were also predictors LVOTO: Family history of MS (RR = 1.75, 95% CI 1.39-2.20), severe LVH (RR = 1.86, 95% CI 1.26-2.74 ), unexplained syncope (RR = 2.27, 95% CI 1.69-3.07), NSVT (RR = 2.79, 95% CI 2.29-3.41) and ABPRE (RR = 1 , 53, 95% CI 1.12-2.08). We reached the power for each marker by multiplying the RR by the publication relevance and adopting rounding processes. The sum was 11 points (family history of SD = 2, severe HVE = 2, unexplained syncope = 2, NSVT = 3, ABPRE = 1 and myocardial fibrosis = 1). As an strategy for stratification, we have suggested that patients may be divided into low risk (0-2 points), medium risk (3-4 points) and high risk (> 5 points). In conclusion, The prognostic score of SD in HCM using myocardial fibrosis was derived. We confirmed the association between myocardial fibrosis and severe arrhythmic outcomes in HCM. We emphasize the need for validation of the model for future clinical applicability.