ABC | Volume 110, Nº6, June 2018

Original Article Prevention of Sudden Cardiac Death in Hypertrophic Cardiomyopathy: What has Changed in The Guidelines? Liliana Reis, Rogerio Teixeira, Andreia Fernandes, Inês Almeida, Marta Madeira, Joana Silva, Ana Botelho, João Pais, José Nascimento, Lino Gonçalves Centro Hospitalar e Universitário de Coimbra, Serviço de Cardiologia, Coimbra – Portugal Mailing Address: Liliana Reis • Serviço de Cardiologia - Centro Hospitalar e Universitário de Coimbra - Hospital Geral Quinta do Vales, São Martinho do Bispo. 3041-801, Coimbra - Portugal E-mail: liliana.teles@hotmail.com Manuscript received July 20, 2017, revised manuscript Ouctober 17, 2017, accepted November 11, 2017 DOI: 10.5935/abc.20180099 Abstract Background: The new European Society of Cardiology guidelines for hypertrophic cardiomyopathy (HCM) define the estimation of sudden cardiac death (SCD) risk as an integral part of clinical management. An implantable cardioverter defibrillator (ICD) is recommended (class IIa) when the risk is ≥ 6%. Objectives: To compare the SCD risk stratification according to the 2011 and 2014 recommendations for ICD implantation in patients with HCM. Methods: Retrospective study including 105 patients diagnosed with HCM. The indication for ICD was assessed using the 2011 and 2014 guidelines. Statistical analysis was performed using SPSS software version 19.0.0.2®. The tests performed were bilateral, considering the significance level of 5% (p < 0.05). Results: Regarding primary prevention, according to the 2011 ACCF/AHA recommendations, 39.0% of the patients had indication for ICD implantation (level of evidence IIa). Using the 2014 guidelines, only 12.4% of the patients had an indication for ICD implantation. Comparing the two risk stratification models for patients with HCM, we detected a significant reduction in the number of indications for ICD implantation (p < 0.001). Of the 41 patients classified as IIa according to the 2011 recommendations, 68.3% received a different classification according to the 2014 guidelines. Conclusion: Significant differences were found when comparing the SCD risk stratification for ICD implantation in the two guidelines. The current SCD risk score seems to identify many low-risk patients who are not candidates for ICD implantation. The use of this new score results in a significant reduction in the number of ICD implanted. (Arq Bras Cardiol. 2018; 110(6):524-531) Keywords: Death, Sudden Cardiac / prevention & control; Cardiomyopathy, Hypertrophic / complications; Defibrillators, Implantable / trends; Syncope; Diagnostic Imaging. Introduction Hypertrophic cardiomyopathy (HCM) is characterized by left ventricular hypertrophy (LVH) not explained only by ventricular overload conditions. 1 It is the most common cardiovascular genetic pathology, with an estimated prevalence in the general population of 1:500 individuals. 2,3 Hypertrophic cardiomyopathy is a complex disease, regarding genetic diversity (for which, more than 1400 mutations have been identified in 11 different genes), phenotypic expression, histological characteristics and manifested symptoms. 4,5 Sudden cardiac death (SCD) is the most unpredictable and devastating consequence of HCM, occurring mainly in young or asymptomatic individuals or those with frustrated symptomatology. 4-6 Recent data have pointed to a 0.7%/year incidence of SCD, the total incidence of cardiovascular death being 1.4%/year. 7 The exclusive efficacy of implantable cardioverter defibrillator (ICD) in the prevention of SCD is well known. 1,8,9 When approaching patients with HCM and their families, the correct assessment of the SCD risk and potential benefit of implanting that device for primary prevention is fundamental. 1-3 According to the American College of Cardiology Foundation/American Heart Association (ACCF/AHA) recommendations for the diagnosis and treatment of HCM published in 2011, the presence of at least one risk factor for SCD [maximal left ventricular (LV) wall thickness ≥ 30 mm, unexplained syncope, nonsustained ventricular tachycardia (NSVT), family history of sudden death and abnormal blood pressure response during exercise] is a class IIa recommendation for the implantation of ICD in primary prevention. 10 However, a recent study by O’Mahony et al. has suggested that the use of those criteria overestimates the risk for SCD, resulting in the excessive and unnecessary implantation of ICD in a substantial percentage of patients, exposing them to unnecessary iatrogenic complications. 11 In addition, 524