ABC | Volume 115, Nº2, August 2020

Original Article Discrepancy between International Guidelines on the Criteria for Primary Prevention of Sudden Cardiac Death in Hypertrophic Cardiomyopathy Beatriz Piva e Mattos, 1, 2 F ernando Luís Scolari, 1, 2 H enrique Iahnke Garbin 2 Hospital de Clínicas de Porto Alegre, 1 Porto Alegre, RS - Brazil Universidade Federal do Rio Grande do Sul - Faculdade de Medicina, 2 Porto Alegre, RS - Brazil Mailing Address: Beatriz Piva e Mattos • Hospital de Clínicas de Porto Alegre - Serviço de Cardiologia - Rua Ramiro Barcelos, 2350. Postal Code 90035-903, Porto Alegre, RS – Brazil Manuscript received March 07, 2019, revised manuscript July 10, 2019, accepted August 14, 2019 DOI: https://doi.org/10.36660/abc.20190161 Abstract Background: Risk stratification for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) is based on different algorithms proposed by the 2011 ACCF/AHA and 2014 ESC guidelines. Objective: To analyze the 2014 ESC model for SCD risk stratification and primary prevention ICD (implantable cardioverter defibrillator) in HCM in comparison to the North American guideline. Methods: An HCM cohort was evaluated and the ESC HCM-Risk SCD score was calculated. Agreement of ICD recommendations criteria between the two guidelines was analyzed with Kappa coefficient. P<0.05 was adopted for the statistical analysis. Results: In 90 consecutive patients followed for 6±3 years, the mean calculated ESC risk score was 3.2±2.5%. The risk predictors that have mainly contributed to the score calculation in the low (1.88% [1.42–2.67]), intermediate (5.17% [4.89–5.70]) and high-risk (7.82% [7.06–9.19]) categories were: maximal left ventricular wall thickness (1.60% [1.25–2.02]; 3.20% [3.18–3.36]; 4.46% [4.07–5.09]), left atrial diameter (0.97% [0.83–1.21]; 1.86% [1.67‑2.40]; 2.48% [2.21–3.51]) and age (-0.91% [0.8–1.13]; -1.90% [1.12–2.03]; -2.34% [1.49–2.73]). The European model decreased the ICD recommendations in 32 (36%) patients. Among the 43 (48%) individuals with class IIa recommendation under the 2011 ACCF/AHA guideline, 8 (18%) were downgraded to class IIb and 24 (56%) to class III. Low agreement was found between the two systems: Kappa=0.355 and p=0.0001. In 8 (9%) patients with SCD or appropriate shock, 4 (50%) met class IIa indication with the 2011 ACCF/AHA guideline, but none achieved this class of recommendation with the 2014 ESC model. Conclusion: Lowagreement was found between the two strategies. The novel ESCmodel decreased the ICD recommendations, especially in those with class IIa recommendation, but left unprotected all patients with SCD or appropriate shock. (Arq Bras Cardiol. 2020; 115(2):197-204) Keywords: Cardiomyopathy,Hypertrophic/genetics; Heredity; Death,Sudden, Cardiac; Arrhythmias, Cardiac; Syncope; Defibrillators,Implantable; Cohort Studies Introduction Hypertrophic cardiomyopathy (HCM) represents the most prevalent form of genetic heart disease, affecting one in 200 individuals. 1 Sudden cardiac death (SCD), presently estimated at 0.5 to 1%/year, occurs at any age, although it predominates in young subjects and athletes. 2-4 The risk stratification for SCD is the basis for the recommendation of implantable cardioverter defibrillator (ICD) in HCM, the only approach considered to be able to modify the disease prognosis. 4-7 There is a consensus about the recommendation in patients with prior cardiac arrest. However, many questions persist regarding primary prevention. Five risk factors identified in longitudinal studies and validated in meta-analyses are recognized as independent predictors of SCD: family history, unexplained syncope, maximal left ventricular wall thickness (MLVWT) ≥30 mm, non-sustained ventricular tachycardia (NSVT) and abnormal blood pressure response to exercise. 5-13 In the 2003 American College of Cardiology (ACC)/ European Society of Cardiology (ESC) Consensus, the ICD recommendation was based on the number of risk markers. 14 The criteria were updated in the 2011 American College of Cardiology Foundation (ACCF)/American Heart Association (AHA) guideline, in which modifying factors were included: malignant mutations, late gadolinium enhancement, left ventricular (LV) apical aneurysms and outflow tract obstruction. 15 A novel mathematical and statistical prediction model endorsed by ESC in 2014 and accessible with an online calculator provides an estimate of the absolute risk and five-year mortality rate, applying 197