ABC | Volume 115, Nº2, August 2020

Original Article Mattos BP et al. Sudden death in hypertrophic cardiomyopathy Arq Bras Cardiol. 2020; 115(2):197-204 different weights to the former five independent predictors mentioned above, in addition to LV outflow gradient, left atrial diameter and age. 16,17 The purpose of the study is to analyze the impact of the 2014 ESC model on the SCD risk stratification and the recommendations of ICD primary prevention compared to the previously proposed 2011 ACCF/AHA criteria. Methods Patient selection A cohort of 108 subjects followed at a dedicated HCM outpatient clinic of a tertiary center fromMarch 2007 to March 2018 was retrospectively studied. All patients were submitted to rest electrocardiogram, 24-hour Holter electrocardiogram and echocardiogram. Cardiac magnetic resonance (CMR) imaging was applied to 40 (45%) subjects. Molecular-genetic testing was performed in 18 (20%) patients, whose results were previously published. 18 Diagnosis was established according to the current guidelines 15,17 based on the identification of unexplained LV hypertrophy detected on echocardiogram and/or magnetic resonance imaging by the presence of MLVWT ≥15 mm measured at any segment, with septum/ posterior wall ratio ≥1.3 in the absence of chamber dilation or other conditions capable of producing a similar pattern of hypertrophy. Eighteen cases were excluded due to a follow-up period <12 months or previous history of cardiopulmonary arrest, ventricular fibrillation or ventricular tachycardia with hemodynamic impairment. The following outcomes were considered for the analysis: 1. Sudden cardiac death: documented ventricular fibrillation, death one hour from the onset of symptoms or at night without previous clinical worsening; 2. Appropriate ICD shock for ventricular tachycardia or ventricular fibrillation. The study was approved by the Ethics Committee of the institution and performed under the principles of the principles of the Declaration of Helsinki. Written informed consent was obtained from all patients. Risk stratification for sudden cardiac death The following predictors were assessed: 1. Age; 2. Family history of SCD in first-degree relatives, <40 years old or at any age with previous diagnosis of the disease; 2. MLVWT measured on echocardiogram; 4. Unexplained syncope within the past 6 months; 5. NSVT defined as three or more successive premature ventricular beats at a heart rate ≥120 beats/min lasting ≤30 s; 6. Abnormal blood pressure response to exercise defined as <25 mmHg rise and/or 10 mmHg drop of maximal systolic blood pressure during peak exercise; 7. Left atrial diameter obtained on M-mode or two-dimensional echocardiogram; 8. Maximum left ventricular outflow tract (LVOT) gradient at rest or with Valsalva maneuver using continuous wave Doppler. The following risk modifiers were considered: 1. LVOT gradient ≥ 30 mmHg; 2. Late gadolinium enhancement on CMR; 3. LV apical aneurysm; 4. Malignant genetic mutations. The probability of SCD in 5 years was calculated with the ESC HCM-Risk SCD equation as follows: Probability of SCD in 5 years = 1 – 0.998 exp(Prognostic index) Prognostic index = [0.15939858 x maximal wall thickness (mm)] - [0.00294271 x maximal wall thickness² (mm²)] + [0.0259082 x left atrial diameter (mm)] + [0.00446131 x maximal (rest/Valsalva) LVOT gradient (mm Hg)] + [0.4583082 x family history SCD] + [0.82639195 x NSVT] + [0.71650361 x unexplained syncope] - [0.01799934 x age at clinical evaluation (years)]. Recommendations of implantable cardioverter defibrillator therapy The following criteria for primary prevention ICD were compared: 1. 2011 ACCF/AHA guideline: Class IIa - A family history of SCD in a first-degree relative or MLVWT ≥ 30 mm or unexplained syncope. Class IIa - NSVT or abnormal blood pressure response to exercise associated with other risk factors or modifiers; Class IIb: Isolated NSVT or abnormal blood pressure response to exercise; Class III – absence of the previously mentioned risk factors. 2. 2014 ESC guideline: Class IIa – HCM Risk-SCD ≥6%; Class IIb - <6% and ≥4%; Class III - <4%. Statistical analysis Normally distributed continuous variables were expressed as mean±standard deviation and non-normally distributed data presented as median and interquartile ranges (percentile 25 and 85). Continuous variables were tested for normality using the Shapiro-Wilk test. Categorical variables were described as absolute and relative frequencies. Continuous variables were compared with Student’s t test or one-way analysis of variance (ANOVA), categorical variables with chi-square or Fisher’s exact test and differences among categories with standardized adjusted residual analysis. The Kappa coefficient was calculated to determine the agreement between the 2011 ACCF/AHA and the 2014 ESC guidelines for primary prevention ICD. The percentages achieved by each of the risk predictors included in the ESC HCM Risk-SCD score were calculated with the weighted average of the variation of each predictor in the equation over the sum of the variations of these predictors. The estimated survival of the sample was determined using the Kaplan-Meier curve. The sample size was estimated at 70 individuals for an expected Kappa=0.3, considering the occurrence of agreement between the guidelines, Kappa=0 for 90% power and p<0.05. SPSS software version 20.0 (SPSS Inc., Chicago, Illinois, USA) was used for the analyses. All comparisons were two-tailed and p<0.05 was considered to be statistically significant. Results Clinical characteristics The study population comprised 90 consecutive patients with HCM, mean age 62±12 years, 85 (94%) ≥40 years and 56 (62%) females. The clinical characteristics of the study patients are described in table 1. Along the follow-up period of 198