Intrinsecoid deflection as a risk predictor for sudden cardiac death in hypertrophic cardiomyopathy

ABSTRACT

INTRODUCTION: Sudden Cardiac Death (SCD) and Malignant Ventricular Arrhythmias (MVA) in patients with Hypertrophic Cardiomyopathy (HCM) occurs in up to 0.9%/ year. Identifying risk predictors for such an event is of paramount importance, considering the indication of Implantable Cardiodefibrillator (ICD) in patients at higher risk. The Intrinsecoid Deflection (ID) measured on the electrocardiogram showed a correlation with cardiovascular outcomes in some studies, but the literature is scarce in the analysis of this parameter in patients with HCM. OBJECTIVES and METHODS: This was a retrospective cohort study, which included patients with HCM and ICD followed in a tertiary hospital. Clinical, therapeutic and echocardiographic parameters were analyzed, in addition to the measurement of ID on the 12-lead ECG. RESULTS: 180 patients were included in the analysis, divided into 2 groups group I (N=55) ­ in secondary prevention or who had MVA (with or without ICD therapy) and group II (N=125) ­ patients in primary prevention, who did not undergo ICD therapy. Group I showed higher values of HCM-Risk SCD (13.5 ± 3.92 vs 6.47 ± 2.76 - p<0.001). septum thickness (25.5 ± 4.63 mm vs 22.4 ± 4.70 mm - p<0.001), EDDLV (46,8 ± 7,47 vs 43,6 ± 6,76 mm ­ p=0,008), ID in v1 (78.9 ± 16 vs 38.5 ± 11.7 - p<0.001) and ID in V5 or V6 (77.1 ± 15.4 vs 40.5 ± 10.8 - p<0.001) - Figure 1. In the multivariate analysis, the ID measurement and the occurrence of NSVT on the 24-hour Holter were the factors that best correlated with the occurrence of MVA. The analysis of the ROC curve showed a cutoff value with better sensitivity and specificity of 58 ms for the ID both in V1 and in V5 or V6 - Figure 2. CONCLUSION: In this study, the increase in ID constituted an independent predictor factor for the occurrence of MVA and, therefore, for a higher risk of SCD, in patients with HCM. The inclusion of this parameter in the risk stratification may help to better indicate an ICD to patients at higher risk.