Assessment of the relationship between the ambulatory electrocardiography-based micro T wave alternans and the predicted risk score of sudden cardiac death at five years in patients with hypertrophic cardiomyopathy

OBJECTIVE: Micro T-wave alternans (MTWA) has been associated with poor arrhythmic prognosis in various cardiac disorders. The aim of this study was to assess the relationship between the presence of MTWA and the predicted 5-year risk of sudden cardiac death (HCM Risk-SCD) among patients with hypertrophic cardiomyopathy (HCM). METHODS: A total of 117 consecutive HCM patients were included in this prospective observational study. Patients were divided into two groups, according to the presence [MTWA (+) group (n=44)] or absence [MTWA (-) group (n=73)] of MTWA on ambulatory (Holter) electrocardiography. RESULTS: The risk of HCM Risk-SCD (%), the rate of high-risk patients (HCM Risk-ECG >6%), the requirement for cardiopulmonary resuscitation, and implanted cardioverter defibrillator therapy, the percentage of some clinical, echocardiographic, and Holter findings were all statistically higher in the MTWA (+) group than in the MTWA (-) group (all p<0.05). Both in the univariate and multivariate analyses, T-wave alternans (+) and the New York Heart Association's functional classification assigned that the HCM Risk-SCD is an independent predictor of high risk. In the receiver operating characteristic curve analysis, the HCM Risk-SCD >4.9% was identified as an effective cutoff point in the MTWA (+) for HCM. The HCM Risk-SCD value of more than 4.9 yielded a sensitivity of 93.2% and a specificity of 84.5%. CONCLUSION: The presence of the MTWA on ambulatory electrocardiogram seems to be significantly associated with increasing percentages of the predicted HCM Risk-SCD score in patients with HCM. The MTWA was determined as an independent high-risk indicator for HCM Risk-SCD.