217 Six-hour holter recording of microvolt T-wave alternans and heart rate turbulence in the CCU compared to classical 24-hour ambulatory ECG

Abstract

T-wave alternans (TWA) and heart rate turbulence (HRT) measured during 24 hour-ECG recordings are 2 powerful non-invasive tools to risk-stratify cardiovascular patients. The aim of our study is to assess whether a fast ECG-holter scan yields different information from classical 24-hour ambulatory ECG regarding TWA and HRT measurements. All consecutive 21 patients with a non-ST-elevated myocardial infarction and admitted in intensive care unit of cardiology, have been monitored with an ECG-holter for classical, TWA and HRT analysis over 24 hours. TWA has been measured with the modified moving average method. Routine reading of the holters has been followed by a specific analysis. Each 24-hour period has been divided into four equal periods. Maximal TWA, T-onset and T-slope for HRT over those four 6-hour periods have been analyzed and compared with full day results using a repeated measures analysis of variance (ANOVA). 16 men and 5 women aged between 31 and 90 (mean 57.5 +/− 24.8) have been included. Mean maximal TWA was 73 ± 25 μV. 6-hour maximal TWA was 59 +/− 23 μV, 55 +/− 26 μV, 56 +/− 30.01 and 48 +/− 23.27 μV (p = 0.11). HRT as assessed by T onset and T slope were −0.00619% +/− 0.02, 0.00333% +/− 0.04, 0.00571% +/− 0.03, −0.00952% +/− 0.03 (p = 0.46) and 3.75 +/− 3.99, 5.46 +/− 7.29, 6.32 +/− 9.13, 5.96 +/− 10.85 (p = 0.46) respectively for each time period. This preliminary study suggests that a 6-hour ECG-Holter recording could be a reliable and feasible method to assess cardiovascular mortality and risk of SCD in patients admitted for an acute coronary syndrome in intensive care unit by studying TWA and HRT. Faster risk stratification could thus be done during hospitalization in order to optimize therapeutics and better identify candidate for fast ICU discharge.