Long-Term Non-Invasive ECG-Based Risk Stratification of Sudden Cardiac Death: Extended 5-Year Results

Abstract

Background: To evaluate predictive value of heart rate turbulence (HRT), deceleration capacity (DC) and microvolt T-wave alternans (mTWA) for risk stratification for sudden cardiac death (SCD) in patients after myocardial infarction (MI) during 60 months of follow-up. Methods We studied 111 patients after MI occurred > 60 days (27 [9; 84] months) before enrollment (84 men; mean age 64.1±10.5 years). All subjects had 24-hour ambulatory ECG monitoring with HRT, DC and mTWA evaluation. Follow-up period was 60 months; primary endpoint was SCD, secondary endpoint included all non-sudden cardiovascular deaths. Results During follow-up, we registered 19 cases of SCD and 11 cases of non-sudden cardiovascular deaths (including 7 fatal MI and 3 fatal strokes). DC had high negative predictive value (97.4% for all-cause mortality and 93.7% for SCD). DC values below 4.15 for allcause mortality and 2.0 for SCD significantly increased risk of all-cause mortality (OR 8.5, 95% CI 2.9 to 24.6, 53 mcV, which increased risk both of all-cause mortality (30.7-fold) and SCD (63.3-fold); however, at 60 months this predictive value for SCD decreased (OR = 20.8 (95% CI 2.8 to 114.0), p <0.001). Conclusions Evaluation of HRT, DC and mTWA during 24-hour ECG monitoring may define the high risk of cardiovascular mortality and SCD in post-MI patients especially during the first 12 months after the baseline examination.