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Additional predictive value of heart rate variability in high-risk patients surviving an acute myocardial infarction
G A Lanza1, M Galeazzi, V Guido
1Istituto di Cardiologia, Università Cattolica del Sacro Cuore, Roma.
Insights
Heart rate variability (HRV) analysis effectively predicts cardiac mortality in high-risk acute myocardial infarction patients. Lower heart rate variability, particularly low frequency and VLF values, indicates increased risk of fatal cardiac events.
Area of Science:
- Cardiology
- Biomedical Engineering
- Clinical Research
Background:
- Patients with recent acute myocardial infarction (AMI) and impaired left ventricular function or frequent ventricular arrhythmias are at high risk for cardiac mortality.
- Predictive markers are crucial for risk stratification and management in these vulnerable patients.
Purpose of the Study:
- To evaluate the utility of heart rate variability (HRV) in predicting cardiac death, including sudden cardiac death, in high-risk AMI patients.
- To identify specific HRV parameters that are significant predictors of mortality.
Main Methods:
- A 24-hour Holter recording was performed on 81 high-risk AMI patients before discharge.
- Time- and frequency-domain HRV parameters were analyzed.
- Patients were followed for a median of 29 months to ascertain cardiac mortality events.
Main Results:
- 18.5% of patients experienced cardiac death, with 13.6% dying from sudden cardiac death.
- Lower median low frequency (LF) and LF/HF ratio were associated with increased total and sudden cardiac death.
- Reduced very-low frequency (VLF) and mean of standard deviations of all RR intervals predicted cardiac death, while VLF and LF/HF ratio predicted sudden death.
Conclusions:
- HRV analysis is a valuable tool for identifying high-risk AMI patients prone to fatal cardiac events.
- Specific HRV parameters, including LF, VLF, and LF/HF ratio, can significantly predict cardiac mortality and sudden death in this population.
Abstract:
The aim of this study was to investigate the usefulness of heart rate variability (HRV) in predicting cardiac mortality in patients with a recent acute myocardial infarction at high risk of events. Time- and frequency-domain HRV was assessed on 24-hour pre-discharge Holter recording of 81 patients (mean age 65 +/- 10 years, 76.5% males) with 1) a recent acute myocardial infarction, and 2) left ventricular ejection fraction < 40% and/or a number of premature ventricular beats > or = 10/hour. There were 15 total cardiac deaths (18.5%) in a follow-up time of 29 +/- 15 months (range 6 to 48 months), with sudden death occurring in 11 patients (13.6%). Median values of low frequency (LF) were lower in patients with, compared to those without, total (p = 0.04) and sudden (p = 0.02) cardiac death. Similarly the low frequency/high frequency (LF/HF) ratio was lower in patients with fatal events (p = 0.03 and p = 0.02, respectively). Furthermore, mean of the standard deviations of all RR intervals for all 5-min segments < 20 ms, among time-domain variables, and very-low frequency (VLF) < 18 ms, among frequency-domain variables, significantly predicted cardiac death (relative risk-RR 2.94, p = 0.03; and RR 3.85, p < 0.005, respectively). Furthermore, VLF < 18 ms and LF/HF ratio < 1.05 significantly predicted the occurrence of sudden death (RR 3.52, p = 0.04; and RR 3.49, p = 0.04, respectively). Thus, our data show that HRV analysis is a useful tool for identifying patients with an actual increased risk of fatal cardiac events among patients who are basically considered at high risk according to the presence of an impaired left ventricular function and/or frequent ventricular arrhythmias.