Risk of arrhythmic death in ischemic heart disease: a prospective, controlled, observer-blind risk stratification
Thomas Pezawas1, André Diedrich2, David Robertson2
1Division of Cardiology, Department of Internal Medicine II, Medical University of Vienna, Vienna, Austria.
Insights
Patients with ischemic heart disease and reduced ejection fraction face similar arrhythmic death risks, regardless of severity. Current risk stratification methods and tests like MTWA and BRS are insufficient for identifying high-risk individuals needing defibrillators.
Area of Science:
- Cardiology
- Electrophysiology
Background:
- Arrhythmic death risk is highest in ischemic heart disease (IHD) with reduced left ventricular ejection fraction (LVEF).
- Non-invasive testing aims to improve decisions for prophylactic implantable cardioverter-defibrillator (ICD) implantation.
Purpose of the Study:
- To evaluate the risk of arrhythmic death in IHD patients with varying degrees of LVEF reduction.
- To assess the efficacy of non-invasive tests in stratifying risk for arrhythmic events.
Main Methods:
- 120 IHD patients with LVEF <50% and 30 controls were followed for 7.5 years.
- Assessments included baroreflex testing (BRS), heart rate variability (HRV), and Microvolt T-wave alternans (MTWA).
Main Results:
- Arrhythmic death or resuscitated cardiac arrest occurred in 15-18% of IHD patients.
- No significant difference in arrhythmic death risk was found between LVEF subgroups (<30% vs. ≥30%).
- MTWA, BRS, HRV, and LF/HF ratio failed to predict arrhythmic death risk in multivariate analysis.
Conclusions:
- IHD patients with LVEF <30% and ≥30% have similar arrhythmic death risks.
- Current risk stratification techniques are insufficient for identifying high-risk patients.
- Prophylactic ICD implantation criteria based solely on LVEF may be inadequate.
Background:
Risk of arrhythmic death is considered highest in ischemic heart disease with severe left ventricular ejection fraction (LVEF) reduction. Non-invasive testing should improve decision-making of prophylactic defibrillator (ICD) implantation.
Design:
We enrolled 120 patients with ischemic heart disease and LVEF < 50% and 30 control subjects without ischemic heart disease and normal LVEF. An initial assessment, a second assessment after 3 years and a final follow-up comprised of pharmacological baroreflex testing (BRS), short-term spectral [low-frequency (LF) to high-frequency (HF) ratio] and long-term time-domain analysis of heart rate variability (SDNN), exercise Microvolt T-wave alternans (MTWA) and others.
Results:
The median follow-up was 7·5 years. Resuscitated cardiac arrest and arrhythmic death due to ventricular arrhythmias ≥ 240/min was observed in 18% and 15% of patients, respectively. Cardiac death was observed in 28% of patients. The incidence of arrhythmic death and resuscitated cardiac arrest was identical in patients with ischemic heart disease with LVEF < 30% and ≥ 30%. No significant difference between subgroups with LVEF of < 30%, 30-39% and ≥ 40% was found either. MTWA, BRS, SDNN and LF to HF ratio failed to identify patients at risk of arrhythmic death in a multiple regression model.
Conclusions:
Ischemic heart disease patients with LVEF < 30% and ≥ 30% face the same risk of arrhythmic death. Stratification techniques fail to identify high-risk patients. Therefore, the current practice to constrain prophylactic ICDs to patients with severely reduced LVEF seems to be insufficient.
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