Baroreflex sensitivity and heart rate variability in the identification of patients at risk for life-threatening...

Area of Science:

• Cardiology
• Clinical Electrophysiology
• Risk Stratification

Background:

• Expanding implantable cardioverter defibrillator (ICD) indications necessitate accurate risk stratification.
• Previous studies like MADIT highlighted left ventricular ejection fraction (LVEF) and nonsustained ventricular tachycardia (NSVT) as risk factors.
• The ATRAMI study identified reduced vagal activity markers (BRS, HRV) as predictors of cardiac mortality post-myocardial infarction.

Purpose of the Study:

• To evaluate the independent and combined predictive value of baroreflex sensitivity (BRS), heart rate variability (HRV), and nonsustained ventricular tachycardia (NSVT) for mortality in post-myocardial infarction patients.
• To determine if BRS can identify high-risk patients with depressed LVEF who lack NSVT.

Main Methods:

• Analysis of 1071 patients from the ATRAMI study with available data on LVEF, 24-hour ECG, and BRS.
• Follow-up duration of 21 ± 8 months to assess cardiac death, sustained VT, and sudden death/sustained VT.
• Statistical analysis to determine independent associations between risk factors and mortality.

Main Results:

• NSVT, depressed BRS, and HRV were independently associated with increased mortality.
• The combination of all three risk factors increased mortality risk by 22-fold.
• In patients with LVEF < 35% and no NSVT, depressed BRS predicted significantly higher mortality (18% vs. 4.6%, P = 0.01).
• Low BRS demonstrated higher sensitivity for predicting cardiac and arrhythmic mortality compared to NSVT and HRV.

Conclusions:

• BRS and HRV significantly contribute to risk stratification beyond traditional markers.
• Depressed BRS identifies a substantial subgroup of patients with reduced LVEF at high risk for cardiac and arrhythmic events.
• BRS analysis offers a valuable tool for identifying candidates for ICD therapy, potentially improving selection without a disproportionate increase in false-positives.