Decreased Deceleration Capacity of Heart Rate Detects Heart Failure Patients at Risk for Malignant Ventricular Arrhythmias
BACKGROUND: Deceleration capacity (DC) of the heart rate has proved an independent predictor of total mortality in post-myocardial infarction (post-MI) patients but it is unknown whether DC predicts the arrhythmic risk as well.
OBJECTIVE: Our aim was to investigate whether DC can predict the arrhythmic sudden cardiac death (SCD) surrogate in patients with heart failure (HF).
PATIENTS AND METHODS: We prospectively screened 145 HF patients with electrocardiogram (ECG), signal averaged ECG, echocardiography, and 24-hour Holter ECG. After 41.2 months, patients were divided into high (n=43) and low risk (n=102) groups according to three arrhythmic surrogates: clinical ventricular tachyarrhythmia (ventricular tachycardia -VT/ ventricular fibrillation-VF) (n=18), appropriate activation of the implantable cardioverter defibrillator (ICD) device (n=23) and confirmed SCD (n=2).
RESULTS: High risk patients had impaired DC with significantly lower values (3.2±1.8 ms vs 4.0±2.1 ms, p=0.025). In the Cox regression analysis model adjusted for age, gender, diabetes, left ventricular ejection fraction (LVEF), filtered QRS, QTc, nonsustained VT episode(s) ≥ 1/24 h, ventricular premature beats ≥240/24 and DC, DC emerged as an important SCD surrogate predictor with a hazard ratio of 0.804, (95% confidence intervals-CI: 0.671- 0.963, p = 0.018). The cutoff point of DC≤3.352 ms (median) presented a hazard ratio of 2.885 (95% CI: 1.342 - 6.199, p=0.007, log rank test: p=0.003) for SCD surrogate.
CONCLUSION: Decreased DC was found to be an important and independent SCD surrogate predictor. The cutoff point of DC≤3.352 ms detects HF patients at increased arrhythmic risk.
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