Key result
A low dominant frequency of ventricular fibrillation (<5.2 Hz) was associated with a significantly lower defibrillation threshold compared to a high dominant frequency (10.5 J vs 13.2 J) in patients not taking class III anti-arrhythmic drugs.
Why the study?
Does the dominant frequency of induced ventricular fibrillation correlate with the defibrillation threshold and clinical characteristics in patients with ICDs?
Observational (n=72)
No
Does the dominant frequency of induced ventricular fibrillation correlate with the defibrillation threshold and clinical characteristics in patients with ICDs?
Absolute Event Rate: 10.5% vs 13.2%
p-value: p=0.026
The dominant frequency of human ventricular fibrillation is associated with right ventricular refractoriness, and a higher dominant frequency correlates with a higher defibrillation threshold.
May inform lower-energy defibrillation settings in ICD patients off class III agents; hypothesis-generating and requires prospective validation.
OBJECTIVE: The dominant frequency (DF) in frequency analyses is considered to represent the objective cycle length and complexity of activation under conditions of ventricular fibrillation (VF). However, knowledge regarding the mechanisms determining the DF in human VF is limited. We studied the characteristics of the DF of human VF and relationship between DF and the defibrillation threshold. METHODS: Seventy-two implantable cardioverter-defibrillator patients and 211 VF were studied. Using defibrillation tests, we performed a frequency analysis with fast Fourier transformation. The correlations between DF and clinical characteristics, including the defibrillation threshold, were assessed. RESULTS: The mean DF of all induced VFs was 5.2±0.8 Hz. The patients were divided into two groups according to DF: the low-DF (DF <5.2 Hz, n=32) and high-DF (DF ≥5.2 Hz, n=40) groups. The frequency of structural heart disease was significantly higher in the low-DF group. In addition, the QRS duration, QT interval and effective refractory period of the right ventricle (RV-ERP) were significantly longer in the low-DF group. A multivariate analysis showed RV-ERP to be the only independent predictor of DF. Excluding patients receiving group III anti-arrhythmic drugs, which are known to have potent defibrillation threshold effects, the defibrillation threshold was significantly lower in the low-DF group (p=0.026). CONCLUSION: We found that the DF of human VF is associated with underlying heart disease, the cardiac function, cardiac conduction, ventricular refractoriness and defibrillation threshold. Our findings may be useful for identifying and managing patients with a high defibrillation threshold.
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Iijima et al. (2015) conducted an observational in Ventricular Fibrillation in Patients with Implantable Cardioverter Defibrillators (n=72). Low dominant frequency of ventricular fibrillation (<5.2 Hz) vs. High dominant frequency of ventricular fibrillation (≥5.2 Hz) was evaluated on Defibrillation threshold (excluding patients on class III anti-arrhythmic drugs) (p=0.026). A low dominant frequency of ventricular fibrillation (<5.2 Hz) was associated with a significantly lower defibrillation threshold compared to a high dominant frequency (10.5 J vs 13.2 J) in patients not taking class III anti-arrhythmic drugs.
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