Key result
Noninvasive spectral-phase analysis of precordial ECGs during early ventricular fibrillation identified predictable activation sequences consistent with the arrhythmogenic substrate location.
Why the study?
Does spectral-phase analysis of the precordial ECG identify predictable activation patterns during induced ventricular fibrillation in patients with Brugada syndrome and ischemic cardiomyopathy?
Observational (n=30)
Does spectral-phase analysis of the precordial ECG identify predictable activation patterns during induced ventricular fibrillation in patients with Brugada syndrome and ischemic cardiomyopathy?
Noninvasive frequency-phase analysis of the precordial ECG during early ventricular fibrillation reveals predictable activation sequences that correlate with the anatomic location of the arrhythmogenic substrate.
May support noninvasive VF substrate mapping; leaves open prospective validation before clinical use.
BACKGROUND: Ventricular fibrillation (VF) has been proposed to be maintained by localized high-frequency sources. We tested whether spectral-phase analysis of the precordial ECG enabled identification of periodic activation patterns generated by such sources. METHODS AND RESULTS: Precordial ECGs were recorded from 15 ischemic cardiomyopathy and 15 Brugada syndrome (type 1 ECG) patients during induced VF and analyzed in the frequency-phase domain. Despite temporal variability, induced VF episodes lasting 19.6±7.9 s displayed distinctly high power at a common frequency (shared frequency, 5.7±1.1 Hz) in all leads about half of the time. In patients with Brugada syndrome, phase analysis of shared frequency showed a V1-V6 sequence as would be expected from patients displaying a type 1 ECG pattern (P<0.001). Hilbert-based phases confirmed that the most stable sequence over the whole VF duration was V1-V6. Analysis of shared frequency in ischemic cardiomyopathy patients with anteroseptal (n=4), apical (n=3), and inferolateral (n=4) myocardial infarction displayed a sequence starting at V1-V2, V3-V4, and V5-V6, respectively, consistent with an activation origin at the scar location (P=0.005). Sequences correlated with the Hilbert-based phase analysis (P<0.001). Posterior infarction (n=4) displayed no specific sequence. On paired comparison, phase sequences during monomorphic ventricular tachycardia correlated moderately with VF (P<0.001). Moreover, there was a dominant frequency gradient from precordial leads facing the scar region to the contralateral leads (5.8±0.8 versus 5.4±1.1 Hz; P=0.004). CONCLUSIONS: Noninvasive analysis of ventricular tachycardia and early VF in patients with Brugada syndrome and ischemic cardiomyopathy shows a predictable sequence in the frequency-phase domain, consistent with anatomic location of the arrhythmogenic substrate.
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Calvo et al. (2015) conducted an observational in Brugada syndrome and ischemic cardiomyopathy (n=30). Spectral-phase analysis of precordial ECG was evaluated on Predictable sequence in the frequency-phase domain consistent with anatomic location of the arrhythmogenic substrate (p=<0.001). Noninvasive spectral-phase analysis of precordial ECGs during early ventricular fibrillation identified predictable activation sequences consistent with the arrhythmogenic substrate location.
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