Clinical application of the fibrillation number in patients with an implantable cardioverter defibrillator

Introduction: Although ventricular tachycardia/fibrillation (VT/VF) develops suddenly with catastrophic results, its prediction is limited. We tested the fibrillation number (FibN) for potential predictor of VT/VF using clinical data of implantable cardioverter-defibrillator (ICD) patients after validating the number by computational modeling. Methods: For clinical application of FibN, we used electrocardiography and echocardiography data: QRS width, QTc, and left ventricular (LV) end-systolic dimension (FibN_VT/VF1) or LV end-diastolic dimension (FibN_VT/VF2). We compared the maintenance duration of VT/VF for various FibN values using computational modeling, and tested FibN_VT/VF in 142 patients with ICD for secondary prevention and 426 patients in age-sex matched control group (81.9% male, 56.1±12.3 years old). Results: 1. Computational results showed a positive correlation between VT/VF maintenance duration and FibN (R=0.82, p<0.001). 2. FibN_VT/VFs were significantly higher in patients with ICD than in control (both FibN_VT/VF1 and FibN_VT/VF2, p<0.001). 3. Within ICD group, FibN_VT/VF values were higher in patients with cardiomyopathy than those without (both FibN_VT/VF1 and FibN_VT/VF2, p<0.001). 4. During 50±39 months follow-up period, the frequency of appropriate ICD therapy was higher in the high FibN_VT/VF group (FibN_VT/VF1, p=0.001; FibN_VT/VF2, p=0.002). Both FibN_VT/VF1 (HR 2.51, 95%CI 1.48-4.24, p=0.001) and FibN_VT/VF2 (HR 2.11, 95%CI 1.25-3.55, p=0.005) were independently associated with appropriate ICD therapy in multi-variate analyses. Conclusion: FibN_VT/VF, a parameter based on wavelength and heart size, correlates well with maintenance of VT/VF in computational modeling, and may have predictive value for VT/VF events in patients with ICD for secondary prevention.