Ventricular Fibrillation in a General Population - A National Database Study

BACKGROUND

Ventricular fibrillation (VF) is a life-threatening disease that can be remedied by prompt defibrillation. However, data regarding such risk in a general population remain limited. This general population study was to explore the epidemiological profile of VF.Methods and Results:We investigated patients with VF younger than 60 years (average population, 19,725,031) using a national database spanning the period 2000-2010. We identified 3,971 (68.4% male) patients with VF (crude incidence rate: 1.83/100,000). Incidence rates were low in patients younger than 10 years and increased steadily after adolescence. Comorbidities were noted in 2,766 (69.7%) patients, with 2,431 (61%) having cardiac diseases. Over half of the adolescent and young adult patients did not have comorbidities. Among the 838 deaths (mortality rate 21.1%), approximately half (381/838, 45.5%) occurred after arrival at emergency services (ES). The proportion of deaths after arrival at ES relative to total deaths increased sharply to a peak in the 15-19-years age group and thereafter remained stationary.

CONCLUSIONS

VF patients, with a male dominance, increased after adolescence and were likely to die at presentation to ES. Approximately half of young adults, with high mortality, did not have comorbidities, suggesting underdiagnosis of underlying primary electrical diseases and the need for implementing automated external defibrillator programs. (Circ J 2016; 80: 2310-2316).

The Relationship Between Cardiac Vulnerability and Restitution Properties of the Ventricular Activation Recovery Interval

INTRODUCTION

The restitution of the action potential duration (APD) is an important contributor to ventricular fibrillation (VF) initiation by a single critically timed ectopic beat. We hypothesized that a steep slope of the activation recovery interval restitution curve was related to the upper limit of vulnerability (ULV).

METHODS AND RESULTS

Fifty-four consecutive patients with implantable cardioverter defibrillators (ICDs) implanted between April 2012 and July 2013 were included. At the implantation, pacing from the right ventricular (RV) coil to an indifferent electrode inserted in the ICD pocket was performed, and the unipolar electrograms from the RV coil were simultaneously recorded. We assessed the standard restitution by introducing extra-stimuli, while measuring the activation recovery interval (ARI). Our protocol for the vulnerability test consisted of delivering three 15 J shocks on the T-peak and within ±20 milliseconds of it. If VF was not induced by that procedure, a ULV of ≤15 J was defined. The relationship between the ULV and maximum slope of the restitution curve was analyzed. A restitution curve could finally be obtained in a total of 40 patients. The background characteristics were similar between the two groups. The maximum slope of the restitution curve was steeper in the ULV > 15 J group than ULV ≤ 15 J group (1.55 ± 0.45 vs. 0.91 ± 0.64, P < 0.05). A maximum slope exceeding 1.0 was the optimal point for discriminating patients with a ULV > 15 J from a ULV ≤ 15 J (sensitivity 61.5% and specificity 96.3%).

CONCLUSION

The maximum slope of the restitution curve was significantly related to the ULV. High defibrillation threshold patients could be detected by the ARI dynamics.