Aims: To develop a simple point score system that can accurately predict the optimal energy of initial rectilinear biphasic (RLB) waveform shock for cardioversion (DC) of persistent atrial fibrillation (AF).
Methods and results: Data from 302 consecutive patients with AF who underwent a step-up protocol of sequential shocks of 50 J-from 1 up to 2 J/kg-200 J of RLB waveform DC were prospectively examined. Using a logistic regression model, three variables independently predicted the need for 2 J/kg shocks: AF duration > 7 months, previous DC, and increased left atrial (LA) diameter > 4.5 cm. A simplified point score system (REBICAF score) that spans from 0 to 4 was developed. The score gives two points for AF duration > 7 months and one point for previous DC or LA diameter > 4.5 cm. The area under the receiver operator curve (ROC) of the proposed score for predicting the need for 2 J/kg shock was 0.84. There was a progressive increase in the need for 1 J/kg, 2 J/kg, and 200 J as the point score increased (P < 0.001, chi2 test for trend). More than 90% cumulative success rate was achieved in the low- (0-1), intermediate- (2), and high-REBICAF (3-4) score subgroups with 1 J/kg, 2 J/kg, and 200 J RLB shocks, respectively.
Conclusion: A simple point score system is useful in prediction of successful initial RLB energy for DC of AF.