Hypothesis The investigators hypothesise that a model incorporating the novel predictors the 17-leads ECG, Oesophageal-ECG and SNPs performs significantly better than existing models using only clinical, echocardiographic and ECG parameters on a standard 12-lead ECG in predicting maintenance of SR after successful DCC. In addition the investigators hypothesise that Oesophageal-ECG is the best single predictor for maintenance of SR after successful DCC.