Atrial fibrillation : prediction of successful cardioversion
Aim: Despite atrial fibrillation being the most commonly occurring sustained cardiac arrhythmia its treatment remains the subject of great debate. DC cardioversion is a treatment option often used to return normal cardiac function. We aimed to assess relapse rates following DC cardioversion and to determine whether transoesophageal echocardiography, P wave signal averaged electrocardiography or heart rate variability measurements had a role in identifying patients likely to relapse to atrial fibrillation. Methods: Patients who were referred for DC cardioversion of chronic non-valvular atrial fibrillation were enrolled into the study. Transoesophageal echocardiography was performed in order to measure left atrial size, left atrial appendage area, and flow velocity within the left atrial appendage, left upper pulmonary vein and across the mitral valve. Patients in whom cardiac thrombus had been excluded proceeded to DC cardioversion. Those patients who achieved sinus rhythm had ap wave signal averaged electrocardiogram recorded one hour following the procedure. At forty eight hours those patients remaining in sinus rhythm had a second p wave signal averaged ECG recorded and a Holter recording in order to determine heart rate variability. Patients were reviewed at three and six months for relapse to atrial fibrillation. Results: DC cardioversion was initially successful in 66 of the 81 patients (8 1 %). At 48 hours 23 patients (35%) had relapsed to AF. No PSAECG measurement differed significantly between these groups. Mean mitral valve flow velocity differed significantly between those who relapsed to AF within 48 hours and those who remained in sinus rhythm (SR group = 83.98cm/s, AF group 71.05cm/s, p=0.048). At three months 48 patients had relapsed to AF (73%) this increased to 51 patients (77%) at six months. No significant difference was observed in any of the TOE, PSAECG or HRV measurements in these groups. Conclusion: No PSAECG or HRV variable helped to predict long term success. TOE measurement of mitral valve flow velocity may allow prediction of early relapse. DC cardioversion without antiarrhythmic prophylaxis leads to a high relapse rate.