**4. Non pharmacological therapy**

When pharmacological intervention is unsuccessful or contraindicated in patients, nonpharmacological therapy may be attempted. These include synchronised electrical cardioversion, catheter based ablation techniques or surgical intervention.25,26,27. Directcurrent cardioversion differs from defibrillation whereby the shock is synchronised to the R wave in the patient's ECG. The patient must be adequately anticoagulated during electrical cardioversion in order to prevent disruption of a pre-existing intra cardiac thrombus which will cause it to embolize to the brain or systemic circulation. The risks of electrical cardioversion include hypotension, bradycardia, pulmonary oedema, systemic embolization, skin burns and ventricular arrhythmias.28 Risks of emboli range from 0.5% to 3% and is further multiplied in patients who experience recurrence and treated with serial cardioversions.29,30

Catheter based ablation techniques were initially developed following Cox's pioneering work with the Maze procedure. These techniques were further influenced by research that demonstrated ectopic foci surrounding pulmonary veins. Isolation of the pulmonary veins remains the cornerstone of most AF catheter ablation procedures. Following heparinization, a percutaneous catheter placed into the femoral vein is advanced to the right atrium. The left atrium is accessed via an interatrial septal puncture. Lesions are created around the pulmonary veins using cryoenergy or radio-frequency energy. These techniques have shown a higher success in treating patients with paroxysmal AF compared to those with enlarged left atrium and persistent or permanent AF.31,32 Complications of catheter ablation include cardiac tamponade, atrioesophageal fistula and stroke33
