2 The procedure
2.1.1 Atrial fibrillation is the most common type of cardiac arrhythmia, and is caused by the irregular and rapid beating of the atria. It can be classified as paroxysmal, persistent or permanent, depending on episode duration and the patient's response to treatment. People with AF may be asymptomatic or they may have symptoms such as palpitations, dizziness, breathlessness and fatigue. Atrial fibrillation is associated with increased risk of death and of embolic stroke from atrial thrombus. Anticoagulation treatment is used to reduce this risk.
2.1.2 Antiarrhythmic medication is used either to help maintain a normal cardiac rhythm following successful cardioversion or to help reduce the heart rate. Ablation procedures can be used when drug therapy is either not tolerated or is ineffective.
2.2.1 The procedure is carried out with the patient under sedation or general anaesthesia. The pericardial space is accessed by a subxiphoid needle puncture under fluoroscopic guidance. A guidewire is introduced through the needle and a sheath is advanced over the guidewire so that the tip is placed inside the pericardial sac. The sheath is aspirated to check for bleeding. A radiofrequency catheter is inserted into the sheath. After electrophysiological mapping to determine target sites for ablation, radiofrequency energy pulses are applied to the epicardium.
2.2.2 During the procedure, catheter position is monitored with a three-dimensional mapping system to avoid collateral damage. Saline is placed in the pericardial space to reduce the risk of oesophageal injury, and steroids are administered to reduce the risk of pericarditis. Patients can have a combined procedure that includes electrophysiological mapping and ablation by both endocardial and epicardial approaches.
Sections 2.3 and 2.4 describe efficacy and safety outcomes which were available in the published literature and which the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the overview.
2.3.1 In a case series of five patients, all of them had percutaneous epicardial catheter radiofrequency ablation after failed endocardial ablation. Four patients were AF free and not on antiarrhythmic medication at 2-month, 6-month, 13-month and 15-month follow-up, respectively. The fifth patient was AF free but on antiarrhythmic medication at 4-month follow-up.
2.3.2 A case report of a patient with persistent AF (refractory to antiarrhythmic medication and with two previous failed electrical cardioversions) reported that the patient was symptom free at 1 month postoperatively.
2.3.3 One Specialist Adviser thought that the key efficacy outcome was freedom from AF. One Specialist Adviser commented that there was uncertainty about the efficacy of the procedure because of the small number of cases reported in the literature.
2.4.1 In the case series of five patients, one patient developed haemopericardium during the percutaneous epicardial puncture, which was successfully drained. In another patient, a tachycardia originating from the left inferior pulmonary vein was observed during the procedure but this was successfully terminated with delivery of further epicardial and endocardial radiofrequency pulses.
2.4.2 The Specialist Advisers considered that potential safety concerns included myocardial puncture; pericarditis; coronary artery damage; perforation of the right ventricle; damage to the oesophagus, bronchi and phrenic nerve; gastric puncture; and damage to abdominal vessels and organs when accessing the pericardial space. One Specialist Adviser considered there to be uncertainty about the long-term safety of the procedure.