Catheter Ablation
Catheter ablation continues to be one of the more popular curative treatment options for atrial fibrillation, and in some cases it may be the appropriate procedure. However, success rates for catheter ablation are significantly below those seen in studies of the five-box thoracoscopic maze procedure for patients with advanced forms of AF.
In the heirarchy of atrial fibrillation treatment, there are two categories of procedures designed to cure atrial fibrillation: catheter-based (or percutaneous), and surgical (or epicardial). As indicated below, because of several challenges involved in catheter-based therapies, surgical treatment may provide a better outcome for many patient groups.
What Is Catheter Ablation?
This technique uses a catheter – a long, thin, flexible tube – that is inserted into a blood vessel in the patient's arm, groin (upper thigh), or neck and guided to the heart through the blood vessel. Radio frequency energy is transmitted through the catheter to re-shape the heart tissue so that the electrical signals which cause the heartbeat can be conducted normally.
The procedure is guided by indirect imaging techniques, such as fluoroscopy and echocardiography, and by direct sensing of abnormal signals in the atrial muscle. The procedure uses multiple point ablations to isolate known arrhythmia-generating areas of the heart, and to target focal zones of abnormal stimuli elsewhere in the atria.
Challenges of This Technique
In attempting to create linear blocking lesions to isolate arrhythmia-generating areas, many point ablations are necessary. The difficulty lies in ensuring that a continuous line is created from many discrete points, in order to prevent electrical leaks. This problem is worsened by the availability of only indirect imaging to guide the ablations. Moreover, verification of successful electrical signal block across these supposedly continuous lines is hampered by the phenomenon of tissue stunning, or temporary loss of conductivity, which recovers within weeks, thereby negating the benefit of the procedure.1, 2 In fact, in all patients who had previously undergone even two failed catheter ablation and then were referred for a five-box thoracoscopic maze procedure, failure of true pulmonary vein isolation has been confirmed by baseline conduction studies performed at the beginning of the operation.
This inconsistency of catheter ablation in achieving basic technical goals impacts on the results of the procedure. A recent study employing rigorous follow-up show that catheter ablation succeeded in long-term restoration of sinus rhythm without anti-arrhythmia drugs in only 34% of patients.3 A second study of only paroxysmal AF patients, who are relatively easy to cure, resulted in long-term success in only 57%, with a serious complication rate of 12%.4 This compares to the 95% published effectiveness of the five-box thoracoscopic maze in curing longstanding persistent atrial fibrillation, the most difficult group of patients to treat.5
More Information
For more details about atrial fibrillation treatments, including the five-box thoracoscopic maze procedure, request a phone consultation with Dr. John Sirak or call his appointment phone at (614) 366-7414.
1. Cheema A, et al. Incidence and Time Course of Early Recovery of Pulmonary Vein Conduction after Catheter Ablation of Atrial Fibrillation. J Cardiovasc Electrophysiol 2007;18(4):387-391.
2. Rostok T, et al. Characterization of Conduction Recovery Across Left Atrial Linear Lesions in Patients with Paroxysmal and Persistent Atrial Fibrillation. J Cardiovasc Electrophysiol 2006;17(10):1106-11.
3. Packer D, et al. CABANA Pilot Study. Presentation at the American College of Cardiology Meeting, Atlanta, 15 March 2010.
4. Packer D, et al. STOP-AF Pilot Study. Presentation at the American College of Cardiology Meeting, Atlanta, 15 March 2010.
5. Sirak J. The Five-Box Thoracoscopic Maze Procedure. Ann Thorac Surg, manuscript in press.