Current Treatment Options for Atrial Fibrillation

Current Treatment Options for Atrial Fibrillation

Most atrial fibrillation treatments are palliative and do not cure atrial fibrillation. The most common are anti-arrhythmic and anticoagulant drugs. However, anti-arrhythmic drug therapy often becomes less effective over time, with approximately half of the patients developing resistance to the drugs. In addition, anti-arrhythmic drugs have potentially severe side effects, including pulmonary fibrosis, impaired liver function, thyroid problems and the development of worse and even life-threatening ventricular arrhythmias.

Cox-Maze Open Heart Procedure – High Success Rate, but Very Invasive Procedure

One highly effective, curative therapy for atrial fibrillation used today is an open-heart operation commonly known as the surgical “Cox-Maze” procedure, which has reported success rates as high as 96%. During this open heart procedure, the physician uses a scalpel to make a series of cuts in a specific “maze-like” formation along the inside walls of the left atrium, and then sutures these cuts back together. The scars create an uninterrupted conduction block containing the chaotic electrical impulses that cause atrial fibrillation, thereby returning the heart to a normal rhythm. The open-heart Cox-Maze procedure is usually done in tandem with another open-heart procedure, such as a valve replacement or coronary artery bypass, because this operation is traumatic to the patient, very expensive, and typically associated with long hospital stays and a three to six month recovery time.

Catheter-based Cardiac Ablation Procedure – Much Less Invasive Procedure, but Low Success Rate

The medical community has worked for years to develop a minimally invasive approach that generates comparable clinical outcomes to the Cox-Maze method. The current minimally invasive approach is performed in the Electrophysiology (EP) Lab where the physician relies upon fluoroscopic imaging to guide a catheter through a blood vessel into the left atrium of the heart. The physician then delivers radiofrequency (RF) energy through the catheter to create lines of lesions and ultimately scar tissue that will block abnormal electrical impulses from being conducted through the heart. Success rates using this minimally invasive technique are significantly lower than for the open-heart Cox-Maze method, as low as 50-75% in some studies. 

What is Needed: A Minimally-Invasive Procedure with a High Success Rate

During the current minimally invasive catheter-based ablation procedure, the physician uses fluoroscopic imaging to guide the positioning of the catheter in the heart. However, fluoroscopic imaging has significant limitations. It does not permit the physician to see the cardiac anatomy and tissue, the location of the catheter in relation to the cardiac tissue, or the intraprocedural creation of the lesions for the conduction block. Furthermore, the use of fluoroscopy exposes both patient and physician to x-ray radiation for an extended period of time.

To achieve the high success rate of the Cox-Maze procedure without a highly invasive open-chest surgery, physicians need to be able to view cardiac tissue in real-time, differentiate between healthy and unhealthy tissue, see the location of the catheter relative to the cardiac tissue and see the lesions as they are made. Unlike the imaging modalities used in the current catheter-based approach, an MRI-based procedure, such as one performed with the ClearTrace® system, will allow the physician to visualize a patient’s cardiac tissue. With this capability, a physician can, for example, distinguish healthy cardiac tissue from fibrotic tissue and see gaps in the lesion lines. MRI can also enable visualization of the ablation lesions created during the procedure. The unique soft tissue visualization and assessment capabilities of MRI make it a superior imaging modality for cardiac interventions. And unlike fluoroscopy, MRI does not expose patients or physicians to radiation. For these reasons, an MRI-guided approach may hold the answers to achieving a success rate similar to the Cox-Maze approach through a minimally invasive catheter-based procedure.