Last Friday the US Food and Drug Administration (FDA) announced it had approved the first ablation catheters for the treatment of atrial fibrillation, one of the most common forms of arrhythmia or abnormal heart rhythms that affects millions of Americans.
Atrial fibrillation is where the upper chambers of the heart contract out of synch with each other, which apart from causing unpleasant symptoms such as palpitations and fainting, and in very severe cases congestive heart failure, it is also a major risk for stroke. The FDA has approved other ablation catheters to treat other types of arrythmia such as atrial flutter and ventricular tachyarrhythmia, but this is the first time the agency has approved them for atrial fibrillation.
The two types of ablation catheter that the FDA has approved are the the NaviStar ThermoCool saline irrigated radio-frequency ablation catheter and the EZ Steer ThermoCool Nav. These can be used to make strategically placed small scars in the tissue of the heart to stop electical waves that cause atrial fibrillation; a bit like inserting a permanently open circuit breaker in an electrical circuit.
Both catheters are made by BioSense Webster of Diamond Bar, California, a Johnson & Johnson company.
The approval has been granted because a clinical trial on 167 patients at 19 medical centers in the US, Brazil, Canada the Czech Republic and Italy showed that the two devices eliminated symptomatic recurrence of atrial fibrillation episodes for one year in about 63 per cent of the participants compared with only 17 per cent in a control group that only received anti-arrhythmic drug (AAD) therapy.
An FDA advisory panel unanimously recommended the two devices for approval when it met in November last year.
Dr Daniel G Schultz, director of the FDA’s Center for Devices and Radiological Health said the FDA approval gives doctors another option for treating this “common and potentially debilitating condition”.
Atrial fibrillation is usually treated with medication, and in severe cases, open heart surgery is also an option. Treatment with catheter ablation should only proceed when other options have failed to keep the symptoms under control, said the FDA.
Also, although atrial fibrillation is a major risk for stroke, there is no conclusive evidence that ablation reduces that risk, so the FDA said it agreed with the recommendations of the American College of Cardiology, the American Heart Association and the European Society of Cardiology, where patients at risk of stroke should continue to take blood thinners after having ablation for atrial fibrillation.
As part of the conditions for FDA approval, BioSense Webster must put in place a training program for doctors and carry out post-marketing studies to gather data on the long term safety and efffectiveness of the two devices. The studies must cover rates of stroke, death, cardiac arrest, major bleeding, and pulmonary vein stenosis (narrowing), plus the effect that doctors’ expertise in using the devices has on safety.
Dr Marcia S Yaross, Vice President for Clinical, Regulatory and Health Policy at BioSense Webster said the landmark FDA decision was a:
“Milestone for electrophysiologists, physicians who specialize in heart rhythm disorders, and their patients throughout the US.”
The approval recognizes the safety of these catheter ablation devices for the:
“Treatment of paroxysmal AFib [atrial fibrillation] and gives the medical community another treatment option for many patients whose often debilitating symptoms are not effectively managed through medical therapy,” she added.
In a press statement, the company said of the clinical trial:
“In this randomized clinical trial, catheter ablation was shown to significantly outperform anti-arrhythmic drug (AAD) therapy for the treatment of drug refractory recurrent symptomatic paroxysmal AFib. These data were first presented in November 2008 at the American Heart Association’s Annual Scientific Sessions.”
The EZ Steer ThermoCool Nav is a bi-directional verson of the NaviStar ThermoCool. Both catheters are compatible with 3-D mapping systems which recognize the CARTO system magnetic location sensors, said the company statement.
Atrial fibrillation is the most common form of arrhythmia, affecting between 2.3 and 5.6 million adults in the US. It is a leading cause of stroke among people over 65 years of age, and worldwide, although 10 million people have the condtion, it is thought that only about 80,000 are treated through ablation, said a statement from BioSense Webster.
According to the company, most patients are treated with anti-arrhythmic drug (AAD) therapy, but about half of them don’t respond well.
They describe cardiac ablation as a “standard of care for simple arrhythmias”, such as Wolff-Parkison-White Syndrome and atrioventricular nodal re-entry tachycardia (AVNRT), and say complex arrhythmias like ventricular tachycardia and atrial flutter are also increasingly being treated with cardiac ablation.
In 2006, the American Heart Association, the American College of Cardiology and the European Society of Cardiology recognized catheter ablation as second-line therapy for atrial fibrillation.
Click here for general information on atrial fibrillation (patient.co.uk).
Click here for FDA premarket approval information on the NaviStar ThermoCool.
Sources: FDA, BioSense Webster.
Written by: Catharine Paddock, PhD