Contact-Force-Sensing Technology Noninferior to Existing Technology, Hints at Better Outcomes

June 18, 2014

NICE, FRANCE — A catheter technology that senses contact force between the catheter and atrium during the ablation procedure appears to be on par with conventional ablation technology for the treatment of atrial fibrillation. In a new study, investigators reported that the TactiCath contact-force–sensing ablation catheter (St Jude Medical) met the noninferiority end point for safety and efficacy when compared with a standard ablation catheter.

Results from the study also suggest that achieving an optimal level of contact force during the catheter ablation of atrial fibrillation results in improved outcomes compared with patients who did not receive lesions with protocol-defined optimal ablation contact[1].

"We've known for a long time that for radiofrequency to create any sort of effective tissue heating, the electrode delivering the current has to be in contact with the tissue," lead investigator Dr Dipen Shah (University of Geneva, Switzerland) told heartwire . "We always assume that a good contact is a prerequisite, but we did not have any way to actually measure it when we were using our catheters in the body. This technology was developed to recognize when the catheter was in contact with the tissue and to optimize lesion effectiveness and safety."

In addition to helping physicians determine optimal contact with the tissue for effective ablation, the technology was also designed to help reduce the risks of the procedure, said Shah. "You can understand that if you have too much contact you might endanger the integrity of the wall," he added.

The results of TOCCASTAR were presented today here at CardioStim 2014 . The study, a randomized, multicenter, noninferiority trial, included 300 patients with paroxysmal atrial fibrillation treated with the TactiCath contact-force radiofrequency ablation catheter or the Navistar Thermocool ablation catheter (Biosense Webster). The study was conducted at 17 European and US sites and included 47 operators.

Regarding the primary effectiveness end point—defined as freedom from off-drug symptomatic recurrence of atrial arrhythmia lasting more than 30 seconds—the two catheters were equivalent. In total, 67.8% of the TactiCath-treated patients and 69.4% of the Thermocool-treated patients were free from atrial arrhythmia recurrence at 12 months. In terms of safety, the TactiCath ablation catheter was noninferior to the Thermocool technology. For those treated with the contact-force technology, there was one case of cardiac perforation/tamponade and two cases of pericarditis.

Shah told heartwire that TOCCASTAR was conducted as part of the US Food and Drug Administration (FDA) premarket approval (PMA) application. Based on the FDA rules, the company was required to show that the technology was noninferior to already-approved, standard technology, which it has done.

As part of the trial, the investigators conducted a prespecified analysis looking at the impact of contact force in the TactiCath cohort. As part of the study protocol, physicians were not required to achieve a specific amount of contact force during the ablation procedure, but "optimal" contact force is defined as 10 to 40 g of pressure. Beyond 60 g of force there is a risk of too much ablation, while less than 5 g is negligible in terms of achieving an adequate lesion.

Of the 145 patients treated with the TactiCath contact-force–sensing catheter, 57% received an optimal amount of contact while 43% fell outside the optimal range. In terms of the primary end point, 76% of patients who received optimal contact during the ablation procedure were free from an arrhythmia recurrence at 12 months compared with 58% of those who received inadequate contact, a statistically significant difference.

"The underlying message is that when you achieve the optimal contact-force parameters, then you get results that are better than those without the optimal parameters and without the technology as well," said Shah.

The TactiCath irrigated contact-force–sensing catheter received CE Mark approval in 2009. The second-generation TactiCath Quartz catheter—which included a new force sensor for added stability and precision—obtained CE Mark approval in 2012.

Shah reports serving as a consultant to Endosense, the developers of the TactiCath. St Jude Medical purchased Endosense in 2013.

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