Fluoroscopy times and radiation dose reduced in atrial fibrillation ablation with contact force-sensing technology


Geoffrey Lee
Geoffrey Lee

A real-world study published in Europace has found that the SmartTouch (Biosense Webster) contact force-sensing catheter coupled with an Advanced Catheter Location feature during atrial fibrillation (AF) ablation reduced fluoroscopy times by 77%, radiation dose by 71% and procedural time by 19%. However, the authors report that this technology does not improve overall safety or reduce the risk of cardiac complications compared to a control group.

A major limitation of AF ablation has been the high rate of AF recurrence and the inability to obtain enduring pulmonary vein isolation with the initial procedure, of which one of the major determinants is electrode-tissue contact during delivery of radiofrequency ablation. However, high contact force at the tissue catheter interface brings with it the risk of catheter perforation and acute tamponade. Operators have, until recently, had to rely on clinical experience and a combination of 3D mapping, electrogram characteristics and impedance changes during ablation and fluoroscopy to infer contact force.

According to the authors, led by Geoffrey Lee, St Bartholomew’s Hospital, London, UK, the SmartTouch contact force-sensing catheter “gives operators an objective measure of contact force and its direction of the myocardium. Meanwhile, the new Advanced Catheter Location feature of the Carto 3.1 software (Biosense Webster) allows a greater length of ablation catheter to be visualised and hence catheter orientation without fluoroscopy,” abilities which are “paramount to both the safety and success of this complex procedure,” the authors write. In this single-centre, retrospective cohort study, Lee and colleagues explored the potential of SmartTouch to reduce fluoroscopy times and radiation exposure during AF ablation.

Data were collected from 1,515 consecutive patients undergoing paroxysmal AF and persistent AF ablation at St Bartholomew’s Hospital between 2009 and 2014. Patients undergoing AF ablation with the SmartTouch catheter and the Advanced Catheter Location feature (SmartTouch group, n=510) were compared with those undergoing AF ablation without this technology (control group, n=1,005). The primary outcomes were total fluoroscopy time and fluoroscopy dose as measured by the dose-area product (mGycm2). Secondary endpoints included total procedure time, total ablation time, and major cardiac complications (tamponade, pericardial effusion, and urgent cardiac surgery).

Lee and colleagues report that the SmartTouch group had “significantly lower” median fluoroscopy times (9.5 vs. 41 minutes, p<0.001), radiation doses (1,044 vs. 3,571 mGycm2, p<0.001), and shorter overall procedural time (195 vs. 240 minutes, p<0.001) when compared with the control group. This was statistically significant for both paroxysmal AF and persistent AF ablation and for both de novo and redo AF procedures. After an initial learning curve, a median fluoroscopy time of 3.5 minutes (interquartile range 6) for all AF ablations was achieved.

There was no difference in the rate of cardiac complications (∼1.5%) between the control and SmartTouch groups. Cardiac tamponade rate was ∼1% in both groups and remained stable in the study period, while all pericardial effusions diagnosed on post-procedural transthoracic echocardiogram were “incidental findings in asymptomatic patients and therefore managed conservatively,” Lee et al write. “The risk of cardiac tamponade remained unchanged despite the introduction of this technology,” the authors continue, “although clearly the event rate is very low, which would make detection of a small decrease difficult.”

Lee told Cardiac Rhythm News that the main reason why contact force-sensing technology has not resulted in a decrease in cardiac perforation and tamponade rates is because” these complications are relatively uncommon in highly experienced ablation centres and a large number of cases would be needed to show a statistically significant decrease in the rates of these complications.”