Radiation exposure in supraventricular tachycardia ablation reduced with minimally fluoroscopic mapping system


Radiofrequency ablation of supraventricular tachycardia guided by the non-fluoroscopic Ensite NavX mapping system (St Jude Medical) has shown lower levels of ionising radiation exposure for the patient and for the operator compared with conventional catheter ablation, according to preliminary results from the NO-PARTY Italian trial.

Michela Casella, Cardiac Arrhythmia Research Centre, Department of Cardiovascular Medicine, Centro Cardiologico Monzino, Milan, Italy, reported preliminary results of the NO-PARTY trial at Venice Arrrhythmias (27–29 October, Venice, Italy).

“Conventional radiofrequency catheter ablation requires the use of fluoroscopy, thus exposing patients and medical staff to ionising radiation,” said Casella. “The NO-PARTY trial aimed to test whether catheter ablation of supraventricular tachyarrhythmias guided by the Ensite NavX mapping system results in a clinically significant reduction in exposure to ionising radiation for the patient and for the operator compared with conventional catheter ablation.”

This multicentre, randomised trial enrolled 262 consecutive patients (mean age 35+11 years, 110 males) with supraventricular tachycardia in six centres in Italy. They underwent radiofrequency catheter ablation to either a conventional ablation technique (128 patients) or with the Ensite NavX mapping system (134 patients). The two groups were comparable in terms of age, sex and arrhythmia characteristics.

Casella told delegates: “The trial found that radiofrequency ablation was successful in all patients and without complications.” The two approaches were not different with regards to procedural times. “In the non-fluoroscopic approach, fluoroscopy was completely left out in 72% of patients, therefore there was a significant time reduction in fluoroscopy time for the non-fluoroscopic approach (162±161 seconds) compared with the conventional approach group (1042±782 seconds),” said Casella. “In the 28% (38 cases) that required some fluoroscopy, the mean fluoroscopy time was 162.2±160.4 seconds (range: 4–569 seconds). In these 38 patients, fluoroscopy was needed in a total of 42 occurrences to check guidewires, to cannulate the coronary sinus, to check catheter stability during radiofrequency delivery, to confirm catheter location or to perform transseptal puncture. In 5% (2 cases) the minimally fluoroscopic procedure was shifted to a conventional procedure because of technical problems with the mapping system. Both procedures were included in the final analysis in an intention-to-treat analysis,” explained Casella.

The results also showed, according to Casella, that the dose area product (DAP) was also higher in the conventional group compared with the non-fluoroscopic group (6138±11637 cGycm2 and 261±1167 cGycm2, respectively).

Importantly, “lower levels of radiation exposure have a clinical benefit reducing the incidence of lifetime attributable risk of cancer for the patient,” said Casella. “In our patient population (average age 35 years) the lifetime risk of developing cancer due to the radiation use during the procedure was 494/100,000 for women and 699/100,000 for men in the conventional approach compared with 6.6/100,000 for women and 9.3/100,000 for men in the non-fluoroscopic approach.” Moreover, “the risk of death for that cancer is 75 times greater with the conventional approach compared with the non-fluoroscopic approach [Conventional approach: 220/100,000 for women and 300/100,000 for men; non-fluoroscopic approach: 2.9/100,000 for women and 4/100,000 for men],” she added.

Casella concluded: “A minimally fluoroscopic approach allows a significant reduction in radiation exposure for both patient and medical staff and therefore a significant reduction of life-time cancer risk incidence and mortality.”

She also said that it is necessary to determine the real cost of the non-fluoroscopy approach with a definitive cost/effectiveness analysis in order to better identify patients to recommend this approach.