Obesity is a major determinant of radiation dose in patients undergoing pulmonary vein isolation for atrial fibrillation.

OBJECTIVES: This study sought to evaluate the impact of obesity on patient radiation dose during atrial fibrillation (AF) ablation procedures under fluoroscopic guidance.
BACKGROUND: Obesity is a risk factor for AF and its recurrence after ablation. It increases patient radiation dose during fluoroscopic imaging, but this effect has not been quantified for AF ablation procedures.
METHODS: Effective radiation dose and lifetime attributable cancer risk were calculated from dose-area product (DAP) measurements in 85 patients undergoing AF ablation guided by biplane low-frequency pulsed fluoroscopy (3 frames/s). Three dose calculation methods were used (Monte Carlo simulation, dose conversion coefficients, and depth-profile dose curves).
RESULTS: Median DAP for all patients was 119.6 Gy x cm2 (range 13.9 to 446.3 Gy x cm2) for procedures with a median duration of 4 h and 83 +/- 26 min of fluoroscopy. Body mass index was a more important determinant of DAP than total fluoroscopy time (r = 0.74 vs. 0.37, p < 0.001), with mean DAP values per hour of fluoroscopy of 58 +/- 40 Gy x cm2, 110 +/- 43 Gy x cm2, and 184 +/- 79 Gy x cm2 in normal, overweight, and obese patients, respectively. The corresponding effective radiation doses for AF ablation procedures were 15.2 +/- 7.8 mSv, 26.7 +/- 11.6 mSv, and 39.0 +/- 15.2 mSv, respectively (Monte Carlo). Use of conversion coefficients resulted in higher effective dose estimates than other methods, particularly in obese patients. Mean attributable lifetime risk of all-cancer mortality was 0.060%, 0.100%, and 0.149%, depending on weight class.
CONCLUSIONS: Obese patients receive more than twice the effective radiation dose of normal-weight patients during AF ablation procedures. Obesity needs to be considered in the risk-benefit ratio of AF ablation and should prompt further measures to reduce radiation exposure.