Circulation: Arrhythmia and Electrophysiology October 2019 Issue

Dr Paul Wang: Welcome to the monthly podcast, On the Beat for Circulation: Arrhythmia and Electrophysiology. I'm Dr Paul Wang, editor in chief, with some of the key highlights from this month's issue.

In our first paper, in a single‐center observational cohort study, Owen Donnellan and Associates compared arrhythmia recurrence rates in morbidly obese patients who underwent prior bariatric surgery, with those of non-obese patients following atrial fibrillation ablation. In addition to morbidly obese patients who did not undergo bariatric surgery, they matched 51 morbidly obese patients' body mass index, 40 kilograms per meter squared, who had undergone prior bariatric surgery in a two to one manner with 102 non-obese patients, and 102 morbidly obese patients without bariatric surgery on the basis of age, gender, and timing of atrial fibrillation ablation. From the time of bariatric surgery to ablation, bariatric surgery was associated with a significant reduction in BMI. 47.6 to 36.7 and reduction in systolic blood pressure, 145 to 118, P < 0.001.

During a mean follow up of 29 months following ablation, recurrent arrhythmia occurred in 10 out of 51 or 20 patients in a bariatric surgery group, compared to 25 out of 102 patients, 24.5% in a non-obese group, and 56 out of 102 or 55% in the non-bariatric surgery morbidly obese group. No procedural complications were observed in the bariatric surgery group. In our next paper, Martin Andreas and Associates examined whether noninvasive, low-level, transcutaneous electrical stimulation of the greater auricular nerve reduced the risk of postoperative atrial fibrillation, in a pilot of patients undergoing cardiac surgery. After cardiac surgery, electrodes were applied in the triangular fossa of the ear. Stimulation, amplitude 1-million-amp frequency, one Hertz for 40 minutes, followed by a 20-minute break, was performed for up to two weeks after cardiac surgery. Patients were randomized into sham, N equals 20 or treatment group, N equals 20, for low- level, transcutaneous electrical stimulation. Patients receiving low-level, transcutaneous stimulation had a significant reduced incidence of postoperative atrial fibrillation. Four out of 20, compared to controls 11 out of 20. P equals 0.02.

The median duration of postoperative atrial fibrillation was comparable between the treatment group and control group. No effect on low-level stimulation on CRP or IL-6 levels was detectable. In our next paper, Kazuki Iso and Associates examine whether the vagal response phenomenon is common to patients without atrial fibrillation. Continuous, high- frequent stimulation of the left atrial ganglion and plexus was performed in 42 patients, undergoing ablation for atrial fibrillation. In 21 patients undergoing ablation for left-sided accessory pathway, the high frequency stimulation, 20 Hertz at 25 milliamps of 10 millisecond pulse duration, was applied for five seconds at three sites within the presumed anatomical area of each of the five major left atrial ganglion plexus, for a total of 15 sites per patient. The authors define vagal response to high frequency stimulation, as prolongation of the R interval by > 50% in comparison to the mean pre-high-frequency stimulation RR interval, average over 10 beats.

In active ganglion plexus areas, is areas in which vagal response was elicited. Overall, more active ganglion plexi or GP areas were found in the atrial fibrillation group patients, than in the non-atrial fibrillation group patients. And in all five major GPS, the maximum R interval during high-frequency stimulation was significantly prolonged in atrial fibrillation patients. After multivariate adjustment, association was established between the total number of vagal response sites and the presence of atrial fibrillation. The authors concluded that the significant increase in vagal responses elicited in patients with atrial fibrillation, compared to responses in non-atrial fibrillation patients, suggests that the vagal responses is to hypercan stimulations, reflect an abnormally increased ganglion plexi activity, specific to atrial fibrillation substrates.

In our next paper, Vidal Essebag and Associates combine the data from the Bruise Control One and Two studies to evaluate the effect of concomitant antiplatelet therapy on clinically significant hematomas, and to understand the relative risk of clinically significant hematomas in patients treated with DOAC versus continued Warfarin. The Bruise Control study demonstrated that perioperative Warfarin continuation, reduced clinically- significant hematomas by 80%, compared to Heparin bridging. 3.5% versus 16%. Bruise Control Two observed a similarly low risk of clinically-significant hematomas when comparing continued versus interrupted direct oral anticoagulant. 2.1% in both groups. A total of 1,343 patients were included in Bruise Control One and Bruise Control Two, the primary out...