Circulation: Arrhythmia and Electrophysiology On the Beat August 2017

Dr. 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. We'll also hear from Dr. Suraj Kapa, reporting on new research from the latest journal articles in the field.

This month's issue of Circulation: Arrhythmia and Electrophysiology has a number of fascinating and important articles. Let's start with the first article by Philip Halbfass and Associates, which describes the use of esophageal endoscopy in patients undergoing atrial fibrillation ablation. Of 1,802 patients undergoing afib ablation, 832 underwent post-procedural esophageal endoscopy. All patients were ablated using a single tip re-circular ablation catheter. Category one lesions described as erythema erosion were seen in 98 out of these 295 patients, while in 52 out of the 295 patients, ulceration was seen. In three of the 832 patients, esophageal perforation occurred, and in two of the 832 patients, atrial-esophageal fistula occurred.

Esophageal perforation only occurred in patients with category two lesions with an absolute risk of 9.6%. The authors concluded that post-ablation esophageal endoscopy is able to identify patients with high-risk lesions. One out of 10 patients with post-ablation esophageal ulcers progressed to perforation, while no patients without esophageal ulcers showed evidence of perforating complications.

In the next article by Christian Sohns and Associates describes the relationship between atrial fibrosis identified with magnetic resonance imaging and atrial rotor activity identified by noninvasive electrophysiological mapping. Ten patients underwent pulmonary vein isolation for persistent atrial fibrillation. Late gadolinium enhancement using magnetic resonance imaging, which projected onto the anatomy used for noninvasive electrophysiologic mapping.

The noninvasive electrophysiologic mapping identified 410 rotors evenly distributed between the left atrium and the right atrium. This study found that there was no statistically significant association between the presence of late gadolinium enhancement and the presence of rotors.

In the next article written by Jereon Venlet examines the endocardial unipolar voltage that best identifies abnormal epicardial electrograms. Thirty-three patients underwent endocardial epicardial right ventricular electro-anatomical mapping in ablation of right ventricular scar-related ventricular tachycardia. Eighty-six percent of abnormal epicardial electrograms had corresponding endocardial sites with bipolar electrogram less than 1.5 millivolts.

The remaining abnormal epicardial electrograms could be identified by endocardial unipolar voltages of less than 3.7 millivolts. The authors concluded that this use of endocardial unipolar voltage cut off at normal bipolar voltage sites improves the identification of all abnormal epicardial electrograms where there is less than 1 millimeter of fat.

The next article by Alan Bulava and Associates examines the outcomes of hybrid epicardial and endocardial radial frequency ablation, a persistent atrial fibrillation. Seventy patients underwent the epicardial thoracoscopic procedure followed by endocardial mapping ablation two to three months later. At the time of catheter ablation, 76% of patients were in sinus rhythm. All four pulmonary veins were found to be isolated in 69% of the patients and the left atrial posterior wall was isolated in 23% of the patients.

In the 12 months after the catheter ablation, 77% were arrhythmia-free, off antirrhythmic drugs. The majority of arrhythmia occurrences occur during the first 12 months following catheter ablation. Using previously ineffective antiarrythmics drugs and re-ablation procedures, arrhythmia-free survival increased to 97% during a mean followup of 936 days. Left atrial volume greater than 165 milliliters, the absence of sinus rhythm before catheter ablation and induce-ability of any sustained tachyarrhythmia at the end of catheter ablation predicted atrial fibrillation recurrence.

The authors concluded that the majority of patients after epicardial ablation required endocardial catheter ablation to complete the linear ablation or pulmonary vein isolation lesion sets. In the next article, Jason Roberts and Associates studied the clinical phenotype of Type 6 Long QT Syndrome, stemming from mutations in the KCNE2 encoded voltage gated channel beta subunit.

The authors examined individuals reported pathogenic KCNE2 mutations collected from inherited arrhythmia clinics in the Rochester LQTS registry as well as previously reported LQT6 cases identified through a med-line database search. Of 44 probands studied, 16 probands had resting QTC intervals and only developed QT prolongation and malignant arrhythmias following exposure to QT prolonging stressors. Ten had other Long QT pathogen...