Circulation: Arrhythmia and Electrophysiology January 2020 Issue

Paul J. 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 the real time mapping of AF drivers RADAR study, Subbarao Choudry and associates examined in a single arm first in human investigator-initiated FDA IDE study, a novel system for real time, high resolution identification of atrial fibrillation, AF drivers, in persistent or long-standing persistent AF. They enrolled 64 subjects at four centers, 73% male age, 64.7 years, BMI 31.7. LA size 54. Longstanding AF, 83% longstanding persistent, 17%. prior AF ablation, 41%. After 12.6 months of follow-up, 68% remained AF free off all antiarrhythmics. 74% remained AF free and 66% remained AF, AT and A-flutter free on or off antiarrhythmic drugs. AF terminated with atrial fibrillation ablation in 35 patients, 55% overall. And in 23 out of 38, 61% of de novo ablation patients. For patients with AF termination during atrial ablation, 82% remained AF free and 74% AF, AT or A-flutter free during follow-up on or off antiarrhythmic drugs. Patients undergoing first time AFib ablation had higher rates of freedom from AF than the redo group.

In our next paper, David Briceño and associates examined 19 consecutive patients presenting with left bundle branch block ventricular tachycardia in the setting of arrhythmogenic right ventricular cardiomyopathy, ARVC, with procedures separated by at least nine months and a mean of 50 months. The authors found there was no significant progression of voltage bipolar 38 centimeters squared versus 53 centimeters squared, p=0.09 or unipolar 116 centimeters squared versus 159 centimeters squared, p=0.36 for the entire group. There was a significant increase in right ventricular RV volumes, percentage increase 28%. 206 milliliters versus 263 milliliters, P less than 0.001 for the entire study population. Larger scars at baseline but not changes over time were associated with a significant increase in RV volume, p=0.006 for bipolar and p=0.03 for unipolar.

Most patients with progressive RV dilatation, 57%, had moderate in two patients or severe in six patients, tricuspid regurgitation recorded either at initial or repeat ablation procedure. The authors found that in patients with ARVC presenting with recurrent ventricular tachycardia, more than 10% increase in right ventricular endocardial surface area of bipolar voltages consistent with scar is uncommon during intermediate follow-up. Most recurrent ventricular tachycardias are localized to regions of prior defined scar.

In our next paper, Susan Heckbert and associates examined detection of atrial fibrillation in 1,556 individuals participating in an ancillary study involving ambulatory ECG monitoring part of the cross-sectional analysis in the multiethnic study of atherosclerosis, MESA, a community based cohort study that enrolled 6,814 Americans free of clinically recognized cardiovascular disease in 2000 to 2002. Among 1,556 participants, 41% were white, 25% African American, 21% Hispanic, 14% Chinese, 51% were women mean age 74 years. The prevalence of clinically detected atrial fibrillation after 14.4 years follow-up was 11.3% in whites, 6.6% in African Americans, 7.8% in Hispanics and 9.9% in Chinese and was significantly lower in African Americans than in whites in both unadjusted and risk factor adjusted analyses, p less than 0.001. By contrast, in the same individuals, the proportion of monitor detected atrial fibrillation using a 14-day ambulatory ECG monitor was similar in the four race or ethnic groups. 7.1%, 6.4%, 6.9% and 5.2% compared with white, all p greater than 0.5.

The authors concluded that the prevalence of clinically detected atrial fibrillation was substantially lower in African Americans than white participants with or without adjustments for atrial fibrillation risk factors. However, unbiased atrial fibrillation detection by ambulatory monitoring the same individuals reveal little difference in the proportion with atrial fibrillation by race, ethnicity, supporting the hypothesis of differential detection by race, ethnicity in the clinical recognition of atrial fibrillation.

In our next paper, Maria Teresa Barrio-Lopez and associates examined the presence of epicardial connections between pulmonary veins and other anatomical structures. The authors considered an epicardial connection was present if one, the first pass around the pulmonary vein antrum did not produce pulmonary vein isolation. And two, subsequent atrial activation during pulmonary vein pacing showed that the earliest site was located away from the ablation line and later activation sites were obscured near the ablation line.

Out of the 534 patients included, 72 or 13.5%, were found to have 81 epicardial connections. There was a significant association between the presence of epicardial connections in structural heart disease, 15.3% in patients without epicardial connections versus 36.5% in patients with epicardial connections, p less than 0.001. In patent foramen ovale, 4.6% versus 13.5%, p=0.002. The presence of a left common trunk was significantly associated with the absence of epicardial connection. 29.6% in patients without epicardial connections versus 16.2% in patients with epicardial connections, p=0.014. Patients with epicardial connections had a lower acute success of pulmonary vein isolation compared to patients with epicardial connection, 99.1% versus 86.1%, p less than 0.001. After adjusting for age, sex, type of atrial fibrillation, left atrial area, hypertension, structural heart disease, presence of left common trunk, patent foramen ovale and time for atrial fibrillation and diagnosis to the ablation, the authors found a significantly higher risk of atrial tachyarrhythmia recurrences in patients with epicardial connections compared to patients without epicardial connections, hazard ratio 1.7, p=0.04.

In our next paper, Benzy Padanilam and associates examined the role of premature His complexes to differentiate AV nodal reentry tachycardia from atrioventricular reentry tachycardia high output pacing at the distal His location delivered premature His complexes. Atrioventricular reentrant tachycardia was predicted when late premature His complexes perturbed tachycardia or when early premature His complexes led to atrial advancement by amount equal or greater than the degree of premature His complex prematurity.

Among the 73 SVTs, the test accurately predicted atrioventricular reentry tachycardia, n=29 in AV nodal reentry tachycardia, n=44 in all cases. Late premature His complexes advanced the circuit in all 29 atrioventricular reentry tachycardias in none of the AV nodal reentry tachycardias, sensitivity and specificity 100%. With earlier premature His complexes, the degree of atrial advancement was equal or greater than the premature His complex prematurity in 26 out of 29 atrioventricular reentrant tachycardia and none of the AV nodal reentrant tachycardias, 90% sensitivity and a 100% specificity. The mean prematurity of the premature His complex required to perturb AV nodal reentry tachycardia was 48 milliseconds, range 28 to 70 milliseconds. And the advancement less than the prematurity of the premature His complex, mean 32 milliseconds range, 18 to 54 milliseconds.

In our next paper, Masateru Takigawa and associates examined the recurrence rate and mechanisms of atrial fibrillation ablation related atrial tachycardia recurrence among 147 patients with atrial tachycardias treated with arrhythmia system. 46.3% had recurrence at a mean of 4.2 months and 44 patients received a redo procedure. Atrial tachycardia circuits in the first procedure were compared to those in the redo procedure. Although mappable atrial tachycardias were not observed in seven patients, 68 atrial tachycardias were observed in 37 patients during the first procedure, perimitral flutter in 26 patients, roof-dependent macroreentrant atrial tachycardia in 18, peritricuspid flutter in 10, non-macro atrial tachycardia in 14 and focal atrial tachycardia in three. During the redo atrial tachycardia procedure, 54 atrial tachycardias were observed in 41 patients, perimitral flutter in 24, roof-dependent macroreentrant atrial tachycardia in 14, peritricuspid flutter in one, non-macroreentrant tachycardia in 14, and focal atrial tachycardia in one. Recurrence of perimitral flutter and roof-dependent macroreentrant atrial tachycardia were observed in 57.7% and 44.4% respectively, while peritricuspid flutter did not recur.

Either the same focal atrial tachycardia nor the same non-macroreentrant tachycardia were observed except in one case with septal scar related to biatrial tachycardia. Epicardial structure related to atrial tachycardia were involved in 18 out of 24 or 75% in perimitral flutter, in 28.6% in roof-dependent macroreentry atrial tachycardia, in 28.6% in non-macroreentry tachycardia. Out of the 21 patients with a circuit including epicardial structures, six patients treated with ethanol infusion in the vein of Marshall did not show any atrial tachycardia recurrence although 53.3% treated with radiofrequency showed atrial tachycardia recurrence, p=0.04.

In our next paper, Yaya Yu, Xuecheng Wang and associates compared the incidence and characteristics of ablation related asymptomatic cerebral emboli between high resolution diffusion weighted DWI and conventional DWI image. They examined 55 consecutive atrial fibrillation ablation patients undergoing high resolution DWI one day prior to ablation and repeated high resolution DWI and conventional DWI within 48 hours of post ablation. The authors found that high resolution DWI revealed a higher incidence of acute asymptomatic cerebral emboli compared to conventional DWI, 67.3% versus 41.8%, p less than 0.001. And significantly more asymptomatic cerebral emboli, 106 versus 45 lesions, p=0.001. For asymptomatic cerebral emboli, seen on both scans, the size measured by high resolution DWI was larger, 5.42 versus 4.21 millimeters, p less than 0.001. No patients had any impaired neurocognitive performance during follow-up. Impaired left ventricular ejection fraction, p=0.012 and low interoperative activated clotting time ACT p=0.009, level was associated with occurrence of asymptomatic cerebral emboli in a multivariate analysis.

In our next paper, Ahmed AlTurki and Mariam Marafi and associates performed a systematic review and meta-analysis to assess the risk of stroke, myocardial infarction and death following postoperative atrial fibrillation after non-cardiac surgery. The authors included 28 studies, enrolling 2,612,816 patients in their final analyses. At one month, in ten studies, postoperative atrial fibrillation with associated with approximately three-fold increased risk of stroke, odds ratio 2.82, p less than 0.001. Postoperative atrial fibrillation was associated with ≈4-fold increase in the long-term risk of stroke, odds ratio 4.12, p ≤ to 0.001. In eight studies with 12 months or greater follow-up, there was a significant increase in the risk of stroke and myocardial infarction associated with postoperative atrial fibrillation, odds ratio 3.44, p value, p less than 0.001. And odds ratio for myocardial infarction 4.02, p less than 0.001. Postoperative atrial fibrillation was associated with a threefold increase in all of cause mortality 30 days, 15.0% versus 5.4%, odds ratio 3.36.

In a research letter, Zhiyong Qian, Xiaofeng Hou, Yao Wang and associates validated physiological left bundle branch block pacing using high density ventricular mapping in a swine model.

In another research letter by Shinsuke Miyazaki and associates, the authors examined whether the durability of pulmonary vein isolation can be predicted by the time to isolation in second generation cryoballoon ablation.

That's it for this month. We hope that you will find the journal to be the go-to place for everyone interested in the field. See you next time.

This program is copyright American Heart Association 2020.