Circulation: Arrhythmia and Electrophysiology April 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, David Okada and associates assess the ability of a novel machine learning approach for quantifying 3D spatial complexity of gray scale patterns on late gadolinium-enhanced cardiac magnetic resonance images to predict ventricular arrhythmias in patients with ischemic cardiomyopathy.

 

They examined 122 consecutive ischemic cardiomyopathy patients with left ventricular ejection fraction of 35%, without prior history of reentrant ventricular arrhythmias. These patients underwent late gadolinium-enhanced cardiac magnetic resonance imaging. From raw gray scale data, the authors generated graphs encoding the 3D geometry of the left ventricle. They then assess the global regularity of signal intensity patterns using Fourier-like analysis and generated a substrate spatial complexity profile for each patient. A machine learning statistical algorithm was employed to discern which substrate spatial complexity profiles correlated with ventricular arrhythmic events. That is appropriate ICD firings and arrhythmic sudden cardiac death.

 

At five years of follow-up from the statistical machine learning results, a complexity score ranging from zero to one was calculated for each patient that was tested using multivariate Cox regression models. At five years of follow-up, 40 patients had ventricular arrhythmia events. The machine learning algorithm classified with overall 81% accuracy and correctly classified 86% of those without ventricular arrhythmia. Overall negative predictive value was 91%. Average complexity score was significantly higher in patients with ventricular arrhythmia events versus those without P<0.0001, and was independently associated with ventricular arrhythmia events in a multivariate model hazard ratio, 1.5 P=0.002.

 

In our next paper, Henry Chubb and associates examine the outcomes of cardiac resynchronization therapy studies in pediatric and or congenital heart disease patients using a propensity score match analysis. They examined 63 matched CRT control pairs. Heart transplant or death occurred in 12 subjects or 19% or 37 controls or 59% with a median follow-up of 2.7 years. Cardiac resynchronization therapy was associated with markedly reduced risk of heart transplant or death. Hazard ratio is 0.24 P<0.001. There were no CRT procedural mortality, and there was one systemic infection at 54 months post-implant.

 

In our next paper Pachon-M and associates examined whether AF nest ablation eliminates the atropine response and decreases RR variability suggesting that they're related to vagal innervation. The authors perform prospective control longitudinal randomized study enrolling 62 patients in two groups, AF nest group that is 32 patients with functional or reflex Bradyarrhythmias or vagal AF treated with AF Nest ablation and a control group, 30 patients with anomalous bundles, ventricular prematures, atrial flutter, AV nodal reentry and atrial tachycardias who were treated with a conventional ablation approach.

 

In the AF nest group, ablation was delivered at the AF nest detected by fragmentation or fractionation of the endocardial electrograms and by 3D anatomical location of the ganglionated plexus. Vagal response was evaluated before, during and post ablation by five seconds non-contact vagal stimulation at the jugular foramen through the internal jugular veins, analyzing 15 seconds mean heart rate, longest RR pauses and AV block. A pre-ablation non-contact vagal stimulation due sinus pauses, asystole, and transient AV block in both groups showing a strong vagal response.

 

Post-ablation non-contact vagal stimulation in the AF nest showed complete abolishment of the cardiac vagal response in all cases, P<0.0001, demonstrating robust vagal denervation. However, in the control group, vagal response remained practically unchanged post-ablation showing that non AF nest ablation promotes no significant denervation.

 

In our next paper, Domingo Uceda and Xiang-Yang Zhu and associates examined whether progressive increases in pericardial fat volume and inflammation, prospectively dampens the heart rate variability in hypercholesterolemic pigs. The author studied wild type or PCSK9 gain-of-function Ossabaw mini-pigs in-vivo before and after three and six months of a normal diet. Four in the wild type group and six in the PKSK9 group. Or high-fat diet, wild type three, in PCSK9, six.

 

At diet completion, they found that the hypercholesterolemic PCSK9 had significantly depressed heart rate variability, and both high fat diet groups had higher sympathovagal balance compared to the normal diet. P<0.05 versus baseline. Pericardial fat volumes, LDL conce