Circulation: Arrhythmia and Electrophysiology September 2019 Issue

Circulation: Arrhythmia and Electrophysiology On the Beat

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.

In our first paper, Ying Tian and associates examine the effects and long-term outcomes of percutaneous stellate ganglion blockade in the setting of drug refractory electrical storm due to ventricular arrhythmia. They studied 30 consecutive patients over nearly a five-year period. They used bupivacaine alone, or in combination with lidocaine injected into the neck with good local anesthetic spread in the vicinity of the left stellate ganglion in 15 patients, or both stellate ganglion in 15 patients.

The mean left ventricular ejection fraction was 34%. At 24 hours, 60% of patients were free of ventricular arrhythmia. Patients whose ventricular arrhythmia was controlled had a lower hospital mortality rate than patients whose ventricular arrhythmia continued. 5.6 versus 50%, P equals 0.009. Implantable cardioverter-defibrillator interrogation showed a significant 92% reduction in ventricular arrhythmia episodes from 26 to 2 in the 72 hours after stellate ganglion blockade, P less than 0.001.

Patients who died during the same hospitalization, N equals 7, were more likely to have ischemic cardiomyopathy, 100% versus 43.5%. And recurrent ventricular arrhythmias within 24 hours, 85.7% versus 26.1%. There were no procedure related complications.

In our next paper, Zachi Attia and associates hypothesized that a convolutional neural network could be trained through a process called 'deep learning' to predict a person's age and gender using only 12-lead electrocardiogram signals. They trained convolutional neural network using 10 second samples of 12-lead ECG signals from 499,727 patients to predict gender and age. The networks were tested on a separate cohort of 275,056 patients. For gender classification, the model obtained 90.4% classification accuracy with an area under the curve of 0.97. In the independent test data, age was estimated as a continuous variable with an average error of 6.9 years, R squared equals 0.7.

Among 100 hundred patients with multiple ECGs over the course of at least two decades of life, most patients, 51%, had an average error between real age and convolutional neural network predicted age of less than seven years. Major factors seen amongst patients with convolutional neural network predicted age that exceeded chronologic age by greater than seven years included low ejection fraction, hypertension, and coronary disease, P less than 0.1. In the 27% of patients whose correlation was greater than 0.8, between convolutional neural network predicted and chronological age, no incident events occurred over follow up 30 years.

The authors concluded that applying artificial intelligence to the ECG allows prediction of patient, gender, and estimation of age. The ability of artificial intelligent algorithm to determine physiological age with further validation may serve as a measure of overall health.

In our next paper, Zain Ul Abideen Asad and associates performed a meta-analysis of randomized control trials in order to compare the efficacy and safety of catheter ablation with medical therapy for atrial fibrillation with the primary outcome being all-cause mortality. They examined 18 randomized controlled trials comprising 4,464 patients. Catheter ablation resulted in significant reduction in all-cause mortality, relative risk of 0.69 that was driven by patients with atrial fibrillation and heart failure in reduced ejection fraction, relative risk 0.52.

Catheter ablation resulted in significantly fewer cardiovascular hospitalizations, hazard ratio of 0.56, and fewer recurrences of atrial arrhythmia, relative risk 0.42. Subgroup analysis suggested that younger patients, age less than 65 years, and men derived more benefit from catheter ablation compared to medical therapy.

In our next paper, Felipe Kazmirczak, Ko-Hsuan Amy Chen, and associates examined patients with cardiac sarcoidosis meeting guideline criteria for implantable defibrillator implantation in a large retrospective cohort study of patients with biopsy proven sarcoidosis and known or suspected cardiac sarcoidosis undergoing cardiovascular magnetic resonance imaging. The authors found that in 290 patients, the class one and class 2A recommendation identified all patients who experienced a composite endpoint of significant ventricular arrhythmia or sudden cardiac death over a mean follow-up of three years.

Patients meeting class one recommendations had a significantly higher incidence of composite endpoint than those meeting class 2A recommendations. Left ventricular ejection fraction greater than 35% with greater than 5.7% late gadolinium enhancement and cardiovascular negative residence imaging was as sensitive as or significantly more specific than left trigger ejection frack greater than 35% with any late gadolinium enhancement. Patients meeting two class 2A recommendations left ventricular ejection fraction greater than 35% would need for a pacemaker, and left ventricle rejection at greater than 35% with late gadolinium enhancement. Greater than 5.7% had high annualized event rates. Excluding two class 2A recommendations, left ventricular ejection fraction greater than 35% with syncope, and left ventricular ejection fraction greater than 35% with inducible ventricular [inaudible] resulted in improved discrimination for the composite endpoint.

In our next paper, Kenji Okubo, Antonio Frontera, and associates examined the ability of a new grid mapping catheter for performing substrate and ventricular tachycardia activation mapping during ventricular tachycardia ablation procedures, identifying the low voltage areas and visualizing diastolic pathways. The authors studied 41 consecutive patients undergoing ventricular tachycardia ablation procedure. The grid mapping catheter was used to create three different maps with three bipolar configurations along the spine, across the spine, high density wave solution.

The median low voltage area drawn by the high-density wave configuration was 28.9 centimeters squared, but it was 13% and 15% smaller with a low voltage area identified by along and across. The late potential areas identified by the three configurations did not differ. Ventricular tachycardia activation mapping visualizes the full diastolic pathway in 22 out of 40, or 55%. The authors found that identifying the full diastolic pathway led to a higher ongoing VT termination rate during the ablation than in the case of partial recordings, 88% versus 45%, P equals 0.03. In addition, when the full diastolic pathway's identified, the targeted VTS were always non-inducible.

In our next paper, Masateru Takigawa, and associates examined whether the spacing orientation, the bipoles of high-density mapping catheters impacts the accuracy of scar detection. The authors analyze the electrograms using high-density HD grid catheter and determine the optimal cutoff for scar detection in six infarcted sheep. For using bipolar voltages to detect MRI defined scar, the area under the receiver operating curve dependent on the spacing and orientation of the bipoles and range from 0.89 to 0.923. The area under the receiver operating curve was significantly larger, P less than 0.01, when only the best points on each site were selected for analysis compared to when all points were used.

In our next paper, Darren Tsang and associates examine the impact of prior sternotomy on transvenous lead extraction outcomes. Of 1,480 patients, 455 had prior sternotomy. When compared to patient with no prior sternotomy, those with prior tsunami were more likely to be older, male, and present with more comorbidities and leads targeted for extraction. No statistical difference was identified in major and minor complication rates, clinical success rates, or in hospital mortality.

In patients with prior sternotomy, there were no instances of pericardial effusion following extraction. Patients with sternotomies prior to lead extraction experienced vascular cardiac perforation, presented clinically with hemothoraces rather than pericardial effusions.

In our next paper, Babak Nazer and associates highlight the electrophysiologic properties in sites of ablation for manifest nodofascicular and nodoventricular accessory pathways that connect the atrial ventricular node and the Purkinje system or ventricular myocardium respectively. Concealed nodoventricular and nodofascicular pathways participate as the retrograde limb of supraventricular tachycardia. Manifest nodofascicular and nodoventricular accessory pathways comprise the antegrade limb of wide complex supraventricular tachycardia but are quite rare.

The authors report on eight patients who underwent electrophysiologic studies for wide complex tachycardia three, narrow complex tachycardia one, and for pre-excitation in four patients. The authors found nodofascicular and nodoventricular accessory pathways were an integral part of the supraventricular tachycardia in three patients. In these three cases, cases one and two revealed wide complex tachycardia due to manifest supraventricular tachycardia. Case three with a bi-directional nodofascicular and nodoventricular accessory pathway that conducted retrograde during supraventricular tachycardia, and antegrade causing pre-excitation during atrial pacing.

The nodofascicular or nodoventricular accessory pathway with a bystander during AV nodal reentry and tachycardia, atrial fibrillation, atrial flutter, and orthodromic AV reentrant tachycardia in four cases, and caused only pre-excitation in one. Successful accessory pathway ablation was achieved empirically in the slow pathway region in one case. In five cases, the ventricular insertion was mapped to the slow pathway region in two cases, or septal right ventricle in three cases. The accessory pathway was not mapped in cases five and seven due to its bystander role. The QRS morphology of pre-excitation predicted the right ventricular insertion sites in four to five cases in which it was mapped. During follow-up, one patient noted recurrent palpitations but no documented supraventricular tachycardia. The authors recommend that ablation should initially target the slow pathway region with mapping of the right ventricular insertion site if slow pathway ablation is not successful, and that the QRS morphology of maximal pre-excitation may be used to predict the successful right ventricular ablation site.

In our next paper, Constanze Schmidt and associates sought to determine if gene therapy targeting TASK-1 atrial specific potassium channel gene would suppress atrial fibrillation and correct cellular electrophysiological modeling in a porcine model of atrial fibrillation. The authors induced atrial fibrillation in pigs using atrial burst stimulation via implanted pacemakers and injected into both atria adeno-associated viral vectors carrying anti TASK-1 SIRNA for gene transfer to suppress TASK-1 channel expression.

After 14 days, porcine cardiomyocytes were isolated from the right and left atrium. The authors found that anti TASK-1 adeno-associated viral vector application significantly reduced atrial fibrillation burden in comparison to pigs. Arrhythmic effects of anti TASK-1 SIRNA were associated with reduction of TASK-1 currents and prolongation of action potential durations in cardiomyocytes to sinus rhythm values. The authors concluded that suppression of atrial fibrillation through selective reduction of TASK-1 currents may represent a new option for anti-arrhythmic therapy.

We have two excellent research letters this month. Jordana Kron and associates reported the presence of Inflammasome within the granulomas in hearts of three cardiac sarcoidosis patients. Providing additional support for the role of IL-1 in the pathogenesis of cardiac sarcoidosis and raising the possibility of ion targeted therapies to treat cardiac sarcoidosis.

Walid Barake and associates examine 549 patients with left bundle branch block, left ventricular ejection fraction greater than 50% at baseline, and a follow-up echocardiogram. Of these, 134, 24.4% had a greater than 10% drop in left ventricular ejection fraction. The patients with possible left bundle branch block induced cardiomyopathy were more likely to be younger and male.

That's it for this month. We hope that you'll 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 2019.