The first original article is titled “Safety of Leadless Pacemaker Implantation in the Very Elderly”. The authors conducted a multicenter study in patients 85 years and older who received a Micra leadless pacemaker or a single-chamber transvenous pacemaker. The authors found that the Micra leadless pacemaker implantation was successful in 98.4% of patients. It was safe with no difference in procedure-related complications compared to the transvenous pacemaker group. The Micra leadless pacemaker resulted in significantly shorter procedure times.

Next up is a paper titled “Transvenous Phrenic Nerve Stimulation for Central Sleep Apnea is Safe and Effective in Patients with Concomitant Cardiac Devices”. Transvenous phrenic nerve stimulation requires placing a lead to stimulate the phrenic nerve and activate the diaphragm for the treatment of central sleep apnea. The authors studied 64 patients with concomitant cardiac implantable devices. There were only 4 oversensing events in 3 patients leading to 1 inappropriate defibrillator shock and delivery of antitachycardia pacing. The authors conclude that concomitant cardiac implantable devices and transvenous phrenic nerve stimulation therapy is safe and does not affect the efficacy in the treatment of central sleep apnea.

The following article is “Predictors of Atrial Mechanical Sensing and Atrioventricular Synchrony with a Leadless Ventricular Pacemaker”. The authors analyzed 64 patients enrolled in The MARVEL 2 study, which tested the efficacy of AV synchronous pacing with a Micra leadless pacemaker. Previously, low amplitude of the Micra-sensed atrial signal (A4) was observed to be a factor of low AV synchrony. In the present study, data were analyzed to identify predictors of A4 amplitude and high AV synchrony. The result show that clinical parameters and echocardiographic markers of atrial function are associated with A4 signal amplitude. High AV synchrony can be predicted by E/A ratio<0.94 and low sinus rate variability at rest on echo.

Coming up next is “Effect of QRS area reduction and myocardial scar on the hemodynamic response to cardiac resynchronization therapy”. The authors performed a study in 26 patients to determine whether reducing QRSarea leads to an acute hemodynamic response and whether scar affects this interaction. They found that changes of QRSarea and QRS duration predicted the changes of LV dP/dtmax after CRT. Myocardial scar adversely affects the changes of the QRSarea and the acute hemodynamic response. These findings may support the use of the changes of QRSarea and cardiac magnetic resonance in optimizing CRT using quadripolar left ventricular lead.

The next article is titled “Morbidity and mortality in patients precluded for transvenous pacemaker implantation: Experience with a leadless pacemaker.” A total of 2817 patients underwent a Micra implantation attempt, of whom 546 (19%) patients deemed ineligible for transvenous permanent pacemaker implantation for reasons such as venous access issues or prior device infections. The authors found that all-cause mortality is higher in Micra patients deemed ineligible for transvenous permanent pacemaker implantation than in nonprecluded Micra patients and those who received a transvenous permanent pacemaker, in part related to a higher incidence of chronic comorbidities in these patients. The overall major complication rate was low and did not differ by preclusion status.

The following article is titled “Safety of Magnetic Resonance Imaging Scanning in Patients with Cardiac Resynchronization Therapy Defibrillators Incorporating Quadripolar Left Ventricular Leads”. The authors studied the MRI safety with CRT-defibrillators (CRT-Ds) incorporating quadripolar left ventricular (LV) leads in a total of 230 subjects. A total of 159 patients completed a protocol-required MRI scan with no scan-related complications. All episodes of VF were appropriately sensed and treated. The authors conclude that in patients with CRT-D systems and quadripolar LV leads undergoing 1.5-T MRI, the scanning was safe with no significant changes in the ICD performance. These results suggest that MRI in patients having a device with quadripolar leads can be performed without negative impact on CRT delivery.

Coming up is “Progressive Implantable Cardioverter-Defibrillator Therapies for Ventricular Tachycardia: The Efficacy and Safety of Multiple bursts, ramps, and low-energy shocks”. The authors investigated the efficacy and safety of progressive therapies for VTs between 150 and 200 beats/min. After 3 failed bursts, the authors compared 3 ramps vs 3 bursts followed by a low-energy shock vs high-energy shock. A total of 1126 VT episodes were included. Programming up to 6 burst ATP therapies for VTs 150-200 beats/min can avoid ICD shocks in most patients. Ramp antitachycardia pacing after failed bursts were similarly effective. Low-energy shocks are less effective and more arrhythmogenic than high-energy shocks.

The final device paper is titled “High rate pacing guided by short-term variability of repolarization prevents imminent ventricular arrhythmias automatically by an implantable cardioverter-defibrillator in the chronic atrioventricular block dog model”. The authors used 8 dogs with complete chronic AV block and torsades de pointes ventricular arrhythmias induced by dofetilide. An ICD was implanted with software to automatically determine short term variability of repolarization in real time. The authors found that short term variability detected by the ICD can guide high rate pacing automatically by an ICD to prevent ventricular arrhythmias. These data suggest a new approach to prevent the torsades de pointes ventricular arrhythmias by implanted devices.

The first one is titled “Alcohol consumption and risk of atrial fibrillation in asymptomatic healthy adults”. The authors screened 19,634 asymptomatic healthy adults and found 160 new-onset AF during mean follow-up of 7 years. The incidence of new-onset AF was higher in drinkers. There was a dose-dependent increase in the risk of AF according to the amount of alcohol consumed, and the risk increased more abruptly in men than in women. The risk of AF was highest in frequent binge drinkers compared to infrequent light drinkers. These findings indicate that in the asymptomatic healthy population, drinking increases the risk of new-onset AF in a dose-dependent manner, regardless of sex.

Next up is “Is Transesophageal Echocardiography Necessary In Patients Undergoing Ablation Of Atrial Fibrillation On An Uninterrupted Direct Oral Anticoagulant Regimen?” A total of 6186 patients were prospectively registered and analyzed. The mean CHA2DS2-VASc score was 2.86. Intracardiac echocardiography ruled out left atrial appendage and left atrial thrombi in all patients and revealed "smoke" in 1672 patients (27.03%). Transient ischemic attack was noted in 1 patient with long-standing persistent AF in the setting of a missed dose of rivaroxaban before ablation. The authors conclude that performing AF ablation in patients on uninterrupted direct oral anticoagulants without TEE is safe and feasible in high stroke risk patients. Elimination of routine preablation TEE would have significant economic and clinical implications.

Next up is “Off-Label Dosing of Non-Vitamin K Antagonist Oral Anticoagulants and Clinical Outcomes in Asian Patients with Atrial Fibrillation”. The purpose of this study was to investigate the associations between inappropriate dosing of novel oral anticoagulants (NOACs) and clinical outcomes in patients within the health care system in Taiwan. They found that about 3 in 10 Asian AF patients were treated with off-label dosing NOACs in daily practice. Compared to on-label dosing, underdosing was associated with a higher risk of ischemic stroke and systemic embolism, whereas overdosing was associated with a higher risk of major bleeding. Thus, even for Asian AF patients at higher risk for bleeding, NOACs still should be prescribed at the dosing based on clinical trial criteria and guideline recommendations.

The next article is “Bipolar radiofrequency ablation for ventricular tachycardias originating from the interventricular septum: Safety and efficacy in a pilot cohort study”. The authors enrolled 21 patients with nonischemic dilated cardiomyopathy scheduled for a bipolar RF ablation procedure because of drug-refractory VT of suspected septal origin. They found that bipolar RF ablation is feasible in patients with nonischemic dilated cardiomyopathy and drug-refractory VT of septal origin. Extra-interventricular septum substrate and inflammatory nonischemic dilated cardiomyopathy etiology were associated with an adverse outcome. However, a larger study will be needed to determine the safety and efficacy of this approach.

The following article is “Determining the Optimal Duration for Premature Ventricular Contraction Monitoring”. VPCs have hour-to-hour and day-to-day variation. The authors studied 116 patch recordings from 107 patients to determine the optimal duration for ambulatory ECG monitoring for accurate assessment of VPC burden. Mean overall VPC burden was 13.4%. The authors found that mobile telemetry for a period of about 7 days accurately reflects overall VPC burden. Measurement of VPC burden for only 24-48 hours may not accurately reflect total burden. Monitoring for 2 weeks or longer adds little additional VPC information.