Faculty Bibliography

BACKGROUND:The MARVEL (Micra Atrial TRacking Using a Ventricular AccELerometer) 2 study assessed the efficacy of atrioventricular (AV) synchronous pacing with a Micra leadless pacemaker. Average atrioventricular synchrony (AVS) was 89.2%. Previously, low amplitude of the Micra-sensed atrial signal (A4) was observed to be a factor of low AVS. OBJECTIVE:The purpose of this study was to identify predictors of A4 amplitude and high AVS. METHODS:We analyzed 64 patients enrolled in MARVEL 2 who had visible P waves on electrocardiogram for assessing A4 amplitude and 40 patients with third-degree AV block for assessing AVS at rest. High AVS was defined as >90% correct atrial-triggered ventricular pacing. The association between clinical factors and echocardiographic parameters with A4 amplitude was investigated using a multivariable model with lasso variable selection. Variables associated with A4 amplitude together with premature ventricular contraction burden, sinus rate, and sinus rate variability (standard deviation of successive differences of P-P intervals [SDSD]) were assessed for association with AVS. RESULTS:In univariate analysis, low A4 amplitude was inversely related to atrial function assessed by E/A ratio and e'/a' ratio, and was directly related to atrial contraction excursion (ACE) and atrial strain (Ɛa) on echocardiography (all P ≤.05). The multivariable lasso regression model found coronary artery bypass graft history, E/A ratio, ACE, and Ɛa were associated with low A4 amplitude. E/A ratio and SDSD were multivariable predictors of high AVS, with >90% probability if E/A <0.94 and SDSD <5 bpm. CONCLUSION/CONCLUSIONS:Clinical parameters and echocardiographic markers of atrial function are associated with A4 signal amplitude. High AVS can be predicted by E/A ratio <0.94 and low sinus rate variability at rest.

Occult atrial fibrillation (AF) can be the underlying cause for cryptogenic stroke (CS). Implantable loop recorders (ILRs) have become an important tool for long-term arrhythmia monitoring in CS patients. Office-based ILR implantation by nonelectrophysiologist physicians is increasingly common. To report the real world diagnostic yield and accuracy of remote ILR monitoring in high risk CS patients, we retrospectively analyzed 145 consecutive patients with CS who underwent ILR implantation between October 2014 and October 2018 at New York University Langone Health. A certified device technician and an electrophysiologist adjudicated all transmissions. The yield and accuracy of Reveal LINQ Intra Cardiac Monitor (ICM), a fourth generation device, was compared to that of TruRhythm Detection algorithm (fifth generation device). AF was diagnosed in 17 patients (12%) over a mean follow-up of 28 ± 12 months. The median time to diagnosis was 7.4 ± 21.3 months. A total of 1,637 remote transmissions (scheduled- and auto-triggered alerts: 756; patient-triggered: 881) were adjudicated. The positive predictive value for AF episodes in the scheduled interrogations increased from 4% in the Reveal LINQ ICM to 16% in the TruRhythm LINQ. Of 881 patient-triggered transmissions, none were found to be true positive. In the Reveal LINQ ICM, for scheduled transmissions, primary causes of false positive (FP) were atrial ventricular premature complexes (80%). In the TruRhythm LINQ, for scheduled transmissions, primary cause of FP were T-wave over-sensing (87%). In conclusion, the real world diagnostic yield of ILR for patients with CS remains suboptimal, with at least 84% of AF alerts being FP. Patient-riggered events did not correlate with arrhythmia and the necessity of patient triggering in this population should be questioned. Expert interpretation of recordings is critical to assure accurate diagnosis.

Chloroquine and hydroxychloroquine are now being widely used as treatments for COVID-19. Both medications prolong the QT interval and accordingly may put patients at increased risk of torsades de pointes and sudden death. Published guidance documents vary in their recommendations for monitoring and managing these potential adverse effects. Accordingly, we set out to conduct a systematic review of the arrhythmogenic effect of short courses of chloroquine or hydroxychloroquine. We searched in MEDLINE and Embase, as well as grey literature up to April 17, 2020, on the risk of QT prolongation, torsades, ventricular arrhythmia, and sudden death with short-term chloroquine and hydroxychloroquine usage. This resulted in 390 unique records, of which fourteen were ultimately selected for qualitative synthesis and which included data on 1515 COVID-19 patients. Approximately 10% of COVID-19 patients treated with these drugs developed QT prolongation. We found evidence of ventricular arrhythmia in two COVID-19 patients out of a group of 28 treated with high-dose chloroquine. A limitation of these results is unclear follow-up and possible publication/reporting bias, but there is compelling evidence that chloroquine and hydroxychloroquine induce significant QT interval prolongation and potentially increase the risk of arrhythmia. Daily ECG monitoring and other risk mitigation strategies should be considered in order to prevent possible harms from what is currently an unproven therapy.

BACKGROUND:There is no known effective therapy for patients with COVID-19. Initial reports suggesting the potential benefit of Hydroxychloroquine/Azithromycin (HY/AZ) have resulted in massive adoption of this combination worldwide. However, while the true efficacy of this regimen is unknown, initial reports have raised concerns regarding the potential risk of QT prolongation and induction of torsade de pointes (TdP). OBJECTIVE:to assess the change in QTc interval and arrhythmic events in patients with COVID-19 treated with HY/AZ METHODS: This is a retrospective study of 251 patients from two centers, diagnosed with COVID-19 and treated with HY/AZ. We reviewed ECG tracings from baseline and until 3 days after completion of therapy to determine the progression of QTc and incidence of arrhythmia and mortality. RESULTS:QTc prolonged in parallel with increasing drug exposure and incompletely shortened after its completion. Extreme new QTc prolongation to > 500 ms, a known marker of high risk for TdP had developed in 23% of patients. One patient developed polymorphic ventricular tachycardia (VT) suspected as TdP, requiring emergent cardioversion. Seven patients required premature termination of therapy. The baseline QTc of patients exhibiting extreme QTc prolongation was normal. CONCLUSION/CONCLUSIONS:The combination of HY/AZ significantly prolongs the QTc in patients with COVID-19. This prolongation may be responsible for life threating arrhythmia in the form of TdP. This risk mandates careful consideration of HY/AZ therapy in lights of its unproven efficacy. Strict QTc monitoring should be performed if the regimen is given.

INTRODUCTION/BACKGROUND:Implantable cardioverter defibrillators (ICDs) are proven to prevent sudden death in patients at elevated risk for sustained ventricular tachycardia or fibrillation. Complications related to ICD failure can stem from lead dysfunction, manufacturing defects, patient characteristics or implantation technique. We conducted a review of all ICD leads implanted at our center from 2011-2017 to determine risk factors for premature lead failure. METHODS:We conducted a retrospective review of patients of all ICD leads implanted from December 2011 to June 2017 at our institution. A total of 660 patients (Biotronik Linox S/SD, n = 281; Sprint Quatro, n = 207; Durata, n = 121; Endotak, n = 51) underwent ICD implantations. Patient and lead characteristics, procedural outcomes and complications were recorded. Lead failure was defined per Heart Rhythm Society lead-management consensus as a lack of procedural or clinical success, thus requiring an extraction of the lead. Patient and lead outcomes were recorded and variables associated with lead failure were assessed by the Kaplan-Meier method. RESULTS:Overall failure rate was similar for all leads: Linox S/SD - 0.29%/year; Sprint Quattro - 0.21%/year, Durata - 0.39%/year and Endotak Reliance - 0.0% (p=0.769). No difference was found in overall survival when comparing all ICD manufacturers during the study period. Subgroup analysis revealed the risk of premature lead failure was particularly pronounced in multi-lead ICD systems implanted via cephalic access (p<0.001). The estimated failure rate of Linox leads implanted via cephalic access in multi-lead systems was 19%/year. The estimated failure rate of non-Linox leads implanted via cephalic access in multi-lead systems was 11%/year. Neither age, nor gender were risk factors for lead failure in the Linox, or non-Linox cohorts. CONCLUSION/CONCLUSIONS:All analyzed ICD leads were found to have a similar overall risk of premature failure. ICD lead implantation via cephalic access in multilead ICD systems may be a previously unidentified risk factor for premature ICD lead failure, although these findings require further validation. This article is protected by copyright. All rights reserved.

INTRODUCTION/BACKGROUND:Catheter stability during atrial fibrillation ablation is associated with higher ablation success rates. Rapid cardiac pacing and high frequency jet ventilation (HFJV) independently improve catheter stability. Simultaneous modulation of cardiac and respiratory motion has not been previously studied. The objective of this study was to determine the effect of simultaneous heart rate and respiratory rate modulation on catheter stability. METHODS:Forty patients undergoing paroxysmal atrial fibrillation ablation received ablation lesions at 15 pre-specified locations (12 left atria, 3 right atria). Patients were randomly assigned to undergo rapid atrial pacing for either the first or the second half of each lesion. Within each group, half of patients received HFJV and half standard ventilation. Contact force and ablation data for all lesions were compared among the study groups. Standard deviation of contact force was the primary endpoint defined to examine contact force variability. RESULTS:Lesions with no pacing and standard ventilation had the greatest contact force standard deviation (5.86 + 3.08g), compared to lesions with pacing and standard ventilation (5.45+3.28g, p<0.01) or to lesions with no pacing and HFJV (4.92+3.00g, P<0.01). Lesions with both pacing and HFJV had the greatest reduction in contact force standard deviation, (4.35+2.81g, p<0.01), confirming an additive benefit of each maneuver. Pacing and HFJV together was also associated with a reduction in the proportion of lesions with excessive maximum contact force (p<0.001). DISCUSSION/CONCLUSIONS:Rapid pacing and HFJV additively improve catheter stability. Simultaneous pacing with HFJV further improves catheter stability over pacing or HFJV alone to optimize ablation lesions. This article is protected by copyright. All rights reserved.

INTRODUCTION/BACKGROUND:Acute hemopericardium during cardiac electrophysiology (EP) procedures may result in significant blood loss and is the most common cause of procedure related death. Matched allogeneic blood is often not immediately available. The feasibility and safety of direct autotransfusion in cardiac electrophysiology patients requiring emergency pericardiocentesis is unknown. METHODS:We retrospectively analyzed records of patients undergoing EP procedures at a single, tertiary care medical center who had procedure-related acute hemopericardium requiring emergency pericardiocentesis during a three-year period. Procedure details, transfusion volumes, and clinical outcomes of patients who received direct autotransfusion of aspirated pericardial blood via a femoral venous sheath were compared to those of patients who did not receive direct autotransfusion. RESULTS:During the study period, 10 patients received direct autotransfusion (group 1) and outcomes were compared with those of 14 control patients who did not receive direct autotransfusion (group 2). Volume of aspirated pericardial blood was similar in groups 1 and 2 (1.6±0.7 L vs. 1.3±1.0 L, respectively; p=0.52). Amongst patients with aspirated volumes < 1L, group 1 patients (n=4) were less likely than group 2 patients (n=8) to require allotransfusion (0% vs. 75%, p=0.02). Amongst patients with aspirated volume ≥ 1L, group 1 patients (n=6) required fewer units of red cell allotransfusion than group 2 patients (n=6) (1.5±0.8u vs. 4.3±2.0u, p=0.01). No procedural complications related to direct autotransfusion occurred. CONCLUSIONS:Direct autotransfusion following emergency pericardiocentesis during electrophysiology procedures requiring systemic anticoagulation is feasible and safe. Utilization of direct autotransfusion may eliminate or reduce the need for allotransfusion. This article is protected by copyright. All rights reserved.