New-onset left bundle branch block-associated idiopathic nonischemic cardiomyopathy and time from diagnosis to cardiac resynchronization therapy: The NEOLITH II study.

BACKGROUND: The optimal timing for cardiac resynchronization therapy (CRT) after diagnosis of new-onset left bundle branch block (LBBB)-associated idiopathic nonischemic cardiomyopathy (NICM) and treatment with guideline-directed medical therapy (GDMT) is unknown. The purpose of this study was to describe relationships between time from diagnosis to CRT and outcomes in new-onset LBBB-associated idiopathic NICM with left ventricular ejection fraction (LVEF) ≤35%. METHODS: A retrospective cohort study examined associations between time from diagnosis to CRT (≤9 months vs >9 months) and clinical and echocardiographic outcomes. RESULTS: In 123 subjects with LBBB-associated idiopathic NICM, time from diagnosis to CRT was ≤9 months in 60 (49%) subjects and 9 months in 63 (51%) subjects. Clinical outcomes were similar for those implanted ≤9 months versus >9 months for adverse clinical events (hazard ratio [HR], 0.85; 95% confidence interval [CI], 0.41-1.78; P = 0.67) and all-cause mortality (HR, 0.57; 95% CI, 0.19-1.70; P = 0.31). Multivariable analyses demonstrated similar results. In 105 subjects with post-CRT echocardiograms, LVEF improvement to >35% was more likely in those implanted ≤9 months when compared to >9 months (odds ratio [OR], 3.53; 95% CI, 1.32-9.46; P = 0.01). This association persisted in the final multivariable model adjusted for age at diagnosis, sex, QRS duration, post-GDMT LVEF, and time from CRT to post-CRT echocardiogram (OR, 5.10; 95% CI, 1.71-15.22; P = 0.004). CONCLUSION: In LBBB-associated idiopathic NICM, earlier CRT implantation was associated with more favorable cardiac remodeling. Delaying CRT may miss a critical period to halt and reverse progressive myocardial damage.

Predictors and implications of early left ventricular ejection fraction improvement in new-onset idiopathic nonischemic cardiomyopathy with narrow QRS complex: A NEOLITH substudy.

BACKGROUND: Predictors and implications of early left ventricular ejection fraction (LVEF) improvement with guideline-directed medical therapy (GDMT) in new-onset idiopathic nonischemic cardiomyopathy (NICM) with narrow QRS complex are not well described. The objectives were to describe predictors of LVEF improvement after 3 months on GDMT and adverse cardiac events based on post-GDMT LVEF status (≤35% vs. >35%). METHODS: A retrospective cohort study was performed in subjects with new-onset NICM, LVEF ≤35%, and narrow QRS complex. Associations for baseline variables with post-GDMT LVEF improvement and absolute change in LVEF (∆LVEFGDMT ) were assessed. Cox proportional hazards models assessed associations for post-GDMT LVEF status with adverse cardiac events. RESULTS: In 70 subjects, 31 (44%) had post-GDMT LVEF ≤35% after a median follow-up time of 97.5 days (interquartile range, 84-121 days). In final multivariable models, severely dilated left ventricular end-diastolic diameter (LVEDD), compared with normal LVEDD, strongly predicted post-GDMT LVEF ≤35% (odds ratio, 7.77; 95% confidence interval [CI], 1.39-43.49; p = .02) and ∆LVEFGDMT (ß = -15.709; standard error = 4.622; p = .001). Subjects with post-GDMT LVEF ≤35% were more likely to have adverse cardiac events over a median follow-up time of 970.5 days (unadjusted hazard ratio, 2.15; 95% CI, 0.93-4.96; p = .07). In the post-GDMT LVEF ≤35% group, 9 of 26 subjects (35%) had long-term LVEF > 35%. CONCLUSION: In new-onset NICM with narrow QRS complex, nondilated LVEDD predicted early LVEF improvement. Those with post-GDMT LVEF ≤35% had higher risk of adverse cardiac events, but a substantial proportion demonstrated continued long-term LVEF improvement.

Electrical dysfunction associated with conductor externalization of a silicone left ventricular lead.

The St. Jude Medical QuickFlex LV lead family (St. Jude Medical, Inc., St. Paul, MN, USA) has been placed under advisory by the manufacturer due to a reported small number of cases of outer insulation failure and conductor externalization. There have been no reports of alteration of any electrical parameters associated with externalization. In this report, a sudden drop of impedance and rise in capture threshold of the left ventricular ring electrode is described, associated with the corresponding externalization of the inner conductor cables confirmed on physical examination. Flexion or torsion of lead was demonstrative of forces favoring externalization of inner conductor cables. Saline bath testing revealed a reproducible, transient reduction in lead resistance associated with conductor externalization. Close monitoring of electrical performance of this lead family is indicated.

Precordial electrocardiographic recording and QT measurement from a novel wearable ring device.

Background: The availability of portable and wearable electrocardiographic (ECG) devices has increased secondary to technological development. Single-lead ECG recordings have been shown to reliably detect and characterize cardiac rhythms such as atrial fibrillation. Acquisition of precordial electrodes for full 12-lead ECG reconstruction from bipolar recordings is complicated by the absence of a body ground/Wilson central terminal electrode. The extent of difference between standard precordial leads and those from a wearable bipolar ECG recorder has not been characterized. Objective: The purpose of this study was to characterize the precordial ECG lead set from sequential bipolar recordings from an ECG ring wearable device. Methods: In 70 patients who wore an ECG device on a right-hand finger, sequential precordial leads (CR1-CR6) were obtained along with chest electrodes (V1-V6). During acquisition of the modified precordial lead CR6, a full standardized 12-lead ECG capture was obtained. Signal quality was assessed using automated analysis software, and correlation values between the ring-derived ECG precordial leads and standard ECG leads were compared with regard to QRS duration, QT width, and RR interval. Results: High concordance in the morphologies of precordial ECG leads obtained in a standard fashion and those recorded through an ECG ring was observed. Morphologic alignment improved with increasing laterality of the precordial lead with chest to right arm ring recording (CR5, CR6) compared with anterior chest leads to right arm (CR1, CR2). Segmental measurements of QRS duration and QT segment were well aligned and of high correlation. Conclusion: Wearable ring-based ECG technology is capable of high-fidelity recordings of precordial leads for nonsimultaneous reconstruction of complete ECG sets. These recordings correlate highly with surface-obtained QRS and QT duration measurements and have significant implications for clinical applications. Uninterpretable tracings were primarily due to electrode noise from poor electrode contact.

Effect of coronary occlusion on intracardiac electrogram morphology.

AIMS: The effect of coronary occlusion on the morphology of intracardiac electrograms (IKG) may be of diagnostic value in recipients of cardiac implantable electronic device (CIED) and in other patients at risk of ischaemic heart disease (IHD), but remains grossly uncharacterized. The aim of the current study was to examine the effect of total occlusions in the major coronary artery distributions on the IKG. METHODS AND RESULTS: Domestic crossbred pigs (n= 11, 20-30 kg) were implanted with dual-coil right ventricular defibrillators, and bipolar right atrial and left ventricular leads. Through the femoral approach, percutaneous balloon total occlusion of the major coronary arteries was performed in random order in the left anterior descending, left circumflex, and right coronary arteries. Each occlusion was maintained for 3-5 min with 30 min periods of reperfusion in between. Simultaneous 15-vector IKG and 12-lead surface electrocardiograms (ECG) were recorded and analysed at baseline and during coronary occlusions. With coronary occlusions, significant ST-segment disturbances are consistently seen on both surface ECG leads and IKG tracings compared with baseline recordings and are reproducible over time. Given the multiple intracardiac recording vectors, each occluded vessel has a specific signature, allowing coronary localization from the IKG. CONCLUSIONS: Total coronary occlusion induces consistent IKG changes with injury patterns that allow the detection and localization of the culprit coronary artery. If duplicated in patients with IHD, these changes are likely to improve the time to diagnosis of acute coronary syndromes and thus favourably impact clinical outcomes.

A novel manoeuvre for discerning supraventricular tachycardia mechanism.

AIMS: Discerning supraventricular tachycardia (SVT) mechanism during catheter ablation procedures can be difficult and time-consuming, which, when combined with diagnostic error, places patients at risk of unnecessary complications. Distinguishing atrial tachycardia (AT) from AV nodal re-entry tachycardia (AVNRT) may be particularly vexatious. Value-added techniques are thus always welcome, particularly if they are not time-consuming nor require complex intracardiac lead configurations. In this study, we assessed whether a new technique, simultaneous right atrial and right ventricular pacing (RA + RV) during ongoing SVT, met these criteria. METHODS AND RESULTS: Using a simple intracardiac lead configuration (right atrial appendage, His bundle, right ventricular apex), the response to RA + RV delivered at 80-90% of the SVT cycle length, was examined in 80 patients referred for catheter ablation. In each patient, the actual tachycardia mechanism was adjudicated by standard electrophysiologic criteria ± successful catheter ablation. Mechanisms of SVT included, non-exclusively, AVNRT (24 patients), accessory pathway-mediated (orthodromic) re-entry (AVRT; 23 patients), AT (10 patients), and sinus tachycardia (ST induced with isoproterenol; 49 patients). Immediately after cessation of RA + RV pacing during persistent SVT, the first intracardiac electrogram observed was right atrial in all AT whereas it was His bundle in all AVNRT. The response during AVRT was mixed. CONCLUSIONS: In this preliminary evaluation, RA + RV pacing appears to add value to the existing armamentarium of electrophysiologic indices to discern SVT mechanism, in particular with respect to discriminating between AVNRT and AT.

12-lead surface electrocardiogram reconstruction from implanted device electrograms.

AIM: Reconstruction of the surface electrocardiogram (EKG) from voltage recordings from implanted leads is not performed by current pacemakers or cardioverter-defibrillators. We investigated the feasibility and accuracy of reconstruction of a full 12-lead surface EKG from an implanted biventricular device. METHODS AND RESULTS: We applied three techniques for surface EKG reconstruction from multiple intracardiac (IC) vector recordings from implanted cardiac leads: single fixed dipole modelling via exact solution, exhaustive best-fit solution, and time-independent association using a transfer matrix. Recordings were performed at biventricular generator change in 10 patients. Overdetermined projection transformation resulted in high fidelity surface EKG reproduction for left-sided implanted devices (correlation coefficient 0.84+/-0.13) with computationally lightweight reconstruction. CONCLUSION: After individual post-implantation correlation with the surface EKG, reconstruction using a time-independent transfer matrix accurately reproduces the surface EKG, is free from gating requirements, and retains validity during aberrant depolarization. These findings have significant implications for further study relating IC electrogram to surface tracings. The techniques may be used for real-time or remote monitoring and diagnosis of rhythm disturbances, cardiac ischaemia, and lead integrity and stability.

Implantable and surface electrocardiography: complementary technologies.

Combining information obtained from the surface electrocardiogram and implantable devices represents an emerging trend in electrocardiology. Important potential applications include ischemia detection and localization, continuous monitoring of cardiac cycle parameters, and telemedicine. This article presents an overview of these emerging applications, focusing on our recent studies that combine the electrograms obtained from body surface and implantable devices to reconstruct a full 12-lead electrocardiogram from the implanted device. These technologies have broad application for detection of ischemia, improvement of the accuracy of ischemic localization, and rhythm discrimination.

Survey of current perspectives on consumer-available digital health devices for detecting atrial fibrillation.

BACKGROUND: Many digital health technologies capable of atrial fibrillation (AF) detection are directly available to patients. However, adaptation into clinical practice by heart rhythm healthcare practitioners (HCPs) is unclear. OBJECTIVE: To examine HCP perspectives on use of commercial technologies for AF detection and management. METHODS: We created an electronic survey for HCPs assessing practice demographics and perspectives on digital devices for AF detection and management. The survey was distributed electronically to all members of 3 heart rhythm professional societies. RESULTS: We received 1601 responses out of 73,563 e-mails sent, with 43.6% from cardiac electrophysiologists, 12.8% from fellows, and 11.6% from advanced practice practitioners. Most respondents (62.3%) reported having recommended patient use of a digital device for AF detection. Those who did not had concerns about their accuracy (29.6%), clinical utility of results (22.8%), and integration into electronic health records (19.8%). Results from a 30-second single-lead electrocardiogram were sufficient for 42.7% of HCPs to recommend oral anticoagulation for patients at high risk for stroke. Respondents wanted more data comparing the accuracy of digital devices to conventional devices for AF monitoring (64.9%). A quarter (27.3%) of HCPs had no reservations recommending digital devices for AF detection, and most (53.4%) wanted guidelines from their professional societies providing guidance on their optimal use. CONCLUSION: Many HCPs have already integrated digital devices into their clinical practice. However, HCPs reported facing challenges when using digital technologies for AF detection, and professional society recommendations on their use are needed.

Death and taxes.

Tax incentives can provide a large financial impetus to change behavior. Current U.S. law establishes a substantial discontinuity in the amount of estate tax that many patients will have to pay in 2010: During this year only, the tax rate drops to zero. This article discusses concerns regarding the sharp change in tax rate and the incentives it creates for persons who are nearing the end of life and provides estimates of the number of people affected by this issue.

Effect of ischemia on implantable defibrillator intracardiac shock electrograms.

INTRODUCTION: Few attempts have been made to extract information from the ventricular electrogram (EGM) recorded by implantable cardioverter defibrillators (ICD) aside from the discrimination of supraventricular tachycardia and ventricular tachycardia. The current study aims to examine the effect of ischemia in the major coronary artery distributions on the shock EGM from ICDs. METHODS: Domestic crossbred pigs (n = 10, 20-40 kg) were implanted with a dual-coil right ventricular defibrillation system. Through the femoral approach, percutaneous balloon occlusion of the major coronary arteries was performed. The left anterior descending (LAD), left circumflex (LCx), and right coronary (RCA) arteries were occluded in random order for 3-5 minutes with 30-minute periods of reperfusion in between and the shock EGMs were recorded and analyzed. RESULTS: During peak ischemia, R wave amplitude increased by a mean of 204.3% (P = 0.003), increased by a mean of 73.8% (P = 0.0009), and decreased by a mean of 28.0% (P = 0.109) in the LAD, LCx, and RCA territories, respectively. During peak ischemia ST segments elevated by a mean of 105.3% (P = 0.041), elevated by a mean of 114.9% (P = 0.064), and decreased by a mean of 584.5% (P = 0.006) in the LAD, LCx, and RCA territories, respectively. CONCLUSIONS: Ischemia affects ICD shock EGMs in a manner that appears to vary depending on the culprit vessel. Our data demonstrate the feasibility of ischemia detection from ICD shock EGMs.

New-onset left bundle branch block-associated idiopathic nonischemic cardiomyopathy and left ventricular ejection fraction response to guideline-directed therapies: The NEOLITH study.

BACKGROUND: Left ventricular ejection fraction (LVEF) response to guideline-directed medical therapy (GDMT) and to early cardiac resynchronization therapy (CRT) in new-onset idiopathic nonischemic cardiomyopathy (NICM) and left bundle branch block (LBBB) is not well described. CRT is recommended if LVEF remains ≤35% after at least 3 months of GDMT. OBJECTIVE: The purpose of this study was to describe LVEF response to GDMT at 3 months and to early CRT in new-onset LBBB-associated idiopathic NICM. METHODS: A retrospective cohort study was performed in subjects with new-onset idiopathic NICM, LVEF ≤35%, and LBBB or narrow (<120 ms) QRS complex morphology. LVEF response between groups was evaluated with log-binomial and linear regression. LVEF response within groups was evaluated using the paired Student t test. RESULTS: In 102 subjects (70 with narrow QRS complex and 32 with LBBB), post-GDMT LVEF was >35% in 39 narrow QRS complex subjects (56%) and 2 LBBB subjects (6%) (P < .0001). The absolute difference between post-GDMT LVEF and initial LVEF was greater in the narrow QRS complex group (16.1% ± 14.6% vs. 3.3% ± 10.7%; P < .0001). Narrow QRS complex, referenced to LBBB, was significantly associated with post-GDMT LVEF >35% (relative risk 10.30; 95% confidence interval 2.63-40.27; P = .0008) and absolute difference between post-GDMT LVEF and initial LVEF (ß = 16.296; standard error = 2.977; P < .0001) in final multivariable analyses. CRT super-response, defined as post-CRT LVEF ≥50%, was observed in 8 of LBBB subjects (35%) who received CRT. CONCLUSION: GDMT did not significantly improve LVEF in new-onset LBBB-associated idiopathic NICM at 3 months. Most remained candidates for CRT, and a high percentage were super-responders. Optimal timing for CRT implantation requires further investigation.

Prophylactic lead extraction at implantable cardioverter-defibrillator generator change.

BACKGROUND: Current implantable cardiac devices have a finite battery life of ≈3 to 7 years for implantable cardioverter-defibrillators. It is current practice to reuse all properly functioning intravascular leads. We tested the hypothesis that a strategy of prophylactic lead removal at the time of device change would be superior under some conditions to the current practice of lead reuse. METHODS AND RESULTS: Using currently available data and a Monte Carlo microsimulation trial, we calculated the risks of leaving an indwelling lead until extraction is indicated because of malfunction versus an aggressive management strategy of prophylactic serial extraction at time of generator change. With a serial lead exchange strategy of leads at generator change, there is reduced overall extraction-related mortality because of fewer late complications attributable to extraction of leads with high dwell time because of infection, recall, or subsequent lead failure. This finding is limited to young patients or those with high expected indwell time of lead. This trend reverses for leads with <40 years expected dwell time. Sensitivity analysis shows high dependence on extraction performance and device longevity. In all cases, serial extraction would be expected to lead to increased adverse events related to the more complex procedure. CONCLUSIONS: A strategy of serial lead extraction, given best available current parameters, yields a lower procedural mortality risk in the long-term management of indwelling implantable cardioverter-defibrillator leads in young patients (>40-year estimated dwell time) driven by high aggregate anticipated risk of lifetime lead complication.