Competing Risks for Monomorphic versus Non-Monomorphic Ventricular Arrhythmias in Primary Prevention Implantable Cardioverter Defibrillator Recipients: Global Electrical Heterogeneity and Clinical Outcomes (GEHCO) Study

BACKGROUND AND AIMS

Ablation of monomorphic ventricular tachycardia (MMVT) has been shown to reduce shock frequency and improve survival. We aimed to compare cause-specific risk factors of MMVT and polymorphic ventricular tachycardia (PVT)/ventricular fibrillation (VF) and to develop predictive models.

METHODS

The multicenter retrospective cohort study included 2,668 patients (age 63.1±13.0 y; 23% female; 78% white; 43% nonischemic cardiomyopathy, left ventricular ejection fraction 28.2±11.1%). Cox models were adjusted for demographic characteristics, heart failure severity and treatment, device programming, and ECG metrics. Global electrical heterogeneity was measured by spatial QRS-T angle (QRSTa), spatial ventricular gradient elevation (SVGel), azimuth, magnitude (SVGmag), and sum absolute QRST integral (SAIQRST). We compared the out-of-sample performance of the lasso and elastic net for Cox proportional hazards and the Fine-Gray competing risk model.

RESULTS

During a median follow-up of 4 years, 359 patients experienced their first sustained MMVT with appropriate ICD therapy, and 129 patients had their first PVT/VF with appropriate ICD shock. The risk of MMVT was associated with wider QRSTa (HR 1.16; 95%CI 1.01-1.34), larger SVGel (HR 1.17; 95%CI 1.05-1.30), and smaller SVGmag (HR 0.74; 95%CI 0.63-0.86) and SAIQRST (HR 0.84; 95%CI 0.71-0.99). The best-performing 3-year competing risk Fine-Gray model for MMVT (ROC(t)AUC 0.728; 95%CI 0.668-0.788) identified high-risk (> 50%) patients with 75% sensitivity, 65% specificity, and PVT/VF prediction model had ROC(t)AUC 0.915 (95%CI 0.868-0.962), both satisfactory calibration.

CONCLUSION

We developed and validated models to predict the competing risks of MMVT or PVT/VF that could inform procedural planning and future RCTs of prophylactic VT ablation.

Adaptive Cardiac Resynchronization Therapy Effect on Electrical Dyssynchrony (aCRT-ELSYNC): A randomized controlled trial

BACKGROUND

Adaptive cardiac resynchronization therapy (aCRT) is known to have clinical benefits over conventional CRT, but the mechanisms are unclear.

OBJECTIVE

Compare effects of aCRT and conventional CRT on electrical dyssynchrony.

METHODS

A prospective, double-blind, 1:1 parallel-group assignment randomized controlled trial in patients receiving CRT for routine clinical indications. Participants underwent cardiac computed tomography and 128-electrode body surface mapping. The primary outcome was change in electrical dyssynchrony measured on the epicardial surface using noninvasive electrocardiographic imaging before and 6 months post-CRT. Ventricular electrical uncoupling (VEU) was calculated as the difference between the mean left ventricular (LV) and right ventricular (RV) activation times. An electrical dyssynchrony index (EDI) was computed as the standard deviation of local epicardial activation times.

RESULTS

We randomized 27 participants (aged 64 ± 12 years; 34% female; 53% ischemic cardiomyopathy; LV ejection fraction 28% ± 8%; QRS duration 155 ± 21 ms; typical left bundle branch block [LBBB] in 13%) to conventional CRT (n = 15) vs aCRT (n = 12). In atypical LBBB (n = 11; 41%) with S waves in V5-V6, conduction block occurred in the anterior RV, as opposed to the interventricular groove in strict LBBB. As compared to baseline, VEU reduced post-CRT in the aCRT (median reduction 18.9 [interquartile range 4.3-29.2 ms; P = .034]), but not in the conventional CRT (21.4 [-30.0 to 49.9 ms; P = .525]) group. There were no differences in the degree of change in VEU and EDI indices between treatment groups.

CONCLUSION

The effect of aCRT and conventional CRT on electrical dyssynchrony is largely similar, but only aCRT harmoniously reduced interventricular dyssynchrony by reducing RV uncoupling.

Development and implementation of standardized study performance metrics for a VA healthcare system clinical research consortium

The cost of conducting clinical trials is continuously increasing and is driven in large part by the time and resources required to activate trials and reach accrual targets. The impact of low enrollment in a clinical trial can negatively affect the validity of study results and delay its generalizability to the broader population. Quality is a multidimensional concept which could relate to the design, conduct, and analysis of a trial, its clinical relevance, protection/safety of study participants, or quality of reporting. Furthermore, the quality of controlled trials is of obvious relevance to systematic reviews and if the "raw material" or "data" is flawed then the conclusions of systematic reviews cannot be trusted. To date, the literature surrounding the establishment of standardized study enrollment and quality metrics to assess site performance in clinical trial consortiums is scarce. The lack of these metrics presents challenges to study site teams, sponsors, and other clinical research enterprise key stakeholders for adequately monitoring and evaluating study site performance as it relates to fulfilling trial enrollment and quality goals. The Department of Veterans Affairs (VA) Cooperative Studies Program (CSP) Network of Dedicated Enrollment Sites (NODES) undertook an effort to determine the feasibility of establishing and implementing standardized study enrollment and quality metrics for a clinical research consortium (NODES) as a tool to evaluate its performance. In this manuscript, we describe the development and implementation of standardized study enrollment and quality metrics to assess site performance across studies in our clinical research consortium.

Competing risks in patients with primary prevention implantable cardioverter-defibrillators: Global Electrical Heterogeneity and Clinical Outcomes study

BACKGROUND

Global electrical heterogeneity (GEH) is associated with sudden cardiac death in the general population. Its utility in patients with systolic heart failure who are candidates for primary prevention (PP) implantable cardioverter-defibrillators (ICDs) is unclear.

OBJECTIVE

The purpose of this study was to investigate whether GEH is associated with sustained ventricular tachycardia/ventricular fibrillation leading to appropriate ICD therapies in patients with heart failure and PP ICDs.

METHODS

We conducted a multicenter retrospective cohort study. GEH was measured by spatial ventricular gradient (SVG) direction (azimuth and elevation) and magnitude, QRS-T angle, and sum absolute QRST integral on preimplant 12-lead electrocardiograms. Survival analysis using cause-specific hazard functions compared the strength of associations with 2 competing outcomes: sustained ventricular tachycardia/ventricular fibrillation leading to appropriate ICD therapies and all-cause death without appropriate ICD therapies.

RESULTS

We analyzed 2668 patients (mean age 63 ± 12 years; 624 (23%) female; 78% white; 43% nonischemic cardiomyopathy; left ventricular ejection fraction 28% ± 11% from 6 academic medical centers). After adjustment for demographic, clinical, device, and traditional electrocardiographic characteristics, SVG elevation (hazard ratio [HR] per 1SD 1.14; 95% confidence interval [CI] 1.04-1.25; P = .004), SVG azimuth (HR per 1SD 1.12; 95% CI 1.01-1.24; P = .039), SVG magnitude (HR per 1SD 0.75; 95% CI 0.66-0.85; P < .0001), and QRS-T angle (HR per 1SD 1.21; 95% CI 1.08-1.36; P = .001) were associated with appropriate ICD therapies. Sum absolute QRST integral had different associations in infarct-related cardiomyopathy (HR 1.29; 95% CI 1.04-1.60) and nonischemic cardiomyopathy (HR 0.78; 95% CI 0.62-0.96) (P_interaction = .022).

CONCLUSION

In patients with PP ICDs, GEH is independently associated with appropriate ICD therapies. The SVG vector points in distinctly different directions in patients with 2 competing outcomes.

Practice Gap in Atrial Fibrillation Oral Anticoagulation Prescribing at Emergency Department Home Discharge

INTRODUCTION

Current U.S. cardiology guidelines recommend oral anticoagulation (OAC) to reduce stroke risk in selected patients with atrial fibrillation (AF), but no formal AF OAC recommendations exist to guide emergency medicine clinicians in the acute care setting. We sought to characterize emergency department (ED) OAC prescribing practices after an ED AF diagnosis.

METHODS

This retrospective study included index visits for OAC-naive patients ≥18 years old who were discharged home from the ED at an urban, academic, tertiary hospital with a primary diagnosis of AF from 2012-2014. Five hypothesis-blinded, chart reviewers abstracted data from patient problem lists and medical history in the electronic health record to assess stroke (CHA₂DS₂-VASc) and bleeding risk (HAS-BLED). The primary outcome was the provision of an OAC prescription at discharge in OAC-naive patients with high stroke risk. Descriptive statistics and multivariable logistic regression assessed associations between OAC prescription and patient characteristics.

RESULTS

We included 138 patient visits in our analysis, of whom 39.9% (n = 55) were low stroke risk (CHA₂DS₂-VASc = 0 in males and 1 in females), 15.9% (n = 22) were intermediate risk (CHA₂DS₂-VASc = 1 in males), and 44.2% (n = 61) were high risk (CHA₂DS₂-VASc ≥ 2). Of patients with high stroke risk and low-to-intermediate bleeding risk (n = 57), 80.7% were not prescribed an OAC at discharge. Cardiology consultation and female gender, but not stroke risk (CHA₂DS₂-VASc score), were predictors of an ED provider prescribing an OAC to an OAC-naive AF patient at ED discharge.

CONCLUSION

The majority of OAC-eligible patients were discharged home without an OAC prescription. In OAC-naive patients discharged home from the ED, cardiology consultation and female gender were associated with OAC prescription. Our findings suggest that access to expert opinion may improve provider comfort with OAC prescribing and highlight the need for improved guidelines specific to ED-management of AF.

Abstract 144: Quality Assurance Measurement of St Jude/Abbott Tendril Pacemaker Leads in Veterans

Background: St Jude/Abbott 1688TC and 2088TC Tendril Pacemaker Leads with a silicone-polyurethane copolymer insulation have been reported to have failure rates as high as 5.7% and 5.2%. The VA National Cardiac Surveillance Program (NCDSP) monitors 45,000 Veterans; many have St Jude/Abbott Leads.

Objective: Examine the survival rate of the 1688TC and 2088TC Tendril Pacemaker Leads in the VA database as an ongoing QA measure.

Method: Model and serial numbers, dates of implant, and out of service (OOS) dates among other variables are listed. Records of OOS leads were analyzed for the OOS reason, and the cause of lead failure: noise, fracture, malfunction, insulation breaks, dislodgement and significant changes in impedance and threshold.

Results: There were 5,550 1688TC Tendril pacemaker leads implanted in 4,140 veterans, for an average of 83 (0-199) months; 185 (3.33%) leads were OOS at an average of 58 (0-152) months. Reasons for OOS were: failures in 69 (1.24%), system upgrades in 51 (0.92%), infections in 55 (0.99%), and other reasons in 10 (0.18%). Of 11,587 2088TC Tendril pacemaker leads implanted in 8,147 veterans for an average of 46 (0-108) months; 224 (1.93%) leads were OOS at an average of 29 (0-92) months. Lead failures occurred in 67 (0.58%), system upgrades in 85 (0.73%), infections in 64 (0.55%), and other reasons in 8 (0.07%). The graph shows the survival rate of the 1688TC and 2088TC Tendril pacemaker leads after implant (excluding upgrades, infections, and other reasons).

Conclusion: At 108 months follow-up, both leads had comparable survival. Lead failure was found in 1.05% of the 1688TC and 0.58% of the St Jude/Abbott 2088TC Tendril pacemaker leads implanted in veterans, much lower than that in other published reports.

Outcomes of Telemedicine Video-Conferencing Clinic Versus In-Person Clinic Follow-Up for Implantable Cardioverter-Defibrillator Recipients

BACKGROUND

Implantable cardioverter-defibrillator (ICD) recipients require close follow-up that can be difficult for patients who have to travel long distances for clinic follow-up. We aimed to compare clinical outcomes between ICD patients followed-up in a telemedicine video-conferencing clinic (TMVC) and a conventional in-person clinic (CIC). We hypothesized that outcomes of patients followed in the TMVC are noninferior to the CIC.

METHODS AND RESULTS

This retrospective study compares time to first appropriate ICD therapy, time to first inappropriate ICD therapy, time to first shock, and overall survival in patients followed in TMVC compared with CIC between 2001 and 2016. Two hundred and eighty-seven patients were followed in the TMVC group and 236 patients in the CIC. The average age of the TMVC and CIC groups was 64.13±9.38 and 65.23±8.57 years, respectively (P=0.164). There was no difference in the modified Seattle heart failure model score between the 2 groups (-0.12±1.0 versus -0.21±0.99; P=0.287). The Charlson comorbidity index score was higher in the CIC group compared with the TMVC group (7.0 versus 6.0; P=0.01). Mean duration of follow-up was 4.8 years. Adjusted and unadjusted tests of noninferiority found TMVC was not inferior to in-person follow-up for the prespecified outcomes.

CONCLUSIONS

Video-conferencing ICD follow-up for patients in areas where electrophysiology subspecialty care is not available leads to outcomes that are noninferior to CIC follow-up.

A Review of the Relationship of Atrial Fibrillation and Acute Coronary Syndrome

Atrial fibrillation (AF) is the most common arrhythmia encountered by clinicians. Clinical decision-making focuses on reducing ischemic stroke risk in AF patients; however, AF is also associated with an increased risk of acute coronary syndromes (ACS). Patients with ACS and concurrent AF are less likely to receive appropriate therapies and more likely to experience adverse outcomes than ACS patients in sinus rhythm (SR). Clinicians may be able to stratify ACS patients at increased risk of AF development based on clinical characteristics. Evidence supporting specific therapeutic options for prevention of ACS in AF patients or for prevention of AF in ACS patients is limited, however there is some evidence of differing effects among oral anticoagulant regimens in these populations. Investigations of the relationship of AF with the full spectrum of ACS are not well described and should be the focus of future research.

Introduction of the Liverpool Care Pathway for end of life care to emergency medicine

AIM

To improve the care of patients presenting to the emergency department who are acutely dying or those in whom further disease-modifying treatment is not appropriate.

DESIGN

A quality improvement report on the implementation of a modified Liverpool Care Pathway for the Dying Patient (LCP) in an emergency medicine department.

SETTING

The emergency medicine department of Ninewells Hospital, Dundee. Ninewells Hospital is the tertiary referral and teaching hospital for the east coast of Scotland and North East Fife.

KEY MEASURES FOR IMPROVEMENT

The pathway was introduced after a 2001 study and a 2003 audit showed that the department had an increasing role in the care of the acutely dying, but some inconsistency in approach. Key measures for improvement were to improve communication between staff, improve the consistency of care and improve the perceived quality of care given. Senior decision making remains a crucial element of the pathway.

STRATEGIES FOR CHANGE

A modified LCP was developed and launched in November 2005. Change was managed via a series of meetings and a pilot process. Serial review and audit allowed ongoing quality review of the pathway and improvements.

RESULTS

The care of the dying patient has become a more consistent and positive endeavour. Nursing staff are very satisfied with its use, and it is hoped that the LCP pathway can be developed further within the organisation.

CONCLUSIONS

It has been a rewarding undertaking to improve the care of dying patients, but one which has taken time and has required consistent management of change to promote the positive outcomes.

Ventricular tachyarrhythmia prediction

Using R-R interval history from 24-hour Holter recorders along with R-R interval history from implantable cardioverter defibrillators (ICD), a particular monotonic heart rhythm acceleration pattern during sinus rhythm, when used as a predictor of an imminent episode of ventricular tachyarrhythmia, can achieve a sensitivity of 44% with corresponding specificity of 94%. A more meaningful quantity than the specificity is the daily rate of Type II error, which is 1.8 event/day in this case. The Type II error rate can be reduced to 0.7 event/day with a nonoptimized sensitivity of 47% by using a double acceleration predictor.

Omega-3 fatty acids: antiarrhythmic, proarrhythmic or both?

Initial epidemiological, clinical trial and animal data have suggested that a diet high in omega-3 fatty acids reduces the risk of cardiac death and that this reduction in the risk was owing to the prevention of fatal arrhythmias. More recent data, however, suggest that, in some patients with heart disease, omega-3 fatty acid supplementation may increase the risk of potentially fatal cardiac arrhythmias and the risk of sudden cardiac death. Additional research needs to be carried out to confirm and characterize the proarrhythmic properties of omega-3 fatty acids and to determine their role in the treatment of patients with heart disease who have not had a recent myocardial infarction.

Follow-up of patients with unexplained syncope and inducible ventricular tachyarrhythmias: analysis of the AVID registry and an AVID substudy. Antiarrhythmics Versus Implantable Defibrillators

INTRODUCTION

A prospective registry and substudy were conducted in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Study to clarify the prognosis and recurrent event rate, risk factors, and impact of implantable cardioverter defibrillator (ICD) therapy in patients with unexplained syncope, structural heart disease, and inducible ventricular tachyarrhythmias.

METHODS AND RESULTS

Included in the AVID registry were patients from all participating sites who had "out of hospital syncope with structural heart disease and EP-inducible VT/VF with symptoms." In addition, 13 collaborating sites provided more in-depth clinical and electrophysiologic data as part of a formal prospective substudy. Patients in the substudy were followed by local investigators for recurrent arrhythmic events and mortality. Registry patients were tracked for fatal outcomes by the National Death Index. A total of 429 patients with syncope were entered in the AVID registry, of whom 80 participated in the substudy. Of the substudy patients, 21 patients (26%) had inducible polymorphic ventricular tachycardia/ventricular fibrillation (VT/VF), 11 patients (14%) had sustained monomorphic VT <200 beats/min, and 48 patients (60%) had sustained monomorphic VT > or = 200 beats/min. The ICD was used as sole therapy in 75% of the syncope substudy patients (and with antiarrhythmic drug in an additional 9%) and in 59% of the syncope registry patients. Survival rates at 1 and 3 years were 93% and 74% for the substudy patients and 90% and 74% for the registry patients, respectively. Survival of the syncope substudy patients (predominantly treated by ICD) was similar to the VT patients treated by ICD and superior to the VT patients treated by an antiarrhythmic drug (P = 0.05) in the randomized main trial. Mortality events in the substudy were marginally predicted by ejection fraction (P = 0.06) but not by electrophysiologic study-induced arrhythmia. The significant predictor of increased mortality in the registry was age (P = 0.003) and of reduced mortality was treatment with ICD (P = 0.006).

CONCLUSION

The results of these analyses support the role of the ICD as primary antiarrhythmic therapy in patients with unexplained syncope, structural heart disease, and inducible VT/VF at electrophysiologic study.

Lead- and device-related complications in the antiarrhythmics versus implantable defibrillators trial

BACKGROUND

Implantation of transvenous implantable cardioverter defibrillators (ICDs) by use of a nonthoracotomy approach has become routine therapy for survivors of life-threatening tachyarrhythmias. The purpose of this study was to identify and prospectively characterize the frequency of lead- and ICD-related complications from the Antiarrhythmics versus Implantable Defibrillators (AVID) Trial.

METHODS AND RESULTS

Between June 1, 1993, and April 7, 1997, 539 patients received nonthoracotomy ICDs either as initial treatment assignment (477) or as crossover from medical management (62). A total of 62 first complications occurred. The subclavian route of insertion resulted in more complications than the cephalic vein route, 46 of 339 (14%) versus 6 of 135 (4%), P = .005, as did the abdominal versus pectoral generator site, 31 of 238 (13%) versus 17 of 291 (6%), P<.02. Most dislodgements and system infections tended to occur in the 3 months after implantation, whereas lead fractures continued to occur throughout follow-up. Failure to use perioperative antibiotics was a predictor of system infection (P = .001).

CONCLUSIONS

These data suggest that cephalic vein access and pectoral generator site may result in fewer complications. The continued occurrence of lead fractures and the need for premature system revision supports the practice of close routine ICD system surveillance.

Recipient to donor conduction of atrial tachycardia following orthotopic heart transplantation

We report a case of atrial tachycardia in a 60-year-old male 8 years postorthotopic heart transplantation. At electrophysiology study, the clinical rhythm was found to arise from the remnant of the recipient atrium and was successfully terminated by delivery of radiofrequency energy. Surgical scars formed at the anastomosis of the recipient and donor atrium during the time of orthotopic heart transplantation are thought to electrically isolate the two areas. Although rarely recognized, dysrhythmias originating from the recipient atrial remnant may occur more often than previously thought.

A prospective randomized evaluation of implantable cardioverter-defibrillator size on unipolar defibrillation system efficacy

BACKGROUND

The active can unipolar implantable cardioverter-defibrillator (ICD) has been shown to defibrillate efficiently, but its current 80-cc size limits use in the pectoral position in many patients. Decreasing can size will facilitate pectoral insertion and will soon be feasible as an inevitable consequence of technological advancements. However, decreasing the can size has the potential to compromise unipolar defibrillation efficacy. It is the purpose of this study, therefore, to prospectively and randomly compare unipolar defibrillation efficacy with 80-cc, 60-cc, and 40-cc can sizes in patients immediately before ICD surgery in anticipation of advances in technology that will make smaller ICDs possible.

METHODS AND RESULTS

Twenty-four consecutive patients underwent prospective, randomized evaluation of the effect of ICD can size on defibrillation efficacy during standard ICD surgery. Each patient had the unipolar defibrillation threshold (DFT) measured with 80-cc, 60-cc, or 40-cc active can placed in the left subcutaneous infraclavicular region. The system included a 10.5F tripolar right ventricular electrode that served as the shock anode. The shock waveform used in each instance was a single capacitor biphasic 65% pulse delivered from a 120-microF capacitor. Stored energy at the DFT for the 80-cc, 60-cc, and 40-cc cans were 8.1 +/- 4.7 J, 8.7 +/- 5.8 J, and 9.5 +/- 4.8 J, respectively. There was no statistical significant difference between the DFTs for the three unipolar can electrodes (P = 39). Leading edge voltage also did not differ significantly among the three unipolar cans (356 +/- 92 V, 365 +/- 110 V, and 387 +/- 94 V, respectively, P = .29). There was, however, a slight progressive increase in resistance with decreasing can size (57 +/- 7 omega, 60 +/- 9 omega, and 65 +/- 9 omega, respectively, P < .001).

CONCLUSIONS

Decreasing can volume from 80 cc to 60 cc to 40 cc does not compromise unipolar defibrillation efficacy despite a slight rise in shock resistance. These findings indicate that technological advances that allow for smaller-volume ICDs will not compromise defibrillation efficacy for unipolar systems.

Virus persists in beta cells of islets of Langerhans and infection is associated with chemical manifestations of diabetes. II. Morphologic observations

Persistence of lymphocytic choriomeningitis (LCM) virus in the islets of Langerhans was associated with mild hyperglycemia and abnormal glucose tolerance test results. Early histopathologic events consisted of occasional perivascular inflammatory mononuclear cells around both islet and acinar cells. Morphometric studies showed an increase in the size of islets from virus-infected mice. By electron microscopy, LCM virions were found within infected beta cells. Cytolytic injury of beta cells was minimal and did not account for the abnormalities of glucose metabolism. In contrast to the findings in islets, ultrastructural studies of acinar cells revealed LCM virions in abundance, vacuolar degeneration, and intracytoplasmic inclusions. This study extends the previous observation that LCM virus infection may persist in beta cells of the islets of Langerhans without causing structural injury but be associated with abnormalities resembling the chemical and histopathologic features of the early stage of Type II (adult-onset) human diabetes mellitus.