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.

Impact of omitting the intravenous heparin bolus on outcomes of leadless pacemaker implantation

BACKGROUND

Early guidance recommended a bolus of intravenous heparin at the beginning of leadless pacemaker (LP) implantation procedures. However, due to concern about bleeding complications, more recent practice has tended toward omitting the bolus and only running a continuous heparin infusion through the introducer sheath. The impact of omitting the heparin bolus on procedural outcomes is not clear.

METHODS

We reviewed all Medtronic Micra LP implants at our institution from 9/2014 to 9/2022. The decision to bolus with heparin was at operator discretion.

RESULTS

Among 621 LP implants, 326 received an intravenous heparin bolus, 243 did not, and 52 patients were excluded because heparin bolus status could not be confirmed. There was a trend toward more frequent omission of the heparin bolus with more recent implants. Median follow-up after LP implant was 14.3 (interquartile range [IQR]: 8.4-27.9) months. There was no difference between heparin bolus and no bolus groups in the number of device deployments/recaptures (1.42 ± 0.81 vs. 1.31 ± 0.66, p = .15). Implant-related adverse events were also similar between heparin bolus and no bolus groups: access-site hematoma requiring intervention (7 vs. 5, p = .99), pseudoaneurysm (1 vs. 1, p = .99), cardiac perforation (1 vs. 1, p = .99), intraprocedural device thrombus formation (2 vs. 4, p = .41), 30-day rehospitalization (21 vs. 15, p = .98), and 30-day all-cause mortality (16 vs. 14, p = .70). There was one additional nonfatal cardiac perforation in a patient who was excluded due to unknown heparin bolus status. Regarding device electrical parameters between heparin bolus and no bolus groups, there were no significant differences at the time of implant: pacing capture threshold 0.5 ± 0.4 vs. 0.5 ± 0.3, p = .10; pacing impedance 739.9 ± 226.4 vs. 719.1 ± 215.4, p = .52; R wave sensing 11.7 ± 5.7 vs. 12.0 ± 5.4, p = .34). Long-term device performance was also similar between groups.

CONCLUSION

Omission of the systemic heparin bolus at the time of LP implantation appears safe in appropriately selected patients. Heparin bolus may still be considered in long cases requiring multiple device deployments or in patients at high risk for thrombotic complications.

Long-term performance of single-connector (DF4) implantable defibrillator leads

AIMS

Single-connector (DF4) defibrillator leads have become the predominantly implanted transvenous implantable cardioverter-defibrillator lead. However, data on their long-term performance are derived predominantly from manufacturer product performance reports.

METHODS AND RESULTS

We reviewed medical records in 5289 patients with DF4 leads between 2011 and 2023 to determine the frequency of lead-related abnormalities. We defined malfunction as any single or combination of electrical abnormalities requiring revision including a sudden increase (≥2×) in stimulation threshold, a discrete jump in high-voltage impedance, or sensing of non-physiologic intervals or noise. We documented time to failure, predictors of failure, and management strategies. Mean follow-up after implant was 4.15 ± 3.6 years (median = 3.63), with 37% of leads followed for >5 years. A total of 80 (1.5%) leads demonstrated electrical abnormalities requiring revision with an average time to failure of 4 ± 2.8 years (median = 3.5). Of the leads that malfunctioned, 62/80 (78%) were extracted and replaced with a new lead and in the other 18 cases, malfunctioned DF4 leads were abandoned, and a new lead implanted. In multivariable models, younger age at implant (OR 1.03 per year; P < 0.001) and the presence of Abbott/St. Jude leads increased the risk of malfunction.

CONCLUSION

DF4 defibrillator leads demonstrate excellent longevity with >98.3% of leads followed for at least 5 years still functioning normally. Younger age at implant and lead manufacturer are associated with an increased risk of DF4 lead malfunction. The differences in lead survival between manufacturers require further investigation.

Safety of same-day discharge after lead extraction procedures

BACKGROUND

Same-day discharge (SDD) after cardiovascular procedures is rapidly gaining ground.

OBJECTIVE

We sought to evaluate the safety of SDD after transvenous lead extraction (TLE).

METHODS

We performed a retrospective chart review of patients who underwent elective TLE between January 2020 and October 2021 at our institution. The primary outcome was SDD, and major procedural complications and readmissions within 30 days of the procedure were secondary outcomes.

RESULTS

In this analysis of 111 patients who underwent elective TLE, 80 patients (72%) were discharged on the same day (SDD group) while 31 patients (28%) stayed overnight (overnight group). Lead malfunction was the most common indication for TLE in both groups. Patients in the overnight group were more likely to have a lead dwell time of ≤10 years than those in the SDD group (38.7% vs 20% of all leads in each group; P = .042), have laser sheaths used for extraction and a higher number of leads extracted. No major complications were reported in both groups. In a multivariate analysis, lower body mass index and the use of laser sheath during TLE were predictors of overnight stay. Patients who underwent a procedure using advanced extraction techniques were 3.5 times more likely to stay overnight (95% confidence interval 1.27-9.78; P = .016).

CONCLUSION

In appropriately selected patients undergoing elective lead extraction, SDD is feasible and safe. Higher body mass index, fewer extracted leads, shorter lead dwell times (<10 years), and less frequent use of laser-powered extraction sheaths were associated with an increased likelihood of SDD.

Outcomes of leadless pacemaker implantation after cardiac surgery and transcatheter structural valve interventions

INTRODUCTION

Permanent pacing indications are common after cardiac surgery and transcatheter structural valve interventions. Leadless pacemakers (LPs) have emerged as a useful alternative to transvenous pacemakers. However, current commercially available LPs are unable to provide atrial pacing or cardiac resynchronization and relatively little is known about LP outcomes after cardiac surgery and transcatheter valve interventions.

METHODS

This retrospective study included patients who received a Micra VR (MicraTM MC1VR01) or Micra AV (MicraTM MC1AVR1) (Medtronic) leadless pacemaker following cardiac surgery or transcatheter structural valve intervention between September 2014 and September 2022. Device performance and clinical outcomes, including ventricular pacing burden, ejection fraction, and need for conversion to transvenous pacing systems, were evaluated during follow-up.

RESULTS

A total of 78 patients were included, of whom 40 received a Micra VR LP implant, and 38 received a Micra AV LP implant. The mean age of the cohort was 65.9 ± 17.9 years, and 48.1% were females. The follow-up duration for the entire cohort was 1.3 ± 1.1 years: 1.6 ± 1.3 years for the Micra VR group and 0.8 ± 0.5 years for the Micra AV group. Among the cohort, 50 patients had undergone cardiac surgery and 28 underwent transcatheter structural valve interventions. Device electrical performance was excellent during follow-up, with a small but clinically insignificant increase in ventricular pacing threshold and a slight decrease in pacing impedance. The mean right ventricle pacing (RVP) burden significantly decreased over time in the entire cohort (74.3% ± 37.2% postprocedure vs. 47.7% ± 40.6% at last follow-up, p < .001), and left ventricle ejection fraction (LVEF) showed a modest but significant downward trend during follow-up (55.0% ± 10.6% vs. 51.5% ± 11.2% p < .001). Patients with Micra VR implants had significantly reduced LVEF during follow-up (54.1% ± 11.9% vs. 48.8% ± 11.9%, p = .003), whereas LVEF appeared stable in the Micra AV group during follow-up (56.1% ± 9.0% vs. 54.6% ± 9.7%, p = .06). Six patients (7.7%) required conversion to transvenous pacing systems, four who required cardiac resynchronization for drop in LVEF with high RVP burden and two who required dual-chamber pacemakers for symptomatic sinus node dysfunction.

CONCLUSION

Leadless pacemakers provide a useful alternative to transvenous pacemakers in appropriately selected patients after cardiac surgery and transcatheter structural valve interventions. Device performance is excellent over medium-term follow-up. However, a significant minority of patients require conversion to transvenous pacing systems for cardiac resynchronization or atrial pacing support, demonstrating the need for close electrophysiologic follow-up in this cohort.

Arrhythmic Effects of Cannabis in Ischemic Heart Disease

Rationale: Cannabis use is increasing worldwide, especially among older individuals at risk for chronic ischemic heart disease (IHD). However, little is known about the arrhythmic effects of cannabis use in IHD. Accordingly, we prospectively assessed the relationship between cannabis use, heart rate (HR), and arrhythmias in healthy age-matched controls and subjects with IHD. Methods: Healthy controls (n=37, 57% men) and subjects with IHD (myocardial infarction ≥3 months ago; n=24, 58% men) who used cannabis wore a Zio® (iRhythm Technologies) monitor for 14 days. Noncannabis using ischemic subjects (n=35, 51% males) wore Zio monitors for standard clinical indications. Baseline HR was compared with average HR measured for 4 h following consumption and changes in HR and frequency of arrhythmias were correlated with cannabis use. Results: In controls, HR increased 20 min (4.99±6.7 bpm, p=0.08) after use, then declined 4 h following use (-7.4±7.7, p<0.001). Conversely, subjects with IHD showed minimal HR increase (1.6±3.9 bpm) and blunted HR decline (-3.4±5.6 bpm, p<0.001). Supraventricular tachycardia (SVT) (29.7% vs. 58.3%; p=0.04) and nonsustained ventricular tachycardia (NSVT) (5.6% vs. 47.8%, p=0.01) were the most frequently occurring arrhythmias in controls and IHD subjects, respectively. Incidence of SVT decreased as cannabis use increased in both groups. Conversely, NSVT tended to increase with increased use in controls, and was significantly more prevalent in IHD. However, overall arrhythmia burden did not differ between cannabis users and nonusers with IHD. Conclusion: Our findings demonstrate that chronic cannabis use is associated with only mild HR changes, which are blunted in IHD. In addition, our data suggest that among cannabis users, arrhythmias are more frequent in IHD subjects that in healthy subjects.

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.

Right ventricular function and cardiopulmonary performance among patients with heart failure supported by durable mechanical circulatory support devices

BACKGROUND

Patients with continuous-flow left ventricular assist devices (CF-LVADs) experience limitations in functional capacity and frequently, right ventricular (RV) dysfunction. We sought to characterize RV function in the context of global cardiopulmonary performance during exercise in this population.

METHODS

A total of 26 patients with CF-LVAD (aged 58 ± 11 years, 23 males) completed a hemodynamic assessment with either conductance catheters (Group 1, n = 13) inserted into the right ventricle to generate RV pressure‒volume loops or traditional Swan‒Ganz catheters (Group 2, n = 13) during invasive cardiopulmonary exercise testing. Hemodynamics were collected at rest, 2 sub-maximal levels of exercise, and peak effort. Breath-by-breath gas exchange parameters were collected by indirect calorimetry. Group 1 participants also completed an invasive ramp test during supine rest to determine the impact of varying levels of CF-LVAD support on RV function.

RESULTS

In Group 1, pump speed modulations minimally influenced RV function. During upright exercise, there were modest increases in RV contractility during sub-maximal exercise, but there were no appreciable increases at peak effort. Ventricular‒arterial coupling was preserved throughout the exercise. In Group 2, there were large increases in pulmonary arterial, left-sided filling, and right-sided filling pressures during sub-maximal and peak exercises. Among all participants, the cardiac output‒oxygen uptake relationship was preserved at 5.8:1. Ventilatory efficiency was severely abnormal at 42.3 ± 11.6.

CONCLUSIONS

Patients with CF-LVAD suffer from limited RV contractile reserve; marked elevations in pulmonary, left-sided filling, and right-sided filling pressures during exercise; and severe ventilatory inefficiency. These findings explain mechanisms for persistent reductions in functional capacity in this patient population.

New insights into resting and exertional right ventricular performance in the healthy heart through real-time pressure-volume analysis

KEY POINTS

Despite growing interest in right ventricular form and function in diseased states, there is a paucity of data regarding characteristics of right ventricular function - namely contractile and lusitropic reserve, as well as ventricular-arterial coupling, in the healthy heart during rest, as well as submaximal and peak exercise. Pressure-volume analysis of the right ventricle, during invasive cardiopulmonary exercise testing, demonstrates that that the right heart has enormous contractile reserve, with a three- or fourfold increase in all metrics of contractility, as well as myocardial energy production and utilization. The healthy right ventricle also demonstrates marked augmentation in lusitropy, indicating that diastolic filling of the right heart is not passive. Rather, the right ventricle actively contributes to venous return during exercise, along with the muscle pump. Ventricular-arterial coupling is preserved during submaximal and peak exercise in the healthy heart.

ABSTRACT

Knowledge of right ventricular (RV) function has lagged behind that of the left ventricle and historically, the RV has even been referred to as a 'passive conduit' of lesser importance than its left-sided counterpart. Pressure-volume (PV) analysis is the gold standard metric of assessing ventricular performance. We recruited nine healthy sedentary individuals free of any cardiopulmonary disease (42 ± 12 years, 78 ± 11 kg), who completed invasive cardiopulmonary exercise testing during upright ergometry, while using conductance catheters inserted into the RV to generate real-time PV loops. Data were obtained at rest, two submaximal levels of exercise below ventilatory threshold, to simulate real-world scenarios/activities of daily living, and maximal effort. Breath-by-breath oxygen uptake was determined by indirect calorimetry. During submaximal and peak exercise, there were significant increases in all metrics of systolic function by three- to fourfold, including cardiac output, preload recruitable stroke work, and maximum rate of pressure change in the ventricle (dP/dtmax ), as well as energy utilization as determined by stroke work and pressure-volume area. Similarly, the RV demonstrated a significant, threefold increase in lusitropic reserve throughout exercise. Ventricular-arterial coupling, defined by the quotient of end-systolic elastance and effective arterial elastance, was preserved throughout all stages of exercise. Maximal pressures increased significantly during exercise, while end-diastolic volumes were essentially unchanged. Overall, these findings demonstrate that the healthy RV is not merely a passive conduit, but actively participates in cardiopulmonary performance during exercise by accessing an enormous amount of contractile and lusitropic reserve, ensuring that VA coupling is preserved throughout all stages of exercise.

Analysis of Outcomes in 8304 Patients Undergoing Lead Extraction for Infection

Background Patients undergoing lead extraction for infected devices have worse outcomes compared with those with noninfected devices. We assessed predictors of in-hospital mortality and procedure-related major adverse events (MAEs) in a large cohort undergoing lead extraction. Methods and Results Deidentified hospital records procedure from 7 states between 1994 and 2013 were aggregated and International Classification of Disease, Ninth Revision (ICD-9) procedure codes were used to identify hospital records reporting lead extraction. MAEs included death, cardiac tamponade, hemothorax, and need for emergent cardiac surgery. Predictors of in-hospital MAEs for infected compared with noninfected leads were identified using multivariate regression. Associations between outcomes and specific microbe were also assessed. In total, 57 220 discharges specified lead extraction. Infected leads accounted for the minority of total lead extractions compared with fractured leads (16.1 versus 59.8%, 25.7% not reported). There were 3298 MAEs (5.8%) including 980 deaths (1.7%). Multivariate predictors of MAE included black race, atrial fibrillation, anemia, heart failure, and admission via either hospital transfer or emergency department versus home (all P<0.001). Infected leads were associated with an increased risk of death (4.6% versus 0.9%, P<0.001) compared with leads with fracture only. Among patients with microbial data, staphylococcal infection was most common, whereas streptococcal infection was associated with the worst outcomes. Conclusions Patients undergoing extraction of infected leads have higher in-hospital mortality and adverse events compared with noninfected leads. Streptococcus, anemia, and heart failure are predictors of adverse outcomes.

Variation in expenditure for common, high cost surgical procedures in a working age population: implications for reimbursement reform

BACKGROUND

In the move toward value-based care, bundled payments are believed to reduce waste and improve coordination. Some commercial insurers have addressed this through the use of bundled payment, the provision of one fee for all care associated with a given index procedure. This system was pioneered by Medicare, using a population generally over 65 years of age, and despite its adoption by mainstream insurers, little is known of bundled payments' ability to reduce variation or cost in a working-age population. This study uses a universally-insured, nationally-representative population of adults aged 18-65 to examine the effect of bundled payments for five high-cost surgical procedures which are known to vary widely in Medicare reimbursement: hip replacement, knee replacement, coronary artery bypass grafting (CABG), lumbar spinal fusion, and colectomy.

METHODS

Five procedures conducted on adults aged 18-65 were identified from the TRICARE database from 2011 to 2014. A 90-day period from index procedure was used to determine episodes of associated post-acute care. Data was sorted by Zip code into hospital referral regions (HRR). Payments were determined from TRICARE reimbursement records, they were subsequently price standardized and adjusted for patient and surgical characteristics. Variation was assessed by stratifying the HRR into quintiles by spending for each index procedure.

RESULTS

After adjusting for case mix, significant inter-quintile variation was observed for all procedures, with knee replacement showing the greatest variation in both index surgery (107%) and total cost of care (75%). Readmission was a driver of variation for colectomy and CABG, with absolute cost variation of $17,257 and $13,289 respectively. Other post-acute care spending was low overall (≤$1606, for CABG).

CONCLUSIONS

This study demonstrates significant regional variation in total spending for these procedures, but much lower spending for post-acute care than previously demonstrated by similar procedures in Medicare. Targeting post-acute care spending, a common approach taken by providers in bundled payment arrangements with Medicare, may be less fruitful in working aged populations.

Repeat ablation of refractory ventricular arrhythmias in patients with nonischemic cardiomyopathy: Impact of midmyocardial substrate and role of adjunctive ablation techniques

INTRODUCTION

Multiple ablations are often necessary to manage ventricular arrhythmias (VAs) in nonischemic cardiomyopathy (NICM) patients. We assessed characteristics and outcomes and role of adjunctive, nonstandard ablation in repeat VA ablation (RAbl) in NICM.

METHODS AND RESULTS

Consecutive NICM patients undergoing RAbl were analyzed, with characteristics of the last VA ablations compared between those undergoing 1 versus multiple-repeat ablations (1-RAbl vs. >1RAbl), and between those with or without midmyocardial substrate (MMS). VA-free survival was compared. Eighty-eight patients underwent 124 RAbl, 26 with > 1RAbl, and 26 with MMS. 1-RAbl and > 1-RAbl groups were similar in age (57 ± 16 vs. 57 ± 17 years; P = 0.92), males (76% vs. 69%; P = 0.60), LVEF (40 ± 17% vs. 40 ± 18%; P = 0.96), and amiodarone use (31% vs. 46%, P = 0.22). One-year VA freedom between 1-RAbl vs. > 1RAbl was similar (82% vs. 80%; P = 0.81); adjunctive ablation was utilized more in >1RAbl (31% vs. 11%, P = 0.02), and complication rates were higher (27% vs. 7%, P = 0.01), most due to septal substrate and anticipated heart block. >1-RAbl patients had more MMS (62% vs. 16%, P < 0.01). Although MMS was associated with worse VA-free survival after 1-RAbl (43% vs. 69%, P = 0.01), when >1RAbl was performed, more often with nonstandard ablation, VA-free survival was comparable to non-MMS patients (85% vs. 81%; P = 0.69). More RAbls were required in MMS versus non-MMS patients (2.00 ± 0.98 vs. 1.16 ± 0.37; P < 0.001).

CONCLUSION

For NICM patients with recurrent, refractory VAs despite previous ablation, effective arrhythmia control can safely be achieved with subsequent ablation, although >1 repeat procedure with adjunctive ablation is often required, especially with MMS.

Acute isoproterenol leads to age-dependent arrhythmogenesis in guinea pigs

Sudden cardiac death from ventricular arrhythmias is more common in adult patients with with heart failure compared with pediatric patients with heart failure. We identified age-specific differences in arrhythmogenesis using a guinea pig model of acute β-adrenergic stimulation. Young and adult guinea pigs were exposed to the β-adrenergic agonist isoproterenol (ISO; 0.7 mg/kg) for 30 min in the absence or presence of flecainide (20 mg/kg), an antiarrhythmic that blocks Na⁺ and ryanodine channels. Implanted cardiac monitors (Reveal LINQ, Medtronic) were used to monitor heart rhythm. Alterations in phosphorylation and oxidation of ryanodine receptor 2 (RyR2) were measured in left ventricular tissue. There were age-specific differences in arrhythmogenesis and sudden death associated with acute β-adrenergic stimulation in guinea pigs. Young and adult guinea pigs developed arrhythmias in response to ISO; however, adult animals developed significantly more premature ventricular contractions and experienced higher arrhythmia-related mortality than young guinea pigs treated with ISO. Although there were no significant differences in the phosphorylation of left ventricular RyR2 between young and adult guinea pigs, adult guinea pigs exposed to acute ISO had significantly more oxidation of RyR2. Flecainide treatment significantly improved survival and decreased the number of premature ventricular contractions in young and adult animals in association with lower RyR2 oxidation. Adult guinea pigs had a greater propensity to develop arrhythmias and suffer sudden death than young guinea pigs when acutely exposed to ISO. This was associated with higher oxidation of RyR2. The incidence of sudden death can be rescued with flecainide treatment, which decreases RyR2 oxidation. NEW & NOTEWORTHY Clinically, adult patients with heart failure are more likely to develop arrhythmias and sudden death than pediatric patients with heart failure. In the present study, older guinea pigs also showed a greater propensity to arrhythmias and sudden death than young guinea pigs when acutely exposed to isoproterenol. Although there are well-described age-related cardiac structural changes that predispose patients to arrhythmogenesis, the present data suggest contributions from dynamic changes in cellular signaling also play an important role in arrhythmogenesis.

Impact of Alcohol Consumption on Atrial Fibrillation Outcomes Following Pulmonary Vein Isolation

Background

Moderate to heavy alcohol use has been shown to be associated with increased atrial fibrillation (AF) incidence. However, the relationship between alcohol use and AF recurrence after pulmonary vein isolation (PVI) is not well known.

Objective

We sought to study the impact of different alcohol consumption levels on outcomes after AF ablation.

Methods

A retrospective analysis was performed of 226 consecutive patients undergoing first time PVI for AF. Clinical data were collected including alcohol intake classified into 3 groups: none-rare (< 1 drink/ week), moderate (1-7 drinks/ week), and heavy (> 7 drinks/ week). Patients were followed for recurrences within the first 3 months (blanking period; early recurrence) and after 3 months up to 1 year (late recurrence) after the ablation.

Results

Paroxysmal and persistent AF had early recurrence rates of 29.1% and 32.2%, and late recurrence rates of 30.2% and 44.1%, respectively. The none-rare alcohol group had a higher frequency of diabetes mellitus (p=0.007). Neither moderate or heavy alcohol consumption, in reference to the none-rare group, was significantly predictive of early or late AF recurrence on adjusted multivariate logistic regression analysis (p>0.05).

Conclusion

Despite known associations between alcohol and incidence of AF, alcohol consumption is not associated with early or late AF recurrence after PVI in this cohort.

Effects of implantable cardioverter/defibrillator shock and antitachycardia pacing on anxiety and quality of life: A MADIT-RIT substudy

Effects of implantable cardioverter/defibrillator (ICD) shocks and antitachycardia pacing (ATP) on anxiety and quality of life (QoL) in ICD patients are poorly understood.

METHODS

We evaluated changes in QoL from baseline to 9-month follow-up using the EQ-5D questionnaire in patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial-Reduce Inappropriate Therapy (MADIT-RIT) (n=1,268). We assessed anxiety levels using the Florida Shock Anxiety Scale (1-10 score) in patients with appropriate or inappropriate shocks or ATP compared to those with no ICD therapy during the first 9 months postimplant. The analysis was stratified by number of ATP or shocks (0-1 vs ≥2) and adjusted for covariates.

RESULTS

In MADIT-RIT, 15 patients (1%) had ≥2 appropriate shocks, 38 (3%) had ≥2 appropriate ATPs. Two or more inappropriate shocks were delivered in 16 patients (1%); ≥2 inappropriate ATPs, in 70. In multivariable analysis, patients with ≥2 appropriate shocks had higher levels of shock-related anxiety than those with ≤1 appropriate shock (P<.01). Furthermore, ≥2 inappropriate shocks produced more anxiety than ≤1 inappropriate shock (P=.005). Consistently, ≥2 appropriate ATPs resulted in more anxiety than ≤1 (P=.028), whereas the number of inappropriate ATPs showed no association with anxiety levels (P=.997). However, there was no association between QoL and appropriate or inappropriate ATP/shock (all P values > .05).

CONCLUSIONS

In MADIT-RIT, ≥2 appropriate or inappropriate ICD shocks and ≥2 appropriate ATPs are associated with more anxiety at 9-month follow-up despite no significant changes in the assessment of global QoL by the EQ-5D questionnaire. Innovative ICD programming reducing inappropriate therapies may help deal with patient concerns about the device.

Abstract 248: Age-specific Differences in Outcomes Following Isoproterenol-induced Sudden Cardiac Death in Guinea Pigs

Background: The pathophysiological mechanisms involved in adult and pediatric heart failure (HF) are unique. One example of clinical differences in these two patient populations is the need for primary prevention implantable defibrillators (ICDs) in adults with HF, whereas pediatric HF patients infrequently have ventricular arrhythmias and rarely require ICDs. To better understand the age-specific molecular mechanisms involved in HF, we are developing a guinea pig model of pediatric HF. We have found age-specific differences in guinea pigs acutely treated with isoproterenol (ISO). Additionally, initial exposure to ISO leads to sudden death in guinea pigs. This sudden death has previously been reported as an interaction with an inhaled volatile anesthesia. We hypothesized that isoproterenol is leading to sustained ventricular arrhythmias in guinea pigs.

Methods: Adult (n= 11) and young (n= 50) guinea pigs were treated with vehicle, 16 mg/kg/day or 32 mg/kg/day of ISO by osmotic pump (Alzet) implanted under isoflurane anesthesia. Cardiac rhythm was monitored in a subset via simultaneously implanted Linq recorders (Medtronic, n= 12).

Results: Acute exposure to ISO in the presence or absence of isoflurane resulted in sudden death in adult and young guinea pigs. Four of the 6 adult guinea pigs exposed to ISO died even with attempts at resuscitation. In contrast, 61% (22 out of 36) of the young guinea pigs treated with ISO arrested and 60% (13 out of 22) were rescued with chest compressions. Analysis of the heart rhythms demonstrated that the guinea pigs experienced ventricular fibrillation. The arrhythmia was transient in the young guinea pigs, but sustained in the adult.

Conclusions: Acute ISO leads to age-dependent differences in arrhythmias and sudden death in guinea pigs. Contrary to prior reports, this response occurs independently of isoflurane. These age-specific differences suggest unique mechanisms in calcium handling, which can lead to arrhythmias. Guinea pigs may be a useful model for the age-related differences in HF arrhythmias seen in humans. A better understanding of these differences may lead to the development of therapies to protect adult HF patients from arrhythmias.

Clinical Presentation and Outcomes by Sex in Arrhythmogenic Right Ventricular Cardiomyopathy: Findings from the North American ARVC Registry

BACKGROUND

Sex differences in clinical presentation and outcomes of hereditary arrhythmias are commonly reported. We aimed to compare clinical presentation and outcomes in men and women with arrhythmogenic right ventricular cardiomyopathy (ARVC) enrolled in the North American ARVC Registry.

METHODS

A total of 125 ARVC probands (55 females, mean age 38 ± 12; 70 males, mean age 41 ± 15) diagnosed, as either "affected" or "borderline" were included. Baseline clinical characteristics and time-dependent outcomes including syncope, ventricular tachycardia (VT), fast VT (>240 bpm), ventricular fibrillation (VF), and death were compared between males and females.

RESULTS

The percentage of ARVC subjects diagnosed as "affected" (84% vs. 89%; P = 0.424) or "borderline" (16% vs. 11%; P = 0.424) was similar between females and males. Among the baseline characteristics, inverted T-waves in V2 trended to be more common in women (P = 0.09), whereas abnormal signal-averaged ECGs (SAECGs; P < 0.001) and inducible VT/VF (P = 0.026) were more frequent in men. During a mean follow-up of 37 ± 20 months, the probability of ICD-recorded VT/VF or death was not significantly different between men and women (P = 0.456). However, there was a trend toward lower risk of fast VT/VF or death in women compared to men (hazard ratio 0.41, 95% CI 0.151-1.113, P = 0.066). Abnormal SAECG and evidence of intramyocardial fat by cardiac MRI was associated with adverse outcomes in men (P = 0.006 and 0.02 respectively).

CONCLUSION

In the North American ARVC Registry, we found similar frequency of "affected" and "borderline" subjects between men and women. Sex-related differences were observed in baseline ECG, SAECG, Holter-recorded ventricular arrhythmias, and VT inducibility. Men showed a trend toward greater risk of fast VT than women.

Early procedure-related adverse events by gender in MADIT-CRT

BACKGROUND

Whether gender differences exist in procedure-related adverse events following cardiac resynchronization therapy (CRT-D) implantation is unknown. We investigated the type and frequency of procedure-related adverse events among those enrolled in MADIT-CRT and identified clinical predictors for gender-specific events.

METHODS

We compared differences in the rate of procedure-related adverse events by gender (444 females and 1,346 males) that occurred ≤30 days after the index procedure in the implantable cardioverter defibrillator (ICD) and CRT-D groups. Eight types of major adverse events were identified, defined as procedure-related complications deemed potentially life-threatening. Best subset regression analysis (P < 0.10) was performed to identify baseline clinical factors associated with procedure-related adverse events that differed by gender.

RESULTS

Women randomized to CRT-D received a greater reduction in the risk of heart failure or death versus men (P < 0.001). Women were twice as likely as men to experience a major procedure-related adverse event (6.3% vs. 2.7%; P < 0.001), including pneumothorax/hemothorax (3% vs. 1%; P < 0.001). Women were more likely to experience a major adverse event related to CRT-D than ICD implantation (7.7% vs. 2.9%; P = 0.018). Clinical predictors of major adverse events in females were smaller body mass index (BMI), elevated blood urea nitrogen, and elevated creatinine. The main predictor for pneumothorax/hemothorax was reduced BMI for women and men.

CONCLUSION

Women demonstrate greater clinical benefit from CRT than men but are more likely to experience adverse procedure-related events within the first 30 days after device implantation. A smaller BMI seems to be a major factor associated with pneumothorax/hemothorax in both females and males.

Effect on cardiac function of cardiac resynchronization therapy in patients with right bundle branch block (from the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy [MADIT-CRT] trial)

Cardiac resynchronization therapy (CRT) is effective for the treatment of patients with heart failure and a wide QRS duration, particularly left bundle branch block. However, subjects with right bundle branch block (RBBB) do not appear to benefit from CRT. The aim of this study was to determine whether patients with specific RBBB conduction patterns responded to CRT in the Multicenter Automatic Defibrillator Implantation Trial with Cardiac Resynchronization Therapy (MADIT-CRT) trial. In the present post hoc analysis, patients with RBBB who received CRT with an implantable cardioverter defibrillator (n = 132) were divided into 2 groups according to the baseline QRS morphology in the inferior and high lateral leads: group 1: left anterior fascicular block (LAFB) pattern (n = 80; 60.6%); and group 2: non-LAFB pattern (n = 52; 39.4%). Subjects with RBBB who received an implantable cardioverter defibrillator served as the control group (n = 87). The primary end point was echocardiographic response to CRT, defined as percent change in left ventricular (LV) and left atrial volumes from baseline to 1 year. The secondary end point was heart failure or death. The non-LAFB group demonstrated a significantly larger percent reduction in LV end-diastolic volume, LV end-systolic volume, and left atrial volume compared to controls (-11%, p <0.0001; -17%, p <0.0001; -15%, p <0.0001, respectively) and LAFB (-5%, p = 0.028; -7%, p = 0.019; -6%; p = 0.022; respectively) by multivariate analysis. No difference was found in the 3-year crude event rates for death or heart failure among the LAFB (22%), non-LAFB (21%), or ICD-only (20%) groups (p = NS). In conclusion, conduction patterns influence echocardiographic response to CRT in patients with RBBB, with favorable reductions in the LV and left atrial volumes in those without an LAFB conduction pattern. This echocardiographic benefit did not translate into a reduction in heart failure or death during a 3-year follow-up period.

Significance of leukocytosis after cardiac device implantation

Infection remains a feared complication after cardiac device implantation. Whether early postprocedural leukocytosis, a recognized marker of infection, is an indicator of impending infection is unclear and was the focus of this study. A retrospective chart review of consecutive patients who underwent implantable cardioverter defibrillator or pacemaker implantation was performed. The association between change in white blood cell (WBC) count and development of infection after device implantation was assessed. Infection was defined as pocket or lead infection or as bacteremia or sepsis <60 days after implantation. Pre- and postprocedural WBC counts were obtained within 48 hours of the procedure. Significant leukocytosis was defined as a ≥50% increase in WBC count; 1,245 device implantations met inclusion criteria. Device-related infections occurred in 8 cases (0.6%). A modest 17.6 ± 30.2% increase in WBC count was observed for the entire cohort. Cases resulting in infection demonstrated minimal change in WBC count (mean +5.5 ± 26.5%). No infections occurred in patients with ≥50% increases in WBC count or postprocedural WBC counts >15,000/μl. Subjects with significant leukocytosis were younger (mean age 61.9 ± 16.5 vs 65.6 ± 15.1 years, p <0.01), had longer procedure times (mean 198 ± 97 vs 170 ± 77 minutes, p <0.001), and received biventricular implantable cardioverter-defibrillators (25% vs 13.9%, p <0.001). In conclusion, after device implantation, a ≥50% increase in WBC count occurred in about 10% to 15% of patients. Age, race, type of device, and procedure time influenced the development of significant leukocytosis. Elevation in WBC count after cardiac device implantation was not associated with an increased risk for early infection.

The value of defibrillator far-field electrograms for ablation of idiopathic ventricular fibrillation

We report a case of idiopathic ventricular fibrillation treated by catheter ablation of the monomorphic initiating premature beat. The initiating focus was identified using intacardiac defibrillator electrograms (EGMs).

Optimal strategies for the management of antiplatelet and anticoagulation medications prior to cardiac device implantation

Choosing the optimal management strategy for antiplatelet and anticoagulation medications at the time of cardiac device implantation can be challenging. Simply withholding or reversing these medications puts patients at risk of subsequent thromboembolic events. Equally, continuing these medications may unnecessarily increase the risk of bleeding complications. This article summarizes recent findings and provides compelling evidence challenging current recommendations outlined by various professional organizations.

Long-term follow-up of patients immunized with AN1792: reduced functional decline in antibody responders

BACKGROUND

Immunization of patients with Alzheimer's disease (AD) with synthetic amyloid-beta peptide (Abeta(42)) (AN1792) was previously studied in a randomized, double-blind, placebo-controlled phase 2a clinical trial, Study AN1792(QS-21)-201. Treatment was discontinued following reports of encephalitis. One year follow-up revealed that AN1792 antibody responders showed improvements in cognitive measures as assessed by the neuropsychological test battery (NTB) and a decrease in brain volume compared with placebo.

METHODS

A follow-up study, Study AN1792(QS-21)-251, was conducted to assess the long-term functional, psychometric, neuroimaging, and safety outcomes of patients from the phase 2a study 4.6 years after immunization with AN1792. The results were analyzed by comparing patients originally identified as antibody responders in the AN1792 phase 2a study with placebo-treated patients.

RESULTS

One hundred and fifty-nine patients/caregivers (30 placebo; 129 AN1792) participated in this follow-up study. Of the 129 AN1792-treated patients, 25 were classified in the phase 2a study as antibody responders (anti-AN1792 titers > or = 1:2,200 at any time after the first injection). Low but detectable, sustained anti-AN1792 titers were found in 17 of 19 samples obtained from patients classified as antibody responders in the phase 2a study. No detectable anti-AN1792 antibodies were found in patients not classified as antibody responders in the phase 2a study. Significantly less decline was observed on the Disability Assessment for Dementia scale among antibody responders than placebo-treated patients (p=0.015) after 4.6 years. Significant differences in favor of responders were also observed on the Dependence Scale (p=0.033). Of the small number of patients who underwent a follow-up MRI, antibody responders showed similar brain volume loss during the follow-up period subsequent to the AN1792 phase 2a study compared with placebo-treated patients.

CONCLUSIONS

Approximately 4.6 years after immunization with AN1792, patients defined as responders in the phase 2a study maintained low but detectable, sustained anti-AN1792 antibody titers and demonstrated significantly reduced functional decline compared with placebo-treated patients. Brain volume loss in antibody responders was not significantly different from placebo-treated patients approximately 3.6 years from the end of the original study. No further cases of encephalitis were noted. These data support the hypothesis that Abeta immunotherapy may have long-term functional benefits.

The metabolic syndrome in women

The metabolic syndrome, an increasingly prevalent disorder, is known to significantly enhance the risk of developing cardiovascular disease and diabetes. The syndrome is defined by a constellation of cardiac risk factors that include obesity, atherogenic dyslipidemia, hypertension, and insulin resistance. There are several unique features of the metabolic syndrome in women. An insulin-resistant state associated with both polycystic ovarian syndrome and increased abdominal fat may contribute to the development of the metabolic syndrome and increase cardiovascular risk when present. Menopause heralds a decline in circulating estrogen levels, which may increase cardiovascular risk through effects on adiposity, lipid metabolism, and prothrombotic state. The key elements involved in managing the metabolic syndrome are dietary and lifestyle modification. Appropriate treatment may also include managing individual cardiac risk factors with the use of antihypertensive and lipid-modifying agents among others.

Balancing diversion control and medical necessity: the case of prescription drugs with abuse potential

Narcotics and other prescription drugs play a significant and legitimate role in medical practice. The illicit use of prescribed medicines, however, remains a major problem. This paper examines the effectiveness of two drug diversion control programs, multiple copy prescriptions programs (MCPP) and electronic data transfer (EDT) systems, and their impact on medical practice. Current evidence demonstrates that these programs decrease prescription drug use, with much of the decrease due to declines in inappropriate use. MCPPs appear more effective than EDT in preventing diversion. More research is needed. however, to assess their effects on medical practice, particularly patient quality of care.