ACC/AHA/NASPE 2002 guideline update for implantation of cardiac pacemakers and antiarrhythmia devices: summary article: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (ACC/AHA/NASPE Committee to Update the 1998 Pacemaker Guidelines)

The Drug And Pace Health cliNical Evaluation (DAPHNE) study: a randomized trial comparing sotalol versus beta-blockers to treat symptomatic atrial fibrillation in patients with brady-tachycardia syndrome implanted with an antitachycardia pacemaker

BACKGROUND

Atrial tachyarrhythmias (ATAs) are mainly treated by pharmacologic therapy for rate control or rhythm control. The aim of our study was to compare sotalol (S) versus beta-blocking agents (BB) in terms of prevention of ATA, cardioversions (CVs), and cardiovascular hospitalizations (H) in patients paced for bradycardia-tachycardia form of sinus node disease (BT-SND).

METHODS

One hundred thirty-five patients (67 males, aged 73 +/- 7 years) were enrolled in a prospective, parallel, randomized, single-blind, multicenter study. All patients received a dual chamber rate adaptive pacemaker; after 1 month, 66 patients were randomly assigned to BB (62 +/- 26 and 104 +/- 47 mg/d for atenolol and metoprolol, respectively) and 69 patients to S (167 +/- 66 mg/d).

RESULTS

After an observation period of 12 months, the percentage of patients free from ATA recurrences was 29% in both BB and S group. Cardioversion and H were significantly (P < .01) fewer in the 12 months after implantation than in the 12 months before both in patients treated with S (CV 69.4% vs 22.2%, H 91.7% vs 33.3%) and in patients treated with BB (CV 58.5% vs 17.1%, H 82.9% vs 26.8%). Kaplan-Meier survival analysis showed a nonsignificant trend toward a lower incidence of the composite end point (CV + H) among BB patients.

CONCLUSIONS

In the complex context of "hybrid therapy" in patients with BT-SND implanted with a modern dual chamber rate adaptive pacemaker device delivering atrial antitachycardia pacing, no differences were found between the use of beta-blocker and the use of S, at the relatively low dose achieved after clinical titration, in terms of prevention of cardiovascular H or need for atrial CV.

Electrocardiographic abnormalities and sudden death in myotonic dystrophy type 1

BACKGROUND

Sudden death can occur as a consequence of cardiac-conduction abnormalities in the neuromuscular disease myotonic dystrophy type 1. The determinants of the risk of sudden death remain imprecise.

METHODS

We assessed whether the electrocardiogram (ECG) was useful in predicting sudden death in 406 adult patients with genetically confirmed myotonic dystrophy type 1. A patient was characterized as having a severe abnormality if the ECG had at least one of the following features: rhythm other than sinus, PR interval of 240 msec or more, QRS duration of 120 msec or more, or second-degree or third-degree atrioventricular block.

RESULTS

Patients with severe abnormalities according to the entry ECG were older than patients without severe abnormalities, had more severe skeletal-muscle impairment, and were more likely to have heart failure, left ventricular systolic dysfunction, or atrial tachyarrhythmia. Such patients were more likely to receive a pacemaker or an implantable cardioverter-defibrillator during the follow-up period. During a mean follow-up period of 5.7 years, 81 patients died; there were 27 sudden deaths, 32 deaths from progressive neuromuscular respiratory failure, 5 nonsudden deaths from cardiac causes, and 17 deaths from other causes. Among the 17 patients who died suddenly in whom postcollapse rhythm was evaluated, a ventricular tachyarrhythmia was observed in 9. A severe ECG abnormality (relative risk, 3.30; 95% confidence interval [CI], 1.24 to 8.78) and a clinical diagnosis of atrial tachyarrhythmia (relative risk, 5.18; 95% CI, 2.28 to 11.77) were independent risk factors for sudden death.

CONCLUSIONS

Patients with adult myotonic dystrophy type 1 are at high risk for arrhythmias and sudden death. A severe abnormality on the ECG and a diagnosis of an atrial tachyarrhythmia predict sudden death. (ClinicalTrials.gov number, NCT00622453.)

Primary prevention of sudden cardiac death using implantable cardioverter defibrillators

Despite substantial advances in prevention and treatment of cardiovascular diseases, sudden cardiac death (SCD) remains a leading cause of death in industrialized countries. Implantable cardioverter defibrillator (ICD) has been demonstrated to be an attractive option for primary prevention of SCD in high-risk patients. This review discusses the progress in the risk stratification for selecting high-risk patients, highlights the clinical trials of primary prevention for SCD, outlines the efficacy of combined use of cardiac resynchronization therapy with ICD, and analyses the cost-effectiveness issue of this device.

Temporal trends in permanent pacemaker implantation: a population-based study

BACKGROUND

Limited data exist regarding temporal trends in permanent pacemaker (PPM) implantation. To describe trends in incidence and comorbidities of PPM recipients, we conducted a retrospective population-based cohort study over a 30-year period.

METHODS

All 1291 adult residents of Olmsted County, Minnesota, undergoing PPM implantation between 1975 and 2004 were included in the study. Trends in PPM implantation incidence, pacing mode and indication, and comorbidities (via Charlson Comorbidity Index [CCI]) were assessed through the Rochester Epidemiology Project. Permanent pacemaker recipients were compared with age- and sex-matched PPM-free controls from the population.

RESULTS

Adjusted implantation incidence rates increased from 36.6 per 100,000 person-years during 1975 to 1979 to 99 per 100,000 person-years during 2000 to 2004 (P < .0001). After adjusting for age (hazard ratio [HR] 1.06 per year), male sex (HR 1.28), and implant year (HR 0.98), the HR for death among PPM recipients by CCI quartiles was 1.0, 1.79, 2.29, and 3.91 for CCI of 0 to 1 (reference), 2 to 3, 4 to 6, and > or = 7, respectively (P < .0001). Overall, PPM recipients had higher CCI than the population-based controls (P = .04), with higher mean CCI noted since 1990. Mean age-adjusted CCI increased from 3.15 to 4.60 among the cases (P < .0001) and from 3.06 to 3.54 among the age- and sex-matched controls (P = .047).

CONCLUSIONS

There have been significant increases in incidence of PPM implantation over 30 years, and PPM recipients have had an age-independent increase in comorbidities relative to the underlying population, especially over the past 15 years.

Kearns-Sayre syndrome presenting as complete heart block

Kearns-Sayre syndrome (KSS) is a rare mitochondrial disorder characterized by large-scale deletions of mitochondrial DNA. Neuromuscular and cardiac conduction systems are most commonly involved in these patients. Here, we discuss a 10-year-old patient with diabetes mellitus who presented in complete heart block leading to the diagnosis of KSS. The cardiovascular complications of this syndrome are reviewed and discussed.

Prevention of inappropriate therapy in implantable defibrillators: A meta-analysis of clinical trials comparing single-chamber and dual-chamber arrhythmia discrimination algorithms

INTRODUCTION

A proposed benefit of dual-chamber arrhythmia discrimination is a reduction in inappropriate therapy in implantable cardioverter-defibrillators (ICDs). The aim of this meta-analysis was to establish whether dual-chamber arrhythmia discrimination algorithms reduce inappropriate device therapy.

METHODS AND RESULTS

Public domain databases, MEDLINE, EMBASE, and Cochrane Register of Controlled Trials, were searched from 1996 to 2006. Two investigators abstracted data independently. Pooled estimates were calculated using both fixed-effects and random-effects models. We retrieved 5 prospective studies comparing dual-chamber with single-chamber arrhythmia discrimination, accumulating data on 748 patients. Pooled per-patient based analysis demonstrated that the number of patients receiving inappropriate ICD therapy was not different between single- and dual-chamber devices (odds ratio [OR] 1.23; 95% CI, 0.83 to 1.81; p=0.31). Per-episode based analysis demonstrated a favoring benefit for dual-chamber arrhythmia discrimination (OR 0.64; 95% CI, 0.52 to 0.78; p<0.001). A mean reduction of 1.1 inappropriately treated atrial episodes per patient was observed with dual-chamber arrhythmia discrimination (p<0.001).

CONCLUSIONS

Dual-chamber arrhythmia discrimination is associated with a reduction in the number of inappropriate treated episodes. The number of patients who experience inappropriate therapy is not reduced by dual-chamber discrimination.

Pacemaker infection secondary to burkholderia pseudomallei

Infection is a relatively rare but devastating complication of intracardiac device implantation. Burkholderia pseudomallei is the organism which causes melioidosis, an endemic and lethal infection in the tropics. We describe a case of pacemaker infection secondary to Burkholderia pseudomallei, which was treated by explantation of the device and appropriate antimicrobial therapy.

Persistent atrial fibrillation worsens heart rate variability, activity and heart rate, as shown by a continuous monitoring by implantable biventricular pacemakers in heart failure patients

BACKGROUND

Atrial fibrillation (AF) induces loss of atrial contribution, heart rate irregularity, and fast ventricular rate.

OBJECTIVES

The objectives of the study were to accurately measure AF incidence and to investigate the mutual temporal patterns of AF and heart failure (HF) in patients indicated to cardiac resynchronization therapy.

METHODS

Four hundred ten consecutive patients (70% male, age 69 +/- 11) with advanced HF (NYHA = 3.0 +/- 0.6), low ejection fraction (EF = 27 +/- 9%), and ventricular conduction delay (QRS = 165 +/- 29 ms) received a biventricular pacemaker. Enrolled patients were divided into two groups: G1 = 249 patients with no AF history, G2 = 161 patients with history of paroxysmal/persistent AF.

RESULTS

In a median follow-up of 13 months, AF episodes longer than 5 minutes occurred in 105 of 249 (42.2%) G1 patients and 76 of 161 (47.2%) G2 patients, while AF episodes longer than one day occurred in 14 of 249 (5.6%) G1 patients and in 36 of 161 (22.4%) G2 patients. Device diagnostics monitored daily values of patient activity, night heart rate (NHR), and heart rate variability (HRV). Comparing 30-day periods before AF onset and during persistent AF, significant (P < 0.0001) changes were observed in patient activity, which decreased from 221 +/- 13 to 162 +/- 12 minutes, and in NHR, which increased from 68 +/- 3 to 94 +/- 7 bpm. HRV significantly decreased (from 75 +/- 5 ms before AF onset to 60 +/- 6 ms after AF termination). NHR during AF was significantly (P < 0.01) and inversely correlated (R(2)= 0.73) with activity, with a significant lower activity associated with NHR >or= 88 bpm.

CONCLUSION

AF is frequent in HF patients. Persistent AF is associated with statistically significant decrease in patient activity and HRV and NHR increase.

Magnetocardiography in the evaluation of fetuses at risk for sudden cardiac death before birth

BACKGROUND

We hypothesized that fetuses at risk for sudden death may have abnormal conduction or depolarization, ischemia, or abnormal heart rate variability (HRV) detectable by magnetocardiography.

METHODS

Using a 37-channel biomagnetometer, we evaluated 3 groups of fetuses at risk for sudden death: group 1, critical aortic stenosis (AS); group 2, arrhythmias; and group 3, heart failure and in utero demise. Five to 10 recordings of 10-minute duration were recorded, and signal was averaged to determine rhythm, conduction intervals, HRV, and T-wave morphology.

RESULTS

In group 1, 2 of 3 had atrial and ventricular strain patterns. In (n = 53) group 2, 15% had prolonged QTc and 17% had T-wave alternans (TWA). Of 23 group 2 fetuses with atrioventricular block, 74% had ventricular ectopy, 21% had junctional ectopic tachycardia, and 29% had ventricular tachycardia. Group 3 (n = 2) had abnormal HRV and TWA.

CONCLUSION

Repolarization abnormalities, unexpected arrhythmias, and abnormal HRV suggest an arrhythmogenic mechanism for "sudden cardiac death before birth."

Biventricular pacing and defibrillator use in chronic heart failure

Since the 1970s when the implantable cardioverter defibrillator (ICD) was developed, multiple clinical trials have documented survival benefits in certain high-risk subsets of heart failure patients. Over the past decade, cardiac resynchronization therapy (CRT) emerged as an important therapy in carefully selected patients with ongoing symptoms despite optimized pharmacological therapy. ICDs should be considered first-line therapy for survivors of life-threatening ventricular arrhythmic events. Subsets of patients with both ischemic and nonischemic dilated cardiomyopathy appear to have a survival benefit from primary ICD therapy. CRT has resulted in substantial symptomatic improvement and survival benefits in a subgroup of chronic heart failure patients. CRT should be considered in heart failure patients undergoing ICD implantation who have evidence of ventricular dyssynchrony.

Management of heart failure in elderly people

AIMS

To review currently available knowledge on presentation, clinical features and management of heart failure (HF) in elderly people.

METHODS

To review currently available evidence, we performed a thorough search of several evidence-based sources of information, including Cochrane Database of Systematic Reviews, Clinical Evidence, Evidence-based guidelines from National Guidelines Clearinghouse and a comprehensive MEDLINE search with the MeSH terms: 'heart failure', 'elderly' and 'management'.

RESULTS

A number of features of ageing may predispose elderly people to HF, and may impair the ability to respond to injuries. Another hallmark of elderly patients is the increasing prevalence of multiple coexisting chronic conditions and geriatric syndromes that may complicate the clinical presentation and evolution of HF. Although diagnosis may be challenging, because atypical symptoms and presentations are common, and comorbid conditions may mimic or complicate the clinical picture, diagnostic criteria do not change in elderly people. Drug treatment is not significantly different from that recommended in younger patients, and largely remains empiric, because clinical trials have generally excluded elderly people and patients with comorbid conditions. Disease management programmes may have the potential to reduce morbidity and mortality for patients with HF.

CONCLUSIONS

Heart failure is the commonest reason for hospitalisation and readmission among older adults. HF shows peculiar features in elderly people, and is usually complicated by comorbidities, presenting a significant financial burden worldwide, nevertheless elderly people have been generally excluded from clinical trials, and thus management largely remains empiric and based on evidence from younger age groups.

Documented transient third-degree atrioventricular block and asystole in a child with familial dysautonomia

An 11-year-old boy with familial dysautonomia presented with palpitations. Continuous 24-h Holter monitoring revealed intermittent high-grade atrioventricular block and asystole. The unopposed parasympathetic tone in patients with dysautonomia may make them susceptible to bradycardia and atrioventricular block. We recommend routine 24-h Holter monitoring screening and, when indicated, consideration of pacemaker implantation to reduce the high risk of sudden death phenomena in this patient population.

Late onset of heart block after open heart surgery for congenital heart disease

Late onset of complete heart block is a potentially dangerous complication after open heart surgery for congenital heart disease. The characteristics of patients with late-onset heart block have not been well described. A retrospective review of a pacemaker database was done to identify patients who presented with new onset heart block between 1988 and 2006, after they had been discharged from the hospital after open heart surgery with normal AV conduction. Fifteen patients were identified. The age at the time of the last surgery before the onset of heart block was 2.0 +/- 3.2 years (range: 3 days to 10 years). Nine had a ventricular septal defect repair, four had an atrioventricular canal, and two other patients had other types of heart defect. The last EKG available for analysis before the onset of heart block had been obtained 5.1 +/- 6.5 years (range: 7 days to 16 years) after surgery. The symptoms at the time of presentation were variable. Four patients presented with fatigue or exercise intolerance, two with syncope, two with congestive heart failure, and one with irritability, and the remaining six patients were diagnosed during routine follow-up. The time between open heart surgery and placement of a permanent pacemaker was 6.8 +/- 7.3 years (range: 2 months to 19 years). There were seven patients in whom the onset of heart block was more than 6 years after surgery. Late onset of complete heart block after open heart surgery could be dangerous when presenting without warning. These data would support the notion that patients should be followed for life after repair of congenital heart defects, with special attention to the conduction system, particularly after repair of septal defects.

Effects of ICD implantation on quality-adjusted life years in patients with congestive heart failure

BACKGROUND

Effects of prophylactic implantable cardioverter-defibrillator (ICD) on quality-adjusted life years (QALYs) in patients with congestive heart failure are uncertain.

METHODS

We developed a decision model for patients at risk of sudden death due to reduced ejection fraction and who had no history of life-threatening ventricular arrhythmias. It estimated the QALYs for ICD strategy as a primary prevention for sudden cardiac death and conventional strategy without antiarrhythmic therapies.

RESULTS

In a 3-year time period, the QALYs for patients with conventional strategy were higher than that of ICD strategy (2.19 years vs. 2.14 years). When the mortality rate of conventional strategy exceeded 8.6%/year and the hazard ratio of death for the ICD strategy was lower than 0.70, the ICD strategy was the superior treatment option.

CONCLUSIONS

The QALYs of patients with ICD could be lower than that of conventional strategy. Incorporating quality of life could affect decision making of ICD implantation.

[Causes of pauses]

We discuss the electrocardiogram and differential diagnosis of an apparent type II second-degree atrioventricular block recorded in a 15-year-old girl after successful radiofrequency ablation of a left-sided concealed accessory pathway.

Bifocal versus unifocal right atrial pacing under plasma level controlled sotalol to prevent atrial fibrillation in patients with symptomatic sinus bradycardia and paroxysmal atrial fibrillation

AIMS

Bifocal right atrial pacing (BP) has been reported to increase arrhythmia-free intervals in patients with paroxysmal atrial fibrillation (PAF) under antiarrhythmic drugs. This study compares AF burden with unifocal pacing (UP) vs BP under sotalol.

METHODS

In 19 patients with PAF a DDDR pacemaker with right atrial lateral and CS ostial leads was implanted. Sotalol was initiated. After a 3 month back-up pacing period patients were randomized to continuous UP or BP for 3 months and crossed over for 3 more months. Primary endpoint was AF burden. Secondary endpoints included number of episodes, time to first recurrence and safety of BP.

RESULTS

The intention to treat analysis revealed 12.4% AF during back-up, 6.2% during UP and BP (p=0.91 UP vs BP, p=0.08 back-up vs UP and p=0.07 back-up vs BP). Per protocol analysis showed no advantage of either pacing mode (UP 4.8% and BP 5.4% AF, p=0.64). Overdrive pacing reduced AF burden to 6.2 vs 8.8% during back-up (p=0.09). Septal lead dislodgement occurred in 3 patients.

CONCLUSION

Atrial pacing tends to reduce AF burden in patients with PAF under sotalol. An incremental effect of BP vs UP cannot be confirmed. BP may be complicated by elevated lead dislodgement rates.

Long-term cardio-respiratory consequences of heart disease in childhood

The dynamic interaction between the heart and lungs leads to a degree of respiratory co-morbidity including both restrictive and obstructive airway abnormalities, which may be overlooked in children with congenital and acquired heart disease. The improving imaging techniques of the heart, both foetal and post-natal coupled with minimally invasive techniques for device implantation and better operative techniques for complex congenital heart disease have resulted in more children with longitudinally documented structural heart disease surviving into their adult years. Children presenting with cardiomyopathy or arrhythmias, as well as those with repaired cardiac disease, can be offered advice with regard to formal exercise testing and participation in sports, which may be particularly helpful in the adolescent years. Furthermore, through the interest of some adult cardiologists in paediatric heart disease over the past 20 years, facilities for the smooth transition of care to adult services are improving.

Two Different Therapeutic Strategies in ICD Lead Defects: Additional Combined LeadVersus Replacement of the Lead

OBJECTIVES

Implantation of an additional HV-P/S lead versus extraction of the defective HV-P/S lead and implantation of a new one is one possible therapeutic approach in cases of a defective high-voltage pace/sense lead (HV-P/S). No information is available on potential differences in clinical outcome in these different approaches.

METHODS

Between January 2000 and February 2006, 86 patients with HV-P/S lead defect received either an additional transvenous HV-P/S lead (n = 33, group 1) or the HV-P/S lead was replaced (n = 53, group 2). The duration of the initially implanted leads was significantly different in the two groups (7.4 +/- 2.9; group 1 and 4.1 +/- 3.4 years; group 2). The outcome of these two groups of patients was retrospectively analyzed.

RESULTS

Seventy-three patients [85%] survived until the end of follow-up of 29 +/- 15 (group 1) and 33 +/- 21 (group 2) months (P = ns), respectively. Thirteen patients died: six in group 1 and seven in group 2 (P = ns). Fourteen patients experienced perioperative complications (group 1: six; group 2: eight; P = ns). ICD system-related complications occurred in 22 patients (group 1: seven; group two: 15; P = ns). The event-free cumulative survival of patients with additional and replaced HV-P/S lead for postoperative events (including death) after 1, 2, and 3 years was 82%, 70%, 70%, and 86%, 81%, 66%, respectively (P = 0.93).

CONCLUSIONS

Implantation of an additional HV-P/S lead or replacement of the HV-P/S lead in case of HV-P/S lead failure is statistically not different concerning mortality and morbidity. There are no predictors for further lead defects. Implantation of an additional HV-P/S lead should not be recommended in young patients or patients with greater likelihood of living many years. Predictors for death were an age over 70 years and renal insufficiency.

Progression of paroxysmal atrial fibrillation to persistent atrial fibrillation in patients with bradyarrhythmias

INTRODUCTION

The experimental concept that "atrial fibrillation (AF) begets AF" implies that atrial tachyarrhythmia (AT)/AF burden uniformly increases over time. However, the temporal patterns of paroxysmal AT/AF burden progression, its conversion to persistent AF, and the relationship to underlying disease in humans are unknown. We analyzed the average daily AT/AF burden in patients with concomitant bradycardia and paroxysmal AF to examine these issues.

METHODS

Three hundred thirty patients with a history of paroxysmal AF (mean age 70 +/- 10 years; 61% male) were implanted with a pacemaker that automatically recorded the cumulative daily AT/AF burden. Persistent AT/AF was defined as 7 consecutive days with >23 hours of AT on the device data logs. Antiarrhythmic drug therapy was required to be stable for at least 7 months.

RESULTS

Average follow-up was 401 +/- 123 days. Seventy-eight patients (24%) progressed to persistent AT/AF during the follow-up period with a mean interval of 147 +/- 149 days. Mean AT/AF burden increased progressively (slope 14 s/d, P < .001) over 500 days after implant, and median AT/AF burden also increased (P < .01) in this subgroup of patients. This increase was highly correlated with the presence of structural heart disease (P < .001). There was a concomitant decrease in atrial premature beat (APB) frequency. Most patients transitioning to persistent AF were in sinus rhythm with minimal AT/AF burden in the days immediately before persistent AF. Neither mean nor median AT/AF burden increased over time in patients remaining in paroxysmal AF (slope 0 s/d, P = .7) despite a higher APB frequency than in patients with heart disease (P =.003) and a higher likelihood of daily AT/AF events (P < .001).

CONCLUSIONS

Temporal patterns of AT/AF burden in patients developing persistent AF show a progressive increase with a sudden transition to persistent AF. This is more consistent with substrate changes, rather than increased density of triggering APBs or paroxysmal AT/AF events. Thus, progression to persistent AF is probably related to an AF substrate, which is undergoing progressive structural remodeling owing to heart disease and other factors and is now suddenly capable of sustaining prolonged or multiple ATs. Therapies directed at the atrial substrate may be needed to prevent persistent AF.

Value of VDD-pacing systems in patients with atrioventricular block: Experience over a decade

BACKGROUND

Even though current guidelines suggest the use of VDD pacemakers in patients with AV block and normal sinus node function, a DDD system is often preferred for fear of either long-term atrial undersensing or late sinus node dysfunction and the resultant need for system upgrades.

METHODS

We evaluated the long-term follow-up of all VDD pacemakers implanted in our center between 1992 and 2001 regarding atrial sensing, maintenance of AV synchrony, incidence of atrial fibrillation (AF), or the need for system upgrade, respectively.

RESULTS

320 consecutive patients (56% men, age 75+/-13 years) received a VDD pacemaker for the following indications: third-degree AV block 54%, second-degree AV block 34%, fascicular block with first-degree AV block and syncope 6%, others 6%. 138 patients (43%) died during follow-up, 3.8+/-2.3 years after implantation. Follow-up duration was 6.1+/-2.5 years in the remaining patients. At the last follow-up, 268 pacemakers (84%) were programmed to the VDD mode, 47 pacemakers (15%) were permanently programmed to the VVI mode (AF 36, undersensing 7, others 4, respectively). In five patients a DDD upgrade was necessary for sinus node dysfunction (3) or lead defect (2). Lead revision was performed in 19 patients (6%) (ventricular lead dislocation 7, atrial undersensing 6, lead fracture 3, others 2, respectively).

CONCLUSION

VDD pacemakers have an excellent long-term performance in patients with AV block. They have a very low incidence of lead revisions for atrial undersensing (2%) and DDD upgrades for secondary sinus node dysfunction (1%).

Biventricular pacing does not affect microvolt T-wave alternans in heart failure patients

BACKGROUND

Microvolt T-wave alternans (MTWA) is a valuable tool for stratification of patients at risk for sudden death and has recently been approved for this purpose by Medicare. Although right atrial (RA) pacing has been applied for MTWA testing, the effects of other pacing modalities on MTWA have not been systematically studied. Accordingly, it is unknown whether biventricular (BiV) pacing might influence MTWA test results.

OBJECTIVE

This study sought to investigate effects of BiV pacing in comparison with other pacing modalities.

METHODS

Congestive heart failure patients (n = 30) receiving cardiac resynchronization therapy were included, and a systematic step-up pacing protocol was performed via the implanted cardioverter-defibrillator.

RESULTS

Of the overall 120 MTWA tests performed, 67 (56%) were nonnegative. Nonnegative MTWA test results were observed in 18 patients (60%) during RA stimulation, whereas 17 (57%), 15 (50%), and 17 test results (57%) were nonnegative during right ventricular (RV), left ventricular (LV), and BiV pacing, respectively. Seven (23%) patients were MTWA negative for all pacing sites. Results of MTWA assessment during RA pacing were concordant with results obtained with RV pacing in 25 (83%) patients (kappa = 0.66, P = .0003), to LV pacing in 21 (70%) patients (kappa = 0.4, P = .025), and to BiV pacing in 25 (83%) patients (kappa = 0.66, P = .0003). Positive and negative predictive values of nonnegative MTWA test results obtained during RA pacing for a similar result obtained with RV pacing were 88% and 76%. Respective values were similar for other pacing modalities (80% and 60% for LV; 88% and 76% for BiV pacing).

CONCLUSION

There is a high level of concordance between MTWA test results obtained during RA pacing and other pacing modalities, and MTWA assessment seems not to be influenced by BiV stimulation in congestive heart failure patients. In general, BiV pacing does not seem to affect an arrhythmogenic substrate as detected by MTWA testing.

Implantation of a permanent pacemaker in a patient with severe Parkinson's disease and a preexisting bilateral deep brain stimulator

Cardiac pacemakers and implantable defibrillators are commonly used therapeutic modalities in cardiac arrhythmias. Thalamic deep brain stimulation has also become an important modality in the treatment of drug-refractory tremors and other complications in advanced Parkinson's disease. Concerns exist about the potential electrical interaction and interference between these 2 devices in the same patient. There are only a limited number of reports that have investigated this issue. We describe a patient with advanced Parkinson's disease and a previously implanted deep brain stimulator, who subsequently needed a permanent cardiac pacemaker due to severe bradyarrhythmia. Despite the probability of interference between the devices, there were no problems during implantation of the cardiac pacemaker; both the deep brain stimulator and cardiac pacemaker functioned appropriately afterwards.

Treatment of arrhythmias and use of implantable cardioverter-defibrillators to improve survival in elderly patients with cardiac disease

Patients who have left ventricular dysfunction and heart failure (HF) are at high risk for ventricular tachyarrhythmias and sudden cardiac death. Randomized clinical trials have demonstrated that pharmacologic management with antiarrhythmic drugs has limited efficacy for the prevention of arrhythmic mortality in this high-risk population, whereas implantation of a defibrillator was shown to be associated with a significant survival benefit. Data on the efficacy of defibrillator therapy in elderly patients, in whom comorbidities are common, are limited. In this article we outline current information on therapeutic modalities for the prevention of arrhythmic mortality in elderly patients who have left ventricular dysfunction and HF, focusing mainly on data on the benefit of device therapy in the older age group.

Heart Failure–Complicating Acute Myocardial Infarction

This article addresses issues related to acute myocardial infarction (MI) complicated by heart failure, particularly in elderly patients. Findings have shown that acute MI complicated by congestive heart failure (CHF) is associated with a high mortality, and that women with acute MI are more likely to be older and to develop CHF than men with acute MI. In general, management of CHF complicating acute MI is similar in older and younger patients. Actions discussed include hemodynamic monitoring; the administration of oxygen; and the use of morphine, diuretics, nitroglycerin, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, spironolactone, beta-blockers, calcium channel blockers, magnesium, digoxin, and positive inotropic drugs. The article also discusses measures for treating arrhythmias and for diagnosing mechanical complications.

Ventricular oversensing in 518 patients with implanted cardiac defibrillators: incidence, complications, and solutions

The present study evaluates the incidence of various complications in implanted cardiac defibrillators (ICD) therapy due to ventricular oversensing (VO) and its complications. From June 1998 to May 2005, we retrospectively screened 518 patients (1085.6 patient years) for the occurrence of VO episodes (441 male, 77 female). The overall incidence was 7.3% (n = 38) with inappropriate shock deliveries accounting for 2.3% (n = 12). All VO episodes were caused by either T-wave oversensing (n = 10), myopotentials (n = 8), electrode failure (n = 5), interference with electromagnetic fields (n = 3), double-counting (n = 4), pacemaker interactions (n = 2), or others (n = 2). There were five life-threatening events due to inappropriate ICD reaction. In eight (22%) cases, ICD reprogramming was able to avoid further oversensing episodes (e.g. adaptation of sensitivity, T-wave suppression feature), 13 (35%) patients had to undergo invasive procedures (e.g. electrode replacing) to suppress VO, 16 (43%) were told to avoid the trigger situation, and one demanded to deactivate all ICD therapies because of inappropriate shock delivery. Our data demonstrate that VO is a rare complication, but might lead to life-threatening events. In most cases, VO episodes could be prevented by appropriate ICD reprogramming or avoidance of the initiating trigger.

An update on the management of Chagas cardiomyopathy

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, infects nearly 18 million people in Latin America and mainly affects the heart, causing heart failure, arrhythmias, heart block, thromboembolism, stroke and death. In this review, the clinical diagnosis and management of Chagas cardiomyopathy are discussed. Particular emphasis is placed on the clinical staging of patients and the use of various diagnostic tests that may be useful in individualizing treatment of the two most relevant clinical syndromes, that is, heart failure and arrhythmias. The relevance of specific treatments are discussed, stressing the important role of parasite persistence in disease pathogenesis. We also discuss new therapy modalities that may have a role in the treatment of Chagas cardiomyopathy.