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ABSTRACTS ARCHIVE  2002, 2003, 2004, 2005, 2006

Last Update: 2007-06-15

Complication Risk with Pulse Generator Change: Implications When Reacting to a Device Advisory or Recall

Background: Recent advisories and recalls of pacemakers and implantable cardioverter-defibrillators (ICDs) have highlighted the need for evidence-based recommendations regarding management of patients with advisory devices. In order to better facilitate decision-making when weighing the relative risks and benefits of performing generator changes in these patients, we conducted a review to assess operative complication rates.
Methods: We reviewed generator changes performed between 2000 and 2005 at the Mayo Clinic-Rochester, including a total of 732 change-outs consisting of 570 done for elective replacement indicators (ERI) and 162 for manufacturer advisories or recalls. Complications included all those requiring reoperation, occurring within a 60-day period postoperatively and directly attributable to the generator change. These included infection requiring device excision, hematoma requiring evacuation, and incisional dehiscence requiring reclosure.
Results: Operation-associated complications requiring intervention were noted in 9 patients, or 1.24% of our population. Of these nine complications, eight occurred among patients receiving pulse generator replacement for ERI (1.40%) and one occurred in a patient receiving replacement for a manufacturer advisory or recall (0.62%). Complications included 5 infections, 3 hematomas, and 1 incisional dehiscence.
Conclusions: Generator replacement is not a benign procedure and associated risks must be weighed in the context of other variables when making management choices in patients with advisory or recall devices.

Single Chamber Atrial Pacing: A Realistic Option in Sinus Node Disease: A Long-Term Follow-up Study of 213 Patients

Background: Despite several decades of experience with atrial pacing, many centers do not apply this mode to any greater extent, mainly because of concerns for the development of future atrioventricular (AV) block or atrial fibrillation. Recent studies have emphasized possible negative effects of right ventricular stimulation, even when AV-synchrony is preserved, and have thus given rise to renewed interest in single chamber atrial pacing for sinus node disease.
Methods: This study presents the results of up to 19 years' follow-up of 213 patients with sinus node disease treated with atrial pacing with respect to survival and causes of death, development of atrial fibrillation and AV block, and total mode survival. Patients were divided into two groups: with or without associated atrial tachyarrhythmias at the time of implant. Results are given for all patients and for the two groups separately.
Results: The mean follow-up time was 10.1 years. The survival of the entire group was lower after 10 years than that of an age and gender-matched general Swedish population. This was caused by patients with the brady-tachy syndrome (BT) having a significantly higher mortality rate than controls, whereas those with bradycardia only (B) had survival comparable to the general population. Permanent atrial fibrillation (AF) developed in 20% of patients and was significantly more common in patients with BT. The majority of patients with AF (78%) no longer needed any pacing, i.e., did not require ventricular stimulation due to slow ventricular rate. The annual incidence of high grade AV block was 1.8%. If patients with preexisting bundle branch block were excluded, the incidence was 1.6%. No fatal episode of AV block was seen. The overall mode survival at the end of follow-up was 75%, with 155 patients still with atrial pacemakers.
Conclusion: Atrial pacing is a safe and reliable mode of pacing in patients with sinus node disease, even in the very long-term.




 

Recurrent Unexplained Palpitations (RUP) Study: Comparison of Implantable Loop Recorder Versus Conventional Diagnostic Strategy

Objectives: The aim of the study was to compare the diagnostic yield and the costs of implantable loop recorder (ILR) with those of the conventional strategy in patients with unexplained palpitations.
Background: In patients with unexplained palpitations, especially in those with infrequent symptoms, the conventional strategy, including short-term ambulatory electrocardiogram (ECG) monitoring and electrophysiological study, sometimes fails to establish a diagnosis.
Methods: We studied 50 patients with infrequent ( 1 episode/month), sustained (>1 min) palpitations. Before enrollment, patients had a negative initial evaluation, including history, physical examination, and ECG. Patients were randomized either to conventional strategy (24-h Holter recording, a 4-week period of ambulatory ECG monitoring with an external recorder, and electrophysiological study) (n = 24) or to ILR implantation with 1-year monitoring (n = 26). Hospital costs of the 2 strategies were calculated.
Results: A diagnosis was obtained in 5 patients in the conventional strategy group, and in 19 subjects in the ILR group (21% vs. 73%, p < 0.001). Despite the higher initial cost, the cost per diagnosis in the ILR group was lower than in the conventional strategy group ( 3,056 ± 363 vs. 6,768 ± 6,672, p = 0.012).
Conclusions: In subjects without severe heart disease and with infrequent palpitations, ILR is a safe and more cost-effective diagnostic approach than conventional strategy.



 

Effect of Rosiglitazone on the Risk of Myocardial Infarction and Death from Cardiovascular Causes

Background Rosiglitazone is widely used to treat patients with type 2 diabetes mellitus, but its effect on cardiovascular morbidity and mortality has not been determined.

Methods We conducted searches of the published literature, the Web site of the Food and Drug Administration, and a clinical-trials registry maintained by the drug manufacturer (GlaxoSmithKline). Criteria for inclusion in our meta-analysis included a study duration of more than 24 weeks, the use of a randomized control group not receiving rosiglitazone, and the availability of outcome data for myocardial infarction and death from cardiovascular causes. Of 116 potentially relevant studies, 42 trials met the inclusion criteria. We tabulated all occurrences of myocardial infarction and death from cardiovascular causes.
Results Data were combined by means of a fixed-effects model. In the 42 trials, the mean age of the subjects was approximately 56 years, and the mean baseline glycated hemoglobin level was approximately 8.2%. In the rosiglitazone group, as compared with the control group, the odds ratio for myocardial infarction was 1.43 (95% confidence interval [CI], 1.03 to 1.98; P=0.03), and the odds ratio for death from cardiovascular causes was 1.64 (95% CI, 0.98 to 2.74; P=0.06).

Conclusions Rosiglitazone was associated with a significant increase in the risk of myocardial infarction and with an increase in the risk of death from cardiovascular causes that had borderline significance. Our study was limited by a lack of access to original source data, which would have enabled time-to-event analysis. Despite these limitations, patients and providers should consider the potential for serious adverse cardiovascular effects of treatment with rosiglitazone for type 2 diabetes.




 

Randomized Comparison of J-Shaped Atrial Leads with and without Active Fixation Mechanism

Background: In this prospective, randomized, controlled study, we compared the performance of J-shaped active fixation (AF) atrial leads with J-shaped passive fixation (PF) leads, over a 1-year follow-up period.
Methods: A total of 200 consecutive patients were prospectively randomized for implantation with a Medtronic 5568 AF lead model (n = 103; Minneapolis, MN, USA) versus a Medtronic 5592 PF model (n = 97), and all lead-related measurements and complications were recorded over one year.
Results: All leads were successfully implanted with a nonsignificant difference in crossover rate to the alternative lead due to failed implantation (1 in the AF and 4 in the PF group, P = NS). Fluoroscopy time during implantation procedure was significantly shorter in the PF group (2.1 ± 3.6 vs 3.3 ± 4.5 minute, P < 0.05). Pacing thresholds during implantation were significantly lower in patients with PF leads (0.7 ± 0.3 V vs 0.9 ± 0.3 V, P < 0.001) and this difference persisted at 1-year follow-up (0.8 ± 0.6 V vs 1.3 ± 0.9 V in PF and AF leads respectively, P < 0.05). Lead-related complications occurred in PF and AF with similar frequency (4% and 9% respectively, P = 0.2). However, pericardial complications occurred only in the AF group (6 cases, P = 0.01). Lead dislodgement was observed in only two cases—both in the PF group (P = 0.3).
Conclusion: Both types of J-shaped atrial leads had reasonable performance. PF leads required shorter fluoroscopy time for implantation, demonstrated a better pacing threshold over a 1-year follow-up period and had no pericardial complications, while AF lead implantation was complicated by pericardial irritation and/or effusion in 6% cases (P = 0.01).

Ineffectiveness of Precordial Thump for Cardioversion of Malignant Ventricular Tachyarrhythmias

Background:The Precordial Thump (PT) is commonly used for cardiopulmonary resuscitations both in and out of hospitals. However, the support for its efficiency relies mainly on sporadic cases. In this current prospective large study, we tested the effectiveness and safety of PT in a wide range of malignant ventricular tachyarrhythmias.
Methods: The study included 80 patients who underwent electrophysiological study and/or implantation of a cardiodefibrillator device. During these procedures, once a malignant ventricular tachyarrhythmia was induced, PT was used as the first treatment option. If the PT failed, other means were used to discontinue the arrhythmia.
Results: Polymorphic ventricular tachycardia occurred in 32 (40%) patients, ventricular fibrillation in 28 (35%) patients, and 20 (25%) patients had sustained monomorphic ventricular tachycardia. Except in one patient with monomorphic ventricular tachycardia, the PT was unsuccessful in terminating any of the other malignant tachyarrhythmias, and internal or external defibrillation was eventually required in all other 79 (99%) patients. The PT was not associated with any damage either to the sternal bone, ribs, or to the cardiodefibrillator device.
Conclusions: PT is not effective in terminating malignant ventricular tachyarrhythmia and should be reserved to a situation in which a defibrillator is not available.

 

Is Home Orthostatic Self-Training Effective in Preventing Neurally Mediated Syncope?

Background: Repeated orthostatic stress may prove to be of benefit in the regulation of neurally mediated syncope. But the role of home orthostatic self-training is not established to prevent symptoms in patients with neurally mediated syncope. We performed a prospective and randomized study to evaluate the effectiveness of repeated home orthostatic self-training in preventing tilt-induced neurally mediated syncope.
Methods and Results: Fourty-two consecutive patients (24 males and 18 females, mean age 39 years, 16–68 years) with recurrent neurally mediated syncope were randomized into the tilt training and control groups. The home orthostatic self-training program consisted of daily sessions for 7 days a week for 4 weeks. In order to determine the effects of home orthostatic self-training, we repeated the head-up tilt test in both groups 4 weeks later. Among the tilt-training group, 9 of 16 patients (56%) had a positive response on follow-up head-up tilt test. Among the untreated control group, 9 of 17 patients (53%) had a positive response on follow-up head-up tilt test. In subgroup analyses according to the number of tilt-training sessions or the classified type, we found no differences in the follow-up head-up tilt test responses. Spontaneous syncope or presyncope over mean follow-up of 16.9 months were observed in 42.9% versus 47.1% in the tilt-training and control group, respectively.
Conclusions: Home orthostatic self-training was ineffective in reducing the positive response rate of head-up tilt test in patients with recurrent neurally mediated syncope.
 

Sedation with Midazolam for Electrical Cardioversion

Background: Electrical cardioversion (ECV) usually requires the assistance of the anesthesiology team. To avoid this dependence, previous studies have considered the use of sedation with benzodiazepines administered by cardiologists. We describe our experience with intravenous Midazolam during cardioversion.
Methods: We performed 280 ECV in 202 patients sedated with intravenous Midazolam, without anesthesiology supervision. In scheduled cardioversions, we tested two protocols of Midazolam administration: a bolus of 3 mg, followed by 2 mg each minute until necessary, and a loading dose of 0.09–0.1 mg/kg. In cardioversions performed during electrophysiology studies or defibrillator implant, Midazolam was administered by small repeated doses during the entire procedure.
Results: Midazolam was effective to obtain adequate sedation in 99% of cases. All patients had amnesia with regards of the cardioversion. A loading dose of Midazolam allowed a shortening of the procedural time without serious adverse events. Intubation or the assistance of an anesthetist was never necessary.
Conclusion: Sedation with Midazolam for ECV is effective and well tolerated, with some cautions discussed. A loading dose of Midazolam is well tolerated and further reduces the procedural time.
 

Evidence for Electrical Remodeling of the Native Conduction System with Cardiac Resynchronization Therapy

Background: Cardiac resynchronization therapy (CRT) improves hemodynamics and decreases heart failure symptoms. However, the potential of CRT to bring about electrical remodeling of the heart has not been investigated.
Methods and Results: We studied 25 patients, of whom 17 had a nonischemic cardiomyopathy, and 8 had an ischemic cardiomyopathy; 16 had left bundle branch block (LBBB), 1 right bundle branch block (RBBB), and 8 nonspecific intraventricular conduction delay. During routine device clinic visits, patients with chronic biventricular pacing (>6 months) were reprogrammed to VVI 40 to allow for native conduction to resume. After 5 minutes of native rhythm, a surface electrocardiogram (ECG) was recorded, and then the previous device settings were restored. This ECG was compared to the preimplant ECG. Preimplant mean ejection fraction was 19% (range, 10%–35%), and follow-up mean ejection fraction was 35% (12.5%–65%). Mean time from implant to follow-up ECG was 14 months (range, 6–31). The QRS interval prior to CRT was 155 ± 29 ms, and shortened to 144 ± 31 ms (P = 0.0006), and the QRS axis shifted from −1 ± 59 to −26 ± 53 (P = 0.03). There was no significant change in PR or QTc interval, or in heart rate.
Conclusion: CRT leads to a decrease in the surface QRS duration, without affecting other surface ECG parameters. The reduced electrical activation time may reflect changes in the specialized conduction system or in intramyocardial impulse transmission.

 

Venous Obstruction After Pacemaker Implantation

Background: Central vein leads are known to predispose to venous obstruction. Although usually asymptomatic, obstruction may render electrode removal difficult. This study aimed at quantifying changes in venous calibers in a prospective fashion by intravenous contrast venography (ICV) before and after pacemaker (PM) or cardioverter-defibrillator implantation.
Methods: One hundred and fifty (mean age 67; 61% male) consecutive patients were enrolled, and followed for 6 months. A successful ICV was done at baseline prior to implantation and at 6-month follow-up in 136 (91%) patients. Minimum (Dmin) and maximum (Dmax) vessel diameters were obtained from both ICVs. A new stenosis was defined as a 50% diameter reduction in a venous segment when compared to baseline. We implanted a total of 230 electrodes: 47 (34.6%) single lead, 84 (61.8%) 2-lead, and 5 (3.7%) 3-lead systems.
Results: At baseline ICV, 10 patients (7%) were found to have venous anomalies, including 8 patients with obstructive lesions, 1 patient with a persistent left superior vena cava, and 1 patient with double axillary vein. At 6 months, a new obstructive venous lesion had developed in a total of 19 (14%) patients, none of whom exhibited any local symptoms. Of these patients 14 (10%) had a stenosis (mean Dmin 4.6 mm and diameter 38% of baseline), and 5 (3.6%) had a complete venous occlusion. In most cases the new stenosis developed in a location where the vessel was narrowest at baseline. Clinical predictors for the development of stenosis were atrial fibrillation at baseline and biventricular PM implantation.
Conclusions: This is the first systematic study to quantify venous changes after PM or ICD implantation. Our study shows that venous anomalies rendering PM implantation difficult are not infrequent. The incidence of new venous obstruction was 14%. Atrial fibrillation and biventricular PM implantation were independent predictors of venous obstruction.
 

Long QT Syndrome and Pregnancy

Objectives This study was designed to investigate the clinical course of women with long QT syndrome (LQTS) throughout
their potential childbearing years.
Background Only limited data exist regarding the risks associated with pregnancy in women with LQTS.
Methods The risk of experiencing an adverse cardiac event, including syncope, aborted cardiac arrest, and sudden death,
during and after pregnancy was analyzed for women who had their first birth from 1980 to 2003 (n _ 391). Timedependent
Kaplan-Meier and Cox proportional hazard methods were used to evaluate the risk of cardiac events during
different peripartum periods.
Results Compared with a time period before a woman’s first conception, the pregnancy time was associated with a reduced
risk of cardiac events (hazard ratio [HR] 0.28, 95% confidence interval [CI] 0.10 to 0.76, p _ 0.01), whereas the
9-month postpartum time had an increased risk (HR 2.7, 95% CI 1.8 to 4.3, p _ 0.001). After the 9-month postpartum
period, the risk was similar to the period before the first conception (HR 0.91, 95% CI 0.55 to 1.5, p _ 0.70).
Genotype analysis (n _ 153) showed that women with the LQT2 genotype were more likely to experience a cardiac
event than women with the LQT1 or LQT3 genotype. The cardiac event risk during the high-risk postpartum period
was reduced among women using beta-blocker therapy (HR 0.34, 95% CI 0.14 to 0.84, p _ 0.02).
Conclusions Women with LQTS have a reduced risk for cardiac events during pregnancy, but an increased risk during the
9-month postpartum period, especially among women with the LQT2 genotype. Beta-blockers were associated
with a reduction in cardiac events during the high-risk postpartum time period.

Isolated Atrial Segment Pacing An Alternative to His Bundle Pacing After Atrioventricular Junctional Ablation

Objectives: This study was designed to investigate a practical alternative to His bundle pacing after atrioventricular (AV) junctional ablation by pacing a small area of isolated atrial tissue surrounding the AV node.
Background: His bundle pacing is preferred after AV junctional ablation in patients with refractory atrial fibrillation. However, it is technically difficult and not clinically useful at the present time.
Methods: This study was conducted in an isolated working swine heart model (n = 5), with real-time imaging capabilities. A small area of atrial tissue surrounding the AV node and the His bundle was isolated using sequential radiofrequency ablation lesions.
Results: Complete AV block created by segmental atrial isolation was achieved in 5 of 5 experiments. The isolated atrial segment was bordered by the ablation lines, the tricuspid annulus, and the AV node–His bundle. The AV conduction was characterized using a pacing electrode implanted into the isolated atrial segment. Pacing from the atria, the ventricles, and the isolated atrial segment at different rates confirmed complete bidirectional block between the atria and isolated area, whereas antegrade and retrograde AV nodal conduction between the isolated atrial segment and the ventricles remained intact. Pacing from the isolated area produced minimal changes in systolic left ventricular pressure compared with baseline sinus rhythm (mean –2 mm Hg).
Conclusions: Isolation of a small area of atrial tissue surrounding the AV node is feasible by transcatheter radiofrequency ablation. This procedure may be a useful alternative to conventional AV junctional ablation because it can create complete AV block, while in effect permitting the equivalent of His bundle pacing after AV junctional ablation.

 

High-degree atrioventricular block during anti-arrhythmic drug treatment: use of a pacemaker with a bradycardia-detection algorithm to study the time course after drug withdrawal

Aim This study examines the recurrence of high-degree atrioventricular block (AVB) during a follow-up period of 2 years in patients with restored AV node function after antiarrhythmic drug withdrawal at implantation of a pacemaker.
Methods Nine men and eight women (77 ± 7 years) taking antiarrhythmic drugs (beta-receptor blockers in 15) and presenting with high-degree AVB were followed for 2 years after being taken off drugs upon receiving a permanent pacemaker with special bradycardia detection software.
Results At inclusion, surface ECG identified two subsets of patients: a QRS duration < 120 ms (n = 5) and those with a QRS duration 120 ms (n = 12). During the 2-year follow-up, progression to high-degree AVB occurred in these groups: 1/5 (20%) and 9/12 (75%) P < 0.05. Six patients had to be restarted on drugs, mostly beta-receptor blockers, due to atrial tachyarrhythmias: 3/5 and 3/12. In total, 16 patients (94%) either developed high-degree AVB needing pacing or atrial tachyarrhythmias requiring drug treatment.
Conclusion Patients on beta-receptor blocking drugs and QRS width 120 ms developing high-degree AVB should be recommended a pacemaker without further investigation or observation.
 

Prevalence of Brugada sign in patients presenting with palpitation in southern Iran

Aims Brugada syndrome is a cardiac channel abnormality that is associated with a high risk of ventricular fibrillation and sudden cardiac death and characterized by an electrocardiographic pattern of right bundle branch block and transient or persistent ST-segment elevation in leads V1–V3. No data regarding the frequency of Brugada syndrome exist in an Iranian population. The aim of this study was to determine the frequency of Brugada-type ECG pattern in southern Iran.
Methods and results All patients presenting with palpitation were enrolled in the study. A Brugada-type ECG pattern was determined according to the criteria recommended by European Heart Association Molecular Basis of Arrhythmias Study Group. A total of 3895 patients (mean age 38.2 ± 11.9 years, 54% women) met all study criteria. One hundred patients (2.56%) had Brugada-type ECG pattern. Of these, 21 patients (0.54%) had definite Brugada sign (Type 1 or Types 2 and 3 with conversion to Type 1 following procainamide test). Of 21 patients with definite Brugada sign, eight had Brugada syndrome, four had history of syncope, two had coved-type ECG in the family, one had polymorphic ventricular tachycardia, and one had history of sudden cardiac death in the family. Five patients underwent ICD implantation. The incidence of a Brugada-type ECG pattern was 2.43% in subjects between 17 and 30 years and 0.13% in subjects >30 years (P = 0.01).
Conclusion Frequency of Brugada sign in an Iranian population presenting with palpitation is greater than some European countries and lower than a Japanese urban population.
 

The contribution of rate adaptive pacing with single or dual sensors to health-related quality of life

Aims The characteristics of sensors to perform rate adaptive pacing are well established but whether their contribution improves health-related quality of life (QoL) remains disputable. To compare the effects on QoL with an integrated dual sensor [minute ventilation (MV) and acceleration, TT sensor] with a single MV sensor, and with no rate adaptive pacing.
Methods and results This Dutch multi centre, prospective, single- (patient) blind study was performed in patients after first pacemaker (PM) implant for sick sinus syndrome or AV block. After a 3-month ‘sensor off’-period following DDD PM implantation, where the latter 2 months permitted the MV sensor to learn the intrinsic rhythm, a 2-month period of DDDR with TT sensor or 2 months of DDDR with MV sensor, subsequently the two modes were crossed over. Quality of life was determined with Aquarel, the disease-specific instrument for PM patients. Heart rate, percentages of sensor driven and intrinsic rhythm were retrieved from PM memories. Sixty-four patients completed the 7-month study. In sick sinus patients, percentages of sensor-driven pacing occurred significantly more frequently than in AV block patients After implant QoL improved significantly: before 71.3 and after 83.5% (P < 0.001) measured with Aquarel and in 3 of 9 SF-36 scales, but no significant additive QoL benefit with dual or MV sensor pacing was observed. Pacing diagnosis, percentages of rate adaptive pacing, and heart rate influencing medication did not influence this result.
Conclusion Pacemaker implantation strongly improves QoL, but neither single- nor dual- sensor-driven pacing offered additional improvement in QoL during the initial 8 months after the first PM implant.
 

Evolution of left ventricular function in paediatric patients with permanent right ventricular pacing for isolated congenital heart block: a medium term follow-up

Aims: We aimed to assess the evolution of left ventricular (LV) systolic function in children with right ventricular apical (RVA) pacing for isolated congenital heart block (ICHB) and to identify possible predictors of LV function deterioration. Right ventricular apical pacing can be detrimental to LV function in a significant number of adults. Effects in children are still controversial.
Methods and results Left ventricular shortening fraction (LV SF) and QRS duration were retrospectively assessed in 45 children with RVA pacing for ICHB: before pacemaker (PM) implantation, immediately after and then regularly during a follow-up of 58.69 ± 45.23 months. Patients were categorized as stable or deteriorators according to an arbitrarily chosen cut-off point of 7% decrease in LV SF. Lupus status was unknown. Overall LV SF did not change significantly (41.42% ± 8.21 before pacing, 39.77% ± 7.03 immediately after PM implant, 37.43% ± 9.91 with chronic pacing, P = NS). Deteriorators (n = 13) had significantly higher baseline heart rate (57.5 ± 8.7 vs. 46.9 ± 10.5 bpm, P < 0.05) and baseline LV SF (46.17 ± 8.13 vs. 38.4 ± 6.4%; P < 0.05), a significantly higher proportion of them being implanted before 2 years of age: 8 of 13 (61.5%) vs. 5 of 25 (20%) in the stable group (P < 0.05). Deteriorators had a higher incidence of an initial epicardial lead and narrower native QRS.
Conclusion Permanent RVA pacing for ICHB does not necessarily affect LV function in children. The risk of deterioration of LV function seems to be higher in children with higher baseline heart rate and better baseline LV SF, especially with pacing at a younger age, a narrower native QRS and RVA epicardial pacing site.
 

Increased incidence of subacute lead perforation noted with one implantable cardioverter-defibrillator

Background
The rapid evolution of implantable cardioverter-defibrillator (ICD) leads has resulted in thinner active fixation leads. While these advances have made the leads more versatile, new configurations may be associated with unforeseen complications.
Objective
The purpose of this study was to determine the incidence of perforation and dislodgement of defibrillator leads in a single center in the year 2005.
Methods
All patients who underwent percutaneous ICD implantation at the Massachusetts General Hospital using an endocardial right ventricular lead were included in this study. The specific leads analyzed were the Riata (1580/1581 and 1590/1591, St. Jude Medical, St Paul, Minnesota, USA;) and Sprint Fidelis (6949–65, Medtronic, Minneapolis, Minnesota, USA.). Information was collected retrospectively.
Results
A total of 130 Riata leads and 111 Sprint Fidelis leads were implanted at the Massachusetts General Hospital during this time period. A total of five lead perforations occurred in patients implanted with the Riata lead as compared with none with the Sprint Fidelis lead (3.8% vs. 0%, respectively; P <.05). Two of the five patients with perforation required pericardiocentesis for tamponade. Clinical symptoms of perforation developed 1–10 days after implant. Moreover, there were five additional lead revisions in the Riata group, which were likely due to dislodgement and/or microperforation, as compared with none in the Sprint Fidelis group (7.7% vs. 0%, respectively; P <.005).
Conclusions
In 2005, at one institution, there were significantly more cardiac perforations and lead revisions with the Riata lead as compared with the Sprint Fidelis right ventricular defibrillator lead. Further data are required to determine whether certain lead characteristics are responsible for this observation.
 

Mortality in randomized trials of antioxidant supplements for primary and secondary prevention: systematic review and meta-analysis.

CONTEXT: Antioxidant supplements are used for prevention of several diseases. OBJECTIVE: To assess the effect of antioxidant supplements on mortality in randomized primary and secondary prevention trials. DATA SOURCES AND TRIAL SELECTION: We searched electronic databases and bibliographies published by October 2005. All randomized trials involving adults comparing beta carotene, vitamin A, vitamin C (ascorbic acid), vitamin E, and selenium either singly or combined vs placebo or vs no intervention were included in our analysis. Randomization, blinding, and follow-up were considered markers of bias in the included trials. The effect of antioxidant supplements on all-cause mortality was analyzed with random-effects meta-analyses and reported as relative risk (RR) with 95% confidence intervals (CIs). Meta-regression was used to assess the effect of covariates across the trials. DATA EXTRACTION: We included 68 randomized trials with 232 606 participants (385 publications). DATA SYNTHESIS: When all low- and high-bias risk trials of antioxidant supplements were pooled together there was no significant effect on mortality (RR, 1.02; 95% CI, 0.98-1.06). Multivariate meta-regression analyses showed that low-bias risk trials (RR, 1.16; 95% CI, 1.05-1.29) and selenium (RR, 0.998; 95% CI, 0.997-0.9995) were significantly associated with mortality. In 47 low-bias trials with 180 938 participants, the antioxidant supplements significantly increased mortality (RR, 1.05; 95% CI, 1.02-1.08). In low-bias risk trials, after exclusion of selenium trials, beta carotene (RR, 1.07; 95% CI, 1.02-1.11), vitamin A (RR, 1.16; 95% CI, 1.10-1.24), and vitamin E (RR, 1.04; 95% CI, 1.01-1.07), singly or combined, significantly increased mortality. Vitamin C and selenium had no significant effect on mortality. CONCLUSIONS: Treatment with beta carotene, vitamin A, and vitamin E may increase mortality. The potential roles of vitamin C and selenium on mortality need further study.
 

Residence close to high traffic and prevalence of coronary heart disease

Aims Long-term exposure to urban air pollution may accelerate atherogenesis and increase cardiopulmonary mortality. We aim to examine the relationship between the long-term residential exposure to traffic and prevalence of coronary heart disease (CHD).
Methods and results We used baseline data from the German Heinz Nixdorf RECALL study, a population-based, prospective cohort study. For 3399 participants from two cities, we assessed the long-term personal traffic exposure and background air pollution, comparing residents living within 150 m of major roads with those living further away. The principal outcome variable was clinically manifest CHD. We evaluated the association with multivariable logistic regression, controlling for background air pollution and individual level risk factors. Of 3399 participants, 242 (7.1%) had CHD. The crude odds ratio (OR) for prevalence of CHD at high traffic exposure was significantly elevated (1.62, 95%CI 1.12–2.34) and rose to 1.85 (95%CI 1.21–2.84) after adjusting for cardiovascular risk factors and background air pollution. Subgroup analysis showed stronger effects for men (OR 2.33, 95%CI 1.44–3.78), participants younger than 60 years (OR 2.67, 95%CI 1.24–5.74) and never-smokers (OR 2.72, 95%CI 1.40–5.29).
Conclusion This study provides epidemiological evidence that the long-term exposure to traffic-related emissions may be an important risk factor for CHD.
 

Effects of cardiac resynchronization therapy on overall mortality and mode of death: a meta-analysis of randomized controlled trials

Aims Cardiac resynchronization therapy (CRT) has been shown to improve symptoms and exercise tolerance in patients with advanced heart failure (HF). However, studies were underpowered to address its effect on overall mortality. To evaluate whether CRT alone (without a combined defibrillator function) reduces overall mortality as compared with optimal pharmacological therapy, and how it affects the mode of death in patients with advanced HF.
Methods and results Public domain databases were systematically searched. Randomized controlled studies that evaluated the effects of CRT alone in patients with advanced HF and a depressed left ventricular systolic performance were selected for this analysis. Trials, which did not independently report data on CRT alone or had a follow-up period of less than 3 months, were excluded. Five studies were identified and analyzed. They included a total of 2371 patients, 1028 controls and 1343 CRT-treated patients. Pooled analysis demonstrated that CRT alone, as compared with optimal medical therapy, significantly reduced all-cause mortality by 29% [16.9 vs. 20.7%; odds ratio (OR), 0.71; 95% confidence interval (CI), 0.57–0.88] and mortality due to progressive HF by 38% (6.7 vs. 9.7%; OR, 0.62; 95% CI, 0.45–0.84). No effect on sudden cardiac death (SCD) was observed with CRT (6.4 vs. 5.9%; OR, 1.04; 95% CI, 0.73–1.22).
Conclusions CRT alone as compared with optimal medical therapy reduces all-cause mortality in patients with advanced HF. It predominantly reduces worsening HF mortality, not affecting SCD.
 

Reversal of Left Ventricular Dysfunction Following Ablation of Atrial Fibrillation

Background: Evaluation of ventricular rate control in atrial fibrillation (AF) can be difficult, and the presence of an AF-induced ventricular cardiomyopathy due to intermittent poor rate control or other causes may be underestimated. The outcome with AF ablation in patients with a decreased left ventricular ejection fraction (LVEF) may provide insight into this important clinical issue.
Objective: To determine the effect of pulmonary vein isolation on LVEF in patients with AF and decreased LVEF (≤50%).
Methods: Ablation consisted of proximal isolation of arrhythmogenic pulmonary veins (PVs) and elimination of non-PV triggers. LVEF was determined within 24 hours after ablation and again at up to 6 months follow-up. Transtelephonic monitoring was performed routinely for 2–3 weeks prior to ablation, at 6 weeks, and 6 months post and with symptoms following ablation. AF control was defined as freedom from AF or marked (>90%) reduction in AF burden on or off previously ineffective antiarrhythmic medication.
Results: AF ablation was performed in 366 patients and 67 (18%) patients had decreased LV function with a mean LVEF of 42 ± 9%. An average of 3.4 ± 0.9 PVs were isolated. AF control in the depressed LVEF group compared favorably with the normal EF group (86% vs. 87% P = NS), although more redo procedures were required (1.6 ± 0.8 vs 1.3 ± 0.6 procedures; P ≤ 0.05). Only 15 of 67 patients (22%) with decreased LVEF had shown tachycardia (>100 bpm) on repeated preablation ECG recordings during AF. In the decreased LVEF group, the LVEF increased from 42 ± 9% to 56 ± 8% (P < 0.001) after ablation.
Conclusions: Patients with AF and decreased LVEF undergoing AF ablation have similar success to patients with normal LVEF and have improvement in LVEF after ablation. These results suggest the presence of a reversible AF-induced ventricular cardiomyopathy in many patients with AF and depressed LV function. The presence of under-recognized and reversible cardiomyopathy even when tachycardia is not persistent is important to recognize.

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