Prospective Randomized Study of Mode Switching in a Clinical Trial of Pacemaker Therapy for Sinus Node Dysfunction

Women with atrial fibrillation undergoing pulmonary vein isolation are more symptomatic but improve more in health-related quality of life and symptom burden than men

Gender differences in symptoms and perceived health-related quality of life (HRQOL) in patients with atrial fibrillation (AF) referred to pulmonary vein isolation (PVI) have been reported previously. Women experience a lower HRQOL, faster heart rate, and more symptoms such as palpitation and dyspnea than men. Furthermore, they experience worse physical functioning independently of other heart diseases or age. This study evaluates referral patterns and symptoms, morbidity, functional impairment, and HRQOL from a gender perspective in patients with AF before and 6 months after PVI. The study includes 242 patients (121 men), mean age 62 ± 9 years, referred for PVI. Symptoms were assessed with the Symptom Checklist: Frequency and Severity (SCL), HRQOL with Short Form 36 (SF-36), and the functional impairment with Sickness Impact Profile (SIP). The patients' own experiences of the referral process and history of their disease were evaluated with a supplementary questionnaire. The results showed that women improved more than men in HRQOL, SIP, and SCL 6 months post PVI. There were no sex differences in proportion of paroxysmal and persistent AF or ablation outcome. At baseline, women scored higher than men in both scales of the SCL (p < 0.001), scored lower in all components in SF-36, and scored higher in five categories of the SIP. Women were not more reluctant to accept referral for ablation when offered. The conclusion is that women with AF undergoing PVI are more symptomatic but also improve more in HRQOL and in symptom burden than men.

Daily distribution of atrial arrhythmic episodes in sick sinus syndrome patients: implications for atrial arrhythmia monitoring

AIMS

Disorders such as paroxysmal atrial fibrillation (AF) and atrial tachyarrhythmias (AT) are difficult to investigate because of their intermittent, and sometimes asymptomatic, nature. The aim of this study was to investigate the daily temporal distribution of AT/AF episodes--onset and occurrence--by analysing data from 250 pacemaker-implanted, brady-tachy syndrome patients who have been enrolled in the Burden II Study.

METHODS AND RESULTS

Data were analysed accounting for the mode switch list which includes date, time, and duration of each mode switch episode. Chi-squared tests for goodness of fit were used to determine whether AT/AF episode were uniformly distributed. The population analysed in the present study suggests the occurrence of a circadian rhythm of paroxysmal AF episodes, similar to that described for other cardiovascular diseases, with clustering of events in the morning from 08:00 and (to a lesser degree) in the afternoon (03:00 to 18:00). The relative risk of AT/AF onset is 13% higher during daytime, 40% lower at night (P < 0.000001).

CONCLUSION

The use of monitoring devices based on daily electrocardiogram (ECG) recording could be optimized with these data, thus increasing the probability to detect AT/AF episodes.

Atrial fibrillation and quality of life after pacemaker implantation for sick sinus syndrome: data from the Mode Selection Trial (MOST)

BACKGROUND

In the Mode Selection Trial (MOST) of 2,010 patients with sinus node dysfunction, dual-chamber-paced patients had less atrial fibrillation (AF) and heart failure and had slightly improved health-related quality of life (QOL) compared with rate modulated right ventricular-paced patients. Our objective was to assess the impact of AF on QOL within MOST.

METHODS

We analyzed serial QOL measures (Short Form-36, Specific Activity Scale, time trade-off) in 3 groups: (1) those without AF; (2) those with paroxysmal AF (PAF), but not chronic AF (CAF); and (3) those with CAF. We carried forward the last known QOL before crossover for all subsequent time points in patients randomized to rate modulated right ventricular pacing who crossed over to dual-chamber pacing for severe pacemaker syndrome.

RESULTS

Three hundred seventeen patients (15.8%) had AF in the year after implantation, 206 patients within 3 months (191 PAF, 15 CAF), and another 159 (124 PAF, 35 CAF) between 3 and 12 months. There were no significant differences among groups in individual Short Form-36 subscales or time trade-off scores at 12 months as compared with baseline or 3 months. Cardiovascular health status was better at 12 months as compared with baseline or 3 months in those without AF.

CONCLUSIONS

Atrial fibrillation after pacemaker implantation in elderly patients with sick sinus syndrome was not a major determinant of QOL. However, there was a trend toward better cardiovascular functional status in patients without AF.

The MINERVA study design and rationale: a controlled randomized trial to assess the clinical benefit of minimizing ventricular pacing in pacemaker patients with atrial tachyarrhythmias

BACKGROUND

Dual-chamber (DDD) pacing has generally been regarded as "physiologic pacing" and therefore expected to be superior to ventricular pacing. Major randomized trials have so far failed to demonstrate significant reductions in the incidences of mortality, stroke, and heart failure. It has been shown that unnecessary ventricular pacing in patients with sinus node dysfunction or only intermittent atrioventricular block is associated with ventricular desynchronization and increased risk of atrial tachyarrhythmias (ATA).

METHODS

The MINimizE Right Ventricular pacing to prevent Atrial fibrillation and heart failure (MINERVA) study is a prospective, multi-center, randomized, international, single-blind, controlled trial designed to determine whether physiologic pacing through the managed ventricular pacing (MVP) algorithm combined with preventive atrial pacing (PAP) and atrial antitachycardia pacing (ATP) is superior to standard DDD pacing in terms of 2-year reduction in death, permanent ATA, and cardiovascular hospitalizations. Patients with standard class I or II indications for permanent DDD pacing and history of ATA will receive a Medtronic EnRhythm implantable pacemaker (Medtronic, Minneapolis, MN). After a 1-month run-in period, patients will be randomized in a 1:1:1 manner to the DDD (control group, all OFF), the DDDRP (MVP + PAP + ATP ON), and the MVP group (only MVP ON). Up to 1,300 patients will be included in approximately 70 centers in Europe, the Middle East, and Asia.

CONCLUSIONS

The MINERVA study will make an important contribution to the management of patients with paroxysmal ATA and accepted indications for dual-chamber pacemaker implantation by determining whether physiologic pacing combined with PAP and ATP is superior to standard DDD pacing in terms of reduction of mortality, incidence of permanent ATA, and cardiovascular hospitalizations.

Pharmacotherapy changes following pacemaker implantation in patients with bradycardia-tachycardia syndrome

The management of bradycardia-tachycardia syndrome (BTS) includes bradycardia and tachyarrhythmia therapy. At present, the treatment for symptomatic bradycardia in BTS patients is permanent cardiac pacing. The pharmacological treatment of atrial tachyarrhythmias comprises of rhythm and rate control, and prevention of thromboembolism. Patients with BTS often require both pacemaker and drug therapy. This article reviews the interactions of pacing and drug therapies in BTS. Drugs that alter cardiac electrophysiological properties may influence pacemaker indications, pacing mode selection, efficacy of pacing algorithms and pacing performance. Pacing by preventing drug-induced bradycardia increases the safety of pharmacotherapy and, thus, allows the intensification of those treatments. Pacing therapy and antiarrhythmic drugs used together as a hybrid therapy have a synergistic effect in the prevention of atrial tachyarrhythmias. Atrial-based pacing may reduce atrial tachyarrhythmia burden, allowing reduction of rhythm and rate control. Contemporary pacemakers' memory functions may help guide rhythm and rate control, as well as anticoagulation pharmacotherapy.

Group Purchasing Organizations: Optimizing Cardiac Device Selection, Therapy Delivery, and Fiscal Responsibility

Group purchasing organizations (GPOs) have played a major role in supporting health care delivery in recent years as the healthcare industry has faced stronger economic pressures. Consequently, a position statement was drafted to act as a guideline for a GPO in creating a fiscally responsible, yet unrestricted environment for physicians to select the most appropriate cardiac device for their patients. This cardiac device selection guideline is to be implemented in hundreds of member hospitals but may be of use in non-member hospitals as well. The guideline will only be effective when the physicians or cardiac device caregivers have the knowledge and skills to optimally program and match device therapies and algorithms to individual patient needs.

Biventricular versus right ventricular pacing decreases immune activation and augments nitric oxide production in patients with chronic heart failure

INTRODUCTION

Immune system activation and oxidative stress are involved in the pathogenesis of heart failure (HF). We aimed to test the hypothesis that upgrading from right ventricular pacing (RVp) to biventricular pacing (BiVp) can counteract these phenomena.

METHODS

28 HF patients, with BiVp were switched to RVp for one week, and then returned to BiVp. Immediately prior to, and 48 h after the return to BiVp, left ventricular (LV) systolic function was evaluated by echocardiography, and serum N-terminal pro-brain natriuretic peptide (NTproBNP), C-reactive protein (CRP), tumor necrosis factor alpha (TNF-alpha), interleukin 6 (IL6), nitric oxide metabolites (NO(x)) and malondialdehyde (MDA) were assayed.

RESULTS

LV systolic function significantly improved 48 h after switching from RVp to BiVp: Ao-VTI (p<0.001), SV (p<0.001) and CO (p<0.001), and mitral regurgitation significantly decreased (p=0.003). At the same time, indices of peripheral immune activation decreased: TNF-alpha (p=0.02) and IL6 (p<0.001). MDA decreased (p<0.001), whereas NO(x) increased (p=0.04). NTproBNP and CRP did not change. In addition, in "responders" (i.e. CO increase >10% during BiVp vs. RVp) NTproBNP decreased and NO(x) increased. However, during BiVp, the decreases in TNF-alpha, IL6, and MDA occurred both in responders and in non-responders and were accompanied by a reduction in mitral regurgitation.

CONCLUSION

The beneficial effect of BiVp compared to RVp extends beyond improving cardiac haemodynamics and comprises a decrease in immune activation accompanied by an increase in serum NO(x) and decrease in serum MDA.

Heart failure during cardiac pacing

BACKGROUND

Right ventricular apical (RVA) pacing creates abnormal left ventricular contraction, hypertrophy, and reduced pump function. The adverse effects of ventricular desynchronization may explain the association of RVA pacing with an increased risk of heart failure hospitalization (HFH) in clinical trials.

METHODS AND RESULTS

Baseline and postimplantation variables were used to predict HFH in the Mode Selection Trial, a 2010-patient, 6-year trial of dual-chamber (DDDR) versus ventricular (VVIR) pacing in sinus node dysfunction. A Cox model showed that New York Heart Association (NYHA) class at baseline and follow-up predicted HFH (hazard ratio [HR], 3.99; 95% confidence interval [CI], 2.74-5.79 for NYHA class III/IV and HR, 2.17; 95% CI, 1.54-3.04 for NYHA class II versus class I); other predictors were heart failure (HR, 2.30; 95% CI, 1.70-3.11), atrioventricular (AV) block (HR, 1.48; 95% CI, 1.11-1.97), and myocardial infarction (MI)(HR, 1.37; 95% CI, 1.00-1.86). Postimplantation predictors were VVIR cumulative percent ventricular pacing (Cum%VP) >80 (HR, 3.58; 95% CI, 1.72-7.45), DDDR Cum%VP >40 or VVIR Cum%VP < or =80 (HR, 1.81; 95% CI, 0.94-3.50) versus DDDR Cum%VP < or =40; whether QRS duration (QRSd) was paced or spontaneous (HR, 2.21; 95% CI, 1.39-3.54; spontaneous versus paced); and drugs for atrial fibrillation (HR, 1.60; 95% CI, 1.19-2.15). Low baseline ejection fraction (EF) and postimplantation RVA-paced or spontaneous QRSd predicted HFH; the increased risk with QRSd was steeper for normal versus low EF (HR, 1.18; 95% CI, 1.11-1.27; versus HR, 1.08; 95% CI, 1.01-1.15; for a 10-ms increase); at a QRSd of approximately 200 ms, normal- and low-EF patients had equivalent risk. HFH risk nearly doubled when VVIR Cum%VP was < or =80 or DDDR Cum%VP was >40 versus DDDR Cum%VP < or =40 and was additive with other risk factors.

CONCLUSIONS

Differences in HFH risk can be explained by interactions between substrate (atrial fibrillation, AV conduction, heart failure, MI, EF) and pacing promoters (ventricular desynchronization-paced QRSd and Cum%VP, and AV desynchronization-pacing mode). Management of RVA pacing is important for reducing the risk of HFH, particularly among patients with low EF and heart failure.

Cardiac pacing for bradycardia support: Evidence-based approach to pacemaker selection and programming

The vast majority of pacemakers implanted in the United States for the treatment of symptomatic bradycardia are dual-chamber systems with a complex array of functions, such as rate responsiveness, dynamic atrioventricular delay, and automatic mode switching. Basic hemodynamic studies have convincingly demonstrated the superiority of maintaining atrioventricular synchrony. However, clinical trials have failed to demonstrate the impressive results expected based on physiologic data. The most recent randomized clinical trials have demonstrated that dual-chamber devices, when compared with single-chamber ventricular pacing, do not prevent mortality or stroke, and lead to an unexpectedly small reduction in heart failure hospitalizations. Although improvements in quality of life have not been consistently found when comparing ventricular-based versus atrial-based pacing, a reduction in the incidence of newly diagnosed atrial fibrillation in dual chamber-paced patients has been reported by most trials. Dual-chamber pacing has been reported to reduce pacemaker syndrome in US trials. The addition of rate modulation, in spite of attempting to replicate the normal response to exercise, has not shown a consistently positive impact on quality of life or treadmill time. The use of pacemakers for the treatment of vasovagal syncope is controversial. Adding dual-chamber sensing ability to current implanted defibrillators considerably reduces the number of inappropriate shocks but may increase mortality if not programmed to minimize ventricular stimulation.