Dual Site Right Atrial Pacing can Improve the Impact of Standard Dual Chamber Pacing on Atrial and Ventricular Mechanical Function in Patients with Symptomatic Atrial Fibrillation: Further Observations from the Dual Site Atrial Pacing for Prevention of Atrial Fibrillation Trial

Atrial resynchronization therapy in patients with atrial fibrillation and heart failure with and without systolic left ventricular dysfunction: a pilot study

BACKGROUND

We examined the long-term (≥ 5 years) outcomes of dual-site atrial pacing (DAP) when added to background antiarrhythmic drugs (AADs) and/or ablation in patients with refractory atrial fibrillation (AF) and heart failure (HF).

METHODS

Seventy-three patients with HF (mean NYHA HF class of 2.5) and AF refractory to AADs and/or ablation were implanted with DAP systems to achieve biatrial electrical and mechanical resynchronization (ART) and rhythm control (RC).

RESULTS

Thirty-eight patients with refractory AF and HF with preserved ejection fraction (HFpEF) and 35 with reduced ejection fraction (HFrEF) were enrolled. HFpEF patients had higher left ventricular ejection fraction compared to HFrEF (53 ± 5 vs. 31 ± 10% p < 0.001). Median follow-up for survival was 9.3 years (mean 9.0 years, SE 0.63) and was similar across subgroups (p = 0.127). After DAP, 87% maintained RC with improvement in NYHA HF class (mean 1.8) at 3 years. RC was similar in HFpEF compared with HFrEF patients (89 vs. 85% respectively, p = NS) and in paroxysmal versus persistent AF (90 vs. 85% respectively, p = NS). Total survival was superior in HFpEF compared HFrEF patients (75% in HFpEF vs. 45% in HFrEF at 5 years, and 60% in HFpEF vs. 34% in HFrEF at 10 years, p = 0.036). Survival trended to be better in patients with RC than those without RC (75 vs. 54% respectively at 5 years, p = .13).

CONCLUSIONS

ART using DAP as add on therapy improved HF and established long-term RC in many patients with HFrEF and HFpEF with refractory AF. Long-term survival rates were superior in HFpEF than HFrEF.

Permanent left atrial pacing therapy may improve symptoms in heart failure patients with preserved ejection fraction and atrial dyssynchrony: a pilot study prior to a national clinical research programme

AIMS

Our group has recently shown that in some patients, heart failure with preserved ejection fraction (HFPEF) may be explained by 'atrial dyssynchrony syndrome' (ADS) due to interatrial conduction delay (IACD), a short left atrioventricular interval (LAVI), and increased left atrial (LA) stiffness. Our primary objective was to evaluate LA pacing therapy as a new treatment to restore left ventricular active filling in patients with no other known causes for HF than ADS.

METHODS AND RESULTS

Six patients with severe HFPEF with IACD (P wave duration >120 ms in lead II), short LAVI during electrophysiological studies (<70 ms), a restrictive filling pattern (E/e' >15), and no standard indication for a pacemaker were implanted with a lead screwed inside the coronary sinus for active LA pacing. After 3 months of active pacing, a 2 week randomized double-blind crossover phase compared active vs. inactive LA pacing. After 3 months of pacing, the mean distance walked in 6 min (6MWD) was 21% greater (240 ± 25 m vs. 190 ± 15m, P < 0.05), mitral A wave duration was longer (104 ± 8 vs. 158 ± 25 ms, P = 0.002), and E/A and E/e' ratios were smaller (3.4 ± 1.3 vs. 1.8 ± 0.9, P = 0.009, and 22.6 ± 4.6 vs. 15.3 ± 4.3, P = 0.006, respectively). Inactivation of pacing for 1 week led to a significant reduction in the 6MWD, with an on/off response.

CONCLUSION

The beneficial effects of LA pacing observed in this pilot study will have to be confirmed by the randomized, controlled crossover 'LEAD' study.

Atrial dyssynchrony syndrome: an overlooked phenomenon and a potential cause of 'diastolic' heart failure

AIMS

The purpose of the present study was too explore the role of interatrial dyssynchrony in heart failure with preserved ejection fraction (HFPEF).

METHODS AND RESULTS

For the case study we selected seven patients with severe HFPEF, with interatrial block on electrocardiogram (ECG), and a delayed and interrupted A wave on mitral Doppler. Echocardiographic left atrial (LA) volumes/functions, mitral E/A and E/e' ratios, mitral A wave duration/deceleration time, and interatrial mechanical delays (IAMDs) at tissue Doppler, were studied. We performed right heart catheterization, and an electrophysiological study (EPS) for the measurement of interatrial conduction delay (IACD) and left atrioventricular interval (LAVI). Mean IAMD was 106 ms. All the patients exhibited a restrictive mitral Doppler pattern, high E/A and E/e' ratios, and short A wave duration/deceleration time. Left atrial volume was increased, with severely depressed functions. Right heart catheterization showed severe post-capillary pulmonary hypertension. The EPS showed an IACD of 170 ± 20 ms, with a short LAVI. Left atrial pacing through the coronary sinus reduced the IACD to 25 ± 15 ms. In the pilot study, 29 patients with HFPEF were compared with 27 age-matched control patients. HFPEF patients had longer P waves, shorter A waves, and a longer IAMD than the controls. Prevalence of severe IAMD >60 ms was 59% in HFPEF and 0% in controls. In the HFPEF group, patients with an IAMD >60 ms had significantly shorter A waves and higher E/e' ratio.

CONCLUSION

Some HFPEF patients present with IACD, delayed LA systole, shortened LA emptying, decreased LA compliance, and increased filling pressures. Whether the condition of these patients could be improved by atrial resynchronization deserves further investigation.

Atrial function during different multisite atrial pacing modalities in patients with bradycardia--tachycardia syndrome

BACKGROUND

Multisite atrial pacing (MAP) was introduced to improve atrial electrical synchrony and prevent recurrence of atrial fibrillation (AF).

METHODS AND RESULTS

In the present study there were 57 patients with sinus node disease, AF recurrence and prolonged P-wave on ECG with 2 MAP modalities. In all patients 1 lead was implanted in the coronary sinus (CS) ostium area. In the right atrial appendage (RAA)+CS group (28 patients) the other atrial lead was in the RAA, and in the BB+CS group (29 patients) in the Bachmann's bundle (BB) region. Tissue Doppler was used to register the electromechanical delay (EMD) in the atrial walls and estimate the atrial contraction synchrony. Cardiac output and myocardial performance index did not differ during the 2 MAP modalities. During BB+CS, in comparison with RAA+CS pacing, the peak of the mitral atrial wave occurred earlier (P<0.01), the usual right-left atrial contraction sequence was reversed more frequently (P<0.004), all atrial EMDs except for the lateral left atrium (LA) were shorter (P<0.05), and LA synchrony was greater (P<0.001).

CONCLUSIONS

In patients treated with MAP, implanting 1 of the atrial leads in the BB area instead of the RAA has no influence on global cardiac hemodynamics, but does result in earlier LA contraction, and reversal of the typical right-left atrial contraction sequence, as well as providing greater LA contraction synchrony.

Optimal site for atrial lead implantation in myotonic dystrophy patients: the role of Bachmann's Bundle stimulation

AIM

The aim of this study was to identify the optimal site for atrial lead implantation in myotonic dystrophy type 1 (MD1) patients.

METHODS

The atrial pacing lead was positioned in the high-lateral right atrial wall (site A), then in the right atrial appendage (site B), and finally on the interatrial septum (site C) in 22 patients. Pacing and sensing thresholds were obtained for all sites. The lead was repositioned and fixed at the optimal site, defined as the location with the lowest pacing and the highest sensing thresholds.

RESULTS

Mean pacing thresholds were 1.46 +/- 0.32 V at site A, 1.45 +/- 0.33 V at site B, and 0.84 +/- 0.24 V at site C. P-wave amplitude was 1.52 +/- 0.45 mV at site A, 1.52 +/- 0.49 mV at site B, and 2.60 +/- 0.48 mV at site C. Atrial lead was implanted at site C in all patients without complications.

CONCLUSIONS

Interatrial septum in the region of Bachmann's Bundle seems to be the optimal site for atrial lead implantation in MD1 patients.

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.

Dual-site right atrial pacing increases left atrial appendage flow in patients with sick sinus syndrome and paroxysmal atrial fibrillation

BACKGROUND

Dual-site right atrial pacing has been proposed as a promising concept for prevention of paroxysmal atrial fibrillation (PAF). Effects of this pacing configuration on left atrial appendage (LAA) flow and transmitral flow may be of prognostic and hemodynamic relevance. This study aims to characterize acute changes in left atrial flow depending on dual-site right atrial pacing.

METHODS

In 12 patients (66 +/- 8.8 years, 4 women) with PAF and sinus bradycardia a pacemaker with a right atrial dual-site lead configuration (right atrial lateral and coronary sinus ostium) was implanted. Flow velocities in the left pulmonary vein (LPV), LAA, and across the mitral valve were assessed by transesophageal echocardiography and compared during sinus rhythm (SR) and dual-site (DS) pacing.

RESULTS

Dual-site pacing resulted in higher maximum (SR: 0.57 m/s; pacing: 0.77 m/s; P < 0.02) and mean (SR: 0.33 m/s; DS: 0.47 m/s; P < 0.01) LAA emptying flow when compared with SR. The passive transmitral flow component (maximum E-wave velocity) was lower during dual-site pacing (SR: 0.53 m/s vs DS: 0.44 m/s, P < 0.02). The E/A ratio tended to be lower during dual-site pacing (SR: 1.21 vs DS: 1.01, P = 0,10). LPV flow velocities during SR and DS pacing did not differ.

CONCLUSION

DS right atrial stimulation in patients with PAF increases the LAA emptying flow velocity and shifts the transmitral flow pattern towards a lower passive component when compared with sinus rhythm. The change in LAA flow may contribute to a lower incidence of thromboembolism and merits further investigation.

Impact of "hybrid therapy" on long-term rhythm control and arrhythmia related hospitalizations in patients with drug-refractory persistent and permanent atrial fibrillation

BACKGROUND

Recently, a "hybrid therapy" strategy has been used for successful rhythm control in persistent and permanent atrial fibrillation (AF) patients. The impact of this strategy on arrhythmia recurrences and subsequent AF related hospitalizations are unknown.

MATERIALS AND METHODS

Forty-seven patients (66 +/- 10 years) with symptomatic persistent (N = 26) or permanent (N = 21) AF underwent "hybrid therapy" and were followed for 24 +/- 15 months. All patients underwent linear right atrial ablation and implantation of pacemaker or atrioventricular defibrillator (AVICD) capable of continuous right atrial pacing with previously ineffective antiarrhythmic drug therapy for AF prevention. Device data-logs were used to monitor AF recurrences.

RESULTS

Freedom from permanent AF was 97, 90, and 83% at 6 months, 2 and 3 years, respectively. Sixteen patients (34%) had no recurrent AF after "hybrid therapy." Thirty-one patients (66%) had a total of 55 AF recurrences (mean 1.8 per patient). There was a significant reduction in the mean AF related hospitalizations (from 3.5 +/- 2.8 to 0.57 +/- 1.1 per patient), cardioversion hospitalizations (from 3.5 +/- 2.2 to 0.38 +/- 0.5 per patient) and DC cardioversions (from 3.1 +/- 3.9 to 0.7 +/- 0.5 per patient) after hybrid therapy compared to event rates before therapy (p < 0.05 for all).

CONCLUSIONS

Rhythm control improves significantly with hybrid therapy in patients with persistent and permanent AF refractory to drugs and cardioversion therapy. This improvement is associated with a significant reduction in AF related hospitalizations and need for cardioversion therapy.

Management of atrial tachyarrhythmias. Rhythm control using implantable devices

Presently, most devices with atrial diagnostic and therapeutic features are implanted in patients for electrical treatment of bradyarrhythmias and ventricular tachyarrhythmias. The painless electrical strategies for prevention and termination of ATa have not demonstrated significant clinical effectiveness in the general population with ATa. The effectiveness of ATP in reducing burden may be significantly higher in a subgroup of patients with a high incidence of stable ATa, but this needs to be evaluated prospectively. Smart sensing and detection schemes will also help provide accurate information and determine when ATa can be terminated with ATP. Although electrical defibrillation is effective, the discomfort associated with atrial shocks has limited the widespread use of this technology. Recent technological advances have increased the capabilities of implantable devices to store large amounts of diagnostic information. In the near future, implantable devices without transvenous leads may be implanted to monitor a variety of physiologic signals. This could help improve clinical outcomes and determine which therapies (pharmacologic, ablative, or electrical) would be most effective as well as monitor their safety and efficacy. Frequent monitoring from home and the availability of this data to the physician/nurse on the Internet can potentially improve the management of patients' ATa at a much lower cost.