Initiation and development of a percutaneous left atrial appendage closure programme: A French centre's experience and literature review.

BACKGROUND: Percutaneous left atrial appendage closure may be considered in selected patients with atrial fibrillation at significant risk of both thromboembolism and haemorrhage. AIMS: To report the experience of a tertiary French centre in percutaneous left atrial appendage closure and to discuss the outcomes compared with previously published series. METHODS: This was a retrospective observational cohort study of all patients referred for percutaneous left atrial appendage closure between 2014 and 2020. Patient characteristics, procedural management and outcomes were reported, and the incidence of thromboembolic and bleeding events during follow-up were compared with historical incidence rates. RESULTS: Overall, 207 patients had left atrial appendage closure (mean age 75.3±8.6 years; 68% men; CHA2DS2-VASc score 4.8±1.5 ; HAS-BLED score 3.3±1.1), with a 97.6% (n=202) success rate. Twenty (9.7%) patients had at least one significant periprocedural complication, including six (2.9%) tamponades and three (1.4%) thromboembolisms. Periprocedural complication rates decreased from earlier to more recent periods (from 13% before 2018 to 5.9% after; P=0.07). During a mean follow-up of 23.1±20.2 months, 11 thromboembolic events were observed (2.8% per patient-year), a 72% risk reduction compared with the estimated theoretical annual risk. Conversely, 21 (10%) patients experienced bleeding during follow-up, with almost half of the events occurring during the first 3 months. After the first 3 months, the risk of major bleeding was 4.0% per patient-year, a 31% risk reduction compared with the expected estimated risk. CONCLUSION: This real-world evaluation emphasizes the feasibility and benefit of left atrial appendage closure, but also illustrates the need for multidisciplinary expertise to initiate and develop this activity.

Catheter ablation in adults with congenital heart disease: A 15-year perspective from a tertiary centre.

BACKGROUND: With the growing adult congenital heart disease (ACHD) population, the number of catheter ablation procedures is expected to dramatically increase. Data reporting experience and evolution of catheter ablation in patients with ACHD, over a significant period of time, remain scarce. AIM: We aimed to describe temporal trends in volume and outcomes of catheter ablation in patients with ACHD. METHODS: This was a retrospective observational study including all consecutive patients with ACHD undergoing attempted catheter ablation in a large tertiary referral centre over a 15-year period. Acute procedural success rate and freedom from recurrence at 12 and 24 months were analysed. RESULTS: From November 2004 to November 2019, 302 catheter ablations were performed in 221 patients with ACHD (mean age 43.6±15.0 years; 58.9% male sex). The annual number of catheter ablations increased progressively from four to 60 cases per year (P<0.001). Intra-atrial reentrant tachycardia/focal atrial tachycardia was the most common arrhythmia (n=217, 71.9%). Over the study period, acute procedural success rate increased from 45.0% to 93.4% (P<0.001). Use of irrigated catheters (odds ratio [OR] 4.03, 95% confidence interval [CI] 1.86-8.55), a three-dimensional mapping system (OR 3.70, 95% CI 1.72-7.74), contact force catheters (OR 3.60, 95% CI 1.81-7.38) and high-density mapping (OR 3.69, 95% CI 1.82-8.14) were associated with acute procedural success. The rate of freedom from any recurrence at 12 months increased from 29.4% to 66.2% (P=0.001). Seven (2.3%) non-fatal complications occurred. CONCLUSIONS: The number of catheter ablation procedures in patients with ACHD has increased considerably over the past 15 years. Growing experience and advances in ablative technologies appear to be associated with a significant improvement in acute and mid-term outcomes.

Catheter ablation of intra-atrial reentrant/focal atrial tachycardia in adult congenital heart disease: Value of final programmed atrial stimulation.

BACKGROUND: While outcomes of intra-atrial reentrant/focal atrial tachycardia (IART/FAT) catheter ablation have considerably improved in adult congenital heart disease (ACHD), recurrences remain common with different circuits frequently encountered. OBJECTIVE: We aimed to assess the value of programmed atrial stimulation after successful clinical IART/FAT catheter ablation in patients with ACHD. METHODS: This is a retrospective study including all patients with ACHD undergoing IART/FAT catheter ablation in a tertiary center. After successful catheter ablation of clinical arrhythmia, survival free from arrhythmia recurrence was analyzed according to whether all inducible IARTs/FATs were targeted. RESULTS: From 2004 to 2020, 238 IART/FAT catheter ablation procedures were performed (mean age 44.1 ± 15.0 years; 61.3% men). Acute procedural success of clinical arrhythmia was achieved in 208 procedures (87.4%). Among 122 procedures with programmed atrial stimulation (58.7%), at least 1 other IART/FAT was induced in 61 patients (50%). All inducible IARTs/FATs were ablated in 54 patients (88.5%), whereas 7 patients (11.5%) presented with at least 1 nontargeted inducible IART/FAT. Patients with nontargeted inducible IART/FAT had a higher risk of atrial arrhythmia episodes than did inducible patients treated with ablation of all IARTs/FATs (hazard ratio 5.7; 95% confidence interval 1.7-18.4; P = .004), with 12-month atrial arrhythmias recurrence rates of 22.9% and 77.7%, respectively. Inducible patients with successful ablation of all IARTs/FATs had a risk of recurrence similar to that of noninducible patients (hazard ratio 0.6; 95% confidence interval 0.3-1.3; P = .215). CONCLUSION: Beyond clinical IART/FAT catheter ablation in patients with ACHD, our findings suggest the interest of systematically targeting all remaining inducible arrhythmias, irrespective of whether previously documented.

Implantable cardiac defibrillator among adults with transposition of the great arteries and atrial switch operation: case series and review of literature.

BACKGROUND: The experience with the implantable cardiac defibrillator (ICD) in patients with transposition of the great arteries (TGA) and history of atrial switch surgery remains limited. METHODS: Retrospective evaluation aiming to assess characteristics and outcomes of consecutive TGA patients with history of atrial switch surgery implanted with an ICD between January 2005 and June 2012 in four French centers. RESULTS: Of the 12 patients (median 34 years [28, 40]; 67% male), 4 patients (33%) were implanted for secondary prevention after symptomatic documented sustained ventricular tachycardia or sudden cardiac arrest. ICDs were implanted for primary prevention in 8 patients (67%), including cardiac resynchronization in 3 patients; severe systemic ventricle dysfunction was present in all cases (median ejection fraction 27% [20, 40]). Overall, one patient died during the ICD implantation secondary to refractory cardiac arrest after defibrillation testing. Over a median follow-up of 19 months [10, 106], 6 patients out of 11 (54%) experienced worsening of congestive heart failure, including 5 who were eventually transplanted. Overall, 3 patients (27%) experienced significant ICD-related complications, whereas only one patient (primary prevention indication) developed appropriate ICD therapy (successful anti-tachycardia pacing without shock). Half of the patients presented with at least one episode of sustained (≥ 5 min) atrial arrhythmia during follow-up. CONCLUSIONS: Our findings underline the key role of progressive heart failure in dictating outcomes among TGA patients with prior atrial switch repair. Our results also underline the need of better risk-stratification for sudden cardiac death in those patients.

Management of ventricular and atrial arrhythmias in humans: towards a patient-specific approach.

The strategy of sudden cardiac death prevention by implantable cardioverter defibrillator, in primary prevention, is mainly based on the value of ejection fraction. That means that the approach is not really patient specific. A lot of implanted patients will not receive any shock. The implantation of large categories of patients is interesting on a global therapeutical point of view but, when considering the economical aspects, it would be more useful to have better selection criteria in order to obtain a more patient-specific approach, avoiding implanting patients who will never receive shocks. The parameters commonly used to select patients for implantations have a good negative predictive value but a low positive predictive value. Concerning atrial fibrillation the approach is quite different. Antiarrhythmic drug treatment has shown many limitations. Antiarrhythmic drugs are useful and safe in atrial fibrillation patients only if the contra-indications are strictly respected. The main difficulty concerns patients with both heart failure and atrial fibrillation. The story of Dronedarone development is illustrative of the necessity of a patient-specific approach in the treatment strategy of atrial fibrillation. The ATHENA trial made with Dronedarone showed a benefit in patients with underlying heart disease but no patient with advanced cardiopathy was included in the study. On the contrary, the PALLAS trial has clearly shown that the drug is contra-indicated in patients with any type of heart failure. In atrial fibrillation, a patient-specific approach is mandatory. This review illustrates the dichotomy of the two different approaches.

Temporary transvenous VDD pacing as a bridge to permanent pacemaker implantation in patients with sepsis and haemodynamically significant atrioventricular block.

AIMS: Permanent pacemaker (PM) implantation is temporarily contraindicated in patients (pts) with sepsis. In patients with symptomatic atrioventricular (AV) block and infection, prolonged VVI pacing is therefore usually ensured by a ventricular pacing lead (PL) connected to an external PM generator. In patients with normal sinus function and heart failure, the VVI mode can exacerbate haemodynamic dysfunction. A single AV PL can be attractive to achieve physiological pacing. This study was designed to assess the efficacy and safety of temporary VDD pacing as a bridge to permanent PM implantation in patients with complete AV block until control of infection. METHODS AND RESULTS: This study included eight patients with complete AV block and sepsis with negative blood culture. Due to the presence of congestive heart failure, a single bipolar AV PL connected to an external VDD PM generator. At VDD implantation, P-wave amplitude was 1.9 ± 1.6 mV and R-wave was 11.3 ± 5.2 mV. The ventricular pacing threshold was 0.53 ± 0.1 V for a 0.5 ms pulse. Antibiotic therapy was instituted in all patients. A permanent VDD or DDD PM was implanted after 8 ± 2.5 days of temporary VDD pacing. At permanent PM implantation, the mean brain natriuretic peptide level had decreased and sepsis was controlled in all patients. No recurrence of sepsis was observed with a mean follow-up of 15.8 ± 5.3 months. CONCLUSION: Temporary VDD pacing is a safe and effective method to achieve prolonged AV physiological pacing in patients with AV block until infection has been controlled.

Treatment of unexplained syncope: a multicenter, randomized trial of cardiac pacing guided by adenosine 5'-triphosphate testing.

BACKGROUND: The origin of 40% of syncope cases remains unknown even after a complete diagnostic workup. Previous studies have suggested that ATP testing has value in selecting successful therapy. This patient-blinded, multicenter, randomized superiority trial tested whether, in patients with syncope of unknown origin, selecting cardiac pacing in those with a positive ATP test leads to fewer recurrences than those who do not receive pacing. METHODS AND RESULTS: From 2000 to 2005, 80 consenting patients (mean age, 75.9±7.7 years; 81% women; 56% without diagnosed structural heart disease) with syncope of unknown origin and atrioventricular or sinoatrial block lasting >10 seconds (average, 17.9±6.8 seconds) under ATP administration (20-mg IV bolus) were recruited from 10 hospitals, implanted with programmable pacemakers, and randomized to either active pacing (dual-chamber pacing at 70 bpm) or backup pacing (atrial pacing at 30 bpm). Patients were followed up regularly for up to 5 years for any syncope recurrence, the primary outcome. Mean follow-up was 16 months. Syncope recurred in 8 of 39 patients (21%) randomized to active pacing and in 27 of 41 (66%) randomized to backup pacing (control), yielding a hazard ratio of 0.25 (95% confidence interval, 0.12-0.56). After recurrence, the 27 recurrent control patients were reprogrammed to active pacing, and only 1 reported subsequent syncope. CONCLUSION: This study suggests that, in elderly patients with syncope of unknown origin and positive ATP tests, active dual-chamber pacing reduces syncope recurrence risk by 75% (95% confidence interval, 44-88). CLINICAL TRIAL REGISTRATION: URL: http://www.controlled-trials.com/ISRCTN00029383. Unique identifier: ISRCTN00029383.

Impact of the revision of arrhythmogenic right ventricular cardiomyopathy/dysplasia task force criteria on its prevalence by CMR criteria.

OBJECTIVES: The purpose of our study was to assess the impact of revised versus original criteria on the prevalence of arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D) criteria in cardiac magnetic resonance (CMR) studies. BACKGROUND: Recently, the ARVC/D task force criteria have been revised, aiming for a better diagnostic sensitivity. The implications of this revision on clinical decision making are unknown. METHODS: We retrospectively evaluated the CMR scans of 294 patients referred for ARVC/D between 2005 and 2010, and determined the presence or absence of major and minor CMR criteria using the original and the revised task force criteria. Previously, major and minor abnormalities were identified by the presence of right ventricle dilation (global or segmental), right ventricle microaneurysm, or regional hypokinesis. The revised criteria require the combination of severe regional wall motion abnormalities (akinesis or dyskinesis or dyssynchrony) with global right ventricle dilation or dysfunction (quantitative assessment). RESULTS: Applying the original criteria, 69 patients (23.5%) had major original criteria, versus 19 patients (6.5%) with the revised criteria. Forty-three patients (62.3%) with major original criteria did not meet any of the revised criteria. Using the original criteria, 172 patients (58.5%) had at least 1 minor criterion versus 12 patients (4%) with the revised task force criteria; 167 patients (97%) with minor original criteria did not meet any of the revised criteria. In the subgroup of 134 patients with complete diagnostic work-up of ARVC, 10 patients met the diagnosis of proven ARVC/D without counting imaging criteria. Only 4 of 10 met major criteria according to the revised CMR criteria; none met minor criteria. However, 112 of 124 patients without ARVC/D were correctly classified as negative by major and minor criteria (specificity 94% and 96%, respectively). CONCLUSIONS: In our experience, the revision of the ARVC/D task force imaging criteria significantly reduced the overall prevalence of major and minor criteria. The revision, although maintaining a high specificity, may not have improved the sensitivity for identifying patients with ARVC/D. Larger studies including follow-up are required.

Predictors for short-term progressive heart failure death in New York Heart Association II patients implanted with a cardioverter defibrillator--the EVADEF study.

BACKGROUND: Sudden cardiac death (SCD) is the predominant cause of mortality in patients with mild heart failure (HF). This 2-year follow-up, multicenter, cohort study aimed to assess the extent to which implantable cardioverter defibrillators (ICDs), by reducing SCD, lead to predominant progressive HF death in mildly symptomatic HF patients at baseline in daily medical practice. METHODS: Between June 2001 and June 2003, 1,030 New York Heart Association II patients received an ICD in 22 French centers. Sudden cardiac death and progressive HF mortality rates were assessed using competing risk methodology, and predictors for progressive HF at baseline were tested in a multivariate regression model. RESULTS: During a mean follow-up of 22 +/- 6 months, 114 deaths occurred: 12 (10.5%) due to SCD and 52 (45.6%) due to progressive HF (24-month cause-specific mortality rates of 1.2% [95% CI 0.6-1.9] and 5.4% [95% CI 4.0-6.8], respectively). Diuretics use (hazard ratio [HR] 2.8, 95% CI 1.5-5.5, P = .002), history of atrial fibrillation (HR 2.09, 95% CI 1.2-3.65, P = .01), and low ejection fraction (HR 2.7, 95% CI 1.4-4.8, P = .0008) were independent predictors for progressive HF death, whereas beta-blocker therapy was a protector (HR 0.6, 95% CI 0.3-0.9, P = .04). Half of the patients (48%) who died from progressive HF within 2 years of ICD implant initially presented with enlarged QRS (> or =120 milliseconds). CONCLUSIONS: Because of ICD efficiency, progressive HF is the main cause of death within 2 years of implant, although these patients are only mildly symptomatic at implantation. In addition to optimal pharmacologic therapy, these results raise the question of systematically implanting ICDs with cardiac resynchronization therapy in patients with electrical asynchronism at baseline.

[Treatment of atrial fibrillation in heart failure]. / Traiter la fibrillation atriale dans l'insuffisance cardiaque.

Treatment of patients with both atrial fibrillation and heart failure remains uneasy. In theory maintenance of sinus rhythm is desirable but the only pharmacological intervention able to do it safely is amiodarone. A trial of strategy randomisation, restoration of sinus rhythm or slowing of atrial fibrillation, has been done in patients with both atrial fibrillation and heart failure. This trial, named AF-CHF has shown neutral results, the 2 strategies, rhythm control or simple rate control were similar in terms of mortality. Dronedarone is an innovative drug bringing new possibilities in the treatment of atrial fibrillation but it is contra-indicated in case of severe heart failure. Another possible approach is that of non pharmacological techniques. Sinus rhythm maintenance may be obtained by pulmonary vein isolation. The other possibility is the ablation of atrio-ventricular node with implantation of a pacemaker, technique which is reserved to selected patients.

Rates and predictors of appropriate implantable cardioverter-defibrillator therapy delivery: results from the EVADEF cohort study.

BACKGROUND: The implantable cardioverter defibrillator (ICD) is the therapy of choice in patients at risk for sudden cardiac death in both primary and secondary prevention indication. There are no recent data concerning the delivery rate and etiology of appropriate ICD therapies in routine medical care. METHODS: The EVADEF study was a French multicenter, prospective, observational cohort study of ICD patients with a 2-year follow-up. Every 6 months we recorded patients' survival status and evaluated appropriate ICD therapies-antitachycardia pacing or shocks. Causes of ICD activation were also recorded from among ventricular tachycardia (VT), fast VT and ventricular fibrillation (VF). RESULTS: From 2001 to 2003, 2296 unselected patients were implanted and followed until 2005. During a mean follow-up of 20.5 months, 274 deaths occurred. In 2009 patients with cardiopathy, 22 patients per 100 person-years had at least one appropriate therapy. Twenty-four and 11 patients per 100 person-years had at least one therapy in secondary and primary prevention, respectively. Age >65 years, left ventricular ejection fraction <30% and secondary prevention were independently associated with appropriate therapy. Besides, 5 patients per 100 person-years had at least 1 episode of life-threatening arrhythmia (fast VT or VF). Left ventricular ejection fraction <30% and secondary prevention were independently associated with life-threatening arrhythmia. In 287 patients without cardiopathy, the rate of appropriate therapy was twice as less, whereas the rate of life-threatening arrhythmia was similar. CONCLUSION: Over a 24-month follow-up, the rate of appropriate therapy was substantial while few patients had life-threatening arrhythmia. Appropriate therapies and life-threatening arrhythmia were more frequent in patients with secondary prevention indication.

Competing risk analysis of cause-specific mortality in patients with an implantable cardioverter-defibrillator: The EVADEF cohort study.

BACKGROUND: Although implantable cardioverter-defibrillator (ICD) therapy has been evaluated in randomized controlled trials, enrolling highly selected patients, mortality events in ICD patients have received little attention in routine medical care. We sought to assess the 24-month total and cause-specific mortality rates and their predictors in "real life" patients with an ICD. METHODS: The Evaluation Médico-Economique du Défibrillateur Automatique Implantable study was a French multicenter, prospective, observational cohort study of ICD patients with a 2-year follow-up. Cause-specific mortality rates and predictors at implantation of sudden cardiac death (SCD) or progressive heart failure (HF) death were assessed using competing risk methodology. RESULTS: From June 2001 to June 2003, 2,296 unselected patients were implanted and followed until June 2005. During a mean follow-up of 20.5 +/- 6.7 months, 274 deaths occurred: 29 (10.6%) were SCD and 146 (53.3%) were HF deaths, corresponding to 24-month cause-specific mortality rates of 1.4% (95% confidence interval 0.9%-1.9%) and 6.9% (95% confidence interval 5.8%-8.0%), respectively. Among the characteristics at implantation, ejection fraction (EF) <30% and history of atrial fibrillation were independently associated with SCD; age, high New York Heart Association class, systemic hypertension, prior atrial fibrillation, QRS duration, EF <30%, and lack of beta-blocker therapy were independently associated with HF death. CONCLUSIONS: In this large cohort of "daily" patients, the 2-year incidence of SCD (1.4%) was comparable with the event rate observed in randomized controlled trials; HF remained the predominant mode of death. An EF <30% at implantation appears to be the most important predictor of ICD-unresponsive SCD.

Relationship between New York Heart Association class change and ventricular tachyarrhythmia occurrence in patients treated with cardiac resynchronization plus defibrillator.

AIMS: In patients with advanced heart failure (HF) and prolonged QRS interval, cardiac resynchronization therapy (CRT) reduces symptoms and risk of death. The added benefit of an implantable cardioverter defibrillator (ICD) remains questionable in some patients. METHODS AND RESULTS: In 332 HF patients treated with CRT-D (CRT with ICD) [65 +/- 10 years, 86% men, 23% New York Heart Association (NYHA) class II, 65% class III, and 11% class IV, 70% primary prevention, 55% ischaemic cardiomyopathy, left ventricular ejection fraction 25 +/- 7.5%, and QRS width 167 +/- 32 ms], we evaluated the relationship between functional status change, death at 6-month follow-up (FU), and the occurrence of ventricular tachyarrhythmia/ventricular fibrillation (VT/VF). A total of 68 patients (20.5%) experienced 1266 spontaneous episodes of VT/VF during FU. There was no difference in baseline characteristics between patients with or without VT/VF, except for ICD indication (primary or secondary prevention). Improvement in NYHA class was significantly associated with a decreased occurrence of VT/VF (P = 0.004). Sixteen patients who died had significantly more often VT/VF than the survivors (50 vs. 19%, P = 0.007). CONCLUSION: Within the initial 6-month post-CRT therapy, 20% of patients received an appropriate ICD therapy. Patients improving on NYHA class (responders to CRT) have less VT/VF episodes than non-responders. Discriminant criteria for CRT response are awaited to optimize the choice of the device (CRT alone, defibrillator alone, or CRT-D).

Pathophysiology of atrial fibrillation: insights into the renin-angiotensin system.

INTRODUCTION: Atrial fibrillation is, to date, a major problem of public health with an important cost in the health care system. DISCUSSION: The therapeutic strategies for atrial fibrillation are complex and their outcomes have been disappointing globally. New ablative techniques have brought important advances but the patient's profile has to be taken into account in the choice of the therapeutic strategies. The renin-angiotensin system plays a major role in the phenomena of remodelling following the onset of atrial fibrillation. CONCLUSION: Drugs blocking the renin-angiotensin system can have a real place in the treatment of atrial fibrillation, not only to maintain sinus rhythm but primarily to prevent cardiovascular accidents in these patients with atrial fibrillation and in some cases to prevent the occurrence of atrial fibrillation, for example in hypertensive patients.

[Atrial fibrillation: the most common arrhythmia]. / Fibrillation atriale : le plus fréquent des troubles du rythme.

The incidence of atrial fibrillation increases rapidly with population age. Atrial fibrillation essentially presents a problem of long-term management. Strategies of rhythm or rate control should be considered on a case-by-case basis for each individual. Anticoagulation treatment is indicated in most cases. Radiofrequency ablation by pulmonary vein isolation is an unquestionably innovative treatment but is reserved for selected patients.

Atrial septal pacing to prevent atrial fibrillation in patients with sinus node dysfunction: results of a randomized controlled study.

BACKGROUND: In order to assess the preventive effects of right atrial septal pacing on atrial fibrillation (AF) in patients with sinus node dysfunction, we conducted a prospective randomized controlled study in patients requiring atrial pacing. METHODS: The inclusion criterion was the presence of a sinus node dysfunction with or without episodes of AF. Pacing sites were randomized to either the right atrial septum or appendage. Patients with permanent AF or with atrioventricular (AV) block without sinus node dysfunction were excluded. Patients were discharged at a pacing rate of 65 beats per minute after setting of the optimal AV delay. The antiarrhythmic therapy remained unchanged until the first recurrence of AF. Sequential analyses were performed with the triangular test. RESULTS: Mean baseline characteristics were not different between the septum (n = 57) and the appendage (n = 67) groups. The triangular test evidenced a lack of effect of septal pacing at the last sequential analysis. The rates of AF-free survival were not different between the septum and the appendage group (65% vs 64%, P =.28). In the subgroup of patients with at least 1 episode of AF 3 months before pacing, AF-free survival was increased by atrial septal pacing (70% vs 40%, P =.018). The mean follow-up was 16 +/- 13 months (range, 1-54). CONCLUSIONS: Atrial septal pacing does not have a preventive effect on the occurrence of AF in patient requiring atrial pacing for sinus node dysfunction. Subgroup analysis suggests that atrial septal pacing may benefit patients with >or=1 episode of AF in the 3 months preceding pacing.

Atrial septal versus atrial appendage pacing: feasibility and effects on atrial conduction, interatrial synchronization, and atrioventricular sequence.

Atrial septal (Se-P) and atrial appendage pacing (Ap-P) were compared in a randomized, controlled study to assess the feasibility, the reliability, and the effects of Se-P on atrial conduction, interatrial synchronization, and the AV sequence. The main baseline characteristics of the patients were comparable in both groups. There was no difference in feasibility or reliability between the two techniques. Compared to Ap-P (n = 28), Se-P (n = 28) decreased the P wave duration, left atrial electromechanical delay (LAEMD), and interatrial interval (-1.6% vs +28%, P < 0.001; -3% vs +30%, P < 0.001; -130% vs +78%, P < 0.001); it induced a smaller increase of the right AEMD, a slight reversal of the timing of the atrial systoles and a shortening of the PR interval (-13% vs +25%, P < 0.001) and of the interval separating atrial systoles from ventricular activation. Finally, the shortening of the PR interval was smaller during high Se-P versus low Se-P. Se-P avoids the undesirable prolongation of the atrial, interatrial, and AV conductions observed during Ap-P. In addition, Se-P creates a slight reversal of the timing of the atrial systoles and induces a shortening of PR interval, the extent of which could depend on the height of the pacing site on the septum.