Comparison of survival for cardiac resynchronization therapy in atrial fibrillation patients with or without atrio-ventricular junction ablation and patients in sinus rhythm: a systematic review and network meta-analysis.

Cardiac resynchronization therapy (CRT) has been established to improve prognosis for patients with heart failure and SR. Whether the benefit observed with CRT on survival was similar in AF patients receiving atrio-ventricular junction ablation (AVJA) or not and patients in SR remains uncertain. The primary purpose of this study was to comprehensively evaluate the impact of CRT on the outcome of survival in atrial fibrillation (AF) patients with or without AVJA and patients in sinus rhythm (SR). Medline, Embase, and the Cochrane Library were searched for inception through June 31, 2018. Two reviewers independently evaluated and extracted data from 4 studies, including a total of 7896 CRT recipients, composed of 554 AF with AVJA (CRT+AF+AVJA), 1071 AF without AVJA (CRT+AF-AVJA), and 6244 SR (CRT+SR). The benefit on survival was comparable between CRT+AF+AVJA and CRT+SR (HR = 1.00; 95% CI, 0.73-1.40). CRT+AF+AVJA and CRT+SR both were associated with significantly higher survival compared with CRT+AF-AVJA, with hazard ratio of 0.64 (95% CI, 0.46-0.91) and 0.63 (95% CI, 0.53-0.75), respectively. The survival benefit was similar for patients with CRT+AF+AVJA and CRT+SR, while it was 36-37% high as compared to CRT+AF-AVJA. Whether aggressive intervention with AVJA in AF should be routinely combined with CRT despite rate-slowing drug treatment is helpful deserves further studies.

A score model to predict risk of events in patients with Brugada Syndrome.

AIMS: Risk stratification in Brugada Syndrome (BS) remains challenging. Arrhythmic events can occur life-long and studies with long follow-ups are sparse. The aim of our study was to investigate long-term prognosis and risk stratification of BS patients. METHODS AND RESULTS: A single centre consecutive cohort of 400 BS patients was included and analysed. Mean age was 41.1 years, 78 patients (19.5%) had a spontaneous type I electrocardiogram (ECG). Clinical presentation was aborted sudden cardiac death (SCD) in 20 patients (5.0%), syncope in 111 (27.8%) and asymptomatic in 269 (67.3%). Familial antecedents of SCD were found in 184 individuals (46.0%), in 31 (7.8%) occurred in first-degree relatives younger than 35 years. An implantable cardioverter defibrillator (ICD) was placed in 176 (44.0%). During a mean follow-up of 80.7 months, 34 arrhythmic events occurred (event rate: 1.4% year). Variables significantly associated to events were: presentation as aborted SCD (Hazard risk [HR] 20.0), syncope (HR 3.7), spontaneous type I (HR 2.7), male gender (HR 2.7), early SCD in first-degree relatives (HR 2.9), SND (HR 5.0), inducible VA (HR 4.7) and proband status (HR 2.1). A score including ECG pattern, early familial SCD antecedents, inducible electrophysiological study, presentation as syncope or as aborted SCD and SND had a predictive performance of 0.82. A score greater than 2 conferred a 5-year event probability of 9.2%. CONCLUSIONS: BS patients remain at risk many years after diagnosis. Early SCD in first-degree relatives and SND are risk factors for arrhythmic events. A simple risk score might help in the stratification and management of BS patients.

Single lead atrial vs. dual chamber pacing in sick sinus syndrome: extended register-based follow-up in the DANPACE trial.

AIMS: The DANPACE trial randomized patients with sick sinus syndrome (SSS) to single lead atrial (AAIR) or dual chamber (DDDR) pacemaker (PM). After 5 years follow-up, no difference in overall survival, stroke or heart failure (HF) was observed, whereas risk of atrial fibrillation (AF) and PM reoperation were increased in the AAIR group. The present study aimed to investigate very long term risk of death, AF hospitalization, stroke, HF and rate of change in pacing mode using national register-based data. METHODS AND RESULTS: The study population consisted of all 1384 patients included at Danish PM centres in the DANPACE trial randomized to AAIR (n = 696) or DDDR (n = 688). Long-term follow-up data was obtained from Danish national registers. Analysis was intention-to-treat. results: During mean follow-up of 8.9 years, 413 patients (59.3%) died in the AAIR-group compared to 367 (53.3%) in the DDDR-group (adjusted hazard ratio 1.03; 95% confidence interval 0.90-1.19; P = 0.65). We observed no difference in risk of AF hospitalization, stroke or HF. During extended follow-up, annual rate of pacing mode change to DDDR in the AAIR group was 4.5%, and higher than the 2.3% observed during trial conduct. CONCLUSION: This register-based long-term follow-up study indicates that there is no difference in mortality among patients with SSS randomized to AAIR or DDDR pacing, even with very long follow-up. Nor is there any difference in risk of AF hospitalization, stroke or HF. The higher rate of pacing mode-change to DDDR in the AAIR group suggests a different management of patients with an AAIR PM after the DANPACE trial.

Long-term clinical effects of ventricular pacing reduction with a changeover mode to minimize ventricular pacing in a general pacemaker population.

AIM: Right ventricular pacing (VP) has been hypothesized to increase the risk in heart failure (HF) and atrial fibrillation (AF). The ANSWER study evaluated, whether an AAI-DDD changeover mode to minimize VP (SafeR) improves outcome compared with DDD in a general dual-chamber pacemaker population. METHODS AND RESULTS: ANSWER was a randomized controlled multicentre trial assessing SafeR vs. standard DDD in sinus node disease (SND) or AV block (AVB) patients. After a 1-month run-in period, they were randomized (1 : 1) and followed for 3 years. Pre-specified co-primary end-points were VP and the composite of hospitalization for HF, AF, or cardioversion. Pre-specified secondary end-points were cardiac death or HF hospitalizations and cardiovascular hospitalizations. ANSWER enrolled 650 patients (52.0% SND, 48% AVB) at 43 European centres and randomized in SafeR (n = 314) or DDD (n = 318). The SafeR mode showed a significant decrease in VP compared with DDD (11.5 vs. 93.6%, P < 0.0001 at 3 years). Deaths and syncope did not differ between randomization arms. No significant difference between groups [HR = 0.78; 95% CI (0.48-1.25); P = 0.30] was found in the time to event of the co-primary composite of hospitalization for HF, AF, or cardioversion, nor in the individual components. SafeR showed a 51% risk reduction (RR) in experiencing cardiac death or HF hospitalization [HR = 0.49; 95% CI (0.27-0.90); P = 0.02] and 30% RR in experiencing cardiovascular hospitalizations [HR = 0.70; 95% CI (0.49-1.00); P = 0.05]. CONCLUSION: SafeR safely and significantly reduced VP in a general pacemaker population though had no effect on hospitalization for HF, AF, or cardioversion, when compared with DDD.

Health economic evaluation of single-lead atrial pacing vs. dual-chamber pacing in sick sinus syndrome.

AIMS: The recent Danish Multicentre Randomized Trial on Single-Lead Atrial (AAIR) Pacing versus Dual-Chamber (DDDR) Pacing in Sick Sinus Syndrome (DANPACE) suggested DDDR pacing as standard care. However, previous findings supported the routine use of AAIR pacing. This study investigated the cost-effectiveness of DDDR pacing compared with AAIR pacing for sick sinus syndrome. METHODS AND RESULTS: A decision-analytical model based on patient-level data from three randomized trials was designed from the Danish healthcare system's perspective. The main outcomes were lifetime costs, quality-adjusted lifeyears (QALYs), and net monetary benefit. Quality-adjusted lifeyears were calculated by utilizing community-based preferences. Costs were calculated by utilizing the extensive data on resource consumption, from the DANPACE trial. Data were pooled and adjusted for baseline differences. Dual-chamber pacing was shown to be cost-effective in all the analyses using a willingness-to-pay (WTP) threshold of £20,000/QALY, and most analyses using a WTP of £30,000/QALY. When pooling the data and adjusting for baseline differences, Monte Carlo simulations revealed a 51-71% probability of DDDR pacing being cost-effective at a WTP of £20,000/QALY, and a 42-58% probability at a WTP of £30,000/QALY. Dual-chamber pacing was most likely to be cost-effective among elderly patients with comorbidity. The expected value of perfect information was low and initiation of additional publicly funded Danish trials was discouraged. CONCLUSION: Dual-chamber pacing is likely to be a cost-effective treatment for sick sinus syndrome patients.

Cardiac pacing in paediatric patients with congenital heart defects: transvenous or epicardial?

AIMS: Cardiac pacing is a difficult technique in children, particularly in patients with congenital heart defects (CHDs). Few studies to date have addressed this topic. METHODS AND RESULTS: We performed a retrospective analysis of the results of a single centre. Between 1982 and 2008, 287 patients with CHD, median age of 5 years (25-75%, 1-11) underwent cardiac pacing for sinus node dysfunction (SND) and atrioventricular block (AVB); 97% of patients underwent at least one heart surgery. Endocardial systems (Endo) were implanted in 117 patients, epicardial systems (Epi) in 170, with 595 leads (228 Endo, 367 Epi). Endocardial systems showed a significantly older age group with more frequent SND; Epi a younger age group, with more frequent AVB, greater number of surgical interventions. Perioperative complications were mortality 0.6% (Epi), pericardial effusion 0.6% (Epi), and haemothorax 3.4% (Endo). The median follow-up is 5 (2-10) years: the pacing system failed in 29% of patients, 13% Endo, and 40% Epi (P < 0.0001). Multivariate analysis showed a significantly higher risk of failure for Epi, a lower implant age, greater the number of leads implanted. The risk of malfunction of the leads increases significantly for Epi and the younger age when implanted. The steroid-eluting leads have a lower risk of malfunction (P = 0.05), steroid-eluting Endo leads provide significantly better outcomes than Epi. CONCLUSION: Cardiac pacing in paediatric patients with CHD shows satisfactory results in the long term. Endocardial systems show significantly better results than Epi systems. A younger age when implanted is a risk factor for complications at follow-up.

A comparison of single-lead atrial pacing with dual-chamber pacing in sick sinus syndrome.

AIMS: In patients with sick sinus syndrome, bradycardia can be treated with a single-lead pacemaker or a dual-chamber pacemaker. Previous trials have revealed that pacing modes preserving atrio-ventricular synchrony are superior to single-lead ventricular pacing, but it remains unclear if there is any difference between single-lead atrial pacing (AAIR) and dual-chamber pacing (DDDR). METHODS AND RESULTS: We randomly assigned 1415 patients referred for first pacemaker implantation to AAIR (n = 707) or DDDR (n = 708) pacing and followed them for a mean of 5.4 ± 2.6 years. The primary outcome was death from any cause. Secondary outcomes included paroxysmal and chronic atrial fibrillation, stroke, heart failure, and need for pacemaker reoperation. In the AAIR group, 209 patients (29.6%) died during follow-up vs. 193 patients (27.3%) in the DDDR group, hazard ratio (HR) 1.06, 95% confidence interval (CI) 0.88-1.29, P = 0.53. Paroxysmal atrial fibrillation was observed in 201 patients (28.4%) in the AAIR group vs. 163 patients (23.0%) in the DDDR group, HR 1.27, 95% CI 1.03-1.56, P = 0.024. A total of 240 patients underwent one or more pacemaker reoperations during follow-up, 156 (22.1%) in the AAIR group vs. 84 (11.9%) in the DDDR group (HR 1.99, 95% CI 1.53-2.59, P < 0.001). The incidence of chronic atrial fibrillation, stroke, and heart failure did not differ between treatment groups. CONCLUSION: In patients with sick sinus syndrome, there is no statistically significant difference in death from any cause between AAIR pacing and DDDR pacing. AAIR pacing is associated with a higher incidence of paroxysmal atrial fibrillation and a two-fold increased risk of pacemaker reoperation. These findings support the routine use of DDDR pacing in these patients. CLINICAL TRIAL REGISTRATION: URL http://www.clinicaltrials.gov. Unique identifier: NCT00236158.

Minimizing ventricular pacing to reduce atrial fibrillation in sinus-node disease.

BACKGROUND: Conventional dual-chamber pacing maintains atrioventricular synchrony but results in high percentages of ventricular pacing, which causes ventricular desynchronization and has been linked to an increased risk of atrial fibrillation in patients with sinus-node disease. METHODS: We randomly assigned 1065 patients with sinus-node disease, intact atrioventricular conduction, and a normal QRS interval to receive conventional dual-chamber pacing (535 patients) or dual-chamber minimal ventricular pacing with the use of new pacemaker features designed to promote atrioventricular conduction, preserve ventricular conduction, and prevent ventricular desynchronization (530 patients). The primary end point was time to persistent atrial fibrillation. RESULTS: The mean (+/-SD) follow-up period was 1.7+/-1.0 years when the trial was stopped because it had met the primary end point. The median percentage of ventricular beats that were paced was lower in dual-chamber minimal ventricular pacing than in conventional dual-chamber pacing (9.1% vs. 99.0%, P<0.001), whereas the percentage of atrial beats that were paced was similar in the two groups (71.4% vs. 70.4%, P=0.96). Persistent atrial fibrillation developed in 110 patients, 68 (12.7%) in the group assigned to conventional dual-chamber pacing and 42 (7.9%) in the group assigned to dual-chamber minimal ventricular pacing. The hazard ratio for development of persistent atrial fibrillation in patients with dual-chamber minimal ventricular pacing as compared with those with conventional dual-chamber pacing was 0.60 (95% confidence interval, 0.41 to 0.88; P=0.009), indicating a 40% reduction in relative risk. The absolute reduction in risk was 4.8%. The mortality rate was similar in the two groups (4.9% in the group receiving dual-chamber minimal ventricular pacing vs. 5.4% in the group receiving conventional dual-chamber pacing, P=0.54). CONCLUSIONS: Dual-chamber minimal ventricular pacing, as compared with conventional dual-chamber pacing, prevents ventricular desynchronization and moderately reduces the risk of persistent atrial fibrillation in patients with sinus-node disease. (ClinicalTrials.gov number, NCT00284830 [ClinicalTrials.gov].).

Two males with sick sinus syndrome in a family with 0.6 kb deletions involving major domains in MECP2.

Mutations in methyl-CpG-binding protein 2 (MECP2) in males can lead to various phenotypes, ranging from neonatal encephalopathy to intellectual disability. In this study, using Nord's method of next-generation sequencing in three siblings, we identified a 0.6 kb deletion involving the transcriptional repression domain (TRD). Two males and one female had intellectual disability and apnea, but none met the criteria of Rett syndrome. Both males had sick sinus syndrome and severe tracheomalacia that resulted in early death. The mother, with skewed X-inactivation, had no symptoms. Therefore, this mutation is pathological for both males and females, resulting in sick sinus syndrome and severe tracheomalacia with strong reproducibility in males. Deletions involving major domains in MECP2 can result in a severe phenotype, and deletion of the TRD domain can cause severe autonomic nervous system dysregulation in males in these cases.

Permanent atrial pacing lead implant route after Fontan operation.

BACKGROUND: Atrial pacing is indicated for sinus node dysfunction (SND) after Fontan surgery; preferred lead implantation technique is debated. We compare outcomes of transvenous (TV) and epicardial (Epi) atrial lead implants in this population. METHODS: Retrospective review of Fontan patients undergoing atrial lead implant between 1992 and 2007. Demographics, lead performance data, and outcomes were analyzed. RESULTS: 78 patients had 90 leads implanted: 25 via TV route and 65 via Epi route. Median follow-up was 1.6 years (TV) and 3.6 years (Epi). TV leads were implanted in older patients (23.1 vs 9.3 years, P < 0.001) and at longer intervals after Fontan (15.2 vs 4.9 years, P < 0.001). Pacing indication for most TV leads was SND, while Epi leads were also indicated for atrioventricular block. Acute complication rates were similar (8% TV vs 19% Epi, P = 0.23), but median hospital stay was shorter for TV (2 vs 5 days, P = 0.03). Thrombus was observed in five patients (two in TV; three in Epi), but no thromboembolic events were observed. Mean lead survival was similar (TV 9.9 vs Epi 7.8 years, P = NS). Energy threshold was lower at implant for TV leads (0.9 vs 2.2 microJ, P = 0.049), but similar at follow-up (1.2 vs 2.6 microJ, P = 0.35). Atrial sensing was unchanged over time for TV (2.2 to 2.1 mV, P = NS), but decreased for Epi (3.3 to 2.5 mV, P = 0.02). CONCLUSIONS: Compared to epicardial leads, transvenous atrial pacing leads may be placed in Fontan patients with lower procedural morbidity and equivalent expectation of lead performance and longevity.

Reduced ejection fraction, sudden cardiac death, and heart failure death in the mode selection trial (MOST): implications for device selection in elderly patients with sinus node disease.

UNLABELLED: Sudden Cardiac Death in Elderly Pacemaker Patients. BACKGROUND: The purpose of this study was to describe the incidence and predictors of sudden cardiac death (SCD) and heart failure (HF) death, and coexisting indications for ICDs and CRT, in patients with sinus node disease (SND) treated with pacemakers. METHODS AND RESULTS: Baseline variables were used to predict SCD and HF death among 1,135 patients in the Mode Selection Trial, a 6-year trial of pacing mode in SND. There were 73 deaths among 177 patients with EF or= 50%. SCD accounted for 21.9%, 23.9%, and 14.3% of deaths with EF or= 50%. HF deaths accounted for 23.3%, 19.6%, and 3.4% of deaths with EF or= 50%. EF or= 120 ms. However, >40% died within 33 months (4-year noncardiac death rate approximately 22%). CONCLUSIONS: Reduced EF predicts SCD and HF death in SND treated with pacemakers. SCD rates among patients with EF

Beat-to-beat QT interval variability is primarily affected by the autonomic nervous system.

BACKGROUND: Beat-to-beat QT interval variability is associated with life-threatening arrhythmias and sudden death, however, its precious mechanism and the autonomic modulation on it remains unclear. The purpose of this study was to determine the effect of drugs that modulate the autonomic nervous system on beat-to-beat QT interval. METHOD: RR and QT intervals were determined for 512 consecutive beats during fixed atrial pacing with and without propranolol and automatic blockade (propranolol plus atropine) in 11 patients without structural heart disease. Studied parameters included: RR, QTpeak (QRS onset to the peak of T wave), QTend (QRS onset to the end of T wave) interval, standard deviation (SD) of the RR, QTpeak, and QTend (RR-SD, QTpeak-SD, and QTend-SD), coefficients of variation (RR- CV, QTpeak-CV, and QTend-CV) from time domain analysis, total power (TP; RR-TP, QTpeak-TP, and QTend-TP), and power spectral density of the low-frequency band (LF; RR-LF, QTpeak-LF, and QTend-LF) and the high-frequency band (HF; RR-HF, QTpeak-HF and QTend-HF). RESULTS: Administration of propranolol and infusion of atropine resulted in the reduction of SD, CV, TP, and HF of the QTend interval when compared to controlled atrial pacing (3.7 +/- 0.6 and 3.5 +/- 0.5 vs 4.8 +/- 1.4 ms, 0.9 +/- 0.1 and 0.9 +/- 0.1 vs 1.2 +/- 0.3%, 7.0 +/- 2.2 and 7.0 +/- 2.2 vs 13.4 +/- 8.1 ms(2), 4.2 +/- 1.4 and 4.2 +/- 1.2 vs 8.4 +/- 4.9 ms(2), respectively). Administration of propranolol and atropine did not affect RR interval or QTpeak interval indices during controlled atrial pacing. CONCLUSIONS: Beat-to-beat QT interval variability is affected by drugs that modulate the autonomic nervous system.

Mechanistic implication of decreased plasma atrial natriuretic peptide level for transient rise in the atrial capture threshold early after ICD or CRT-D implantation.

PURPOSE: Despite the use of steroid-eluting leads, a transient but not persistent rise in the atrial/ventricular capture threshold (TRACT/TRVCT) can occur early after pacemaker implantation in patients with sick sinus syndrome. This study aimed to assess the prevalence, predictors, and mechanisms of TRACT/TRVCT in patients with heart failure undergoing implantable cardioverter defibrillator (ICD) or cardiac resynchronization therapy (CRT) implantation. METHOD: One hundred twenty consecutive patients underwent ICD (N = 70) or CRT (N = 50) implantation. Capture threshold was measured at implantation, 7-day, 1-month, and 6-month post-implantation. TRACT/TRVCT was defined as a threshold rise at 7 days by more than twice the height of the threshold at implantation, with full recovery during follow-up. Atrial and brain natriuretic peptide (ANP and BNP) levels were measured before implantation. RESULTS: TRACT and TRVCT were observed in 13 (11%) and 10 (8%) patients, respectively. Patients with TRACT had lower ANP level (median 72 [42-105] vs. 99 [49-198] pg/mL, P = 0.06), lower ANP/BNP ratio (0.29 [0.20-0.36] vs. 0.50 [0.33-0.70], P < 0.01), lower atrial sensing amplitude (2.0 ± 0.8 vs. 2.7 ± 1.3 mV, P = 0.02), and lower left ventricular ejection fraction (32 ± 12 vs. 40 ± 14%, P = 0.04) than those without TRACT. TRACT recovered within 1 month, whereas TRVCT recovered within 6 months. In multivariable analysis, ANP/BNP ratio was the only independent predictor of TRACT (OR, 0.018; 95% CI, 0.001-0.734; P = 0.034). CONCLUSIONS: Atrial degenerative change characterized by lower ANP/BNP ratio was associated with the occurrence of TRACT in patients with heart failure. TRVCT could also occur, but it required a longer recovery time than TRACT.

Rate control in patients with pacemaker affected by brady-tachy form of sick sinus syndrome.

BACKGROUND: In sinus node disease (SND) atrial tachyarrhythmias (ATs) may frequently occur, after implant of a pacemaker for bradycardia, and are to be managed by rate or rhythm control. METHODS: We evaluated ventricular heart rate (HR) during AT, AT-related symptoms and hospitalizations in 333 patients who received DDDRP pacemakers for SND. RESULTS: In days with 24 hours of AT, mean daily HR during AT was > 80, 90, 100, 110, and 120 beats per minute (bpm) in 191 (57%), 114 (34%), 55 (16%), 23 (7%), and 11 (3%) patients, respectively. The proportion of patients with a mean daily HR > 80 bpm during AT despite the use of rate control agents was 28% among patients treated with calcium-channel blockers, 43% with digoxin, 49% with a combination of agents, 54% with amiodarone, 64% with sotalol, and 69% with beta blockers. Patients with HR > 100 bpm experienced a higher prevalence of both AT-related hospitalizations and cardiovascular hospitalizations than those with HR < or = 100 bpm (36% vs 21%, P = .013; 42% vs 28%, P = .003) and a significantly higher number of AT-related symptoms (1.8 +/- 0.9 vs 1.4 +/- 1.0, P = .008). CONCLUSIONS: Limited attention has been dedicated to rate control in patients with pacemaker. This is the first study to evaluate the prevalence and implications of inappropriate rate control in patients with pacemaker. We found that in a substantial proportion of patients with SND who have recurrent ATs despite pacing, mean daily HR during AT is high and that these patients present increased hospitalizations and more symptoms, thus suggesting the need to improve rate control.

Results of pacemaker implantation in 104 dogs.

OBJECTIVES: To document the outcome, survival and complications involved in pacemaker implantation in dogs in a retrospective study. METHODS: Case records for all dogs in which pacemaker implantation was performed were reviewed. RESULTS: A total of 104 dogs underwent pacemaker implantation. Dogs were presented with atrioventricular (AV) block (71), sick sinus syndrome (25) or vasovagal syncope (eight). Age at presentation varied from six months to 13 years with a median age of seven years and two months. The Labrador was the most commonly represented breed (17 cases). All but one dog survived pacemaker implantation, with 93 showing resolution of their clinical signs while 10 dogs showed intermittent residual signs. One-, three- and five-year survival estimates were 86, 65 and 39 per cent, respectively. Major complications after implantation were documented in 15 dogs and three of these led to fatalities. Minor complications were noted in 23 dogs. Sudden death occurred in six dogs three to 55 months following successful pacemaker implantation. CLINICAL SIGNIFICANCE: Transvenous pacemaker implantation was successful in reducing or eliminating clinical signs in over 90 per cent of dogs with third-degree atrioventricular (AV) block or sick sinus syndrome. In dogs with vasovagal syncope, six of eight dogs had greatly reduced frequency of collapse and two became asymptomatic. Although the procedure was associated with complications, these were rarely life threatening and good survival was documented in the majority of cases.

Value of Combining Left Atrial Diameter and Amino-terminal Pro-brain Natriuretic Peptide to the CHA2DS2-VASc Score for Predicting Stroke and Death in Patients with Sick Sinus Syndrome after Pacemaker Implantation.

BACKGROUND: The CHA2DS2-VASc score is used clinically for stroke risk stratification in patients with atrial fibrillation (AF). We sought to investigate whether the CHA2DS2-VASc score predicts stroke and death in Chinese patients with sick sinus syndrome (SSS) after pacemaker implantation and to evaluate whether the predictive power of the CHA2DS2-VASc score could be improved by combining it with left atrial diameter (LAD) and amino-terminal pro-brain natriuretic peptide (NT-proBNP). METHODS: A total of 481 consecutive patients with SSS who underwent pacemaker implantation from January 2004 to December 2014 in our department were included. The CHA2DS2-VASc scores were retrospectively calculated according to the hospital medical records before pacemaker implantation. The outcome data (stroke and death) were collected by pacemaker follow-up visits and telephonic follow-up until December 31, 2015. RESULTS: During 2151 person-years of follow-up, 46 patients (9.6%) suffered stroke and 52 (10.8%) died. The CHA2DS2-VASc score showed a significant association with the development of stroke (hazard ratio [HR] 1.45, 95% confidence interval [CI] 1.20-1.75, P< 0.001) and death (HR 1.45, 95% CI 1.22-1.71, P< 0.001). The combination of increased LAD and the CHA2DS2-VASc score improved the predictive power for stroke (C-stat 0.69, 95% CI 0.61-0.77 vs. C-stat 0.66, 95% CI 0.57-0.74, P= 0.013), and the combination of increased NT-proBNP and the CHA2DS2-VASc score improved the predictive power for death (C-stat 0.70, 95% CI 0.64-0.77 vs. C-stat 0.67, 95% CI 0.60--0.75, P= 0.023). CONCLUSIONS: CHA2DS2-VASc score is valuable for predicting stroke and death risk in patients with SSS after pacemaker implantation. The addition of LAD and NT-proBNP to the CHA2DS2-VASc score improved its predictive power for stroke and death, respectively, in this patient cohort. Future prospective studies are warranted to validate the benefit of adding LAD and NT-proBNP to the CHA2DS2-VASc score for predicting stroke and death risk in non-AF populations.

Outcome and survival in canine sick sinus syndrome and sinus node dysfunction: 93 cases (2002-2014).

INTRODUCTION: To evaluate the clinical presentation, diagnosis, treatment, and outcomes of a group of dogs with sinoatrial node abnormalities. ANIMALS: Ninety-three client-owned dogs at a referral institution. MATERIALS AND METHODS: Medical records were reviewed for clinical history, diagnostic testing, and medical or permanent artificial pacemaker (PAP) treatment. Owners or veterinarians were contacted for long-term follow-up. RESULTS: Sixty-one dogs were symptomatic for their bradyarrhythmia and were diagnosed with sick sinus syndrome (SSS). Thirty-two dogs were asymptomatic for their bradyarrhythmia and were diagnosed with sinus node dysfunction (SND). Miniature Schnauzers, West Highland White terriers, Cocker spaniels, and female dogs were overrepresented. Medical management with positive chronotropic drugs successfully controlled syncope long-term in 54% of SSS dogs, and acted as a bridge to PAP in 20%. Positive atropine response predicted medical treatment success. Forty-six percent of SSS dogs eventually underwent PAP implantation. Median survival time was approximately 18 months in SND and SSS dogs regardless of treatment strategy. Congestive heart failure (CHF) associated with progressive valvular heart disease occurred commonly in all groups, particularly in dogs with bradycardia-tachycardia syndrome. CONCLUSIONS: Sinus node dysfunction and SSS represent a spectrum of sinoatrial node disease, which for some dogs may also involve a component of autonomic dysfunction. Dogs with SND do not require treatment. Dogs with SSS often require treatment to reduce the frequency of syncope; medical management is often useful, particularly in atropine responsive dogs. Prognosis of SSS with treatment is good, though development of CHF does not appear to be mitigated by treatment.

Deleterious effects of long-term single-chamber ventricular pacing in patients with sick sinus syndrome: the hidden benefits of dual-chamber pacing.

Nine hundred fifty patients who received three modes of primary pacemaker systems (581 dual-chamber universal [DDD], 84 atrioventricular-sequential ventricular-inhibited [DVI] and 285 ventricular-inhibited [VVI]) over 12 years were studied retrospectively to determine the effect of pacing mode on patient longevity and the subsequent development of chronic atrial fibrillation or flutter. All patients were followed up continuously for 7 to 8 years. Patients were classified according to indication for permanent pacing (sick sinus syndrome or other indication), age at pacemaker implantation (less than or equal to 70 or greater than 70 years) and history of atrial tachyarrhythmia. Fourteen percent of patients developed atrial fibrillation at some time during the study period. Of those, 4% had a DDD pacemaker, 8% had a DVI pacemaker and 19% had a VVI pacemaker. At 7 years, atrial fibrillation was significantly more frequent in the VVI group than in the DDD and DVI groups. In patients with sick sinus syndrome, the incidence rate was even higher in the VVI group but approximately the same in the DDD and DVI groups. Patients in the VVI and DVI groups who had had previous atrial tachyarrhythmia had a significantly higher incidence of atrial fibrillation at 7 years than did those in the DDD group. During the entire period there were 130 deaths in the study group, including 22% of patients with a DDD pacemaker, 38% of those with a DVI pacemaker and 50% of those with a VVI pacemaker. Patient survival at 7 years was lower in the VVI group than in the DDD or DVI groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Natural history of sinus node disease treated with atrial pacing in 213 patients: implications for selection of stimulation mode.

OBJECTIVES: This study was designed to analyze the incidence and determinants of complications and long-term survival in sinus node disease treated with atrial pacing. BACKGROUND: Knowledge of the natural history of sinus node disease treated with different pacing modes is imperfect, and controversy exists regarding the optimal pacemaker therapy. METHODS: A consecutive series of 213 patients with sinus node disease initially treated with atrial pacing was studied for a median follow-up period of 60 months. The end points studied were permanent atrial fibrillation, high grade atrioventricular (AV) block, P wave undersensing, pacing mode change, reoperation and death. Several prognostic factors were evaluated statistically and the survival rate was compared with that of a matched general population. RESULTS: The incidence rate of permanent atrial fibrillation during follow-up was 7% (1.4%/year). The risk of this arrhythmia increased substantially with age greater than or equal to 70 years at pacemaker implantation. Only 2 of the 15 patients who developed permanent atrial fibrillation required ventricular pacing. High grade AV block occurred in 8.5% (1.8%/year) and its incidence was much greater in patients with complete bundle branch block or bifascicular block (35%) than in patients without such conduction disturbances (6%). A change to ventricular or dual-chamber stimulation was necessary in 14% of all patients, primarily because of early lead dislodgment or high grade AV block. Surgical intervention with maintenance of atrial pacing was required in 7% of patients. The survival rates of 97% at 1 year, 89% at 5 years and 72% at 10 years did not differ significantly from those of a matched general population. CONCLUSIONS: In sinus node disease, atrial pacing can be successfully applied during long-term follow-up. Patients with complete bundle branch or bifascicular block in addition to sinus node disease should initially receive a dual-chamber pacemaker, but routine application of dual-chamber stimulation does not appear to be warranted.