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.

Atrial Fibrillation Arising from the Left Atrial Appendage.

A 63-year-old patient presented for curative treatment of drug-resistant paroxysmal atrial fibrillation (AF). After pulmonary vein antrum isolation was achieved, AF could be still induced and persisted, while rapid activation at the left atrial appendage was conducted to the left atrium in a decremental conduction manner. A step-wise incremental discrete radiofrequency energy application at the ostium of left atrial appendage completely eliminated the AF. Neither AF nor atrial tachyarrhythmias reappeared, even under isoproterenol infusion and vigorous rapid atrial stimulations. The patient has experienced no symptoms or exhibited ECG evidence of AF during a 6-month follow-up.

[Chronic outcome of patients with nonparoxysmal atrial fibrillation underwent CARTO-guided stepwise ablation].

OBJECTIVE: To investigate the efficacy of CARTO-guided stepwise ablation approaches for treatment of patients with nonparoxysmal atrial fibrillation(AF). METHODS: Stepwise ablation approaches were performed in 40 patients with nonparoxysmal atrial fibrillation. Pulmonary vein atrium isolation (PVAI), linear ablation in atria, complex fractionated atrial electrograms (CFAEs) ablation and cardioversion were applied sequentially till sinus rhythm (SR) restoration. All patients were followed up 6 to 18 months. RESULTS: SR was restored in 11 patients after PVAI, in 11 patients after linear ablation and in 6 patients after CFEAs ablation. SR was restored in the remaining 13 patients post cardioversion. During follow-up, 3 atrial fibrillation, 3 atrial tachycardia and 5 atrial flutter were evidenced. Seven out of the 11 patients with reoccurred arrhythmia were treated only by PVAI. CONCLUSIONS: CARTO-guided stepwise ablation approaches are safe and effective in the treatment of patients with nonparoxysmal atrial fibrillation. PVAI approach was associated with lower successful rate and high recurrence rate.

Angiotensinogen polymorphisms and acquired atrial fibrillation in Chinese.

Genetic predisposition may be underlying the prevalence of acquired atrial fibrillation (AF). We investigated the association between polymorphism in angiotensinogen (AGT) and angiotensin-converting enzyme gene and risk of acquired AF in a pair-matched case-control study conducted in Chinese Hans. We selected 9 single nucleotide polymorphisms (SNPs) in the AGT gene and 3 SNPs in the angiotensin-converting enzyme gene using a tagging-SNP strategy. We observed significant association between tagging-SNP rs699 (M235T), located in exon 2 of the AGT gene, and AF. The AA genotype of rs699 increased the risk of AF by 70% (95% confidence interval, 1.01-2.85; P = .044) under a recessive model (AA vs AG + GG). The significance remained after controlling for covariates age, smoking, body mass index, hypertension, diabetes, and left atrial dimension, with an increased risk of AF by 90% (95% confidence interval, 1.04-3.46; P = .036). We provide evidence that polymorphism in AGT gene may confer predisposition to acquired atrial fibrillation in Chinese Hans.

Genetic polymorphism of KCNH2 confers predisposition of acquired atrial fibrillation in Chinese.

INTRODUCTION: Nonfamiliar atrial fibrillation (AF) is usually associated with acquired structural heart disease, including valvular heart disease, coronary artery disease, and hypertension. Suggestive evidence indicates that these forms of acquired AF are more likely to occur in individuals with a genetic predisposition. We investigated the effect of the potassium channel voltage-gated subfamily member 2 (KCNH2) gene on the prevalence of acquired AF in a Chinese population. METHODS: In a pair-matched, hospital-based case control study (297 vs 297) conducted in Chinese Hans, we investigated 4 tagging single nucleotide polymorphisms (tSNPs), rs1805120, rs1036145, rs3807375, and rs2968857 in the KCNH2 gene, and determined their association with AF acquired from structural heart diseases. RESULTS: We did not observe the association of rs1036145, rs3807375, and rs2968857 with AF. However, we determined that the tSNP, rs1805120, in exon 6 confers the risk of AF in Chinese Hans. Both genotype and allele frequencies of rs1805120 were distributed differently in cases and controls (P = 0.0289 and P = 0.0172, respectively). The most significant association was observed under a recessive model for the minor GG genotype with a 1.45-fold risk of developing AF (95% confidence interval 1.09-1.93, P = 0.012). The significance remained after controlling for the covariates of age, smoking, BMI, hypertension, and diabetes. CONCLUSION: We report a new genetic variation (rs1805120) in the KCNH2 gene that predisposes Chinese Han individuals to the risk of acquired AF. Further genetic and functional studies are required to identify the etiological variants in linkage disequilibrium with this polymorphism.

Quantitative analysis of the duration of slow conduction in the reentrant circuit of ventricular tachycardia after myocardial infarction.

BACKGROUND: Few data are available to define the circuits in ventricular tachycardia (VT) after myocardial infarction and the conduction time (CT) through the zone of slow conduction (SCZ). This study assessed the CT of the SCZ and identified different reentrant circuits. METHODS: During VTs, concealed entrainment (CE) was attempted. The SCZ was identified by a difference between postpacing interval (PPI) and VT cycle length (VTcl) < or =30 ms. Since the CT in the normally conducting part of the VT circuit is constant during VT and CE, a CE site within the reentrant circuit with (S-QRS)/PPI > or = 50% was classified as an inner reentry in which the entire circuit was within the scar, and a CE site with (S-QRS)/PPI < 50% as a common reentry in which part of the circuit was within the scar and part out of the scar. RESULTS: CE was achieved in 20 VTs (12 patients). Six VTs (30%) with a (S-QRS)/PPI > or =50% were classified as inner reentry and 14 VTs (70%) with a (S-QRS)/PPI <50% during CE mapping as common reentry. The EG-QRS interval (308 +/- 73 ms vs 109 +/- 59 ms, P < 0.0001) was significantly longer and the incidence of systolic potentials higher (4/6 vs 0/12, P < 0.001) in the inner reentry group. For the 14 VTs with a common reetry, the CT of the SCZ was 348 +/- 73 ms, while the CT in the normal area was 135 +/- 50 ms. CONCLUSION: According to the proposed classification, 30% of VTs after myocardial infarction had an entire reentrant circuit within the scar. In VTs with a common reentrant circuit, the CT of the SCZ is approximately four times longer than the CT in the normal area, accounting for more than 70% of VTcl.

Refinement of CARTO-guided substrate modification in patients with ventricular tachycardia after myocardial infarction.

BACKGROUND: Substrate modification guided by CARTO system has been introduced to facilitate linear ablation of ventricular tachycardia (VT) after myocardial infarction (MI). However, there is no commonly accepted standard approach available for drawing these ablation lines. Therefore, the aim of the present study was to practically refine this time consuming procedure. METHODS: Substrate modification was performed in 23 consecutive patients with frequent VTs after MI using the CARTO system. The initial target site (ITS) for ablation was identified by pace mapping (PM) during sinus rhythm and/or entrainment pacing (EM) during VT. According to the initial target site, two approaches were used. The initial target site in approach one has a similar QRS morphology as VT and an interval from the stimulus to the onset of QRS complex (S-QRS) of = 50 ms during PM in sinus rhythm or a difference of the post pacing interval and VT cycle length = 30 ms during concealed entrainment pacing of VT; The initial target site in approach two has an similar QRS morphology as VT and an S-QRS of < 50 ms during PM in sinus rhythm. RESULTS: Overall, 50 lines were performed with a length of (35 +/- 11) mm. Procedure time averaged (232 +/- 56) minutes, fluoroscopy time (10 +/- 8) minutes. Sixteen patients were initially involved into approach one. After completion of 3 +/- 1 ablation lines, no further VT was inducible in 13 patients. The remaining 3 patients were switched to use the alternative approach. However, in none of them the alternative approaches were successful. Approach two was initially used in 7 patients. After completion of 3 +/- 1 ablation lines, no further VT was inducible in only 2 patients. The remaining 5 patients were switched to approach one, which resulted in noninducibility of VT in 4 of them. The initial successful rate was significantly higher in the group of approach one compared to that in the group of approach two (13/16 patients vs 2/7 patients, P = 0.026). CONCLUSIONS: The approach for substrate modification of VT after MI can be optimized by identifying the appropriate initial target site with specific characteristics within the zone of slow conduction. The refined approach may facilitate linear ablation of VT, and further reduce the procedure and fluoroscopy time.

Stepwise approach to substrate modification of ventricular tachycardia after myocardial infarction.

BACKGROUND: Recently, substrate mapping (SM) has been described to facilitate catheter ablation of stable and unstable ventricular tachycardia (VT) after myocardial infarction. However, SM is time consuming with potential disadvantages of multiple ablation lines such as impairment of ventricular function or proarrhythmia. The aim of the present study was to delineate a stepwise approach to SM to shorten procedure time and limit the possibility of complications. METHODS: SM was performed in 14 infarct survivors referred for VT ablation using an electroanatomical mapping system (CARTO) to define infarct regions. A new stepwise approach for SM was designed as follows. The initial ablation site was identified by pace- and entrainment mapping in case of stable VT and by pace mapping only in case of unstable VT. Based on the CARTO voltage mapping, linear ablation was done from this site to the center of the scar and perpendicular to the boundary of the scar or to the mitral annulus. Additional lines were performed only when VT remained inducible. A maximum of 3 ablation lines were created during one procedure. RESULTS: A total of 57 VTs (21 stable, 36 unstable) were induced during the procedures. VT was no longer inducible after the first linear ablation in 2 patients, after the second linear ablation in 6 patients and after the third linear ablation in 3 patients. Either VT or ventricular fibrillation was still inducible at the end of the procedure in 3 patients. Procedure time averaged (291 +/- 85) minutes, fluoroscopy time (10 +/- 7) minutes. VT recurred in 3 patients. Following a second procedure in 2 patients, there were no further VT recurrences. Overall, there was a significant reduction in VT episodes 3 months after [median: 0, interquartile ranges (IQR): 0 - 1] compared with 3 months before ablation (median: 25, IQR: 16 - 105, P < 0.01). CONCLUSIONS: This stepwise approach to SM is effective in facilitating ablation of stable and unstable VT. It reduces procedure and fluoroscopy time, and may help to improve the risk-benefit ratio of VT ablation.

Radiofrequency catheter ablation in patients with symptomatic atrial flutter/tachycardia after orthotopic heart transplantation.

BACKGROUND: Atrial tachycardia or flutter is common in patients after orthotopic heart transplantation. Radiofrequency catheter ablation to treat this arrhythmia has not been well defined in this setting. This study was conducted to assess the incidence of various symptomatic atrial arrhythmias and the efficacy and safety of radiofrequency catheter ablation in these patients. METHODS: Electrophysiological study and catheter ablation were performed in patients with symptomatic tachyarrhythmia. One Halo catheter with 20 poles was positioned around the tricuspid annulus of the donor right atrium, or positioned around the surgical anastomosis when it is necessary. Three quadripolar electrode catheters were inserted via the right or left femoral vein and positioned in the recipient atrium, the bundle of His position, the coronary sinus. Programmed atrial stimulation and burst pacing were performed to prove electrical conduction between the recipient and the donor atria and to induce atrial arrhythmias. RESULTS: Out of 55 consecutive heart transplantation patients, 6 males [(58 +/- 12) years] developed symptomatic tachycardias at a mean of (5 +/- 4) years after heart transplantation. Electrical propagation through the suture line between the recipient and the donor atrium was demonstrated during atrial flutter or during recipient atrium and donor atrium pacing in 2 patients. By mapping around the suture line, the earliest fragmented electrogram of donor atrium was assessed. This electrical connection was successfully ablated in the anterior lateral atrium in both patients. There was no electrical propagation through the suture line in the other 4 patients. Two had typical atrial flutter in the donor atrium which was successfully ablated by completing a linear ablation between the tricuspid annulus and the inferior vena cava. Two patients had atrial tachycardia which was ablated in the anterior septal and lateral donor atrium. There were no procedure-related complications. Patients were free of recurrent atrial tachyarrhythmias after a follow-up of (8 +/- 7) months. CONCLUSIONS: Four electrophysiological mechanisms have been found to contribute to the occurrence of symptomatic supraventricular arrhythmias following heart transplantation. Radiofrequency catheter ablation in patients with atrial flutter/tachycardia is feasible and safe after heart transplantation.

Application of remote sensing for surveillance of snail habitats in Poyang Lake, China.

OBJECTIVE: To identify snail habitats and monitor the changes by combining remote sensing technique with the ground-based ecological data. METHODS: Of 100 survey sites selected throughout Poyang Lake, 75 were randomly identified from 574 land mass units: 50 were from snail habitats and 25 were from non-snail habitats based on a historical survey (1982-1984); 25 sites with habitats that did not have snails were also selected. Each site, covering 10,000 m2, was divided into a grid of 100 cells from which 20 cells were randomly selected. Snails, when present, were collected from a 4 m2 frame placed in the center of the selected cell. Satellite Landsat TM images were obtained for the same period as the ground survey data collected. Unsupervised classification was used to classify the images. Identified land-cover types were correlated with snail habitat. RESULTS: The sensitivity and specificity of classified snail habitat were 90.0%-95.6% and 61.1%-68.6%, respectively. Based on the classification, estimated snail habitat areas in Poyang Lake increased from 623.4 km2 in 1999 to 762.8 km2 in 2000. CONCLUSION: Snail habitats are associated with grassland-covered areas. Classified images can be used to identify snail habitats, determine their areas, and monitor snail habitat changes caused by annual fluctuations of key environmental factors.