Case report: Torsade de pointes induced by the bigeminy result from retrograde ventriculoatrial activation in VVI pacing and resolved by intentional atrial pacing.

Introduction: While pacing has been used for long QT syndrome (LQTs), the optimal pacing modality is controversial. Case: We report a woman with bradycardia and a recently implanted single-chamber pacemaker experienced multiple syncope. No device dysfunction was found. Multiple Torsade de Pointes (TdP) induced by the bigeminy result from retrograde ventriculoatrial (VA) activation in VVI pacing were demonstrated in the scenario of previously unidentified LQTs. Replacement for a dual-chamber ICD and intentional atrial pacing eliminated the VA conduction and symptoms. Conclusion: Pacing without atrioventricular sequence might be catastrophic in LQTs. Atrial pacing and atrioventricular synchrony should be highlighted.

Atrial Fibrillation Burden Detected by Dual-Chamber Pacemakers as a Predictor for Cardiac Outcomes: A Retrospective Single-Center Cohort Study.

Background: Atrial fibrillation (AF) might lead to adverse cardiac consequences. The association between AF burden and cardiac prognosis is unknown. Methods and Results: This retrospective cohort study enrolled 204 patients (117 males; age 74.5 ± 11.5 years) who underwent dual-chamber pacemaker implantation in our center from October 2003 to May 2017. During a median follow-up of 66.5 months, AF could be detected in 153 (75%) of the 204 pacemaker patients. Primary endpoint events (composite cardiac readmission, stroke or systemic embolism, and all-cause death) occurred in 83 cases (40.7%). In logistic regression analysis, AF detection was associated with increased risks of composite endpoints [odds ratio (OR) = 2.9, 95% confidence interval (CI): 1.3-6.2, p = 0.007], and the hazard was mainly driven by increased cardiac readmission (OR = 2.2, 95% CI: 1.1-4.7, p = 0.034). No significantly elevated risk for new-onset stroke, systemic embolism, or deaths were found in patients with AF detected than those without AF recorded. AF duration grade of more than 6 min suggested progressively increased composite endpoints (OR = 1.8, 95% CI: 1.2-2.7, p for trend = 0.005), cardiac readmission (OR = 1.8, 95% CI: 1.2-2.7, p for trend = 0.005), especially heart failure or acute coronary syndrome-associated readmission (OR = 1.8, 95% CI: 1.2-2.9, p for trend = 0.010), than those with shorter (<6 min) or no AF episodes. Kaplan-Meier analyses and Cox regression also suggested that episodes of AF more than 6 min predicted future cardiac events. Conclusions: AF detected by pacemakers were common. Higher AF burden predicted more adverse cardiac outcomes and might suggest the intervention of rhythm control in these population.

Is the left bundle branch pacing a choice to conquer the right bundle branch block?-A case report.

In patients with preserved ejection fraction or right bundle branch block (RBBB) pattern requiring a high percentage of ventricular pacing, His-bundle pacing (HBP) might be an alternative to biventricular pacing, although the high threshold occasionally occurs. We provided a case of the intrinsic RBBB correction by capturing intra-Hisian left bundle branch (LBB) or distal His-bundle with different output settings. LBB pacing had the advantage of a much lower threshold while remained most synchrony as HBP. LBB pacing might be a promisingly safe and effective procedure for patients with high-grade atrioventricular (AV) block and RBBB pattern.

Pacemaker-detected atrial fibrillation burden and risk of ischemic stroke or thromboembolic events-A cohort study.

BACKGROUND: Atrial fibrillation (AF) burden might link to increased risk of systemic embolism. Current scoring systems for evaluating stroke risks such as CHA2DS2-VASc do not incorporate AF burden partly because of the difficulty to assess these data. Patients with dual-chamber pacemakers implanted have opportunities to acquire incidence and duration of AF. OBJECTIVES: We aimed to evaluate the AF burden and its association with thromboembolism in patients with dual-chamber pacemakers. METHODS: This retrospective cohort study enrolled patients who underwent dual-chamber pacemaker implantation at our center between October 2003 and May 2017. We excluded patients with prior thromboembolism or receiving anticoagulants. The incidence and duration of pacemaker-detected AF were compared between patients with and without thromboembolic outcomes. Propensity score matching (1:1) was conducted based on clinical characteristics. Multivariate regressions were performed to determine the predictors of thromboembolic outcomes. Survival free from stroke and thromboembolism was assessed using Kaplan-Meier analysis in groups with different AF burden. RESULTS: Among the 152 patients enrolled (43.4% women; age 73.2 ±â€¯13.3 years), ten experienced thromboembolic events within a median follow-up of 67 months. Patients with thromboembolisms had higher CHA2DS2-VASc scores but not higher AF burden. Higher CHA2DS2-VASc score was associated with increased risk for systemic thromboembolism [hazard ratio (HR), 1.87; 95% confidence interval (CI), 1.07-3.24; P = 0.027). In the propensity score-matched cohort with comparable CHA2DS2-VASc score, patients with thromboembolism had higher AF burden. Pacemaker-detected AF was associated with increased risk for thromboembolism (propensity-adjusted HR, 9.33; 95% CI, 1.19-72.99; P = 0.033). Experiencing AF episodes lasting >6 min was a predictor of significantly higher risk of future stroke or thromboembolism (propensity-adjusted HR, 6.75; 95% CI, 1.30-35.11; P = 0.023). CONCLUSION: In patients with dual-chamber pacemakers and comparable CHA2DS2-VASc score, pacemaker-detected AF burden is associated with elevated risk for thromboembolism. Further research is needed to clarify how pacemaker-detected AF burden could incorporate with CHA2DS2-VASc score variables and help to guide anticoagulation.

A Pilot Study on Parameter Setting of VisiTag™ Module during Pulmonary Vein Isolation.

OBJECTIVES: To identify optimal predefined criteria (OPC) for filters of the VisiTag™ module in the CARTO 3 system during pulmonary vein isolation (PVI). METHODS: Thirty patients with atrial fibrillation (AF) who experienced PVI first were enrolled. PVI was accomplished by using a Thermocool SmartTouch catheter. Ablation lesions were tagged automatically as soon as predefined criteria of the VisiTag™ module were met. OPC should be that ablation with the setting resulting in the conduction gap (CG) as few as possible, while contiguous encircling ablation line (CEAL) without the tag gap (TG) on the 3D anatomic model as much as possible. RESULTS: When ablation with parameter setting is being catheter movement with a 3 mm distance limit for at least 20 s and force over time (FOT) being off, there were 60 CEAL without TG on the 3D anatomic model. However, 26 CGs were found. After changing FOT setting to be a minimal force of 5 g with 50% stability time, 22 TGs were displayed. Of them, 20 TGs were accompanied by CGs. On reablation at sites of TG with changed parameter setting, 18 CGs were eliminated when 20 TGs disappeared. When reablation with FOT is being a minimal force of 10 g with 50% stability time, 6 remaining CGs were eliminated. However, there was no CEAL. With a mean of follow-up 10.93 months, 2 patients with persistent AF suffered AF recurrence. CONCLUSION: A 3 mm distance limit for at least 20 s and FOT being a minimal force of 5 g with 50% stability time might be OPC for the VisiTag™ module.

Combining fragmented QRS and TIMI score for predicting in-hospital short-term prognosis after acute myocardial infarction.

Acute myocardial infarction (AMI) has a high mortality rate and poor prognosis for patients. The primary causes of death are arrhythmia and heart failure. For patients admitted because of myocardial infarction, various risk evaluations are initiated to foresee possible complications. The thrombolysis in myocardial infarction (TIMI) risk score, which can be used to predict the prognosis and the need for revascularisation, is the most convenient and commonly used system, but is inadequate for AMI patients on admittance. Fragmented QRS (fQRS) has been shown to be a valuable electrocardiographic (ECG) index for predicting the prognosis of patients with coronary heart disease. Also, fQRS is considered to predict an increased likelihood of a poor outcome and mortality in patients with coronary artery disease (CAD), even for some successfully revascularized AMI patients. So what would happen if fQRS and the TIMI risk score were combined? This study focused on the investigation of the short-term prognostic value of fQRS combined with the TIMI risk score for patients with AMI.

[Left atrial size predicts adverse cardiac events in patients with non-obstruction hypertrophic cardiomyopathy].

OBJECTIVE: To evaluate the relationship between left atrial size and the risk of cardiac events in patients with non-obstruction hypertrophic cardiomyopathy. METHODS: In the study, 39 patients who met inclusion criteria were followed up for (28.0±7.7) months. The patients were divided into two groups with or without major adverse cardiac events (a composite of arrhythmia, angina, syncope and congestive heart failure). Clinical and echocardiographic data of the two groups were compared. The predictive value of left atrial diameter (LAD) and left atrial volume index (LAVI) were reviewed by using receive operating characteristic curve (ROC). The events analysis was performed by using the Kaplan-Meier analysis. RESULTS: Cardiac events occurred in 11 patients (28.2%). LAD, LAD index (LADI), LAV and LAVI were significantly greater in the patients with cardiac events than those without cardiac events [LAD: (4.28±0.63) cm vs. (3.85±0.48) cm, P=0.025; LADI: (0.048 9±0.011 1) cm/m(2) vs. (0.040 8±0.005 8) cm/m(2), P=0.005; LAV: (60.8±16.2) mL vs. (46.2±14.0) mL, P=0.008; LAVI: (66.5±23.8) mL/m(2) vs. (49.6±15.9) mL/m(2), P=0.014]. An LAD of >4.29 cm identified patients with cardiac events with a sensitivity of 63.6% and a specificity of 89.3%. An LAVI of >53.1 mL/m(2) identified patients with cardiac events with a sensitivity of 72.7% and a specificity of 71.4%. The Kaplan-Meier analysis indicated that the patients with LAD>4.29 cm or LAVI>53.1 mL/m(2) had higher incidence of cardiac events. CONCLUSION: LAD and LAVI may be effective markers for predicting adverse cardiac events in patients with non-obstruction hypertrophic cardiomyopathy.

Correlation between fragmented QRS and the short-term prognosis of patients with acute myocardial infarction.

This study is aimed to investigate the clinical significance and the short-term prognostic value of fragmented QRS (fQRS) for patients with acute myocardial infarction (AMI). Three hundred patients with AMI were tested with retrospective analysis on the patients' clinical information, hospitalized treatment, fQRS onset time, location of lesions, and other relevant data, in order to assess the relationship between the presence of fQRS and its prognosis. The rates of malignant cardiac arrhythmia, left ventricular systolic dysfunction (LVSD), and mortality in the positive fQRS group were 13.6%, 29.2%, and 23.7%, respectively, with all showing a p value <0.05. For the ST segment elevation myocardial infarction (STEMI) subgroup, all the rates showed significant differences with a p value <0.01, while for the non-STEMI (NSTEMI) subgroup showed no significant differences. In patients with a positive fQRS, there were no differences in malignant cardiac arrhythmia between patients with and without percutaneous coronary intervention (PCI) (p>0.05). As for the LVSD and mortality, the p values between patients with and without PCI were 0.031 and 0.000, respectively, suggesting statistical significance. The results imply that AMI patients with positive fQRS especially for the patients with STEMI had higher rates of malignant cardiac arrhythmia, LVSD, and mortality than the non-fQRS group. Patients of AMI with positive fQRS, who underwent early revascularization, could lower the incidence of the cardiovascular event. In addition, the presence of fQRS could be used as an indication of early intervention treatment for patients.

[The effect of different loading doses of clopidogrel on platelet aggregation].

OBJECTIVE: To compare the short-term efficacy and safety of high loading dose (600 mg) clopidogrel treatment with those of routine loading dose (300 mg) in patients with acute coronary syndrome and provide evidence for planning clopidogrel treatment. METHODS: 60 patients were randomized into two groups, One group received 300 mg loading dose clopidogrel, while the other received 600 mg and both were followed by 75 mg daily thereafter. Adenosine diphosphate (ADP) (5 micromol/L and 20 micromol/L) induced platelet aggregation was examined at baseline (before administration), 2 hours and 6 hours after administration and the count of white blood cell and platelet 3 days after loading dose. The primary end points were hemorrhagic events, granulocytopenia and thrombocytopenia within 3 days after administration. RESULTS: With a high-dose agonist (20 micromol/L ADP), loading doses of clopidogrel at 300 mg and 600 mg both produced greater inhibition of baseline ADP (20 micromol/L) induced aggregation 6 hours after administration than 2 hours [group of 300 mg: (29.75+/-12.11)% vs (43.63+/-14.31)%, P<0.05. Group of 600 mg: (28.86+/-10.24)% vs (34.86+/-10.84)%, P<0.05]. Treatment with clopidogrel at 600 mg loading dose had a marked earlier effect on platelet aggregation 2 hours after administration than that of 300 mg [(34.86+/-10.84)% vs (43.63+/-14.31)%, P<0.05]. The platelet aggregation of the two groups tended towards similar at 6 hours after the procedure [(28.86+/-10.24)% vs (29.75+/-12.11)%, P>0.05]. There were no episodes of hemorrhagic events, granulocytopenia and thrombocytopenia within 3 days after the procedure. CONCLUSIONS: In Chinese patients with acute coronary syndrome platelet aggregation can be inhibited more rapidly and more effectively with clopidogrel at 600 mg loading dose when compared with that at 300 mg loading dose and the safety aspect between the two different loading doses is equivalent.