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Background: Although Lesion size index (LSI) has been reported to highly predict radiofrequency lesion size in vitro, its accuracy in lesion size and steam pop estimation has not been well investigated for every possible scenario. Methods: Initially, radiofrequency ablations were performed on porcine myocardial slabs at various power, CF, and time settings with blinded LSI. Subsequently, radiofrequency power at 20, 30, 40, 50, and 60 W was applied at CF values of 5, 10, 20, and 30 g to reach target LSIs of 4, 5, 6, and 7. Lesion size and steam pops were recorded for each ablation. Results: Lesion size was positively correlated with LSI regardless of power settings (p < 0.001). The linear correlation coefficients of lesion size and LSI decreased at higher power settings. At high power combined with high CF settings (50 W/20 g), lesion depth and LSI showed an irrelevant correlation (p = 0.7855). High‐power ablation shortened ablation time and increased the effect of resistive heating. LSI could predict the risk of steam pops at high‐power settings with the optimal threshold of 5.65 (sensitivity, 94.1%; specificity, 46.1%). The ablation depth of the heavy heart was shallower than that of the light heart under similar ablation settings. Conclusions: LSI could predict radiofrequency lesion size and steam pops at high power settings in vitro, while synchronous high power and high CF should be avoided. Lighter hearts require relatively lower ablation settings to create appropriate ablation depth. [ABSTRACT FROM AUTHOR]

Abstract: Background: Vagus nerve injury during catheter ablation for atrial fibrillation can significantly impact quality of life and result in lingering gastrointestinal symptoms. This study was designed to define risk factors of vagus nerve injury, symptoms, prevalence, and temporal resolution. Methods: A total of 100 patients undergoing radiofrequency catheter ablation (RFCA) were enrolled and consented to participate in the study. Patients completed a 22‐item questionnaire that included questions specific to vagus nerve injury symptomatology during their baseline visit and at 1 and 3 months post‐RFCA. Results: The average age of the population was 63 ± 10.6 years and 68% were male. A total of 100 patients completed their baseline questionnaire (90 patients completed the 1‐month questionnaires and 85 patients completed the 3‐month questionnaires). Symptoms rated as moderate were prevalent at baseline (trouble swallowing 13%, bloating 26%, feeling full 20%), and increased in all categories analyzed at 1 month and with the exception of trouble swallowing returned to the preablation percentages at 3 months (heartburn 22.4%, trouble swallowing 18.8%, bloating 16.5%, nausea 8.2%, vomiting 3.5%, constipation 18.8%, diarrhea 16.4%, feeling full 15.3%). Severe rated symptoms of trouble swallowing (2–5.5%), bloating (5–7.6%), and early satiety (5–9.8%) increased at 1 month and bloating and early satiety percentages remained approximately two times higher at 3 months (trouble swallowing 2.4%, bloating 8.2%, early satiety 7.1%). Conclusion: The majority of symptoms were resolved by 3 months, although those patients who rate bloating and early satiety at a severe rating may have persistent symptoms. [ABSTRACT FROM AUTHOR]

Background: There are limited options for patients who present with antiarrhythmic-drug (AAD)-refractory ventricular tachycardia (VT) with recurrent implantable cardioverter defibrillator (ICD) shocks. Ranolazine is a drug that exerts antianginal and antiischemic effects and also acts as an antiarrhythmic in isolation and in combination with other class III medications. Ranolazine may be an option for recurrent AAD-refractory ICD shocks secondary to VT, but its efficacy, outcomes, and tolerance are unknown. Methods and Results: Twelve patients (age 65 ± 9.7 years) were treated with ranolazine. Eleven (92%) were male, and 10 (83%) had ischemic heart disease with an average ejection fraction of 0.34 ± 0.13. All patients were on a class III AAD (11 amiodarone, one sotalol), with six (50%) receiving mexilitene or lidocaine. Five patients had a prior ablation and two were referred for a VT ablation at the index presentation. The QRS increased nonsignificantly from 128 ± 31 ms to 133 ± 31 ms, and the QTc increased nonsignificantly from 486 ± 32 ms to 495 ± 31 ms after ranolazine initiation. Over a follow-up of 6 ± 6 months, 11 (92%) patients had a significant reduction in VT and no ICD shocks were observed. VT ablation was not required in those referred. In two patients, gastrointestinal side effects limited long-term use. Of these two patients, one died due to progressive heart failure. In one patient, severe hypoglycemia limited dosing to 500 mg daily, but this was sufficient for VT control. Conclusion: Ranolazine proved effective in reducing VT burden and ICD shocks in patients with AAD-refractory VT. Ranolazine should be further tested for this indication and considered for clinical application when other options have proven ineffective. (PACE 2011; 34:1600-1606) [ABSTRACT FROM AUTHOR]

Background: Previous studies have observed that short-term exposure to elevated concentrations of particulate matter (PM) air pollution increases risk of acute ischemic heart disease events and heart failure hospitalization, alters cardiac autonomic function, and increases risk of arrhythmias. This study explored the potential associations between short-term elevations in PM exposure and atrial fibrillation (AF). Methods and Results: A case-crossover study design was used to explore associations between fine PM (PM2.5, particles with an aerodynamic diameter ≤2.5 μm) and 10,457 AF hospitalizations from 1993 to 2008 of patients who lived on Utah's Wasatch Front. Patients were hospitalized at Intermountain Healthcare facilities with a primary diagnosis of AF. Concurrent day exposure and cumulative lagged exposures for up to 21 days were explored and the data were stratified by sex, age, and previous or subsequent admission for myocardial infarction. Although the estimated associations between PM2.5 and AF hospitalizations for the various lag structures and strata were consistently positive suggestive of risk, they were not statistically significant and they were extremely small compared to previously observed associations with ischemic heart disease events and heart failure hospitalizations. Further, we observed no additive risk between PM2.5 and AF hospitalization in those with respiratory disease or sleep apnea. Conclusions: Unlike previously observed associations with ischemic heart disease events and heart failure hospitalizations using similar study design and approaches, this study found that hospitalization for AF was not significantly associated with elevations in short-term exposure to fine PM air pollution. (PACE 2011; 34:1475-1479) [ABSTRACT FROM AUTHOR]

Background: Radiofrequency ablation is an effective treatment for atrial fibrillation (AF). With improved safety, the therapy has been offered to increasingly older populations. Arrhythmia mechanisms, medical comorbidities, and safety may vary in the very elderly population. Methods: Patients presenting for AF ablation were divided into two groups [≥80 years (n = 35), <80 years (n = 717)]. AF ablation consisted of pulmonary vein antral isolation with or without additional linear lesions. A successful outcome was defined as no further AF and off all antiarrhythmic medications >3 months following 1 + ablation procedures. Results: The type of AF was similar in both groups (paroxysmal: 46% in the older group vs 54% in the younger, P = 0.33). Older patients were more likely to have a higher CHADS2 score, coronary artery disease, and less likely to have had a prior ablation. The hospital stay on average was longer in the older cohort (2.9 ± 7.7 vs 2.1 ± 1.1 days, P = 0.001). There was no increased risk of peri-procedural complications. One-year survival free of AF or flutter was 78% in those >80 and 75% in those younger (P = 0.78). There was no difference between groups if the AF was paroxysmal (P = 0.44) or persistent/chronic (P = 0.74). Over a 3-year follow-up period, five patients died and four strokes occurred all in the younger cohort. Conclusion: Octogenarian patients, despite more coexistent cardiovascular diseases, have favorable outcomes after AF ablation measured by successful rhythm management. On an average their hospital stay is longer, but no significant increase in short- or long-term complications was observed. These data support AF ablation in select octogenarians. (PACE 2010; 33:146–152) [ABSTRACT FROM AUTHOR]

Background: Atrial fibrillation (AF) is associated with an increased risk of mortality and stroke. However, it is unclear if AF is independently associated with these poor outcomes or it is merely a risk marker of other processes that convey the risk. Methods: Consecutive patients who underwent angiography for suspicion of coronary artery disease, but without a history of AF, were studied. Traditional CHADS2 (congestive heart failure, hypertension, age >75 years, diabetes, stroke/transient ischemic attack) risk factors for each patient were recorded. Results: A total of 343 AF patients (age = 69 ± 10 years, 215 [63%] male) and 2,945 non-AF patients (age = 63 ± 12 years, 2,012 [67%] male) were studied. Among AF patients, 51 (15%) had a myocardial infarction (MI), 35 (10%) had a stroke, and 180 (52%) died. CHADS2 score incrementally increased risk of stroke (adjusted hazard ratio [HR] for 1:1.92, 2:2.30, 3:1.14, 4:3.83, 5:10.96; P-trend = 0.14), death (HR for 1:1.83, 2:2.34, 3:3.69, 4:2.27, 5:4.53; P-trend < 0.001), and major adverse cardiac event (MACE) (HR for 1:1.29, 2:1.54, 3:2.07, 4:2.41, 5:2.68; P-trend = 0.002). Among non-AF patients, CHADS2 score incrementally increased risk of stroke (HR for 1:1.18, 2:3.17, 3:5.08, 4:10.78, 5:7.50; P-trend < 0.001), MI (HR for 1:1.05, 2:1.46, 3:1.57, 4:0.53, 5:4.76; P-trend = 0.002), death (HR for 1:1.79, 2:3.22, 3:6.23, 4:9.09, 5:14.00; P-trend < 0.001), and MACE (HR for 1:1.47, 2:2.36, 3:4.16, 4:5.91, 5:7.56; P-trend < 0.001). Among all patients, both CHADS2 score (all P ≤ 0.001) and AF were independent risk factors for stroke (AF: P = 0.002), MI (AF: P = 0.035), death (AF: P < 0.001), and MACE (AF: P < 0.001). Conclusion: The CHADS2 score is a powerful predictor of stroke and death. AF increases the risk of these outcomes in an independent manner. These data support the concept that AF is a risk factor of future cardiovascular disease. [ABSTRACT FROM AUTHOR]

Background: Inflammation has been shown to have a direct role in the initiation, maintenance, and recurrence of atrial fibrillation (AF) although the underlying mechanisms are unknown. Similarly, it is unclear if inflammatory markers are elevated due to the AF alone or the coexisting cardiovascular diseases that increase the risk of AF. Methods: Consecutive patients who underwent angiography for suspicion of coronary artery disease, but without a myocardial infarction, were studied. Serum was analyzed to determine high-sensitivity C-reactive protein (hs-CRP) level. Patients’ AF status was determined through ICD-9 codes, review of hospital discharge summaries, clinical evaluations, and electrocardiograms. Results: A total of 2,340 patients were studied (64± 12 years). Comorbid diseases included 1,438 (61%) coronary artery disease, 1,309 (56%) hypertension, 433 (19%) diabetes, 345 (15%) congestive heart failure, and 43 (2%) a prior stroke. The hs-CRP level was significantly higher in patients with AF (n = 238) compared to those without (14.0 mg/L vs 9.1 mg/L, P < 0.001). Greater CHADS2 score was also significantly associated with higher hs-CRP in a linear fashion (medians [mg/L], 0: 1.99, 1: 2.91, 2: 3.49, 3: 3.89, 4–5: 4.82, P <0.001). The presence of AF was associated with higher hs-CRP level across all scores (medians [mg/L], 0: 2.22 vs 1.98, P = 0.83, 1: 3.85 vs 2.86, P = 0.057, 2: 4.96 vs 3.29, P = 0.021, 3: 6.29 vs 3.17, P = 0.09, 4–5: 4.82 vs 4.50, P = 0.87). Conclusion: Risks factors associated with AF were associated with higher hs-CRP in an incremental manner. The presence of AF increased hs-CRP across the CHADS2 score strata is supportive of the concept that AF is an inflammatory process and may convey independent risk. [ABSTRACT FROM AUTHOR]

The authors reflect on phrenic nerve pacing during atrial ablation and on the article "Electrical Isolation of the Superior Vena Cava Using Upstream Phrenic Pacing to Avoid Phrenic Nerve Injury" by T. Kimura et al. They suggest that Kimura et al should be congratulated on informing readers about the benefits of using phrenic nerve pacing to avoid phrenic nerve injury during ablation. They argue that physicians who perform ablation should be familiar with the benefits of phrenic pacing.