Atrioesophageal Fistula Rates Before and After Adoption of Active Esophageal Cooling During Atrial Fibrillation Ablation.

BACKGROUND: Active esophageal cooling reduces the incidence of endoscopically identified severe esophageal lesions during radiofrequency (RF) catheter ablation of the left atrium for the treatment of atrial fibrillation. A formal analysis of the atrioesophageal fistula (AEF) rate with active esophageal cooling has not previously been performed. OBJECTIVES: The authors aimed to compare AEF rates before and after the adoption of active esophageal cooling. METHODS: This institutional review board (IRB)-approved study was a prospective analysis of retrospective data, designed before collecting and analyzing the real-world data. The number of AEFs occurring in equivalent time frames before and after adoption of cooling using a dedicated esophageal cooling device (ensoETM, Attune Medical) were quantified across 25 prespecified hospital systems. AEF rates were then compared using generalized estimating equations robust to cluster correlation. RESULTS: A total of 14,224 patients received active esophageal cooling during RF ablation across the 25 hospital systems, which included a total of 30 separate hospitals. In the time frames before adoption of active cooling, a total of 10,962 patients received primarily luminal esophageal temperature (LET) monitoring during their RF ablations. In the preadoption cohort, a total of 16 AEFs occurred, for an AEF rate of 0.146%, in line with other published estimates for procedures using LET monitoring. In the postadoption cohort, no AEFs were found in the prespecified sites, yielding an AEF rate of 0% (P < 0.0001). CONCLUSIONS: Adoption of active esophageal cooling during RF ablation of the left atrium for the treatment of atrial fibrillation was associated with a significant reduction in AEF rate.

Integration of new technology into clinical practice after FDA approval.

Development of new medical technology is a crucial part of the advancement of medicine and our ability to better treat patients and their diseases. This process of development is long and arduous and requires a significant investment of human, financial and material capital. However, technology development can be rewarded richly by its impact on patient outcomes and successful sale of the product. One of the major regulatory hurdles to technology development is the Food and Drug Administration (FDA) approval process, which is necessary before a technology can be marketed and sold in the USA. Many businesses, medical providers and consumers believe that the FDA approval process is the only hurdle prior to use of the technology in day-to-day care. In order for the technology to be adopted into clinical use, reimbursement for both the device as well as the associated work performed by physicians and medical staff must be in place. Work and coverage decisions require Current Procedural Terminology (CPT) code development and Relative Value Scale Update Committee (RUC) valuation determination. Understanding these processes is crucial to the timely availability of new technology to patients and providers. Continued and better partnerships between physicians, industry, regulatory bodies and payers will facilitate bringing technology to market sooner and ensure appropriate utilization.

Management of Periprocedural and Early Pericardial Effusions With Tamponade Following Ablation of Atrial Fibrillation With Uninterrupted Factor Xa Inhibitors: A Case Series.

INTRODUCTION: Because of the absence of a dedicated reversal agent, the outcome of pericardial effusion (PE) following procedures performed with uninterrupted apixaban or rivaroxaban is unknown. We report the characteristics of PEs presenting with tamponade in patients undergoing AF ablation with uninterrupted factor Xa inhibition (FXaI) to understand their management and prognosis. METHODS AND RESULTS: We performed a multicenter cross-sectional survey in 10 centers across the United States. Patient data were obtained by chart review. In all patients the procedure was performed with uninterrupted FXaI. A total of 16 PEs requiring intervention were reported from 5 centers. Two patients were on apixaban 5 mg BD, the remaining on rivaroxaban 20 mg OD. Eleven PEs occurred in the periprocedural setting, and 5 PEs occurred from 1 to 28 days after the procedure. Pericardiocentesis and drainage were performed in all cases. Protamine and 4-factor prothrombin complex concentrate (4F-PCC) were given in all periprocedural cases. Two patients required surgery: in one case coagulation of the pericardial blood prevented effective drainage, and in the other bleeding was secondary to a steam pop-induced atrial tear. None of the postprocedural cases required FXaI reversal and the dose of rivaroxaban was temporarily reduced. No fatal outcomes or thromboembolic events were reported. CONCLUSION: Pericardiocentesis and drainage with FXaI reversal proved effective in the management of acute PEs with tamponade occurring periprocedurally in patients undergoing AF ablation with uninterrupted FXaI. Early postprocedural effusions can be treated with pericardiocentesis without the need of a reversal agent.

Ablation of Stable VTs Versus Substrate Ablation in Ischemic Cardiomyopathy: The VISTA Randomized Multicenter Trial.

BACKGROUND: Catheter ablation reduces ventricular tachycardia (VT) recurrence and implantable cardioverter defibrillator shocks in patients with VT and ischemic cardiomyopathy. The most effective catheter ablation technique is unknown. OBJECTIVES: This study determined rates of VT recurrence in patients undergoing ablation limited to clinical VT along with mappable VTs ("clinical ablation") versus substrate-based ablation. METHODS: Subjects with ischemic cardiomyopathy and hemodynamically tolerated VT were randomized to clinical ablation (n = 60) versus substrate-based ablation that targeted all "abnormal" electrograms in the scar (n = 58). Primary endpoint was recurrence of VT. Secondary endpoints included periprocedural complications, 12-month mortality, and rehospitalizations. RESULTS: At 12-month follow-up, 9 (15.5%) and 29 (48.3%) patients had VT recurrence in substrate-based and clinical VT ablation groups, respectively (log-rank p < 0.001). More patients undergoing clinical VT ablation (58%) were on antiarrhythmic drugs after ablation versus substrate-based ablation (12%; p < 0.001). Seven (12%) patients with substrate ablation and 19 (32%) with clinical ablation required rehospitalization (p = 0.014). Overall 12-month mortality was 11.9%; 8.6% in substrate ablation and 15.0% in clinical ablation groups, respectively (log-rank p = 0.21). Combined incidence of rehospitalization and mortality was significantly lower with substrate ablation (p = 0.003). Periprocedural complications were similar in both groups (p = 0.61). CONCLUSIONS: An extensive substrate-based ablation approach is superior to ablation targeting only clinical and stable VTs in patients with ischemic cardiomyopathy presenting with tolerated VT. (Ablation of Clinical Ventricular Tachycardia Versus Addition of Substrate Ablation on the Long Term Success Rate of VT Ablation (VISTA); NCT01045668).

The Effects of Catheter Ablation Therapy on Medication Use and Expenditures in Patients with Atrial Fibrillation.

Background: Atrial fibrillation (AF) is the most common cardiac arrhythmia encountered in clinical practice. Catheter ablation has become an important treatment option for many AF patients. Catheter ablation has been hypothesized to reduce the need for continued medical therapy for patients with AF, but there are few empirical data which demonstrate this. Objective: The objective of this study was to estimate the impact of catheter ablation on antiarrhythmic drug (AAD) utilization and total drug expenditures among AF patients. Methods: A retrospective analysis using the Truven Health Analytics MarketScan® Research Database was performed. Patients with AF and a catheter ablation procedure who had continuous enrollment in the database 6 months prior to their first ablation and a minimum of 1-year follow-up post first ablation were compared to AF patients who were treated with AADs and not ablation. Propensity matching was used to account for baseline differences between groups, and multivariable regression models adjusted for patient characteristics and baseline healthcare resource utilization. Sub-analyses were performed for patients age ≥65. Results: AF patients treated with catheter ablation had significantly lower AAD utilization and total prescription drug costs than those treated with AADs only. These results persisted for the subset of patients age ≥65. The effects were strongest in the matched sample, where approximately 30% of ablation patients discontinued use of rhythm medication after receiving catheter ablation. Per-patient total medication expenditures were reduced by $800 to $1,200 per year in the matched sample. Conclusion: Catheter ablation for AF reduced AAD utilization and total prescription drug expenditures in a sustainable fashion up to 3 years post ablation. This reduction was consistent and significant in both the non-Medicare and Medicare populations.

Acute safety outcomes in younger and older patients with atrial fibrillation treated with catheter ablation.

PURPOSE: Catheter ablation for atrial fibrillation (AF) has been demonstrated to be safe and effective in subsets of patients with AF, but primarily in patients age <65. This study compared acute safety in patients age ≥65 vs. those <65 who have undergone catheter ablation for AF. METHODS: A retrospective analysis of data from two Thomson Reuters MarketScan® research databases was performed on 5,947 patients who underwent catheter ablation for treatment of AF. Acute safety was measured as a composite endpoint of procedure-related adverse events coded ≤7 days post-procedure. A logistic regression model was fitted to this endpoint, using age (<65, ≥65) and relevant covariates. Peri-procedural mortality rates were examined among patients with inpatient ablation procedures, where death rates could be determined by discharge status. RESULTS: The acute safety event rate was nearly identical between both groups. This finding persisted after adjusting for covariates in the logistic regression model (p = 0.6648). There were no peri-procedural mortalities among the 3,575 index ablation procedures performed in an inpatient setting. CONCLUSION: Acute safety of catheter ablation for AF in patients ≥65 was consistent with that of younger patients. A prior history of hypertension and stroke was associated with a high risk for complications with AF ablation. These findings in a large, real world population may have implications for Medicare patients with AF.

Health outcomes with catheter ablation or antiarrhythmic drug therapy in atrial fibrillation: results of a propensity-matched analysis.

BACKGROUND: Patients with atrial fibrillation (AF) face significant risks of stroke and heart failure. The objective of this study was to determine whether AF ablation reduces the long-term risk of stroke or heart failure compared with antiarrhythmic drug therapy. METHODS AND RESULTS: A coding algorithm was used to identify AF patients treated with catheter ablation (n=3194) or antiarrhythmic drugs without ablation (n=6028) between 2005 and 2009 using The MarketScan Research Database from Thomson Reuters From this sample, 801 pairs were propensity matched, based on 15 demographic and clinical characteristics and baseline medication use. Rates of stroke/transient ischemic attack (TIA) and heart failure hospitalizations for up to 3 years were examined. Patients treated with catheter ablation had a significantly lower rate of stroke or TIA (3.4% per year) than a group of patients with AF managed with antiarrhythmic drugs only (5.5% per year), with an unadjusted hazard ratio of 0.62 (95% CI, 0.44-0.86; P=0.005). The rates for heart failure hospitalization were 1.5% per year in the ablation group and 2.2% per year in the antiarrhythmic drug group, with an unadjusted hazard ratio of 0.69 (95% CI, 0.42-1.15; P=0.158). These results were minimally altered in Cox proportional hazards models, which further adjusted for potential confounders not well balanced by the propensity matching. CONCLUSIONS: In a large propensity-matched community sample, AF ablation was associated with a reduced risk of stroke/TIA and no significant difference in heart failure hospitalizations compared with antiarrhythmic drug therapy. These findings require confirmation with randomized study designs.

Healthcare utilization and expenditures in patients with atrial fibrillation treated with catheter ablation.

AIM: The aim was to estimate the impact of catheter ablation on short- and long-term healthcare utilization and expenditures among atrial fibrillation (AF) patients in general and Medicare populations. METHODS: Data were analyzed from The MarketScan(®) Databases. MarketScan data contain deidentified patient-level records from employer-sponsored and public health insurance plans. Multivariable regression models for utilization and expenditures were built for all patients, with subanalyses performed for patients ≥65 years. Results were compared to preablation figures and reported for 5 time groups, based on duration of available postablation follow-up: 6-12 months; 12-18 months; 18-24 months; 24-30 months; and 30-36 months. RESULTS: A total of 3,194 patients were identified who had undergone catheter ablation for treatment of AF, had continuous enrollment in the database 6 months prior to first ablation, and had at least 1-year follow-up postablation. Compared to the 6 months prior to ablation, there were significant reductions in the number of outpatient appointments, inpatient days, and emergency room visits in the total study population and in the subset ≥65 years. There was a statistically significant (P < 0.01) decrease in total healthcare expenditures across 4 of the 5 6-month time periods, with annual savings ranging from $3,300 to $9,200. For patients ≥65 years, annual savings ranged from $3,200 to $9,200. Drug utilization also significantly declined (P < 0.01), with average annual medication savings ranging from $670 to $890, and from $740 to $880 for patients ≥65 years. CONCLUSION: Catheter ablation for AF reduced healthcare utilization and expenditures up to 3 years postablation. This reduction was consistent, significant, and had implications for general and Medicare populations.

Detection of repolarization alternans with an implantable cardioverter defibrillator lead in a porcine model.

Mechanistic links have been suggested between repolarization alternans (RPA) and the onset of ventricular tachycardia (VT) and/or fibrillation. Endocardial detection of RPA may, therefore, be an important step in future device-based treatments of arrhythmias. Here, we investigate if RPA could be detected during acute ischemia using an implantable cardioverter defibrillator (ICD) lead (tip to distal coil) located in the right ventricular apex. In 18 pigs, the right coronary (n = 10) or left anterior descending coronary (n = 8) artery was occluded for 10 min using a balloon catheter, followed by reperfusion for 30 min, and re-occlusion for 30 min. RPA magnitude, computed using the modified moving average (MMA) method, showed a sharp increase in all 18 animals, from a mean baseline level of 1.9 +/- 1.3 mV to 3.0 +/- 1.3 mV during first occlusion (p < 0.001). RPA magnitude showed a prominent increase in 10 animals during re-occlusion, from a mean baseline level of 1.7 +/- 1.0 mV to 3.3 +/- 1.5 mV (p < 0.001). The protocol was terminated during the first two stages of occlusion and reperfusion for the remaining 8 animals due to the occurrence of ventricular fibrillation (VF). These results confirm that RPA increases under ischemic conditions and that it is possible to detect and track RPA dynamics with an ICD lead that is positioned in a clinically realistic location. Such an approach may be useful in formulating improved arrhythmia detection and control algorithms.

Effect of beta-adrenergic blockade on dynamic electrical restitution in vivo.

The slope of the action potential duration (APD) restitution curve may be a significant determinant of the propensity to develop ventricular fibrillation, with steeper slopes associated with a more arrhythmogenic substrate. We hypothesized that one mechanism by which beta-blockers reduce sudden cardiac death is by flattening the APD restitution curve. Therefore, we investigated whether infusion of esmolol modulates the APD restitution curve in vivo. In 10 Yorkshire pigs, dynamic APD restitution curves were determined from measurements of APD at 90% repolarization with a monophasic action potential catheter positioned against the right ventricular septum during right ventricular apical pacing in the basal state and during infusion of esmolol. APD restitution curves were fitted to the three-parameter (a, b, c) exponential equation, APD = a.[1 - e((-b.DI))] + c, where DI is the diastolic interval. Esmolol decreased the maximal APD slope, 0.68 +/- 0.14 vs. 0.94 +/- 0.24 (baseline), P = 0.002, and flattened the APD restitution curve at shorter DIs, 75 and 100 ms (P < 0.05). To compare the slopes of the APD restitution curves at similar steady states, slopes were also computed at points of intersection between the restitution curve and the lines representing pacing at a fixed cycle length (CL) of 200, 225, 250, 275, and 300 ms using the relationship CL = APD + DI. Esmolol decreased APD restitution slopes at CLs 200-275 ms (P < 0.05). Esmolol flattens the cardiac APD restitution curve in vivo, particularly at shorter CLs and DIs. This may represent a novel mechanism by which beta-blockers prevent sudden cardiac death.

Effect of age and gender on heart rate recovery after submaximal exercise during cardiac rehabilitation in patients with angina pectoris, recent acute myocardial infarction, or coronary bypass surgery.

The effect of exercise training on the heart rate recovery (HRR) response to submaximal effort was examined in 81 patients during 12 weeks of phase II cardiac rehabilitation. Although HRR after submaximal effort was relatively reduced in older patients with heart disease and in women, its increase during exercise training in men and women of all ages was consistent with enhancement of parasympathetic tone during activities of daily living.

Endocardial detection of repolarization alternans.

Repolarization alternans (RPA) is prognostic of sudden cardiac death and is thought to be mechanistically linked to the initiation of ventricular tachyarrhythmias. Thus, implantable cardiac device detection of RPA may be therapeutically valuable. Because alternans detection is currently limited to surface electrocardiograms, we investigated whether RPA could be measured using a single right-ventricular endocardial lead in humans. Such a location was chosen because it is consistent with the requirements for long-term implantable-device implementation. During diagnostic electrophysiological testing, 28 patients (23 male, 5 female; 61 +/- 15 years) were evaluated for surface T-wave alternans (TWA; the current "gold standard" for RPA detection) and endocardial RPA during 5 min of 550-ms right-atrial pacing. Power spectral analysis indicated that 11/28 patients had both surface TWA and endocardial RPA, 9/28 patients had neither, and 8/28 patients had discordant results (71% concordance; p = 0.02). Importantly, unlike surface TWA, endocardial RPA was detectable on a beat-to-beat basis. Given the putative mechanistic link between RPA and ventricular arrhythmias, beat-to-beat endocardial RPA detection might be of diagnostic or therapeutic utility.

Response to adenosine differentiates focal from macroreentrant atrial tachycardia: validation using three-dimensional electroanatomic mapping.

BACKGROUND: We previously proposed that adenosine has mechanism-specific effects on atrial tachycardia (AT), such that adenosine terminates AT attributable to triggered activity, transiently suppresses automatic rhythms, and has no effect on macroreentrant AT. This, however, remains controversial, because other studies have reported that adenosine terminates reentrant AT. To clarify this issue, we used 3D electroanatomic mapping to delineate the tachycardia circuit and thereby determine whether the response to adenosine differentiates focal from macroreentrant AT. METHODS AND RESULTS: We examined the effect of adenosine on 43 ATs in 42 consecutive patients (59+/-15 years of age; 26 female) who received adenosine during tachycardia and whose mechanism of AT was characterized by pharmacological perturbation, entrainment, 3D electroanatomic mapping, and results of radiofrequency ablation. Eight tachycardias were macroreentrant (noncavotricuspid isthmus-dependent), and 35 ATs were focal (either triggered or automatic). Adenosine administered during AT (at doses sufficient to result in AV block) terminated or transiently suppressed focal AT in 33 of 35 cases, whereas 8 of 8 macroreentrant ATs were adenosine insensitive (P<0.001). Twenty-eight of 35 focal ATs were located along the crista terminalis or tricuspid annulus. CONCLUSIONS: The response of AT to adenosine can immediately differentiate atrial tachycardia arising from a focal source from that attributable to macroreentry. This finding can be exploited to facilitate developing a focused, strategic ablative approach at the onset of a procedure.