The effect of esophageal cooling on esophageal injury during radiofrequency catheter ablation of atrial fibrillation.

INTRODUCTION: Catheter ablation of atrial fibrillation (AF) may lead to collateral damage to the esophagus. We tested the hypothesis that luminal esophageal temperature (LET)-guided esophageal cooling might reduce the incidence of esophageal thermal lesions (ETL). METHODS: Seventy-six patients from August 2015 to March 2017 with paroxysmal or persistent AF underwent a first-time catheter ablation procedure with or without LET-guided active esophageal cooling through an orogastric tube placed in the esophagus. Esophageal cooling occurred if and only if LET exceeded 0.5 °C from baseline while ablating the LA posterior wall. All patients underwent esophagogastric endoscopy the next day. RESULTS: Of the 76 patients studied, 38 (50%) patients underwent esophageal cooling. Baseline characteristics of the non-cooled and cooled groups were comparable. Of these, 59% of patients had ETL. There was a non-significant trend for more severe lesions (grades 3, 4) in the non-cooled group (29% vs. 13.5%, p = 0.10). Average power delivered on the left atrial posterior wall (27 ± 1.8 W vs. 27 ± 3.8 W, p = 0.34) and average force of contact (10.1 g vs. 9.8 g, p = 0.38) were similar in both groups while more time was spent ablating on the posterior wall in the non-cooled group (24.6 ± 7.3 min vs. 20.4 ± 5.9 min, p = 0.014). In a multivariate analysis, esophageal cooling had no significant effect on the esophageal lesion grade post-ablation. CONCLUSION: The incidence of ETL in patients undergoing left atrial posterior wall isolation is substantial. Our method of esophageal cooling did not decrease the incidence of ETL. There was a non-significant trend toward fewer severe lesions with cooling, but one cannot conclude the value of cooling from this pilot study.

High-power, low-flow, short-ablation duration-the key to avoid collateral injury?

BACKGROUND: A common approach to ablating along the posterior wall of the left atrium in atrial fibrillation ablation is to use low power with longer duration for durable lesions and reducing thermal injury. We hypothesize that similar lesions can be safely obtained at high power with low open-irrigation flow and low duration. METHODS: Twenty-two porcine ventricles were placed in a tissue bath with circulating 0.45% NaCl at a maintained temperature of 37 °C. Bipolar radiofrequency ablation (RFA) with a 4-mm-tip irrigated, force-sensing catheter was performed with various combinations of irrigation, power, and duration at 20g of contact force. Fiber optic temperature probes were placed at depths of 3 mm and 5 mm. Temperature was measured during and 30 s after each ablation. RESULTS: Two hundred sixty-eight lesions were made. At a fixed power and flow rate, lesion surface diameter, maximum lesion width, and lesion depth all increased with longer ablation duration. At fixed duration and irrigation flow rate, increased power led to increased lesion dimensions. At a lower flow rate (2 ml/min), surface lesion diameter and maximum width were significantly larger compared to a higher flow rate (17 ml/min), but lesion depth was not significantly different. The maximum temperature and the rate of temperature rise at a depth of 5 mm with different power settings and ablation durations were lower as compared to a depth of 3 mm at both flow rates (2 ml/min and 17 ml/min). CONCLUSIONS: Effective lesions can be performed with high-power and short-ablation durations, thereby reducing RFA procedure time. Higher power, shorter duration lesions result in adequate temperature for myocardial lesion formation at 3 mm, but do not result in excessive temperature at 5 mm depth, potentially reducing the risk of collateral injury. Compared to higher irrigation flow rate, larger surface lesions and comparable maximum lesion width are achieved with lower irrigation flow rate, thus resulting in better lesion contiguity.

Figure-of-eight suture for venous hemostasis in fully anticoagulated patients after atrial fibrillation catheter ablation.

INTRODUCTION: Limited data exists for types of venous closure and its associated complications in patients after atrial fibrillation (AF) catheter ablation. We evaluated the subcutaneous figure-of-eight closure (FO8) for achieving venous hemostasis after AF catheter ablation compared to manual pressure. METHODS: 284 consecutive patients that underwent AF catheter ablation by two operators were included. All patients received continuous therapeutic warfarin or interrupted novel oral anticoagulants (NOAC) and heparin (ACT300-400 s) without reversal. Patients were divided into two groups: 1) sheaths were left in place and pulled once ACT < 180 s, with hemostasis being achieved with manual pressure (MP); and 2) a subcutaneous FO8 suture closed the venous access site immediately after the ablation on each groin site and sheaths were removed immediately after the ablation despite full anticoagulation with heparin and warfarin or interrupted NOAC. Sutures were removed after four hours, and the patients laid flat for an additional two hours. RESULTS: The MP group (n = 105) was similar to the FO8 group (n = 179). Time in bed was 573 ± 80 min for MP group vs. 373 ± 49 min for FO8 group (p < 0.0001). Eleven hematomas were seen in the MP group compared to seven in the FO8 group (P = 0.041). CONCLUSIONS: In fully anticoagulated patients undergoing AF catheter ablation, excellent hemostasis was achieved with figure-of-eight sutures, with no major vascular complications, a lower hematoma rate, and a significantly shorter flat-time-in-bed compared to manual pressure.

Atrioesophageal Fistula Following Radiofrequency Catheter Ablation of Atrial Fibrillation.

Atrioesophageal fistula (AEF) is a rare but catastrophic complication of catheter ablation of atrial fibrillation (AF), with an incidence of 0.03% to 1.5% per year. We report two cases and review the epidemiology, clinical features, pathogenesis, and management of AEF after AF ablation. The principal clinical features of AEF include fever, hematemesis, and neurologic deficits within 2 months after ablation. The close proximity of the esophagus to the posterior left atrial wall is considered responsible for esophageal injury during ablation and the eventual development of AEF. Prophylactic proton pump inhibitors, esophageal temperature monitoring, visualization of the esophagus during catheter ablation, esophageal protection devices, esophageal cooling, and avoidance of energy delivery in close proximity to the esophagus are some techniques to prevent esophageal injury. Eliminating esophageal injury during AF ablation is of utmost importance in preventing AEF. A high index of suspicion and early intervention are necessary to prevent fatal outcomes. Early surgical repair is the mainstay of treatment.

Pacemaker-induced tricuspid regurgitation is uncommon immediately post-implantation.

BACKGROUND: Prior studies report permanent pacemaker (PPM)-induced tricuspid regurgitation (TR) in up to one third of cases late post-implantation. We sought to assess the extent of immediate PPM-induced TR. METHODS: Forty patients undergoing PPM implant were prospectively enrolled. Patients with pre-existing moderate or severe TR or an RVSP >50 mmHg were excluded. Pre- and immediate post-implantation transthoracic echocardiography (TTE) analyzed TR grade according to established methods. 3D TTE was utilized to determine lead position in relation to tricuspid leaflets as well as lead mobility across the TV. RESULTS: Of 40 patients, four were excluded due to baseline moderate TR (n = 3) or RVSP >50 mmHg (n = 1). In the remaining cohort (n = 36), immediate post-implantation TTE showed no increase in TR grade in 30 patients (83%), whereas a one-grade increase from no/trace to mild occurred in six (17%) others. In no patient did immediate moderate or severe TR develop. Exclusive RV pacing was present in 47% of the patients; however, only two of the six patients with increased TR were paced. 3D TTE identified lead position in 92% of the cases-more than 50% of the cases showed RV lead distribution in the middle or post eroseptal commissure of the TV. Lead immobility was seen in only three of the six patients with increased TR. CONCLUSIONS: These findings show that significant PPM-induced TR is uncommon immediately post-implantation and, when it occurs, causes no greater than mild TR. RV pacing and lead mobility do not correlate with worsening of TR. 3D TTE is highly reliable at identifying lead position.

Incidence of Pocket Infection Postcardiac Device Implantation Using Antibiotic versus Saline Solution for Pocket Irrigation.

BACKGROUND: Preprocedure systemic antibiotic prophylaxis reduces infections in patients undergoing cardiac implantable electronic devices (CIEDs) implantations. Whether pocket irrigation with antibiotic solution offers any advantage over saline solution in CIED implantation is unknown. METHODS: Records from 327 consecutive patients who underwent CIED implantation by three operators from February 2011 to January 2014 were reviewed. From February 2011 to January 2012, the antibiotic solution was used for pocket irrigation; from February 2012 to January 2014, saline solution was used. All patients received preprocedural IV antibiotics. Baseline demographics, comorbidities, lab data, and occurrence of any pocket infection postimplant were collected. RESULTS: There were 118 and 209 patients in the antibiotic solution and saline solution group, respectively. A total of four (1.2%) patients had CIED infection: two in the antibiotic solution group and two in the saline solution group. Median time to infection from implant date was 81.5 ± 35 days. Two patients (50%) had infection after first device implantation. Of the four patients, one had positive blood culture, three had positive pocket cultures, one had lead vegetation, one underwent pocket exploration, and all of them had devices/leads extracted, with reimplantation on the contralateral side. No mortality was observed due to infectious complications. CONCLUSION: When compared to pocket irrigation in the antibiotic solution group, the saline solution group was not associated with increased incidence of infectious complications after CIED implantation. The use of saline solution pocket irrigation alone may be used in CIED pocket irrigation periprocedurally.  Further evaluation in larger randomized trials is needed.

Inadvertent electrical isolation of the left atrial appendage during catheter ablation of persistent atrial fibrillation.

BACKGROUND: Left atrial appendage (LAA) isolation is rare and may be associated with impaired transport function and thromboembolism. OBJECTIVE: The purpose of this study was to determine the mechanisms of inadvertent isolation of the LAA during atrial fibrillation (AF) ablation. METHODS: This study consisted of 11 patients (ejection fraction 0.43 +/- 0.18, left atrial diameter 51 +/- 8 mm) with persistent AF who had LAA conduction block during a procedure for AF (n = 8) or atrial tachycardia (AT) (n = 3). RESULTS: LAA conduction block occurred during ablation at the Bachmann bundle region in 6 patients, mitral isthmus in 3, LAA base in 2, and coronary sinus in 1. The mean distance from the ablation site to the LAA base was 5.0 +/- 1.9 cm. LAA isolation was transient in all 6 patients in whom LAA conduction was monitored and was permanent in the 4 patients in whom conduction was not monitored during energy delivery. The remaining patient was noted to have LAA isolation during a redo procedure before any ablation. Nine of (82%) the 11 patients have remained arrhythmia-free without antiarrhythmic drugs at mean follow-up of 6 +/- 7 months, and all have continued taking warfarin. CONCLUSION: Electrical isolation of the LAA may occur during ablation of persistent AF and AT even when the ablation site is remote from the LAA. This likely is due to disruption of the Bachmann bundle and its leftward extension, which courses along the anterior left atrium and bifurcates to surround the LAA. Monitoring of LAA conduction during ablation of persistent AF or AT is important in avoiding permanent LAA isolation.

No benefit from defibrillation threshold testing in the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial).

OBJECTIVES: This study investigated whether defibrillation threshold (DFT) testing during implantable cardioverter-defibrillator (ICD) implantation predicts clinical outcomes. BACKGROUND: Defibrillation testing is often performed during insertion of ICDs to confirm shock efficacy. There are no prospective data to suggest that this procedure improves outcomes when modern ICDs are implanted for primary prevention of sudden death. METHODS: The analysis included the 811 patients who were randomized to the ICD arm of the SCD-HeFT (Sudden Cardiac Death in Heart Failure Trial) and had the device implanted. The DFT testing protocol in SCD-HeFT was designed to limit shock testing in a primary prevention heart failure population. RESULTS: Baseline DFT data were available for 717 patients (88.4%). All 717 patients had a DFT of < or =30 J, the maximum output of the device in this study. The DFT was < or =20 J in 97.8% of patients. There was no survival difference between patients with a lower DFT (< or =10 J, n = 547) and a higher DFT (>10 J, n = 170) (p = 0.41). First shock efficacy was 83.0% for the first clinical ventricular tachyarrhythmia event; there were no differences in shock efficacies when the cohort was subdivided by baseline DFT. CONCLUSIONS: Low baseline DFTs were obtained in patients with stable, optimally treated heart failure during ICD implantation for primary prevention of sudden death. First shock efficacy for ventricular tachyarrhythmias was high regardless of baseline DFT testing results. Baseline DFT testing did not predict long-term mortality or shock efficacy in this study.

Prevalence and characteristics of continuous electrical activity in patients with paroxysmal and persistent atrial fibrillation.

BACKGROUND: Complex fractionated atrial electrograms (CFAEs) may play a role in the genesis of atrial fibrillation (AF). One type of CFAE is continuous electrical activity (CEA). The prevalence and characteristics of CEA in patients with paroxysmal and persistent AF are unclear. METHODS AND RESULTS: In 44 patients (age = 59 +/- 8 years) with paroxysmal (25) or persistent (19) AF, bipolar electrograms were systematically recorded for > or =5 seconds at 24 left atrial (LA) sites, including 8 antral sites, and 2 sites within the coronary sinus (CS). CEA was defined as continuous depolarization for >1 second with no isoelectric interval. CEA was recorded at the LA septum (79%), antrum (66%), posterior (68%) and anterior walls (67%), roof (66%), base of the LA appendage (61%), inferior wall (61%), posterior mitral annulus (48%), CS (41%), and in the LA appendage (14%). Antral CEA was equally prevalent in patients with paroxysmal (63%) and persistent AF (70%, P = 0.12). In patients with paroxysmal AF, the prevalence of CEA was similar among antral and nonantral LA sites, except for the LA appendage. However, in patients with persistent AF, CEA was more prevalent at the nonantral (80%) than antral sites (70%, P = 0.03). CEA at nonantral sites except the CS was more prevalent in persistent than in paroxysmal AF (80% vs 57%, P < 0.001). The mean duration of intermittent episodes of CEA was longer in persistent than in paroxysmal AF (P < 0.001). CONCLUSIONS: The higher prevalence and duration of CEA at nonantral sites in persistent than in paroxysmal AF is consistent with a greater contribution of LA reentrant mechanisms in persistent AF. However, the high prevalence of CEA at nonantral sites in paroxysmal atrial fibrillation (PAF) suggests that CEA alone is a nonspecific marker of appropriate target sites for ablation of AF. The characteristics of CEA that most accurately identify drivers of AF remain to be determined.