Improved Ablation Efficiency in PVI Guided by Contact Force and Local Impedance: Chronic Canine Model

Background: The purpose of this study was to assess the effect local impedance (LI) has on an ablation workflow when combined with a contact force (CF) ablation catheter.Methods: Left pulmonary vein isolation was performed in an in vivo canine model (N = 8) using a nominal (30 W) or an elevated (50 W) power strategy with a CF catheter. The catheter was enabled to measure LI prior to and during ablation. LI was visible for only one of the vein isolations.Results: Chronic block was achieved in all animals when assessed 30 ± 5 days post-ablation procedure with a median LI drop during RF ranging from 23.0 to 34.0 Ω. In both power cohorts, the median radiofrequency (RF) duration decreased if LI was visible to the operator (30 W only CF: 17.0 s; 30 W CF + LI: 14.0 s, p = 0.009; 50 W only CF: 6.0 s; 50 W CF + LI: 4.0 s, p = 0.019). An inverse relationship between the LI prior to RF delivery and the RF duration required to achieve an effective lesion was observed. There was no correlation between the magnitude of the applied force and the drop in LI, once at least 5 g was achieved.Conclusions: An elevated power strategy with the context of CF and LI led to the most efficient titration of successful RF energy delivery. The combination of feedback allows for customization of the ablation strategy based on local tissue variation rather than a uniform approach that could potentially lead to overtreatment. Higher LI drops were more readily achievable when an elevated power strategy was utilized, especially in conditions where the catheter was coupled against tissue with low resistivity. Clinical study is warranted to determine if there is an additive safety benefit to visualizing the dynamics of the tissue response to RF energy with LI when an elevated power strategy is used.

Regional pericarditis following uncomplicated catheter ablation procedure: a case report

Background Acute post-ablation pericarditis is the most common complication of epicardial ablation of ventricular arrhythmias (VA), while regional pericarditis following an initially uneventful endocardial catheter ablation (CA) procedure is a rare and elusive diagnosis. Case summary We report a case of a 66-years old Russian female who developed chest pain accompanied by ECG changes—biphasic T waves in V1-V4 leads after an initially uncomplicated premature ventricular complex (PVC) CA procedure. After examination and investigations, including transthoracic echocardiography (TTE), cardiac magnetic resonance imaging (CMR) and cardiac computed tomography (CCT), she was diagnosed with regional pericarditis, which occurred even though the ablation was uneventful with the limited number of radiofrequency applications. Furthermore, the diagnosis was difficult due to normal body temperature and the absence of pericardial effusion and myocardial abnormalities on TTE, findings that are not characteristic of pericarditis. The patient's last office visit was in six months after the procedure. Neither patient had any complaints, nor there were any changes on ECG and TTE. Discussion Regional post-ablation pericarditis is a relatively rare type of postcardiac injury syndrome (PCIS). The varying severity of the PCIS clinical course makes the diagnosis of post-ablation pericarditis initially difficult, especially in patients undergoing an uneventful catheter ablation procedure. Non-invasive imaging modalities as cardiac magnetic resonance imaging (CMR) and cardiac computed tomography (CCT) should be considered initially in elusive cases of PCIS.

Atrial Fibrillation Ablation Using Robotic Magnetic Navigation Reduces the Incidence of Silent Cerebral Embolism

Background: The incidence of silent cerebral embolisms (SCEs) has been documented after pulmonary vein isolation using different ablation technologies; however, it is unreported in patients undergoing with atrial fibrillation (AF) ablation using Robotic Magnetic Navigation (RMN). The purpose of this prospective study was to investigate the incidence, risk predictors and probable mechanisms of SCEs in patients with AF ablation and the potential impact of RMN on SCE rates.Methods and Results: We performed a prospective study of 166 patients with paroxysmal or persistent AF who underwent pulmonary vein isolation. Patients were divided into RMN group (n = 104) and manual control (MC) group (n = 62), and analyzed for their demographic, medical, echocardiographic, and risk predictors of SCEs. All patients underwent cerebral magnetic resonance imaging within 48 h before and after the ablation procedure to assess cerebral embolism. The incidence and potential risk factors of SCEs were compared between the two groups. There were 26 total cases of SCEs in this study, including 6 cases in the RMN group and 20 cases in the MC group. The incidences of SCEs in the RMN group and the MC group were 5.77 and 32.26%, respectively (X2 = 20.63 P < 0.05). Univariate logistic regression analysis demonstrated that ablation technology, CHA2DS2-VASc score, history of cerebrovascular accident/transient ischemic attack, and low ejection fraction were significantly associated with SCEs, and multivariate logistic regression analysis showed that MC ablation was the only independent risk factor of SCEs after an AF ablation procedure.Conclusions: Ablation technology, CHA2DS2-VASc score, history of cerebrovascular accident/transient ischemic attack, and low ejection fraction are associated with SCEs. However, ablation technology is the only independent risk factor of SCEs and RMN can significantly reduce the incidence of SCEs resulting from AF ablation.Clinical Trial Registration: ChiCTR2100046505.

Cryoballoon Ablation Strategy in Persistent Atrial Fibrillation

Background: Cryoballoon ablation is established for pulmonary vein isolation (PVI) in paroxysmal atrial fibrillation (AF). The objective was to evaluate CBA strategy in consecutive patients with persistent AF in the initial AF ablation procedure.Material and Methods: Prospectively, patients with symptomatic persistent AF scheduled for AF ablation all underwent cryoballoon PVI. Technical enhancements, laboratory management, safety, single-procedure outcome, predictors of recurrence, and durability of PVI were evaluated.Results: From 2007 to 2020, a total of 1,140 patients with persistent AF, median age 68 years, underwent cryoballoon ablation (CBA). Median left atrial (LA) diameter was 45 mm (interquantile range, IQR, 8), and Congestive heart failure, Hypertension, Age ≥75 years (doubled), Diabetes mellitus, prior Stroke or TIA or thromboembolism (doubled), Vascular disease, Age 65 to 74 years, Sex category (CHA2DS2-VASc) score was 3. Acute isolation was achieved in 99.6% of the pulmonary veins by CBA. Median LA time and median dose area product decreased significantly over time (p < 0.001). Major complications occurred in 17 (1.5%) patients including 2 (0.2%) stroke/transitory ischemic attack (TIA), 1 (0.1%) tamponade, relevant groin complications, 1 (0.1%) significant ASD, and 4 (0.4%) persistent phrenic nerve palsy (PNP). Transient PNP occurred in 66 (5.5%) patients. No atrio-esophageal fistula was documented. Five deaths (0.4%), unrelated to the procedure, occurred very late during follow-up. After initial CBA, arrhythmia recurrences occurred in 46.6% of the patients. Freedom from atrial arrhythmias at 1-, and 2-year was 81.8 and 61.7%, respectively. Independent predictors of recurrence were LA diameter, female sex, and use of the first cryoballoon generation. Repeat ablations due to recurrences were performed in 268 (23.5%) of the 1,140 patients. No pulmonary vein (PV) reconduction was found in 49.6% of the patients and 73.5% of PVs. This rate increased to 66.4% of the patients and 88% of PVs if an advanced cryoballoon was used in the first AF ablation procedure.Conclusion: Cryoballoon ablation for symptomatic persistent AF is a reasonable strategy in the initial AF ablation procedure.

Perioperative coronary artery spasms in patients undergoing catheter ablation of atrial fibrillation

Purpose Catheter ablation (CA) is an established treatment for atrial fibrillation (AF). Although coronary artery spasms (CAS) during or after ablation procedures have been described as a rare complication in some case reports, the incidence and characteristics of this complication have not been fully elucidated. The present observational study aimed to clarify the CAS in a large number of patients experiencing AF ablation. Methods A total of 2913 consecutive patients (male: 78%, mean 66 ± 10 years) who underwent catheter ablation of AF were enrolled. Results Nine patients (0.31%, mean 66 ± 10 years, 7 males) had transient ST-T elevation (STE). Eight out of the 9 patients had STE in the inferior leads. STE occurred after the transseptal puncture in 7 patients, after the sheath was pulled out of the left atrium in 1, and 2 h after the ablation procedure in 1. Six patients had definite angiographic CAS without any sign of an air embolization on the emergent coronary angiography. In the3 other patients, the STE improved either directly after an infusion of nitroglycerin or spontaneously before the CAG. The patients with CAS had a higher frequency of a smoking habit (89% vs. 53%; P = .04), smaller left atrial diameter (36 ± 6 vs. 40 ± 7; P = .07), and lower CHADS2 score (0.6 ± 0.5 vs. 1.3 ± 1.1; P = .004) than those without. Conclusions Although the incidence was rare (0.31%), CAS should be kept in mind as a potentially life-threatening complication throughout an AF ablation procedure especially performed under conscious sedation.

Abstract 1122‐000070: Multiple Watershed Strokes Following Catheter Ablation Procedure

Introduction : Cerebral watershed strokes involve the junction of two non‐anastomosing arterial systems, which are hemodynamic zones at risk. Strokes occur in 3% to 9% of patients after cardiac procedures. The mechanism underlying post‐cardiac surgery watershed stroke involves a combination of hypoperfusion and embolization, but the role of hypoperfusion has not been well elucidated. Watershed strokes in the general population are usually secondary to global hypoperfusion, such as during cardiac arrest, but may also be attributable to stenosis of the carotid artery or other major vessel, leading to local hypoperfusion. Atrial fibrillation confers a threefold to fivefold increase in the risk of stroke, causing 15–20% of all thromboembolic events in the United States. Catheter ablation of atrial fibrillation is the treatment of choice, and currently one of the most commonly performed electrophysiology procedures in the United States. Successful catheter ablation in patients with atrial fibrillation is associated with a decrease in systolic blood pressure. One study showed that in patients with hemodynamically significant stenosis, the average decrease in mean blood pressure during TIA attack was 26.4. mm Hg. In addition, carotid artery stenosis is frequently associated with stenosis of the vertebral arteries, carotid siphon, and cerebral arteries. In these patients, cerebral blood flow is directly dependent on perfusion pressure, due to the loss of normal autoregulatory capacity in the cerebral circulation. Methods : Single Case Study Results : 84‐year‐old male patient with a past medical history of hypertension, gastrointestinal hemorrhage, coronary artery disease status post coronary artery bypass graft, prostate cancer, and atrial flutter on Apixaban status post recent catheter ablation performed five days prior to presentation at the hospital. Patient presented to the emergency room with complaints of spotty vision. The remainder of the neurologic exam was unremarkable. Patient’s vision changes started after the cardiac ablation procedure and progressively worsened. At the time of assessment, NIH score was 1 due to left eye hemianopsia. CT scan of the head without contrast was done and was negative for hemorrhage. CTA of the neck showed 60% stenosis of the left carotid artery. MRI of the brain was done and showed infarct zones between the right anterior cerebral artery and right middle cerebral artery, the right middle cerebral artery and right posterior cerebral artery, the left anterior cerebral artery and left middle cerebral artery, and in the area supplied by the right posterior cerebral artery. Interestingly, based on the radiologic features, all of these strokes happened at approximately the same time. Conclusions : This case demonstrates that even in asymptomatic patients with hemodynamically insignificant carotid stenosis, hypotensive episodes can elicit hemodynamically significant changes that may result in ischemic stroke. Current guidelines don’t include radiologic assessment of the carotid arteries before catheter ablation procedure in patients with known atherosclerotic disease. Based on our findings, in patients with known atherosclerotic disease, we recommend radiologic assessment of the carotid arteries prior to catheter ablation. Patient who undergo catheter ablation usually have an echocardiogram done prior to the procedure.