Posterior left atrial epicardial adipose tissue: scope of the problem and impact of new technology.

PURPOSE OF REVIEW: Patients with persistent forms of atrial fibrillation are seeking treatments based on the promise of better restoration of sinus rhythm with newer therapies. Successful catheter ablation and maintenance of atrial fibrillation in this subgroup is negatively impacted by the presence of epicardial adipose tissue (EAT) associated with the posterior left atrium. RECENT FINDINGS: EAT is now understood to be hormonally active and promotes adverse atrial remodelling, including fibrosis and myopathy. Despite being dominantly adipose tissue, it is known to be electrically active, comprising ganglia, neural tissue and ectopic atrial myocardium that may contribute to endo-epicardial dissociation and persistent electrical activity and atrial fibrillation despite good endocardial electrical silencing. Hybrid procedures that include direct epicardial ablation of the posterior wall, including the EAT, are associated with superior outcomes in nonparoxysmal atrial fibrillation. SUMMARY: Therapies for persistent atrial fibrillation that also ablate the EAT as part of a well tolerated transmural posterior wall ablation may improve outcomes in this challenging subset of patients.

Efficacy of Balloon Expandable Extreme-Low Temperature Ventricular Epicardial Cryoablation: A Preclinical Proof of Concept Evaluation.

BACKGROUND: Current epicardial ablation technologies are limited by the inability to create adequate depth lesions and risk of collateral injury to extracardiac structures. OBJECTIVE: To evaluate the feasibility and efficacy of ventricular epicardial ablation with a novel balloon-expandable extreme-low temperature (XLT) cryoablation catheter with an embedded insulation pontoon for protection of extracardiac structures which has been specifically designed for epicardial ablation. METHODS: 10 healthy swine underwent surgical (6) and subxiphoid percutaneous (4) epicardial access respectively. A total of 3-6 sites were targeted in the right and left ventricular wall for different exposure durations. Ablation was performed with a large footprint (surgical) and smaller footprint (percutaneous) version of the HeartPad® (Corfigo Inc., Montclair, NJ) XLT system. The system consists of the balloon-expandable cryoablation catheter and a console. The console vaporizes liquid helium (-269˚C) and controls continuous delivery of extremely cold helium gas at high flow rates through a high-efficiency ablation element mounted on an expandable insulation pontoon to protect extracardiac structures. Ablation lesions were assessed by gross pathology and histological examination. RESULTS: A total of 42 epicardial lesions were created. The mean lesion depth increased progressively with the ablation time (surgical catheter: 11±2 mm at ≤30 seconds, 13±4 mm at 60 seconds, 15±3 mm at ≥120 seconds, P =0.001; percutaneous catheter: 10±2 mm at 30 seconds, 14±2 mm at 60 seconds, 16±2 mm at 120 seconds], P =0.001). Lesion geometry appeared unaffected by presence and thickness of epicardial fat. One episode of ventricular fibrillation occurred following ablation over the atrioventricular groove and 2 adjacent obtuse marginal arteries. CONCLUSION: Surgical or percutaneous epicardial ablation using the HeartPad® XLT cryoablation system is feasible and can efficiently produce deep ventricular lesions in different epicardial locations.

Atrial fibrillation symptom reduction and improved quality of life following the hybrid convergent procedure: a CONVERGE trial subanalysis.

Background: CONVERGE was a prospective, multicenter, randomized controlled trial that evaluated the safety of Hybrid Atrial Fibrillation Convergent (HC) and compared its effectiveness to endocardial catheter ablation (CA) for the treatment of persistent atrial fibrillation (PersAF) and longstanding PersAF (LSPAF). In 2020, we reported that CONVERGE met its primary safety and effectiveness endpoints. The primary objective of the present study is to report CONVERGE trial results for quality of life (QOL) and Class I/III anti-arrhythmic drug (AAD) utilization following HC. Methods: Eligible patients had drug-refractory symptomatic PersAF or LSPAF and a left atrium diameter ≤6.0 cm. Enrolled patients were randomized 2:1 to receive HC or CA. Atrial Fibrillation Severity Scale (AFSS) and the 36-Item Short Form Health Survey (SF-36) were assessed at baseline and 12 months; statistical comparison was performed using paired t-tests. AAD utilization at baseline through 12 and 18 months post-procedure was evaluated; statistical comparison was performed using McNemar's tests. Results: A total of 153 patients were treated with either HC (n=102) or CA (n=51). Of the 102 HC patients, 38 had LSPAF. AFSS and SF-36 Mental and Physical Component scores were significantly improved at 12 months versus baseline with HC overall and for the subset of LSPAF patients treated with either HC or CA. The proportion of HC patients (n=102) who used Class I /III AADs at 12 and 18 months was significantly less (33.3% and 36.3%, respectively) than baseline (84.3%; P<0.001). In LSPAF patients who underwent HC (n=38), AADs use was 29.0% through 18 months follow-up versus 71.1% at baseline (P<0.001). Conclusions: HC reduced AF symptoms, significantly improved QOL, and reduced AAD use in patients with PersAF and LSPAF. ClinicalTrialsgov Identifier: NCT01984346.

Hybrid epicardial-endocardial ablation for long-standing persistent atrial fibrillation: A subanalysis of the CONVERGE Trial.

Background: Favorable clinical outcomes are difficult to achieve in long-standing persistent atrial fibrillation (LSPAF) with catheter ablation (CA). The CONVERGE (Convergence of Epicardial and Endocardial Ablation for the Treatment of Symptomatic Persistent Atrial FIbrillation) trial evaluated the effectiveness of hybrid convergent (HC) ablation vs endocardial CA. Objective: The study sought to evaluate the safety and effectiveness of HC vs CA in the LSPAF subgroup from the CONVERGE trial. Methods: The CONVERGE trial was a prospective, multicenter, randomized trial that enrolled 153 patients at 27 sites. A post hoc analysis was performed on LSPAF patients. The primary effectiveness was freedom from atrial arrhythmias off new or increased dose of previously failed or intolerant antiarrhythmic drugs (AADs) through 12 months. The primary safety endpoint was major adverse event incidence through 30 days with HC. Key secondary effectiveness measures included (1) percent of patients achieving ≥90% AF burden reduction vs baseline and (2) AF freedom. Results: Sixty-five patients (42.5% of total enrollment) had LSPAF; 38 in HC and 27 in CA. Primary effectiveness was 65.8% (95% confidence interval [CI] 50.7%-80.9%) with HC vs 37.0% (95% CI 5.1%-52.4%) with CA (P = .022). Through 18 months, these rates were 60.5% (95% CI 50.0%-76.1%) with HC vs 25.9% (95% CI 9.4%-42.5%) with CA (P = .006). Secondary effectiveness rates were higher than CA with HC at 12 and 18 months. Freedom from atrial arrhythmias off AADs was 52.6% (95% CI 36.8%-68.5%) and 47.4% (95% CI 31.5%-63.2%) with HC at 12 and 18 months vs 25.9% (95% CI 9.4%-42.5%) and 22.2% (95% CI 6.5%-37.9%) with CA, respectively (12 months: P = .031; 18 months: P = .038). Three (7.9%) major adverse events occurred within 30 days of HC. Conclusion: Post hoc analysis demonstrated effectiveness and acceptable safety of HC compared with CA in LSPAF.

Co-occurrence of Anomalous Right Coronary Artery Origin and Subaortic Membrane in an Adult Male.

Anomalous origin of the right coronary artery (ARCA) represents <3% of congenital coronary anomalies, while the subaortic membrane represents 6.5% of congenital heart anomalies. Symptomatic co-occurrence of ARCA and subaortic membrane in an adult is rare. A 68-year-old man developed a non-ST-elevation myocardial infarction necessitating percutaneous coronary intervention (PCI) four years prior to presentation at our hospital. In the years after his PCI, he developed progressive exertional breathlessness. Following a positive treadmill EKG, he underwent coronary CT angiography that indicated RCA dominance with ARCA arising from the left coronary sinus and coursing between the ascending aorta and pulmonary artery, causing 50-60% intraluminal narrowing at rest without atherosclerotic plaque. Echo showed normal left ventricular ejection fraction (LVEF) and a surprise finding of the subaortic membrane, with a modest gradient. He underwent successful resection of the subaortic membrane and unroofing of the anomalous RCA tunnel with tract marsupialization. The post-operative period was complicated by arrhythmias necessitating electrical cardioversion. At discharge, he was sent home on apixaban, bisoprolol, aspirin, atorvastatin, and an amiodarone taper. The subaortic membrane would not have required intervention independently because it was not associated with a severe gradient. However, surgery is recommended for symptomatic ARCA or subaortic membrane; hence, our patient underwent surgical management. Atrial fibrillation and flutter are the most common arrhythmias following cardiac surgery. Due to the patient's increased risk of complications, cardioversion and anticoagulation were pursued. Although ARCA is congenital, our patient had been asymptomatic for most of his life, suggesting that the development of the subaortic membrane might have triggered symptom onset, combining a modest subaortic gradient with previously asymptomatic exercise-induced right coronary ischemia. Clinicians should consider evaluating for secondary structural heart conditions in newly symptomatic adult patients with ARCA due to the risk of sudden cardiac death, to provide the most complete treatment.

Cardiogenic shock due to partial occlusion of the left coronary ostium in infective endocarditis: a case report.

The case is presented of chronic aortic valve endocarditis in a previously asymptomatic 54-year-old male. The main initial clinical manifestation was cardiogenic shock, but further examination revealed the presence of a large mobile mass attached to a bicuspid aortic valve, partially occluding the left coronary ostium. The patient underwent emergency surgery to excise the vegetative mass and preserve the aortic valve. The postoperative outcome was satisfactory.

Forme fruste or 'Incomplete' bicuspid aortic valves with very small raphes: The prevalence of bicuspid valve and its significance may be underestimated.

BACKGROUND: Bicuspid aortic valve (BAV) comprises a broad spectrum of phenotypes. The importance of BAV in thoracic aortic aneurysm management has been debated. A subtle phenotype of BAV has been identified recently that could impact this debate. METHODS AND RESULTS: 101 consecutive patients with intact aortic valves operated in the setting of ascending aneurysm between January 2011-January 2014 were retrospectively identified. 20 were excluded because of valve calcification. 79 of 81 remaining had aortic valve phenotype described in operative reports, including tri-leaflet, bicuspid, and difficult-to-classify valves with small degrees of non-calcific fusion (raphe) at the commissures. Photographs of some three-leaflet valves with very small raphes were obtained. 18/79 (22.8%) had obvious BAVs and 61/79 (77.2%) were initially considered tri-leaflet valves. 18/61 (29.5%) of these had distinct but very small raphes and 12/18 (66.7%) involved the right/left commissure. Moderate or greater aortic insufficiency was found in 13/43 (30%) of patients with tri-leaflet valves, 8/18 (44.4%) with obvious BAVs, and in 9/18 (50%) three-leaflet valves with very small raphes. Retrospective review of computed tomography, magnetic resonance imaging and trans-esophageal (but not trans-thoracic) echocardiography sometimes identified very small raphes. CONCLUSIONS: Three-leaflet aortic valves exhibiting very small raphes occur in the setting of thoracic aneurysm and aortic insufficiency and may represent forme fruste BAVs. They are sometimes identifiable with high-resolution valve imaging. Without accounting for forme fruste BAVs, the true prevalence and impact of BAV on aortic complications may have been historically underestimated. This entity warrants further study in a prospective multi-center registry.

Hemodilution elevates cerebral blood flow and oxygen metabolism during cardiopulmonary bypass in piglets.

BACKGROUND: Hemodilution continues to be widely used during cardiopulmonary bypass (CPB) for both adults and children. Previous studies with nonbypass models have suggested that an increase in cerebral blood flow (CBF) compensates for the reduced oxygen-carrying capacity; however, this increased CBF is achieved by an increase in cardiac output. We hypothesized that even with the fixed-flow perfusion of CPB, CBF would be increased during hemodilution. METHODS: Two experiments were conducted and analyzed separately. In each experiment, 10 piglets were randomized to two different groups, one with a total blood prime yielding a high hematocrit (25% or 30%), and the other with a crystalloid prime resulting in a low hematocrit (10% or 15%). Animals were cooled with pH-stat strategy at full flow (100 or 150 mL.kg(-1).min(-1)) to a nasopharyngeal temperature of 15 degrees C, a period of low flow (50 mL.kg(-1).min(-1)) preceding deep hypothermic circulatory arrest (45 or 60 minutes), and a period of rewarming at full flow. Cerebral blood flow was measured at the beginning of CPB, at the end of cooling, at the end of low flow, 5 minutes after the start of rewarming, and at the end of rewarming by injection of radioactive microspheres. RESULTS: Mean arterial pressure was significantly greater with higher hematocrit at each time point (p< 0.05). Cerebral blood flow and the cerebral metabolic rate of oxygen decreased during cooling and further during low flow bypass but were significantly greater with lower hematocrit during mild hypothermia and at the end of rewarming (p< 0.05). CONCLUSIONS: Hemodilution is associated with decreased perfusion pressure, increased CBF and increased the cerebral metabolic rate of oxygen during hypothermic CPB.

Perioperative predictors of midterm survival after aortic valve replacement.

BACKGROUND: Elderly patients with aortic stenosis are under-referred for aortic valve replacement surgery. This study investigated the perioperative factors associated with midterm outcomes in a consecutive series of patients undergoing aortic valve replacement with or without coronary artery bypass graft surgery. METHODS: From 2006 to 2010, 509 patients having aortic valve replacement or aortic valve replacement with coronary artery bypass were grouped according to age (<80 years and ≥80 years) and procedure (aortic valve replacement ± coronary artery bypass). Patient survival was followed up for 5 years (mean 2.6 years). Midterm survival was evaluated using Kaplan-Meier and Cox proportional hazards regression model statistics. RESULTS AND CONCLUSIONS: 5-year survival among octogenarians was 59.2% with an observed 30-day mortality of 1% for aortic valve replacement and 3% for aortic valve replacement with coronary artery bypass. Kaplan-Meier survival analysis showed that age ≥80 years, New York Heart Association functional class III/IV, and left ventricular ejection fraction <35% were significantly associated with increased midterm mortality. Cox regression modeling demonstrated that age ≥80 years was the only significant independent factor associated with midterm mortality; older patients had a 3-fold increase in mortality (adjusted hazard ratio = 3.231, 95% confidence interval: 1.764-5.920, p < 0.0001). While hospital and 30-day mortality were not statistically different between age groups, age ≥80 years was the most powerful predictor of midterm death. These results support early aortic valve replacement with or without coronary artery bypass in aortic stenosis management.