James L. Cox

Surgical Ablation of Atrial Fibrillation in the United States: Trends and Propensity Matched Outcomes

BACKGROUNDnSurgical ablation (SA) for atrial fibrillation (AF) effectively restores sinus rhythm. Incompletely defined risk has previously limited concomitant performance of SA during cardiac operations. The study goals were to define performance trends and risk-adjusted outcomes for contemporary SA.nnnMETHODSnFrom July 2011 to June 2014, 86,941 patients with AF, but without endocarditis, underwent primary nonemergent cardiac operations in The Society of Thoracic Surgeons (STS) database. Cochran-Armitage tests examined performance trends of SA for six operative categories: mitral valve repair or replacement (MVRR) with or without coronary artery bypass graft surgery (CABG), aortic valve replacement (AVR) with or without CABG, CABG, AVR with MVRR, stand-alone SA, and other concomitant operations. The risk of concomitant SA was analyzed by propensity matching 28,739 patient-pairs with and without SA by AF type, primary operation, and STS comorbid risk variables using greedy 1:1 matching algorithms.nnnRESULTSnAmong all patients with AF, 48.3% (42,066 of 86,941) underwent SA. Mitral operations had the highest rate of SA (MVRR ± CABG 68.4% [14,693 of 21,496]; MVRRxa0+ AVR 59.1% [1,626 of 2,750]). The AVR ± CABG and isolated CABG rates were 39.3% (6,816 of 17,349) and 32.8% (9,156 of 27,924), respectively. Nearly half of other concomitant operations underwent SA, 47.6% (6,939 of 14,586). Performance frequency increased throughout the study period. After propensity matching, SA was associated with a reduction in relative risk (RR) of 30-day mortality (RR 0.92, 95% confidence interval [CI]: 0.85 to 0.99) and stroke (RR 0.84, 95% CI: 0.74 to 0.94), but an increase in renal failure (RR 1.12, 95% CI: 1.03 to 1.22) and pacemaker implantation (RR 1.33, 95% CI: 1.24 to 1.43).nnnCONCLUSIONSnContemporary utilization of SA is increasing across all operative categories. Performance of SA is accompanied by a 30-day reduction in mortality and stroke. These findings further refine our understanding of the role of SA in the treatment of AF.

Epicardial left atrial appendage AtriClip occlusion reduces the incidence of stroke in patients with atrial fibrillation undergoing cardiac surgery

AimsnLeft atrial appendage (LAA) occlusion has emerged as an interesting alternative to oral anticoagulation (OAC) for stroke prevention in patients with atrial fibrillation (AF). We report the safety, efficacy, and durability of concomitant device-enabled epicardial LAA occlusion during open-heart surgery. In addition to long-term follow-up, we evaluate the impact on stroke risk in this selected population.nnnMethods and resultsnA total of 291 AtriClip devices were deployed epicardially in patients (mean CHA2DS2-VASc-Score: 3.1u2009±u20091.5) undergoing open-heart surgery (including isolated coronary artery bypass grafting, valve, or combined procedures) comprising of forty patients from a first-in-man device trial (NCT00567515) and 251 patients from a consecutive institutional registry thereafter. In all patients (nu2009=u2009291), the LAA was successfully excluded and overall mean follow-up (FU) was 36u2009±u200923months (range: 1-97u2009months). No device-related complications were detected throughout the FU period. Long-term imaging work-up (computed tomography) in selected patients ≥5years post-implant (range: 5.1-8.1u2009years) displayed complete LAA occlusion with no signs of residual reperfusion or significant LAA stumps. Subgroup analysis of patients with discontinued OAC during FU (nu2009=u2009166) revealed a relative risk reduction of 87.5% with an observed ischaemic stroke-rate of 0.5/100 patient-years compared with what would have been expected in a group of patients with similar CHA2DS2-VASc scores (expected rate of 4.0/100 patient-years). No strokes occurred in the subgroup with OAC.nnnConclusionnThe long-term results from our first-in-man prospective human trial plus our institutional registry of epicardial LAA occlusion with the AtriClip in patients with AF undergoing cardiac surgery demonstrate the safety and durability of the procedure. In addition, our data are suggestive for the potential efficacy of LAA occlusion in reducing the incidence of stroke. If validated in future large randomized trials, routine LAA occlusion in patients undergoing cardiac surgery (with contraindications to treatment with oral anticoagulants) may represent a reasonable adjunct procedure to reduce the risk of future stroke.nnnClinical Trial RegistrationnURL: http://www.clinicaltrials.gov. Unique identifier: NCT00567515.

De novo atrial fibrillation after mitral valve surgery.

Objectives We sought to determine the incidence and risk factors for de novo atrial fibrillation (>90 days after surgery) in patients without preoperative atrial fibrillation. Methods From 2004 to 2014, 2261 patients underwent mitral valve surgery; 1288 patients (57%) did not have a history of atrial fibrillation, and 930 patients had rhythm information more than 90 days after surgery. De novo atrial fibrillation and death probabilities were estimated using a semi‐competing risks, multi‐state model. Univariable and multivariable risk factors for developing atrial fibrillation were identified using the Fine–Gray model. Results The 5‐ and 10‐year incidences of de novo atrial fibrillation were 14% and 23%, respectively. Univariable risk factors were older age, more complex operations, more tricuspid regurgitation, and congestive heart failure (all P < .05). Patients with degenerative mitral regurgitation were less likely to develop atrial fibrillation (hazard ratio [HR], 0.4; 95% confidence interval [CI], 0.24‐0.65; P < .001). Multivariable risk factors for de novo atrial fibrillation were tricuspid valve surgery (HR, 1.80; 95% CI, 1.22, 2.65; P = .003), aortic valve surgery (HR, 1.49; 95% CI, 1.03‐2.17; P = .035), and older age (HR, 1.03; 95% CI, 1.02‐1.05; P < .001). De novo atrial fibrillation did not affect overall survival (P = .41). Among patients who developed de novo atrial fibrillation, we observed increased use of warfarin (P < .001) and a strong trend toward an increased risk of stroke (P = .055). Conclusions De novo atrial fibrillation develops progressively after mitral surgery and is associated with a strong trend toward stroke. Patients at high risk could be studied in a trial to reduce atrial fibrillation.

Burden of preoperative atrial fibrillation in patients undergoing coronary artery bypass grafting

Background: This study compares early and late outcomes in patients undergoing coronary artery bypass grafting with and without preoperative atrial fibrillation in a contemporary, nationally representative Medicare cohort. Methods: In the Medicare‐Linked Society of Thoracic Surgeons database, 361,138 patients underwent isolated coronary artery bypass from 2006 to 2013, of whom 37,220 (10.3%) had preoperative atrial fibrillation; 13,161 (35.4%) were treated with surgical ablation and were excluded. Generalized estimating equations were used to compare 30‐day mortality and morbidity. Long‐term survival was summarized using Kaplan‐Meier curves and Cox regression models. Stroke and systemic embolism incidence was modeled using the Fine‐Gray model and the CHA2DS2‐VASc score was used to analyze stroke risk. Median follow‐up was 4 years. Results: Preoperative atrial fibrillation was associated with a higher adjusted in‐hospital mortality (odds ratio [OR], 1.5; P < .0001) and combined major morbidity including stroke, renal failure, prolonged ventilation, reoperation, and deep sternal wound infection (OR, 1.32; P < .0001). Patients with preoperative atrial fibrillation experienced a higher adjusted long‐term risk of all‐cause mortality and cumulative risk of stroke and systemic embolism compared to those without atrial fibrillation. At 5 years, the survival probability in the preoperative atrial fibrillation versus no atrial fibrillation groups stratified by CHA2DS2‐VASc scores was 74.8% versus 86.3% (score 1–3), 56.5% versus 73.2% (score 4–6), and 41.2% versus 57.2% (score 7–9; all P < .001). Conclusions: Preoperative atrial fibrillation is independently associated with worse early and late postoperative outcomes. CHA2DS2‐VASc stratifies risk, even in those without preoperative atrial fibrillation.

Epicardial Left Atrial Appendage Exclusion Reduces Blood Pressure in Patients With Atrial Fibrillation and Hypertension

BACKGROUNDnPercutaneous left atrial appendage exclusion (LAAE) has evolved as an alternative strategy for stroke prevention in atrial fibrillation (AF). Recent observational data have suggested that epicardial LAAE can have substantial impact on arrhythmia burden and hemodynamic profile.nnnOBJECTIVESnThe authors aimed to study the impact of epicardial versus endocardial LAAE on systemic blood pressure in hypertensive AF patients.nnnMETHODSnThis was a prospective, nonrandomized study comparing 247 patients who underwent epicardial LAAE with 124 patients with endocardial exclusion. Clinical outcomes were measured at 3xa0months and 1 year. Primary outcome was improvement in systolic blood pressure (SBP) between both groups compared with baseline. Secondary outcome included changes in diastolic pressures (DBP), serum electrolytes, and creatinine.nnnRESULTSnThere was no significant difference in baseline SBP between epicardial and endocardial groups. SBP was significantly lower in the epicardial group both at 3xa0months (122 ± 11.8xa0mmxa0Hg vs. 129.7 ± 8.2xa0mmxa0Hg; pxa0< 0.001) and 1xa0year (123 ± 11.6xa0mmxa0Hg vs. 132.2 ± 8.8xa0mmxa0Hg; pxa0< 0.001) compared with the endocardial group. An adjusted multivariate linear mixed effects model demonstrated that epicardial LAAE significantly decreased SBP by 7.4xa0mmxa0Hg at 3xa0months and by 8.9xa0mmxa0Hg at 1 year (pxa0< 0.0001). There was a trend toward lower DBP with epicardial LAAE at 3xa0months by 1.3xa0mmxa0Hg (pxa0=xa00.2) and at 1 year by 1.8xa0mmxa0Hg (pxa0=xa00.09). There was no significant difference in serum electrolytes and creatinine between both groups.nnnCONCLUSIONSnIn hypertensive AF patients, epicardial LAAE significantly decreases SBP both at 3 and 12xa0months compared with endocardial exclusion.

Strokes associated with left ventricular assist devices

Ventricular assist devices (VADs) have improved dramatically over the past several decades but stroke remains a problem. There are multiple etiologies of both ischemic and hemorrhagic strokes associated with VADs. While this problem is yet to be solved, there are continuing efforts at improving the design of VADs to decrease the incidence of stroke and to improve long‐term survival in patients requiring mechanical circulatory assistance. The purpose is to review the incidence and underlying causes of stroke in VAD patients.

When is a Maze Procedure a Maze Procedure

The initial surgical attempts to treat atrial fibrillation (AF) were isolation procedures designed to confine the arrhythmia to a specific area of the heart for relief of symptoms. The first surgical attempt to ablate AF was unsuccessful but was quickly followed by the Maze-I procedure on September 25, 1987. Because of several adverse sequelae of the Maze-I procedure, it was sequentially modified to the Maze-II and then Maze-III procedures. The Maze-IV procedure was introduced some 10 years later; these are the only 4 procedures that adhere to the concept of a maze pattern of lesions to ablate AF and leave both atria capable of being activated during normal sinus rhythm. The term maze procedure has become generic for virtually any operation designed to treat AF, but procedures that do not adhere to the concept of creating lesions of conduction block in the pattern of a maze are not maze procedures. These include, among others, the Wolf Mini-Maze, the Left-Sided Maze, and the 5-Box Maze, none of which are truly based on the maze-pattern concept. The cardinal feature of maze procedures that is necessary for both effectiveness and comparability to classical maze procedures includes lines of conduction block that preclude macro-reentry anywhere in either atrium while leaving both atria capable of activation by a sinus-generated impulse. Components essential to achieving this include appropriate lesions in both atria, the absence of gaps that allow electrical activity to bypass an intended line of block, and the absence of alternate pathways by which impulses can reach the intended maze exit.

The Maze Procedure and Postoperative Pacemakers

BACKGROUNDnThere is concern that the right atrial lesions of the maze procedure lead to more permanent pacemakers postoperatively and that they provide little therapeutic advantage over left atrial lesions alone.nnnMETHODSnA discussion of the pertinent anatomy related to atrial fibrillation and the performance of the maze procedure, the potential ways that the specialized conduction system could theoretically be damaged by the procedure, non-procedure-related causes for increased postoperative pacemaker requirements, and the basis for the efficacy of the right atrial lesions of the maze procedure are presented. Several factors that can lead to a dysfunctional sinoatrial node preoperatively in patients with atrial fibrillation are also discussed.nnnRESULTSnThe reasons new permanent pacemakers are required after a maze procedure include the high success rates of the surgery with subsequent unmasking of preoperative sick sinus syndrome, excessive extracardiac dissection that damages the autonomic nerve input to the heart, premature pacemaker implantation for a temporary junctional rhythm immediately postoperatively, surgical error, and patient selection.nnnCONCLUSIONSnThere are numerous reasons why patients need new pacemakers after a maze procedure, but the right atrial lesions of the procedure rarely, if ever, are the cause.

A Hybrid Maze Procedure for Long-Standing Persistent Atrial Fibrillation

BACKGROUNDnCatheter ablation (CA) for long-standing persistent atrial fibrillation (LSPAF) is suboptimal, and open surgical ablation, although more successful, is too invasive to be a first-line therapy. Less invasive hybrid procedures that combine thoracoscopic surgery (TS) with CA have been only marginally more successful for LSPAF than CA alone.nnnMETHODSnJoint hybrid procedures for LSPAF are based on the assumption that AF surgery and CA procedures can be guided by intraoperative mapping. However, intraoperative mapping is not always dependable because of the transient nature of the sustaining reentrant drivers. The best results in patients with LSPAF have been attained with the non-guided, anatomy-based surgical Maze-III and Maze-IV procedures. Likewise, a staged TS/CA hybrid procedure that creates a combination of lesions that adhere to the concept of a Maze pattern, that is, a Hybrid Maze-IV procedure, should be more effective for LSPAF.nnnRESULTSnInitial TS includes all lesions of the Maze-IV procedure except the mitral line, coronary sinus lesion, and one right atrial lesion. Follow-up CA at 3 months includes touching up any incomplete TS lesions, a cavotricuspid isthmus lesion, and a mitral line/coronary sinus lesion in the 10% to 15% of patients with post-TS perimitral flutter. This combination of TS and CA lesions creates a complete Maze-IV procedure.nnnCONCLUSIONSnIt is possible to create the complete lesion pattern of a Maze-IV procedure with a staged TS/CA hybrid procedure. The success of this Hybrid Maze procedure in patients with LSPAF should be the same as that attained with an open surgical Maze-IV procedure.

Cardiovascular Therapies Targeting Left Atrial Appendage

Left atrial appendage (LAA) closure has evolved as an effective strategy for stroke prevention in patients with atrial fibrillation who are considered suitable for oral anticoagulation. There is strong evidence based on randomized clinical trials with 1 percutaneous device, as well as a large registry experience with several devices, regarding the safety and efficacy of this strategy. In addition, there is encouraging data regarding the effect of epicardial LAA closure on decreasing arrhythmia burden and improvements in systemic homeostasis by neurohormonal modulation. However, there are several unresolved issues regarding optimal patient selection, device selection, management of periprocedural complications including device-related thrombus, residual leaks, and pericarditis. In this review, we summarize the rationale, evidence, optimal patient selection, and common challenges encountered with mechanical LAA exclusion.