Low voltage-guided ablation of posterior wall improves 5-year arrhythmia-free survival in persistent atrial fibrillation.

INTRODUCTION: The posterior wall (PW) has been proposed as a standard target for ablation beyond pulmonary vein antral isolation (PVI) in patients with persistent atrial fibrillation (AF). However, studies have shown inconsistent outcomes with the addition of PW ablation. The presence or absence of low voltage on the PW may explain these inconsistencies. We evaluated whether PW ablation based on the presence or absence of low voltage improves long-term arrhythmia-free outcomes. METHODS: We retrospectively reviewed 5-year follow-up in 152 consecutive patients who received either standard ablation (SA) with PVI alone or PVI + PW ablation (PWA) based on physician discretion (n = 77) or voltage-guided ablation (VGA) with PVI and addition of PWA only if low voltage was present on the PW (n = 75). RESULTS: The two groups were well matched for baseline characteristics. At 5-year follow-up, 64% of patients receiving VGA were atrial tachyarrhythmia (AT)/AF free compared to 34% receiving SA (HR 0.358 p < .005). PWA had similar AF recurrence in SA and VGA groups (0.30 vs. 0.27 p = .96) but higher AT recurrence when comparing SA and VGA groups (0.39 vs. 0.15 p = .03). In multivariate analysis, both VGA and PWA predicted AF arrhythmia-free survival (HR 0.33, p = .001 and HR 0.20, p = .008, respectively). For AT, VGA predicted arrhythmia-free survival (HR 0.22, p = .028), while PWA predicted AT recurrence (HR 4.704, p = .0219). CONCLUSION: VGA of the posterior wall ablation beyond PVI in persistent AF significantly improves long-term arrhythmia-free survival when compared with non-voltage-guided ablation. PW ablation without voltage-guidance reduced AF recurrence but at the cost of a higher incidence of AT.

Post-ROSC Atrial fibrillation is not associated with rearrest but is associated with stroke and mortality following out of hospital cardiac arrest.

BACKGROUND: Atrial fibrillation (AF) in patients resuscitated from cardiac arrest (CA) is associated with increased short-term mortality. However, whether this is because AF adversely affects early resuscitation success, causes post-resuscitation morbidity, or because it is a marker for patient co-morbidities, remains unclear. We aimed to determine the prevalence of AF in patients with ROSC to test the hypothesis that AF is associated with increased risk of rearrest and to determine its impact on mortality and stroke risk. METHODS: We performed a retrospective study of emergency medical services patients with OHCA and ROSC. To examine long-term morbidity and mortality due to AF, an additional observational cohort analysis was performed using a large electronic health record (EHR) database. RESULTS: One hundred nineteen patients with ROSC prior to ED arrival were identified. AF was observed in 39 (33%) of patients. Rearrest was not different between AF and no AF groups (44% vs. 41%, p = 0.94). In the EHR analysis, mortality at one year in patients who developed AF was 59% vs. 39% in no AF patients. Odds of stroke was 5x greater in AF patients (p < 0.001), with the majority not anticoagulated (93%, p < 0.001) and comorbidities were greater p < 0.001). CONCLUSIONS: AF was common following ROSC and not associated with rearrest. AF after CA was associated with increased mortality and stroke risk. These data suggest rhythm control for AF in the immediate post-ROSC period is not warranted; however, vigilance is required for patients who develop persistent AF, particularly with regards to stroke risk and prevention.

Spontaneous Repolarization Alternans Causes VT/VF Rearrest That Is Suppressed by Preserving Gap Junctions.

BACKGROUND: Ventricular tachycardia (VT)/ventricular fibrillation (VF) rearrest after successful resuscitation is common, and survival is poor. A mechanism of VT/VF, as demonstrated in ex vivo studies, is when repolarization alternans becomes spatially discordant (DIS ALT), which can be enhanced by impaired gap junctions (GJs). However, in vivo spontaneous DIS ALT-induced VT/VF has never been demonstrated, and the effects of GJ on DIS ALT and VT/VF rearrest are unknown. OBJECTIVES: This study aimed to determine whether spontaneous VT/VF rearrest induced by DIS ALT occurs in vivo, and if it can be suppressed by preserving Cx43-mediated GJ coupling and/or connectivity. METHODS: We used an in vivo porcine model of resuscitation from ischemia-induced cardiac arrest combined with ex vivo optical mapping in porcine left ventricular wedge preparations. RESULTS: In vivo, DIS ALT frequently preceded VT/VF and paralleled its incidence at normal (37°C, n = 9) and mild hypothermia (33°C, n = 8) temperatures. Maintaining GJs in vivo with rotigaptide (n = 10) reduced DIS ALT and VT/VF incidence, especially during mild hypothermia, by 90% and 60%, respectively (P < 0.001; P < 0.013). Ex vivo, both rotigaptide (n = 5) and αCT11 (n = 7), a Cx43 mimetic peptide that promotes GJ connectivity, significantly reduced DIS ALT by 60% and 100%, respectively (P < 0.05; P < 0.005), and this reduction was associated with reduced intrinsic heterogeneities of action potential duration rather than changes in conduction velocity restitution. CONCLUSIONS: These results provide the strongest in vivo evidence to date suggesting a causal relationship between spontaneous DIS ALT and VT/VF in a clinically realistic scenario. Furthermore, our results suggest that preserving GJs during resuscitation can suppress VT/VF rearrest.

The Burden of Cardiac Arrhythmias in Gout: A National Representative Database Study.

The association between gout and arrhythmias has not been thoroughly examined. This study discusses the underappreciated burden, patterns, and outcomes of several arrhythmias, which may have prognostic value in patients with gout. This is a retrospective cohort study that used the US National Inpatient Sample for 2015-2019. Complex samples multivariable logistic and linear regression models were used to assess the incidence and trends in gout-related arrhythmia and consequential inpatient mortality, hospital length of stay (LOS), hospitalization charges, and predictors of mortality. Hospitalizations that included a diagnosis of gout accounted for 60,360 admissions. Arrhythmias affected roughly one-fourth of those. When compared to individuals without arrhythmia, those who experienced arrhythmias were older. Arrhythmias were found to be equally common in both men and women. The most common subtype was AF (88%), followed by atrial flutter (6.2%), conduction disorders (4.7%), and ventricular tachycardia (3.2%). In individuals with gout, there was a rising trend in arrhythmia-related hospital admissions and mortality. The gout-arrhythmia group had more traditional cardiac comorbidities. After adjusting for baseline variables, the arrhythmia group had significantly greater mortality (693 vs 77 per 100,000 hospitalizations), mean LOS (4.3 vs 3.7 days), and hospital costs ($33,057 vs $28,384). In gout, incident arrhythmia dramatically raised the risk of death (adjusted odds ratio, 2.06; 95% CI, 1.95-2.16; P < 0.001). Gout patients who are hospitalized with concurrent arrhythmia have a likelihood of longer stays in the hospital and higher mortality. Early identification and treatment of arrhythmia may benefit outcomes in gout patients.

Determining the Safety of Radiofrequency Ablation in Cardiovascular Implantable Electronic Devices.

Radiofrequency catheter ablation (RFCA) is an effective treatment for arrhythmias. The effects of RFCA on cardiovascular implantable electronic devices (CIED) function have varied. We aim to study the effect of RFCA on device parameters and clinical outcomes in patients with CIED. We conducted a single-center retrospective cohort study between 2011 and 2018. Generator and lead parameters were compared pre- and post-ablation using paired sample t-test. The median follow-up interval for documentation of procedure-related complications and clinical outcomes was 8 weeks. We identified 119 eligible patients; whose mean age was 64.5 ± 11.91 years and 22 (18.4%) were females. Types of CIED include single-chamber implantable cardioverter defibrillators (8.93%), dual-chamber implantable cardioverter defibrillators (41.96%), and either dual-chamber or biventricular pacemakers (44.54%). Arrhythmias for which patients underwent RFCA include atrial fibrillation/atrial tachycardia (15.22%), atrial flutter (38.14%), atrioventricular node reentrant tachycardia (13.56%), and premature ventricular complex or ventricular tachycardia (20.34%). No statistically significant difference was observed in pre- and post-ablation: (1) atrial sensing thresholds, pacing thresholds, lead impedance; (2) right ventricle sensing and pacing thresholds; and (3) left ventricle pacing threshold and impedance. A decrease in right ventricle impedance after ablation (549.77 ± 173 ohm vs 507.40 ± 129.0 ohm, P-value <0.004) was observed. Zero complications or deaths were observed. In this single-center study, RFCA did not significantly impact CIED function and was not associated with short-term complications. However longer follow-up is required to confirm these findings.

Clinical outcomes and predictors of complications in patients undergoing leadless pacemaker implantation.

BACKGROUND: Leadless pacemakers have emerged as a viable alternative for traditional transvenous pacemakers to reduce the risk of device-related complications. OBJECTIVE: The purpose of this study was to examine the real-world clinical outcomes and complications associated with the implantation of leadless pacemaker devices. METHODS: Using the National Readmission Database (NRD), we examined patient demographics, and in-hospital and 30-day procedural outcomes after leadless pacemaker implantation from 2016-2018. Our cohort comprised adults (≥18 years) with an ICD-10 procedural code for leadless pacemaker implantation. RESULTS: Our cohort included a total of 7821 patients who underwent leadless pacemaker implantation. Overall immediate procedure-related complications, as defined broadly in this study, occurred in 7.5% of patients. Pericardial effusion without the need for pericardiocentesis occurred in 1.9% of patients, with pericardiocentesis performed in 1.0%. Vascular complications occurred in 2.3% of patients; 0.33% required repair, and device dislodgment occurred in 0.51%. The most significant predictor for procedural complications was end-stage renal disease (odds ratio [OR] 1.65; 95% confidence interval [CI] 1.17-2.32; P = .004), congestive heart failure (OR 1.28; 95% CI 1.01-1.62; P = .04), and coagulopathy (OR 1.77; 95% CI 1.34-2.34; P <.001). All-cause readmission occurred in 17.9% of patients within 30 days from device implant, with 1.36% of readmissions being procedure related. At 30 days postimplant and after discharge, 0.25% of patients needed a new pacemaker, and 0.18% had pericardial complications. CONCLUSION: In our large real-life cohort, we found the rate of serious complications after leadless pacemaker implantation to be relatively low and comparable to prior studies in a high-risk population with multiple comorbid conditions.

Safety of nerve conduction studies in patients with peripheral intravenous lines.

Nerve conduction studies (NCS) may be deferred because of a perceived risk of cardiac arrhythmia in the presence of same-limb peripheral intravenous lines. Patients with implanted pacemakers or defibrillators provide a model in whom this risk can be assessed. Twenty patients, seven with pacemakers and 13 with defibrillators, had peripheral intravenous lines placed during routine care and underwent NCS in the same limb. NCS were performed with the intravenous line clamped and then with saline open to gravity. The implanted cardiac device was interrogated before and after the study. During NCS the surface electrocardiogram and intracardiac electrograms were monitored continuously. Electrical impulses generated during routine NCS were never detected by the sensing amplifiers of the pacemakers/defibrillators and did not affect the programmed settings or interfere with pacing of the device. Routine NCS are safe in patients with same-limb peripheral intravenous lines, even with saline open to gravity.

Idiopathic Ventricular Fibrillation: Diagnosis, Ablation of Triggers, Gaps in Knowledge, and Future Directions.

Idiopathic ventricular fibrillation (IVF) is a diagnosis of exclusion made when no underlying cause is identified in a cardiac arrest survivor. Although the frequency of this diagnosis has declined over time due to advances in diagnostic techniques, it remains a substantial cause of sudden cardiac arrest. Further, IVF tends to recur. This article reviews the criteria for diagnosis, patient characteristics, the two primary arrhythmic phenotypes-short-coupled variant of torsades de pointes and recurrent paroxysmal IVF-and the electrophysiologic features, treatment, and ablation of premature ventricular complexes that can trigger IVF.

Ventricular Arrhythmias.

Ventricular tachycardia is commonly seen in medical practice. It may be completely benign or portend high risk for sudden cardiac death. Therefore, it is important that clinicians be familiar with and able to promptly recognize and manage ventricular tachycardia when confronted with it clinically. In many cases, curative therapy for a given ventricular arrhythmia may be provided after a thorough understanding of the underlying substrate and mechanism. In this article, the authors broadly review the current classification of the different ventricular arrhythmias encountered in medical practice, provide brief background regarding the different mechanisms, and discuss practical diagnosis and management scenarios.

Ventricular Tachycardia Triggered by Loperamide and Famotidine Abuse.

A 32-year-old male developed recurrent ventricular tachycardia after taking mega doses of loperamide and famotidine in order to experience an opiate-like euphoric effect. He was taking up to 200 mg of loperamide and multiple doses of famotidine each day. He developed palpitations and syncope. Electrocardiography demonstrated ventricular tachycardia and QT interval prolongation (corrected QT interval was 597 ms). He was diagnosed with loperamide-induced QT prolongation resulting in incessant ventricular tachycardia. Loperamide was discontinued, and he was treated with electrolyte replacement, supportive care, and monitoring. After 5 days, his electrocardiogram (ECG) normalized and he had no more ventricular tachycardia. A Naranjo assessment score of 8 was obtained, indicating a probable relationship between QT prolongation and his use of loperamide. Large doses of loperamide can cause QT interval prolongation and life-threatening arrhythmias. These effects may be accentuated when histamine-2 receptor blockers are also abused.

Whole-exome sequencing reveals microsatellite DNA markers for response to dofetilide initiation in patients with persistent atrial fibrillation: A pilot study.

BACKGROUND: Dofetilide is a class III antiarrhythmic drug effective for the treatment of atrial fibrillation (AF). Dofetilide initiation (DI) associates with corrected QT interval (QTc) prolongation. Significant QTc prolongation during DI mandates dose adjustment or discontinuation of the drug. Microsatellite DNA are novel genetic markers associated with congenital and acquired health conditions. HYPOTHESIS: DNA microsatellite polymorphism may associate with QTc response to dofetilide initiation in patients with persistent AF. METHODS: We performed whole-exome sequencing in a cohort of patients with persistent AF undergoing DI. Electrocardiographic variables and clinical data were assessed. We defined patients as eligible for DI when no significant QTc prolongation (>20% compared with baseline) was seen with a 500-µg dose. We defined patients as ineligible for DI when significant QTc prolongation was seen during DI with 500 µg. We investigated polymorphisms for 11 919 DNA microsatellite loci in relation to QTc response to DI. RESULTS: During the study, 14 consecutive patients with persistent AF presenting for DI were enrolled. Whole-exome sequencing revealed 14 different microsatellite loci in the 2 groups. All genes or proximal genes that harbor these loci are known to have expression in the human heart. Two genes, MYH6 and TRAK2, are known to have expression in the atria. TRAK2 is known to interact with KCNJ2, the inward-rectifier potassium channel 1. CONCLUSIONS: Microsatellite DNA polymorphisms seem to associate with QTc response to DI therapy in patients with persistent AF who are deemed otherwise eligible for dofetilide therapy.

Intercalated Disk Extracellular Nanodomain Expansion in Patients With Atrial Fibrillation.

Aims: Atrial fibrillation (AF) is the most common sustained arrhythmia. Previous evidence in animal models suggests that the gap junction (GJ) adjacent nanodomain - perinexus - is a site capable of independent intercellular communication via ephaptic transmission. Perinexal expansion is associated with slowed conduction and increased ventricular arrhythmias in animal models, but has not been studied in human tissue. The purpose of this study was to characterize the perinexus in humans and determine if perinexal expansion associates with AF. Methods: Atrial appendages from 39 patients (pts) undergoing cardiac surgery were fixed for immunofluorescence and transmission electron microscopy (TEM). Intercalated disk distribution of the cardiac sodium channel Nav1.5, its ß1 subunit, and connexin43 (C×43) was determined by confocal immunofluorescence. Perinexal width (Wp) from TEM was manually segmented by two blinded observers using ImageJ software. Results: Nav1.5, ß1, and C×43 are co-adjacent within intercalated disks of human atria, consistent with perinexal protein distributions in ventricular tissue of other species. TEM revealed that the GJ adjacent intermembrane separation in an individual perinexus does not change at distances greater than 30 nm from the GJ edge. Importantly, Wp is significantly wider in patients with a history of AF than in patients with no history of AF by approximately 3 nm, and Wp correlates with age (R = 0.7, p < 0.05). Conclusion: Human atrial myocytes have voltage-gated sodium channels in a dynamic intercellular cleft adjacent to GJs that is consistent with previous descriptions of the perinexus. Further, perinexal width is greater in patients with AF undergoing cardiac surgery than in those without.

Left atrial appendage exclusion and the risk of thromboembolic events following mitral valve surgery.

OBJECTIVES: We aimed to evaluate left atrial appendage (LAA) exclusion in patients undergoing mitral valve surgery with respect to thromboembolic events. BACKGROUND: LAA is the predominant source of emboli in patients with atrial fibrillation. Prophylactic LAA exclusion at the time of heart surgery has been recommended to reduce the risk of future thromboembolism. METHODS: An observational cohort of 136 patients undergoing LAA exclusion during mitral valve surgery was identified between May 1993 and November 1998 at our institution. RESULTS: During a mean follow-up of 3.6 +/- 1.3 years, there were 14 (12.3%) thromboembolic events. Compared with patients who received warfarin upon hospital discharge, there were more thromboembolic events in patients not prescribed warfarin upon hospital discharge (n = 7/67, 10% vs n = 6/40, 15%, respectively). The warfarin status was not known for one patient. The majority of thromboembolic events (n = 10/14, 71%) occurred in those who underwent mitral valve repair. CONCLUSION: In this observational study, patients who undergo LAA exclusion during mitral valve surgery to reduce the risk of thromboembolism have a significant incidence of thromboembolic events, especially when warfarin therapy is not prescribed upon hospital discharge.

Cardiac Involvement in Peripheral Neuropathies.

Cardiac autonomic neuropathy (CAN) is the least recognized and understood complication of peripheral neuropathy. However, because of its potential adverse effects including sudden death, CAN is one of the most important forms of autonomic neuropathies. CAN presents with different clinical manifestations including postural hypotension, exercise intolerance, fluctuation of blood pressure and heart rate, arrhythmia, and increased risk of myocardial infarction. In this article, the prevalence, clinical presentations, and management of cardiac involvement in certain peripheral neuropathies, including diabetic neuropathy, Guillain-Barré syndrome, chronic inflammatory polyneuropathy, human immunodeficiency virus-associated neuropathy, hereditary neuropathies, and amyloid neuropathy are examined in detail.

Plasma B-type natriuretic peptide levels predict postoperative atrial fibrillation in patients undergoing cardiac surgery.

BACKGROUND: Postoperative (postop) atrial fibrillation (AF) occurs in up to 60% of patients after cardiac surgery, leading to longer hospital stays and increased healthcare costs. Recently, B-type natriuretic peptide (BNP) has been reported to predict occurrence of nonpostoperative AF. This study evaluates whether elevated preoperative (preop) plasma BNP levels predict the occurrence of postop AF. METHODS AND RESULTS: One hundred eighty-seven patients with no history of atrial arrhythmia who had a preoperative BNP level and had undergone cardiac surgery were identified. Their records were reviewed, and postoperative ECG and telemetry strips were analyzed for AF until the time of discharge. Postop AF was documented in 80 patients (42.8%). AF patients were older (68+/-11 versus 64+/-14 years, P=0.04), but there was no difference in sex distribution, hypertension, left ventricular (LV) function, LV hypertrophy (LVH), left atrial size, history of coronary artery disease (CAD), or beta-blocker use. Preop plasma BNP levels were higher in the postop AF patients (615 versus 444 pg/mL, P=0.005). After adjustment for age, sex, type of surgery, hypertension, LV function, LVH, left atrial size, CAD, and beta-blocker use, the odds ratios of postop AF according to increasing quartiles, compared with patients with lowest quartile, were 1.8, 2.5, and 3.7 (P(trend)=0.03). CONCLUSIONS: An elevated preop plasma BNP level is a strong and independent predictor of postop AF. This finding has important implications for identifying patients at higher risk of postop AF who could be considered for prophylactic antiarrhythmic or beta-blocker therapy.

New criteria during right ventricular pacing to determine the mechanism of supraventricular tachycardia.

BACKGROUND: Right ventricular pacing (RVP) during supraventricular tachycardia produces progressive QRS fusion before the QRS morphology becomes stable. This transition zone (TZ) may provide useful information for differentiating orthodromic reciprocating tachycardia (ORT) from atrioventricular nodal reentrant tachycardia and atrial tachycardia independent of entrainment success. METHODS AND RESULTS: We studied the effect of properly timed RVP on atrial timing during the TZ in 92 patients with supraventricular tachycardia who had RVP within 40 ms of the tachycardia cycle length. The TZ during RVP includes progressively fused QRS complexes and the first paced complex with a stable QRS morphology based on analysis of the 12-lead ECG. We also measured the stimulus-atrial interval from the end of the TZ and with each QRS complex thereafter until pacing was terminated or ventriculo-atrial block occurred. A fixed stimulus-atrial interval was defined as variation <10 ms during RVP. Atrial preexcitation, postexcitation, or supraventricular tachycardia termination with abrupt ventriculo-atrial block was observed within the TZ in 32 of 34 patients with ORT. A fixed stimulus-atrial interval was established within the TZ in 33 of 34 patients with ORT. At least 1 of these 2 responses was observed in all patients with ORT. None of the patients with atrioventricular nodal reentrant tachycardia or atrial tachycardia had atrial timing perturbed or a fixed stimulus-atrial interval established within the TZ. CONCLUSIONS: During RVP within 40 ms of the tachycardia cycle length, ORT is the likely mechanism when atrial timing is perturbed or a fixed stimulus-atrial interval is established within the TZ.

Predictive value of high sensitivity C-reactive protein in the diagnosis and outcomes of acute aortic syndromes.

OBJECTIVE: The purpose of this study was to determine whether high-sensitivity C-reactive protein (hsCRP) levels differ among patients with acute aortic syndromes (AAS) and if hsCRP could predict their long-term outcomes. DESIGN: Retrospective observational study. SETTING: Cleveland Clinic Hospital, Cleveland, Ohio. PATIENTS: 115 consecutive patients with AAS admitted to the cardiac intensive care unit. INTERVENTIONS: HsCRP and other laboratory data were measured within 24 h of admission. Demographic, imaging and laboratory data were obtained at the time of presentation. For the long-term survival analysis, the social security death index was used to determine all-cause mortality. MAIN OUTCOME MEASURES: HsCRP levels among AAS patients. RESULTS: Hospital mortality was 4.3% for AAS patients. HsCRP levels differed significantly among AAS; the median hsCRP was higher in the aortic dissection group (49 mg/l) than in those with penetrating aortic ulcer (28 mg/l), symptomatic aortic aneurysm (14 mg/l), and intramural haematoma (10 mg/l); (p=0.02). In multivariable analysis, aortic dissection patients had higher hsCRP levels than intramural haematoma (p=0.03) and symptomatic aortic aneurysm (p=0.04) patients, after adjusting for age and gender. Multivariable Cox regression analyses showed that elevated hsCRP levels at presentation were associated with a higher long-term mortality (p=0.007). CONCLUSIONS: Among patients with AAS, those with aortic dissection have the highest hsCRP levels at presentation. Elevated hsCRP independently predicted a higher long-term mortality in AAS patients.

Incidence of atrial fibrillation in heart transplant patients: long-term follow-up.

BACKGROUND: The incidence of atrial fibrillation (AF) in heart transplant patients has not been well documented. METHODS: To determine the incidence of AF in a cohort of patients undergoing cardiac transplantation, clinical data were obtained from a prospectively collected database for all consecutive orthotopic heart transplantation (OHT) patients and for all consecutive coronary artery bypass graft (CABG) surgery patients between January 1984 and March 2004 at our institution. A cohort of 1,714 OHT patients and low-risk CABG (normal ejection fraction [EF] and no left ventricular hypertrophy [LVH]) patients were age- and sex-matched. RESULTS: The average age in the two groups was 56 +/- 7 years with 87% male and 81% white race and body mass index (BMI) of 26 +/- 4. There were 3 cases of AF (0.3%) in the OHT group and 757 cases of AF (21%) in the low-risk CABG group. The strongest independent predictor of freedom from postoperative AF was having had a transplant (odds ratio [OR] 96, 95% confidence interval [CI] 13-720). The incidence of AF, atrial flutter (AFL), and supraventricular tachycardia (SVT) in OHT was 0.33, 2.8%, and 1.3%, respectively. Given that incidence of AF, AFL, and SVT in historical post-CABG population is 25%, 17%, and 4.3%, transplanted patients appear to have lower incidence of AF, AFL, and SVT than the reference population. Consistent with this, transplanted patients underwent few ablation procedures for atrial arrhythmias. Additionally, the three patients with AF had bicaval anastomoses suggesting the possibility of PACs originating in the donor superior vena cava (SVC) or IVC (inferior vena cava) initiating AF in these patients. CONCLUSIONS: In a cohort study of transplant and low-risk CABG patients, the strongest independent predictor of freedom from AF is having undergone transplant surgery. One potential explanation for the markedly lower incidence of AF may be effective isolation of thoracic veins with documented cases retaining the native SVC.