Evaluation of lead-based echodensities on transesophageal echocardiogram in patients with cardiac implantable electronic devices.

INTRODUCTION: Transesophageal echocardiography (TEE) is recommended to rule out endocarditis in patients with cardiac implantable electronic devices (CIED). A lead-based echodensity (LBE), however, is often found on TEE in patients with a CIED and may not represent an infection. We sought to evaluate the predictors, characteristics, and clinical significance of LBEs seen on TEE in patients with a CIED. METHODS: Patients with a CIED were retrospectively identified from a database using International Classification of Diseases (ICD)-9/ICD-10 codes and were cross-matched with Current Procedural Terminology codes for a TEE. Clinical and follow-up data were collected. A blinded echo board-certified cardiologist reviewed all TEEs. RESULTS: Out of the 231 patients in the cohort, 191 had TEE performed for a noninfection-related indication while 40 TEEs were part of an endocarditis workup. A total of 50 LBEs were identified, and a majority were in the noninfection cohort. Systemic anticoagulant use in the noninfection cohort was associated with a decreased odds of having LBE on TEE (odds ratio [OR] of 0.23 [95% confidence interval [CI]: 0.06-0.60, p = .003]). Lead dwell time in the noninfection cohort was associated with an increased odds of having LBE on TEE (OR 1.21 (95% CI: 1.04-1.39, p = .009]). CONCLUSION: In our cohort of patients who had TEE for noninfection indications we found that systemic anticoagulant use is associated with fewer LBEs on TEEs, suggesting possible thrombin fibrin composition of LBE.

Anatomical location of leadless pacemaker and the risk of pacing-induced cardiomyopathy.

BACKGROUND: It is unclear if the location of implantation of the leadless pacemaker (LP) makes a difference in the incidence of pacing-induced cardiomyopathy (PICM). AIM: The aim of this study was to compare the incidence of PICM based on the location of implantation of LP. METHODS: A total of 358 consecutive patients [women: 171 (48%), mean age: 73 ± 15 years] with left ventricular ejection fraction (EF) > 50%, who received an LP (Micra) between January 2017 and June 2022, formed the study cohort. Micra-AV and Micra-VR were implanted in 122 (34%) and 236 (66%) patients, respectively. Fluoroscopically, the location of implantation of LP in the interventricular septum (IS) was divided into two equal halves (apex/apical septum [AS] and mid/high septum [HS]). During follow-up, PICM was defined as an EF drop of ≥10%. RESULTS: LP was implanted in 109 (34%) and 249 (66%) patients at AS and HS locations, respectively. During a mean 18 ± 8 months follow-up, 28 patients (7.8%) developed PICM. Among the 249 patients with HS placement of LP, 10 (4%) developed PICM, whereas among the 109 patients with AS placement of LP, 18 (16.5%) developed PICM (p = .002). AS location was associated with a higher risk of PICM compared to HS locations (adjusted hazard ratio: 4.42, p < .001). CONCLUSION: AS location of LP was associated with a higher risk of PICM compared to HS placement. Larger randomized studies are needed to confirm our findings.

Association of T-wave abnormalities with major cardiovascular events in diabetes: the ACCORD trial.

AIMS/HYPOTHESIS: T-wave abnormalities (TWA) are often found on ECG and signify abnormal ventricular repolarisation. While TWA have been shown to be associated with subclinical atherosclerosis, the relationship between TWA and hard cardiovascular endpoints is less clear and may differ in the presence of diabetes, so we sought to explore these associations in participants from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. METHODS: TWA were operationally defined as the presence of any Minnesota Codes 5-1 through 5-4 in any lead distribution. Multivariable Cox proportional hazards models were constructed to examine relationships between TWA and clinical cardiovascular events. Secondary analyses explored the risks conferred by major vs minor TWA, differential effects of TWA by anatomic localisation (anterolateral, inferior or anterior lead distributions), and differing associations in those with or without prevalent CVD. RESULTS: Among 8176 eligible participants (mean 62.1 ± 6.3 SD years, 61.4% male), there were 3759 cardiovascular events, including 1430 deaths (473 of a cardiovascular aetiology), 474 heart failure events, 1452 major CHD events and 403 strokes. Participants with TWA had increased risks of all-cause mortality (HR 1.45 [95% CI 1.30, 1.62], p < 0.0001), cardiovascular mortality (HR 1.93 [1.59, 2.34], p = 0.0001), congestive heart failure (HR 2.04 [1.69, 2.48], p < 0.0001) and major CHD (HR 1.40 [1.26, 1.57], p < 0.0001), but no increased risk of stroke (HR 0.99 [0.80, 1.23], p = 0.95). Major TWA conferred a higher risk than minor TWA. When TWA were added to the UK Prospective Diabetes Study risk engine, there was improved discrimination for incident CHD events, but only for those with prevalent CVD (area under the receiver operating characteristic curve 0.5744 and 0.6030 with p = 0.0067). Adding TWA to the risk engine yielded improvements in reclassification that were of greater magnitude in those with prevalent CVD (net reclassification improvement [NRI] 0.24 [95% CI 0.16, 0.32] in those with prevalent CVD, NRI 0.14 [95% CI 0.07, 0.22] in those without prevalent CVD). CONCLUSIONS/INTERPRETATION: The presence and magnitude of TWA are associated with increased risk of clinical cardiovascular events and mortality in individuals with diabetes and may have value in refining risk, particularly in those with prevalent CVD. Graphical abstract.

New-onset atrial fibrillation incidence and associated outcomes in the medical intensive care unit.

BACKGROUND: In patients with critical medical illness, data regarding new-onset atrial fibrillation (NOAF) is relatively sparse. This study examines the incidence, associated risk factors, and associated outcomes of NOAF in patients in the medical intensive care unit (MICU). METHODS: This single-center retrospective observational cohort study included 2234 patients with MICU stays in 2018. An automated extraction process using ICD-10 codes, validated by a 196-patient manual chart review, was used for data collection. Demographics, medications, and risk factors were collected. Multiple risk scores were calculated for each patient, and AF recurrence was also manually extracted. Length of stay, mortality, and new stroke were primary recorded outcomes. RESULTS: Two hundred and forty one patients of the 2234 patient cohort (11.4%) developed NOAF during their MICU stay. NOAF was associated with greater length of stay in the MICU (5.84 vs. 3.52 days, p < .001) and in the hospital (15.7 vs. 10.9 days, p < .001). Patients with NOAF had greater odds of hospital mortality (odds ratio (OR) = 1.92, 95% confidence interval (CI) 1.34-2.71, p < .001) and 1-year mortality (OR = 1.37, 95% CI 1.02-1.82, p = .03). CHARGE-AF scores performed best in predicting NOAF (area under the curve (AUC) 0.691, p < .001). CONCLUSIONS: The incidence of NOAF in this MICU cohort was 11.4%, and NOAF was associated with a significant increase in hospital LOS and mortality. Furthermore, the CHARGE-AF score performed best in predicting NOAF.

Prognostic value of Goldberger's electrocardiographic criteria for left ventricular dysfunction.

BACKGROUND: The ability of the Goldberger electrocardiographic (ECG) triad criteria to detect left ventricular dysfunction (LVD) is well-established. However, the prognostic significance of this triad as a predictor of poor outcomes is not known. OBJECTIVE: We explored the association between the Goldberger ECG-LVD triad with all-cause mortality and cardiovascular mortality in the general population. METHODS: This analysis included 8426 participants (60.5 ±â€¯13.6 years, 51.5% women, 50% non-Hispanic white) from the Third National Health and Nutrition Examination Survey. The Goldberger ECG-LVD triad was defined as follows: high precordial QRS voltage (SV1 or SV2 + RV5 or RV6 ≥ 3500 µV); low limb lead QRS voltage (mean QRS amplitude in each of the limb leads ≤800 µV); and poor R wave progression (RV4/SV4 < 1). Mortality was ascertained using the National Death Index. RESULTS: At baseline, 1384 (47.3%) of the participants had at least one of the criteria of Goldberger triad (1193 had only one and 191 participants had 2 or more). During a median follow up of 13.8 years, 3184 deaths occurred, of which 1405 were cardiovascular. In multivariable-adjusted Cox proportional hazards models, presence of at least one of the Goldberger triad criteria (vs. none) was associated with increased risk of all-cause (HR 1.17, 95% CI 1.08-1.26, p ≤0.0001) and cardiovascular mortality (1.19, 1.06-1.33, p = 0.003). CONCLUSION: The Goldberger ECG-LVD triad for left ventricular dysfunction may offer prognostic value in addition to its reported diagnostic utility.

Management of ventricular arrhythmias in patients with LVAD.

PURPOSE OF REVIEW: Left ventricular assist devices (LVADs) have extended the life expectancy of patients with heart failure. The hemodynamic support afforded by LVADs in this population has also resulted in patients having prolonged ventricular arrhythmias. The purpose of this article is to review the mechanisms of ventricular arrhythmias in LVADs and the available management strategies. RECENT FINDINGS: Recent evidence suggests that prolonged ventricular arrhythmias may result in increased mortality in patients with LVADs. SUMMARY: Successful management of ventricular arrhythmias in patients with LVAD requires interdisciplinary collaboration between electrophysiology and heart failure specialists. Medical management, including changes to LVAD changes, heart failure medication management, and antiarrhythmics constitute the initial treatment for ventricular arrhythmias. Surgical or endocardial ablation are reasonable options if VAs are refractory.

P-wave axis is associated with all-cause mortality in diabetes: The ACCORD trial.

Abnormal P-wave axis (PWA) has emerged as a novel marker of risk for both cardiovascular disease (CVD) and all-cause mortality (ACM) in the general population, though this relationship has not been adequately explored among those with type 2 diabetes (DM2). We aimed to explore the association between abnormal PWA and ACM among a large, well-phenotyped group of participants with DM2 from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. This analysis included 8899 ACCORD participants with available PWA data on baseline electrocardiogram. Cox proportional hazards models were used to examine the association between PWA and ACM in models adjusted for demographics, ACCORD trial treatment assignment, and potential confounders. PWA was modeled as either normal (0° -75°) or abnormal (<0° or >75°). Over 44,000 person-years of follow up, there were 609 deaths. Participants with abnormal PWA had increased risk of ACM (HR 1.61, 95% CI 1.25-2.08). After multivariable adjustment, the association remained significant (HR 1.33, 95% CI 1.03-1.72). This relationship was similar in subgroups stratified by age, race, sex, and history of CVD. Among ACCORD trial participants, abnormal PWA was associated with an increased risk of mortality. Abnormal PWA may have added value beyond traditional risk factors in prediction models.

QRS duration is associated with all-cause mortality in type 2 diabetes: The diabetes heart study.

BACKGROUND: QRS-duration predicts mortality in patients with heart failure and, to a lesser extent, the general population. However, in patients with diabetes, its prognostic significance is unknown. To better understand how QRS-duration relates to mortality among those with diabetes, we explored survival as a function of QRS-duration in the Diabetes Heart Study. METHODS: The study population included 1335 participants. Cox proportional hazards modeling was used to evaluate the relationship between QRS-duration and all-cause mortality, comparing those with QRS-duration ≤120 vs. >120 (ms). Multivariable models adjusted for age, sex, race, hypertension, smoking, years with diabetes, BMI, systolic blood pressure, cholesterol, triglycerides, glomerular filtration rate, and hemoglobin A1c. RESULTS AND CONCLUSIONS: Participants were: mean age 61 ± 9, 55% women, 83% white; 99 participants (7.5%) had a QRS-duration >120. After 11,000 person-years of follow-up (median 8.5 years; maximum 13.9 years), 266 participants had died (20%). Participants with baseline QRS-duration >120 had an adjusted hazard ratio for all-cause mortality of 1.56 (95% CI 1.05-2.24; p = 0.027). Modeling QRS-duration as a continuous variable, we found an 11% increase in all-cause mortality for each 10 ms increase in QRS-duration. In conclusion, QRS-duration is associated with subsequent all-cause mortality among those with type 2 diabetes-participants with QRS-duration >120 ms had a 56% increase in all-cause mortality, even after adjustment for conventional risk factors. Given the ubiquitous presence of ECG data in the medical record, QRS-duration may prove to be a useful prognostic measure, especially among those with diabetes.

Imaging-based predictors of permanent pacemaker implantation after transcatheter aortic valve replacement.

BACKGROUND: Cardiac conduction abnormalities requiring permanent pacemaker (PPM) implantation are major complications of transcatheter aortic valve replacement (TAVR). We aimed to investigate whether the relationship between prosthetic valve size and cardiac-gated computed tomography (CT)-based aortic root complex measurements can aid in recognizing patients at risk for PPM implantation post-TAVR. METHODS: We included 83 of 114 consecutive patients who underwent TAVR with the Edwards Sapien valve (Edwards Lifesciences, Irving, CA, USA) at our institution. We excluded patients with preexisting PPM, patients who required conversion to an open surgical procedure, and patients without CT data. We assessed the significance of various potential predictors of PPM placement post-TAVR. RESULTS: Following TAVR, eight patients (9.6%) required PPM. Prosthetic valve to sinus of Valsalva (SOV) index was significantly higher in those patients requiring a PPM post-TAVR (84.1 ± 9.3 vs 76.8 ± 7.1, P  =  0.009). CONCLUSIONS: The prosthetic valve size to diameter of SOV index was identified as a novel predictor of PPM implantation after TAVR.

A safe, simple technique for transseptal catheterization.

Transseptal catheterization is required for atrial fibrillation ablation and many ablations for atrial tachycardias, left atrial flutters, and accessory pathways. Using a Brockenbrough needle or other specialized device adds time, expense, and risk of potential complications such as atrial or aortic perforation, pericardial effusion, and tamponade to these procedures. We present a simple, low-risk technique for transseptal catheterization.

Right ventricular septal pacing in patients with right bundle branch block.

BACKGROUND: Cardiac resynchronization therapy (CRT) has been shown to improve left ventricular (LV) function and exercise performance in patients with left bundle branch block. Patients with right bundle branch block (RBBB) do not have a similar positive response to standard CRT. We hypothesized that single site pacing of the right ventricular septum (RVS) near the proximal right bundle could restore more normal activation of the LV in RBBB patients. METHODS: 78 consecutive patients (56 M, 22 F) with baseline RBBB underwent pacemaker or ICD implantation. Leads were placed in the right atrium and RVS. RESULTS: Baseline QRS duration was 120-220 ms (mean QRSd = 147 ms). At the optimal AV delay, the fused QRSd was 56-160 ms (mean QRSd = 112 ms). The mean decrease in QRSd was 34 ± 20.4 ms (p<0.001). CONCLUSION: RVS pacing in patients with RBBB resulted in a marked decrease in QRS duration and often normalized the ECG.

Perioperative atrial fibrillation and the long-term risk of ischemic stroke.

IMPORTANCE: Clinically apparent atrial fibrillation increases the risk of ischemic stroke. In contrast, perioperative atrial fibrillation may be viewed as a transient response to physiological stress, and the long-term risk of stroke after perioperative atrial fibrillation is unclear. OBJECTIVE: To examine the association between perioperative atrial fibrillation and the long-term risk of stroke. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cohort study using administrative claims data on patients hospitalized for surgery (as defined by surgical diagnosis related group codes), and discharged alive and free of documented cerebrovascular disease or preexisting atrial fibrillation from nonfederal California acute care hospitals between 2007 and 2011. Patients undergoing cardiac vs other types of surgery were analyzed separately. MAIN OUTCOMES AND MEASURES: Previously validated diagnosis codes were used to identify ischemic strokes after discharge from the index hospitalization for surgery. The primary predictor variable was atrial fibrillation newly diagnosed during the index hospitalization, as defined by previously validated present-on-admission codes. Patients were censored at postdischarge emergency department encounters or hospitalizations with a recorded diagnosis of atrial fibrillation. RESULTS: Of 1,729,360 eligible patients, 24,711 (1.43%; 95% CI, 1.41%-1.45%) had new-onset perioperative atrial fibrillation during the index hospitalization and 13,952 (0.81%; 95% CI, 0.79%-0.82%) experienced a stroke after discharge. At 1 year after hospitalization for cardiac surgery, cumulative rates of stroke were 0.99% (95% CI, 0.81%-1.20%) in those with perioperative atrial fibrillation and 0.83% (95% CI, 0.76%-0.91%) in those without atrial fibrillation. At 1 year after noncardiac surgery, cumulative rates of stroke were 1.47% (95% CI, 1.24%-1.75%) in those with perioperative atrial fibrillation and 0.36% (95% CI, 0.35%-0.37%) in those without atrial fibrillation. In a Cox proportional hazards analysis accounting for potential confounders, perioperative atrial fibrillation was associated with subsequent stroke both after cardiac surgery (hazard ratio, 1.3; 95% CI, 1.1-1.6) and noncardiac surgery (hazard ratio, 2.0; 95% CI, 1.7-2.3). The association was significantly stronger for perioperative atrial fibrillation after noncardiac vs cardiac surgery (P < .001 for interaction). CONCLUSIONS AND RELEVANCE: Among patients hospitalized for surgery, perioperative atrial fibrillation was associated with an increased long-term risk of ischemic stroke, especially following noncardiac surgery.

Preoperative sleep apnea screening protocol reduces medical emergency team activation in patients with atrial fibrillation.

STUDY OBJECTIVES: The association of in-hospital medical emergency team activation (META) among patients with atrial fibrillation (AF) at risk for obstructive sleep apnea (OSA) is unclear. This study evaluates the performance of the DOISNORE50 sleep questionnaire as an OSA screener for patients with AF and determines the prevalence of META among perioperative patients with underlying AF who have a diagnosis or are at risk for OSA. METHODS: A prospective perioperative cohort of 2,926 patients with the diagnosis of AF was assessed for DOISNORE50 questionnaire screening. Propensity-score matching was used to match patients' physical characteristics, comorbidities, length of stay, and inpatient continuous positive airway pressure device usage. META and intensive care unit admissions during the surgical encounter, 30-day hospital readmissions, and 30-day emergency department visits were evaluated. RESULTS: A total of 1,509 out of 2,926 AF patients completed the DOISNORE50 questionnaire and were enrolled in the OSA safety protocol. Following propensity-score matching, there were reduced adjusted odds of META in the screened group of 0.69 (95% confidence interval: 0.48-0.98, P < .001) in comparison to the unscreened group. The adjusted odds of intensive care unit admissions and emergency department visits within 30 days of discharge were statistically lower for the screened group compared with the unscreened group. CONCLUSIONS: Among perioperative AF patients, evidence supports DOISNORE50 screening and implementation of an OSA safety protocol for reduction of META. This study identified decreased odds of META, intensive care unit admissions, and emergency department visits among the screened group. The high-risk and known OSA group showed reduced odds of META following the implementation of an OSA safety protocol. CITATION: Saha AK, Sheehan KN, Xiang KR, et al. Preoperative sleep apnea screening protocol reduces medical emergency team activation in patients with atrial fibrillation. J Clin Sleep Med. 2024;20(5):783-792.

Paroxysmal supraventricular tachycardia and the risk of ischemic stroke.

BACKGROUND AND PURPOSE: It is unknown whether supraventricular arrhythmias other than atrial fibrillation or flutter are associated with stroke. METHODS: To examine the association between paroxysmal supraventricular tachycardia (PSVT) and stroke, we performed a retrospective cohort study using administrative claims data from all emergency department encounters and hospitalizations at California's nonfederal acute care hospitals in 2009. Our cohort comprised all adult patients with ≥ 1 emergency department visit or hospitalization from which they were discharged alive and without a diagnosis of stroke. Our primary exposure was a diagnosis of PSVT recorded at an encounter before stroke or documented as present-on-admission at the time of stroke. To reduce confounding, we excluded patients with diagnoses of atrial fibrillation. We defined PSVT, stroke, and atrial fibrillation using International Classification of Diseases, Ninth Revision, Clinical Modification codes previously validated by detailed chart review. RESULTS: Of 4 806 830 eligible patients, 14 121 (0.29%) were diagnosed with PSVT and 14 402 (0.30%) experienced a stroke. The cumulative rate of stroke after PSVT diagnosis (0.94%; 95% confidence interval, 0.76%-1.16%) significantly exceeded the rate among patients without a diagnosis of PSVT (0.21%; 95% confidence interval, 0.21%-0.22%). In Cox proportional hazards analysis controlling for demographic characteristics and potential confounders, PSVT was independently associated with a higher risk of subsequent stroke (hazard ratio, 2.10; 95% confidence interval, 1.69-2.62). CONCLUSIONS: In a large and demographically diverse sample of patients, we found an independent association between PSVT and ischemic stroke. PSVT seems to be a novel risk factor that may account for some proportion of strokes that are currently classified as cryptogenic.

Utility of high resolution mapping to guide ablation of ventricular arrhythmias from the aortic sinuses of Valsalva.

PURPOSE: Left ventricular outflow tract (LVOT) arrhythmias are commonly targeted from the aortic sinuses of Valsalva (SOV). Both presystolic potentials during ventricular arrhythmia (VA) and late diastolic potentials during sinus rhythm have been recognized as markers of successful ablation sites. The study aimed to evaluate the utility of high resolution mapping (HRM) with small and closely spaced electrodes for guiding ablation of VA from the SOV. METHODS: Seventeen patients with LVOT VA underwent HRM in the SOV with either PentaRay (13) or Orion (4) catheters. Ablation was guided by low amplitude high frequency potentials that were identified with HRM and tagged on the electroanatomic map. RESULTS: High frequency low amplitude potentials during sinus rhythm (late) or VA (early) were demonstrated with HRM in all 17 consecutive patients; while these potentials were either absent or usually had a far-field appearance in the recordings obtained at the same sites with a 3.5-mm standard ablation catheter. On intracardiac echocardiogram, sites with these potentials corresponded to the bases of the sinuses adjacent to the LV ostium. Ablation was acutely successful in 16 out of 17 patients. Significant reduction in VA burden (≥ 90%) was noted in 15 patients. CONCLUSIONS: High frequency low amplitude potentials during sinus rhythm (late) and VA (early) are consistently recorded using HRM in the SOV in patients with VA arising from the aortic sinuses of Valsalva. Standard ablation catheters have limited resolution for detecting these potentials. HRM may potentially improve outcomes of ablation of VA originating from the aortic SOV.

Rapid atrial pacing above the maximum sensor rate: a case report.

Background: While ventricular-based timing modes are known to cause elevated atrial pacing above the lower rate when intrinsic atrioventricular (AV) conduction is shorter than programmed AV delay, there is one case report in 2015 by Jafri et al. where rapid atrial pacing was induced in an Abbott device set DDI with a lower rate of 90 by an unsensed premature atrial complex and slow intrinsic AV conduction allowing pacemaker 'crossover.' Case summary: We present a very unusual case of rapid atrial pacing at >180 b.p.m. due to a perfect storm of events that we believe has not been previously reported. A patient with a St. Jude Abbott DCPPM set DDDR had an atrial tachyarrhythmia causing a mode switch to DDIR, which uses ventricular-based timing. This was followed by a period of rapid atrial pacing that terminated spontaneously. Discussion: This phenomenon depended on an initial atrial tachyarrhythmia causing a mode switch to DDIR. In addition, the set lower rate would not have led to a short enough calculated ventriculo-atrial interval (VAI), but because rate responsive pacing was enabled, the calculated VAI was short enough to promote the crossover in setting of slow AV conduction and allow the rapid atrial pacing. Understanding this unique mechanism requires careful attention to pacemaker timing cycles and appreciation of the limitations of device programming. While it appears that a similar phenomenon was reported once in the literature, we believe that this episode of rapid atrial pacing was even more serendipitous due to the unlikely series of events required for its inception.

Incidence, predictors, and outcomes associated with postoperative atrial fibrillation after major noncardiac surgery.

BACKGROUND: Although major noncardiac surgery is common, few large-scale studies have examined the incidence and consequences of post-operative atrial fibrillation (POAF) in this population. We sought to define the incidence of POAF and its impact on outcomes after major noncardiac surgery. METHODS: Using administrative data, we retrospectively reviewed the hospital course of adults who underwent major noncardiac surgery at 375 US hospitals over a 1-year period. Clinically significant POAF was defined as atrial fibrillation occurring during hospitalization that necessitated therapy. RESULTS: Of 370,447 patients, 10,957 (3.0%) developed clinically significant POAF while hospitalized. Of patients with POAF, 7,355 (67%) appeared to have pre-existing atrial fibrillation and 3,602 (33%) had newly diagnosed atrial fibrillation. Black patients had a lower risk of POAF (adjusted odds ratio, 0.53; 95% CI, 0.48-0.59; P < .001). Patients with POAF had higher mortality (adjusted odds ratio, 1.72; 95% CI, 1.59-1.86; P < .001), markedly longer length of stay (adjusted relative difference, +24.0%; 95% CI, +21.5% to +26.5%; P < .001), and higher costs (adjusted difference, +$4,177; 95% CI, +$3,764 to +$4,590; P < .001). These findings did not differ by whether POAF was a recurrence of pre-existing atrial fibrillation, or a new diagnosis. CONCLUSION: POAF following noncardiac surgery is not uncommon and is associated with increased mortality and cost. Our study identifies risk factors for POAF, which appear to include race. Strategies are needed to not only prevent new POAF, but also improve management of patients with pre-existing atrial fibrillation.

Arrhythmia Following Pulse Generator Change: What Is the Mechanism?

We present an unusual case of a "reverse" pacemaker-mediated endless loop arrhythmia with native atrioventricular conduction serving as the anterograde limb of the tachycardia circuit and the atrial depolarization stimulated by the pacemaker in response to the sensed ventricular QRS. The electrocardiogram findings can be explained by lead reversal in the header during pulse generator change, with the ventricular lead connected to the atrial port and the atrial lead connected to the ventricular port. Careful examination of the electrocardiogram with attention to the 2 closely spaced pacing stimuli separated by the paced atrioventricular delay provided an important clue for diagnosis this case.