Noninvasive Electrical Mapping Compared with the Paced QRS Complex for Optimizing CRT Programmed Settings and Predicting Multidimensional Response

The aim was to test the hypothesis that left ventricular (LV) and right ventricular (RV) activation from body surface electrical mapping (CardioInsight 252-electrode vest, Medtronic) identifies optimal cardiac resynchronization therapy (CRT) pacing strategies and outcomes in 30 patients. The LV80, RV80, and BIV80 were defined as the times to 80% LV, RV, or biventricular electrical activation. Smaller differences in the LV80 and RV80 (|LV80-RV80|) with synchronized LV pacing predicted better LV function post-CRT (p = 0.0004) than the LV-paced QRS duration (p = 0.32). Likewise, a lower RV80 was associated with a better pre-CRT RV ejection fraction by CMR (r =  - 0.40, p = 0.04) and predicted post-CRT improvements in myocardial oxygen uptake (p = 0.01) better than the biventricular-paced QRS (p = 0.38), while a lower LV80 with BIV pacing predicted lower post-CRT B-type natriuretic peptide (BNP) (p = 0.02). RV pacing improved LV function with smaller |LV80-RV80| (p = 0.009). In conclusion, 3-D electrical mapping predicted favorable post-CRT outcomes and informed effective pacing strategies.

2023 HRS/APHRS/LAHRS guideline on cardiac physiologic pacing for the avoidance and mitigation of heart failure

Cardiac physiologic pacing (CPP), encompassing cardiac resynchronization therapy (CRT) and conduction system pacing (CSP), has emerged as a pacing therapy strategy that may mitigate or prevent the development of heart failure (HF) in patients with ventricular dyssynchrony or pacing-induced cardiomyopathy. This clinical practice guideline is intended to provide guidance on indications for CRT for HF therapy and CPP in patients with pacemaker indications or HF, patient selection, pre-procedure evaluation and preparation, implant procedure management, follow-up evaluation and optimization of CPP response, and use in pediatric populations. Gaps in knowledge, pointing to new directions for future research, are also identified.

Cardiac Magnetic Resonance, Electromechanical Activation, Kidney Function, and Natriuretic Peptides in Cardiac Resynchronization Therapy Upgrades

As the mechanism for worse prognosis after cardiac resynchronization therapy (CRT) upgrades in heart failure patients with RVP dependence (RVP-HF) has clinical implications for patient selection and CRT implementation approaches, this study's objective was to evaluate prognostic implications of cardiac magnetic resonance (CMR) findings and clinical factors in 102 HF patients (23.5% female, median age 66.5 years old, median follow-up 4.8 years) with and without RVP dependence undergoing upgrade and de novo CRT implants. Compared with other CRT groups, RVP-HF patients had decreased survival (p = 0.02), more anterior late-activated LV pacing sites (p = 0.002) by CMR, more atrial fibrillation (p = 0.0006), and higher creatinine (0.002). CMR activation timing at the LV pacing site predicted post-CRT LV functional improvement (p < 0.05), and mechanical activation onset < 34 ms by CMR at the LVP site was associated with decreased post-CRT survival in a model with higher pre-CRT creatinine and B-type natriuretic peptide (AUC 0.89; p < 0.0001); however, only the higher pre-CRT creatinine partially mediated (37%) the decreased survival in RVP-HF patients. In conclusion, RVP-HF had a distinct CMR phenotype, which has important implications for the selection of LV pacing sites in CRT upgrades, and only chronic kidney disease mediated the decreased survival after CRT in RVP-HF.

Defining dyssynchrony: The ongoing search for cardiac resynchronization therapy "response"

The first trial to demonstrate the benefits of cardiac resynchronization therapy (CRT) was published in 2001. The single-blind crossover study demonstrated significant improvement in quality of life, NYHA class, and 6 minute walk test for patients with a left ventricular ejection fraction less than 35%, NYHA class III, an enlarged left ventricle, and a QRS duration greater than 150 ms.¹ CRT represented an exciting advancement in cardiac implantable electronic device (CIED) therapy. While implantable cardioverter defibrillators (ICDs) had been in use for decades and represented a reliable, life-saving measure to treat fatal ventricular arrhythmias, for the first time, there was a device therapy that could improve quality of life for heart failure patients. The CARE-HF trial went on to demonstrate reduction in hospitalization and mortality in a similar population, and subsequent studies, such as MADIT-CRT suggested that the benefits extended to patients with NYHA class I or II.^2,3 This article is protected by copyright. All rights reserved.

First-in-human noninvasive left ventricular ultrasound pacing: A potential screening tool for cardiac resynchronization therapy

Background

A screening tool to predict response to cardiac resynchronization therapy (CRT) could improve patient selection and outcomes.

Objective

The purpose of this study was to investigate the feasibility and safety of noninvasive CRT via transcutaneous ultrasonic left ventricular (LV) pacing applied as a screening test before CRT implants.

Methods

P-wave-triggered ultrasound stimuli were delivered during bolus dosing of an echocardiographic contrast agent to simulate CRT noninvasively. Ultrasound pacing was delivered at a variety of LV locations with a range of atrioventricular delays to achieve fusion with intrinsic ventricular activation. Three-dimensional cardiac activation maps were acquired via the Medtronic CardioInsight 252-electrode mapping vest during baseline, ultrasound pacing, and after CRT implantation. A separate control group received only the CRT implants.

Results

Ultrasound pacing was achieved in 10 patients with a mean of 81.2 ± 50.8 ultrasound paced beats per patient and up to 20 consecutive beats of ultrasound pacing. QRS width at baseline (168.2 ± 17.8 ms) decreased significantly to 117.3 ± 21.5 ms (P <.001) in the best ultrasound paced beat and to 125.8 ± 13.3 ms (P <.001) in the best CRT beat. Electrical activation patterns were similar between CRT pacing and ultrasound pacing with stimulation from the same area of the LV. Troponin results were similar between the ultrasound pacing and the control groups (P = .96), confirming safety.

Conclusion

Noninvasive ultrasound pacing before CRT is safe and feasible, and it estimates the degree of electrical resynchronization achievable with CRT. Further study of this promising technique to guide CRT patient selection is warranted.

Machine learning for multidimensional response and survival after cardiac resynchronization therapy using features from cardiac magnetic resonance

Background

Cardiac resynchronization therapy (CRT) response is complex, and better approaches are required to predict survival and need for advanced therapies.

Objective

The objective was to use machine learning to characterize multidimensional CRT response and its relationship with long-term survival.

Methods

Associations of 39 baseline features (including cardiac magnetic resonance [CMR] findings and clinical parameters such as glomerular filtration rate [GFR]) with a multidimensional CRT response vector (consisting of post-CRT left ventricular end-systolic volume index [LVESVI] fractional change, post-CRT B-type natriuretic peptide, and change in peak VO₂) were evaluated. Machine learning generated response clusters, and cross-validation assessed associations of clusters with 4-year survival.

Results

Among 200 patients (median age 67.4 years, 27.0% women) with CRT and CMR, associations with more than 1 response parameter were noted for the CMR CURE-SVD dyssynchrony parameter (associated with post-CRT brain natriuretic peptide [BNP] and LVESVI fractional change) and GFR (associated with peak VO₂ and post-CRT BNP). Machine learning defined 3 response clusters: cluster 1 (n = 123, 90.2% survival [best]), cluster 2 (n = 45, 60.0% survival [intermediate]), and cluster 3 (n = 32, 34.4% survival [worst]). Adding the 6-month response cluster to baseline features improved the area under the receiver operating characteristic curve for 4-year survival from 0.78 to 0.86 (P = .02). A web-based application was developed for cluster determination in future patients.

Conclusion

Machine learning characterizes distinct CRT response clusters influenced by CMR features, kidney function, and other factors. These clusters have a strong and additive influence on long-term survival relative to baseline features.

Arrhythmias in Pregnancy

Increasing maternal mortality and incidence of arrhythmias in pregnancy have been noted over the past 2 decades in the United States. Pregnancy is associated with a greater risk of arrhythmias, and patients with a history of arrhythmias are at significant risk of arrhythmia recurrence during pregnancy. The incidence of atrial fibrillation in pregnancy is rising. This review discusses the management of tachyarrhythmias and bradyarrhythmias in pregnancy, including management of cardiac arrest. Management of fetal arrhythmias are also reviewed. For patients without structural heart disease, β-blocker therapy, especially propranolol and metoprolol, and antiarrhythmic drugs, such as flecainide and sotalol, can be safely used to treat tachyarrhythmias. As a last resort, catheter ablation with minimal fluoroscopy can be performed. Device implantation can be safely performed with minimal fluoroscopy and under echocardiographic or ultrasound guidance in patients with clear indications for devices during pregnancy. Because of rising maternal mortality in the United States, which is partly driven by increasing maternal age and comorbidities, a multidisciplinary and/or integrative approach to arrhythmia management from the prepartum to the postpartum period is needed.

CMR DENSE and the Seattle Heart Failure Model Inform Survival and Arrhythmia Risk After CRT

OBJECTIVES

This study sought to determine if combining the Seattle Heart Failure Model (SHFM-D) and cardiac magnetic resonance (CMR) provides complementary prognostic data for patients with cardiac resynchronization therapy (CRT) defibrillators.

BACKGROUND

The SHFM-D is among the most widely used risk stratification models for overall survival in patients with heart failure and implantable cardioverter-defibrillators (ICDs), and CMR provides highly detailed information regarding cardiac structure and function.

METHODS

CMR Displacement Encoding with Stimulated Echoes (DENSE) strain imaging was used to generate the circumferential uniformity ratio estimate with singular value decomposition (CURE-SVD) circumferential strain dyssynchrony parameter, and the SHFM-D was determined from clinical parameters. Multivariable Cox proportional hazards regression was used to determine adjusted hazard ratios and time-dependent areas under the curve for the primary endpoint of death, heart transplantation, left ventricular assist device, or appropriate ICD therapies.

RESULTS

The cohort consisted of 100 patients (65.5 [interquartile range 57.7 to 72.7] years; 29% female), of whom 47% had the primary clinical endpoint and 18% had appropriate ICD therapies during a median follow-up of 5.3 years. CURE-SVD and the SHFM-D were independently associated with the primary endpoint (SHFM-D: hazard ratio: 1.47/SD; 95% confidence interval: 1.06 to 2.03; p = 0.02) (CURE-SVD: hazard ratio: 1.54/SD; 95% confidence interval: 1.12 to 2.11; p = 0.009). Furthermore, a favorable prognostic group (Group A, with CURE-SVD <0.60 and SHFM-D <0.70) comprising approximately one-third of the patients had a very low rate of appropriate ICD therapies (1.5% per year) and a greater (90%) 4-year survival compared with Group B (CURE-SVD ≥0.60 or SHFM-D ≥0.70) patients (p = 0.02). CURE-SVD with DENSE had a stronger correlation with CRT response (r = -0.57; p < 0.0001) than CURE-SVD with feature tracking (r = -0.28; p = 0.004).

CONCLUSIONS

A combined approach to risk stratification using CMR DENSE strain imaging and a widely used clinical risk model, the SHFM-D, proved to be effective in this cohort of patients referred for CRT defibrillators. The combined use of CMR and clinical risk models represents a promising and novel paradigm to inform prognosis and device selection in the future.

The use of non-invasive mapping in persistent AF to predict acute procedural outcome

BACKGROUND

ECG imaging (ECGI) with phase mapping has been used to identify rotational activity non-invasively that can be targeted during atrial fibrillation (AF) ablation. Acute termination of AF using this method has shown improved clinical outcomes. In this study we sought to evaluate whether patterns of rotational density are associated with acute procedural outcomes when using a step-wise ablation strategy.

METHODS

50 patients with persistent or long-standing persistent AF underwent non-invasive 3D mapping with CardioInsight™ prior to AF ablation. Composite maps of rotational activity were created and prioritized based on the density of rotations on a biatrial model. Stepwise ablation of pulmonary vein isolation (PVI) ± rotations ± linear lesions was done with AF termination as the procedural endpoint.

RESULTS

Acute termination of AF was achieved in 34 patients (68%). Median number of rotations in the left atrium (LA), interatrial septum and right atrium (RA) were 22.2 (9.4 to 29.3), 12.0 (4.3 to 13.4), 25.0 (14.5 to 31.3), respectively. In patients with acute AF termination, a higher number of rotations in the LA was observed, 20.3 (10.0 to 37.1) compared to 10.6 (7.7 to 17.2) in the RA (p = 0.02). Additionally, high density of rotations in the posterior inferior right atrium (segment 2B on the biatrial model) was observed in patients without acute AF termination (p = 0.02).

CONCLUSION

Acute termination of persistent and long-standing persistent AF using rotational ablation guided by ECGI phase mapping can be achieved in a high percentage of both index and re-do cases. The distribution and pattern of these rotations may be associated with procedural outcomes and could potentially be used to stratify patients.

Effectiveness of implantation of a subcutaneous implantable cardioverter-defibrillator in a patient with complete heart block and a pacemaker

The subcutaneous implantable cardioverter-defibrillator (S-ICD) represents an important alternative to traditional ICD therapy. The major limitation of this technology is the inability to provide pacing. Here, we present a case of a patient with complete heart block and a pacemaker who underwent placement of an S-ICD. Special considerations had to be taken with regards to evaluation and implantation of the S-ICD because of the pacemaker. In conclusion, implantation of an S-ICD can be done in patients with pacemaker effectively with appropriate electrocardiographic screening, device testing, and programming.

Cost of a recall of a single-center experience managing the Riata defibrillator lead

Riata and Riata ST defibrillator leads (St. Jude Medical, Sylmar, California) were recalled in 2011 due to increased risk of insulation failure leading to externalized cables. Fluoroscopic screening can identify insulation failure, although the relation between mechanical failure and electrical failure is unclear. At the time of the recall, the University of Virginia developed a screening program, including fluoroscopic evaluation, education sessions, device interrogation, and remote monitoring for patients with this defibrillator lead. The aim of this study was to review the outcomes of the screening program, including costs, which were absorbed by our institution. Costs were calculated using Medicare reimbursement estimates. Forty-eight patients participated in the screening program. At initial screening, 31% were found to have evidence of insulation failure but electrical function was normal in all leads. The cost of this program was $35,358.72. The cost per diagnosis of mechanical lead failure was $2,357.25. During 2 years of follow-up, 1 patient experienced Riata lead electrical failure without fluoroscopic evidence of insulation failure. Patients were more likely to have a lead revision if there was evidence of insulation failure. Lead revisions occurred at the time of generator change in 88% of patients with insulation failure but in only 14% of patients with a fluoroscopically normal lead (p = 0.04). The cost of recall-related defibrillator lead revisions was $81,704.55. In conclusion, our Riata screening program added expense without clear benefit to patients. In fact, patients may have been put at more risk by undergoing defibrillator lead revisions based solely on the results of the fluoroscopic screening.

Independent multicenter study of Riata and Riata ST implantable cardioverter-defibrillator leads

BACKGROUND

Riata and Riata ST leads (St Jude Medical, Sylmar, CA) are prone to failure. There are no independent multicenter reports regarding Riata or Riata ST lead performance.

OBJECTIVE

To conduct a retrospective multicenter study of Riata and Riata ST leads that were implanted and followed at 7 centers.

METHODS

The study included adults who received St Jude Medical Riata or Riata ST leads. Data for Quattro Secure leads were obtained from an earlier study.

RESULTS

From 2002 to 2010, 1081 patients received a Riata (n = 774) or Riata ST (n = 307) lead. Follow-up was longer for Riata than Riata ST leads (4.2 ± 2.4 years vs 3.3 ± 1.7 years; P<.0001). During the study, 67 leads failed (6.2%), including 62 of 774 Riata (8.0%) and 5 of 307 Riata ST (1.6%) leads. Forty-seven of 67 lead failures (70.1%) were caused by electrical malfunction, and 20 lead failures (29.9%) were due to externalized conductors (ECs) that were electrically intact. Of 110 leads examined fluoroscopically, ECs were found in 26 of 81 Riata (32%) and 1 of 29 Riata ST (3.4%) leads. Of 26 Riata leads with ECs, 7 (27%) were malfunctioning. Riata leads had lower overall and malfunction free survival compared to Quattro leads (P<.0001), while Riata ST lead survival was not different (P = .422).

CONCLUSIONS

The survival of Riata (but not Riata ST) leads was lower than Quattro leads; however, Riata ST leads had significantly shorter follow-up than Riata leads. ECs were common in Riata leads, and more than a quarter of Riata leads that had ECs were malfunctioning. Our observations suggest that systematic fluoroscopic examination of patients with Riata leads is appropriate.

Impact of the CHA2DS2-VASc score on anticoagulation recommendations for atrial fibrillation

BACKGROUND

The Congestive heart failure, Hypertension, Age ≥ 75 years, Diabetes mellitus, Stroke (CHADS(2)) score is used to predict the need for oral anticoagulation for stroke prophylaxis in patients with atrial fibrillation. The Congestive heart failure, Hypertension, Age ≥ 75 years, Diabetes mellitus, Stroke, Vascular disease, Age 65-74 years, Sex category (CHA(2)DS(2)-VASc) schema has been proposed as an improvement. Our objective is to determine how adoption of the CHA(2)DS(2)-VASc score alters anticoagulation recommendations.

METHODS

Between 2004 and 2008, 1664 patients were seen at the University of Virginia Atrial Fibrillation Center. We calculated the CHADS(2) and CHA(2)DS(2)-VASc scores for each patient. The 2006 American College of Cardiology/American Heart Association/Heart Rhythm Society guidelines for atrial fibrillation management were used to determine anticoagulation recommendations based on the CHADS(2) score, and the 2010 European Society of Cardiology guidelines were used to determine anticoagulation recommendations based on the CHA(2)DS(2)-VASc score.

RESULTS

The average age was 62±13 years, and 34% were women. Average CHADS(2) and CHA(2)DS(2)-VASc scores were 1.1±1.1 and 1.8±1.5, respectively (P<.0001). The CHADS(2) score classified 33% as requiring oral anticoagulation. The CHA(2)DS(2)-VASc score classified 53% as requiring oral anticoagulation. For women, 31% had a CHADS(2) score ≥ 2, but 81% had a CHA(2)DS(2)-VASc score ≥ 2 (P = .0001). Also, 32% of women with a CHADS(2) score of zero had a CHA(2)DS(2)-VASc score ≥ 2. For men, 25% had a CHADS(2) score ≥ 2, but 39% had a CHA(2)DS(2)-VASc score ≥ 2 (P<.0001).

CONCLUSION

Compared with the CHADS(2) score, the CHA(2)DS(2)-VASc score more clearly defines anticoagulation recommendations. Many patients, particularly older women, are redistributed from the low- to high-risk categories.

Sonication of explanted cardiac rhythm management devices for the diagnosis of pocket infections and asymptomatic bacterial colonization

BACKGROUND

Correct diagnosis of the causative organism is critical for the treatment of pacemaker and defibrillator pocket infections. No gold standard for this exists, although swab and tissue cultures are frequently used. The purpose of this study was to determine the value of ultrasonication of explanted generators in the diagnosis of pocket infections and asymptomatic bacterial colonization.

METHODS

Samples were prospectively collected during pacemaker and defibrillator generator extractions for elective replacements, upgrades, or pocket infections. The devices were placed in an ultrasonicator for 5 minutes and the fluid sent for culture, along with swab and tissue cultures.

RESULTS

Eighty-two patients with pacemakers (n = 46) or defibrillators (n = 36) underwent generator explantation, 66 of these for elective reasons and 16 for pocket infection. In patients with pocket infection, 15 (94%) received a definitive bacterial diagnosis using a combination of all three-culture modalities. Cultures were positive in 15 sonicated fluid, 13 tissue, and 11 swab samples, with Staphylococcus aureus and other skin flora commonly seen. In asymptomatic patients, 14 (21%) had positive cultures. Cultures were positive in 11 sonicated fluid, eight tissue, and two swab samples. Skin flora was commonly seen, but three of the sonicated fluid cultures grew gram-negative rods. No patients with asymptomatic colonization developed clinical infection during the follow-up period.

CONCLUSIONS

Ultrasonication is an inexpensive and simple technique that improves the bacteriologic diagnosis of device pocket infections. It also identifies a significant proportion of patients with asymptomatic colonization, although this is not a marker of future pocket infection.

Gender and Racial Characteristics of Patients Referred to a Tertiary Atrial Fibrillation Center

Atrial Fibrillation Centers (AFCs) are becoming increasingly common and are often developed at institutions to provide comprehensive evaluation and management for patients with atrial fibrillation (AF) including catheter and surgical ablation. Studies have shown that women and racial minority patients are less likely to be offered aggressive or invasive therapies. The University of Virginia (UVA) AFC was opened in 2004. We analyzed data collected during initial visits to our AFC from 2004-2008 to determine the gender and racial characteristics of a tertiary AFC population. Multivariable regression analysis was used to compare clinical characteristics. There were a total of 1664 consecutive initial patient visits. Cardiologists referred 61% and primary care physicians referred 37% of patients. Twice as many men were referred as women (570 vs. 1094; P<0.0001). Women were older (68.0±11.9 vs. 62.4±13.0 years; P<0.0001) and more symptomatic with palpitations (80% vs. 73%; P=0.008), but otherwise were not substantially different from men. Our referring physicians treated the majority of both men and women with anticoagulant and rate-controlling medications. African American patients accounted for 2.8% of AFC initial visits. In contrast, they accounted for 7.4% of patients seen for a primary diagnosis of AF at all other UVA outpatient clinics (P<0.0001). In conclusion, the demographics of a tertiary AFC are different than those of the general population. Women and racial minority patients are underrepresented, and the women have few comorbidities and symptoms than the known epidemiology would lead us to expect.

Pressure frequency characteristics of the pericardial space and thorax during subxiphoid access for epicardial ventricular tachycardia ablation

BACKGROUND

Nonsurgical subxiphoid pericardial access may be useful in ventricular tachycardia ablation and other electrophysiologic procedures but has a risk of right ventricular puncture.

OBJECTIVE

The purpose of this study was to identify a signature pressure frequency that would help identify the pericardial space and guide access.

METHODS

The study consisted of 20 patients (8 women and 12 men; mean age 59.1 +/- 14.2 years; left ventricular ejection fraction 25.2% +/- 12.2%; failed 1.8 +/- 0.5 endocardial ablations; unresponsive to 2.0 +/- 1.0 antiarrhythmic drugs; 6 ischemic cardiomyopathy, 12 nonischemic cardiomyopathy, 2 normal heart; 4 previous sternotomy) undergoing epicardial ventricular tachycardia ablation. After pericardial access was obtained, a 10Fr long sheath was used to record pressure inside the pericardium and pleural space. Pressures were analyzed using a fast Fourier transform to identify dominant frequencies in each chamber.

RESULTS

Mean pressures in the pleural space and the pericardium were not different (7.7 +/- 1.9 mmHg vs 7.8 +/- 0.9 mmHg, respectively). However, the pericardial space in each patient demonstrated two frequency peaks that correlated with heart rate (1.16 +/- 0.21 Hz) and respiratory rate (0.20 +/- 0.01 Hz), whereas the pleural space in each patient had a single peak correlating with respiratory rate (0.20 +/- 0.01 Hz).

CONCLUSION

The pericardial space demonstrates a signature pressure frequency that is significantly different from the surrounding space. This difference may make minimally invasive subxiphoid pericardial access safer for nonsurgeons and may have important implications for electrophysiologic procedures.

Unresolved issues in implantable cardioverter-defibrillator therapy

Over the last 15 years, a series of well-designed randomized clinical trials has clearly demonstrated that implantable cardioverter-defibrillator (ICD) therapy reduces mortality in select high-risk populations. Despite the widespread acceptance of ICD therapy, many questions related to its optimal use remain. This article discusses several key issues now confronting clinicians.

Common issues in sports cardiology

Many cardiac conditions found in athletes are amenable to athletic participation if well-managed. As always, a respect for the causes of sudden cardiac death in athletes is paramount. Although rare, sudden cardiac death in athletes is frequently preventable by careful pre-participation screening. The authors hope that more athletes will undergo screening, and that basic investigations, including but not limited to electrocardiography, will become more widespread. A high degree of surveillance for cardiac pathology in athletes is the duty of any sports medicine practitioner.

Influence of the randomized trials, AFFIRM and RACE, on the management of atrial fibrillation in two University Medical Centers

The results of the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) and the Rate Control Versus Electrical Cardioversion for Persistent Atrial Fibrillation (RACE) study were presented in March 2002. These large studies showed no benefit of a rhythm-control strategy over a rate-control strategy in managing atrial fibrillation (AF). Cardioversion and atrioventricular junctional ablation are forms of rhythm control and rate control, respectively. The numbers of cardioversions and atrioventricular junctional ablations performed at the University of Virginia and the Medical College of Virginia during the 52 months before AFFIRM and RACE results were released and the 21 months afterward were compared. From January 1998 to March 2002, monthly averages of 31 +/- 8 elective cardioversions and 6 +/- 3 atrioventricular junctional ablations were performed; from April 2002 to December 2003, the monthly averages were 21 +/- 6 cardioversions (p = 0.001) and 9 +/- 3 ablations (p = 0.001). AF management changed at these institutions shortly after the RACE and AFFIRM results were released.

Usefulness of implantable loop recorders in office-based practice for evaluation of syncope in patients with and without structural heart disease

Early use of an implantable loop recorder for evaluating unexplained syncope in an office-based electrophysiology practice is an effective approach in patients with and without structural heart disease. Documentation of rhythm with an implantable loop recorder at the time of symptoms is possible in approximately 50% and 80% of patients in both groups after 1 and 2 years of follow-up, respectively.