Girish M. Nair

Device‐Related Infection Among Patients With Pacemakers and Implantable Defibrillators: Incidence, Risk Factors, and Consequences

Risk Factors and Complications of Pacemaker and ICD Infection. Background: Device‐related infection is a major limitation of device therapy for cardiac arrhythmia.

Pacemaker-Detected Atrial Fibrillation in Patients With Pacemakers: Prevalence, Predictors, and Current Use of Oral Anticoagulation

BACKGROUND Dual-chamber pacemakers frequently document atrial fibrillation (AF) in patients without symptoms. Pacemaker-detected AF is associated with a 2.5-fold increased risk of stroke, although it is not established whether oral anticoagulation reduces this risk. This study sought to determine the prevalence and predictors of pacemaker-detected AF and to document current oral anticoagulant use. METHODS A retrospective analysis included all patients from a single academic hospital who had pacemakers capable of documenting AF. Blinded evaluation of all echocardiograms conducted within 6 months of implantation was performed. RESULTS Of 445 patients, pacemaker-detected AF was present in 246 (55.3%), who were older (74.3 ± 13.7 years vs 71.7 ± 14.4, P = 0.046), more likely to have a history of clinical AF (29.7% vs 19.1%, P = 0.01), and had a larger left atrial volume index (34.4 ± 11.8 mL/m(2) vs 30.0 ± 9.9 mL/m(2), P = 0.019) than the patients without pacemaker-detected AF. Among patients without a clinical history of AF, left atrial volume index was higher among those with pacemaker-detected AF (33.7 ± 11.3 mL/m(2) vs 29.0 ± 10.1 mL/m(2), P = 0.034). Anticoagulants were used in 35.3% of patients with pacemaker-detected AF, compared with 21.6% of patients without (P < 0.05). In patients with pacemaker-detected AF, anticoagulants were used more frequently among patients who also had clinical AF (58.9%) compared with those without (23.7%, P < 0.001). CONCLUSIONS Pacemaker-detected AF occurs in 50% of pacemaker patients and is treated with anticoagulants in less than 25% of patients who do not have a history of clinical AF. Clinical trials are needed to determine the role of anticoagulation in this population.

Atrioesophageal Fistula in the Era of Atrial Fibrillation Ablation: A Review

The purpose of this review is to understand the epidemiology, clinical features, etiopathogenesis, and management of atrioesophageal fistula (AEF) after atrial fibrillation (AF) ablation. The incidence of AEF after AF ablation is 0.015%-0.04%. The principal clinical features include fever, dysphagia, upper gastrointestinal bleeding, sepsis, and embolic strokes. The close proximity of the esophagus to the posterior left atrial wall is responsible for esophageal injury during ablation. Prophylactic proton pump inhibitors, esophageal temperature monitoring, visualization of the esophagus during catheter ablation, esophageal protection devices, and avoidance of energy delivery in close proximity to the esophagus play an important role in preventing esophageal injury. Early surgical repair or esophageal stenting are the mainstay of treatment. Eliminating esophageal injury during AF ablation is of utmost importance in preventing AEF. A high index of suspicion and early intervention is necessary to prevent fatal outcomes.

Atrioventricular Block as the Initial Manifestation of Cardiac Sarcoidosis in Middle-Aged Adults

Atrioventricular block (AVB) can be caused by several conditions, including cardiac sarcoidosis (CS). The prevalence of CS causing this presentation in a North American population has not been investigated and was the purpose of this study.

Selective Complex Fractionated Atrial Electrograms Targeting for Atrial Fibrillation Study (SELECT AF) A Multicenter, Randomized Trial

Background—This study compared generalized complex fractionated atrial electrograms (CFAE) ablation versus a selective CFAE ablation strategy targeting areas of continuous electric activity. Methods and Results—Subjects with symptomatic, persistent/high-burden paroxysmal atrial fibrillation (AF) were enrolled at 6 centers (n=86) and randomized to 1 of 2 arms. For group I, all CFAE regions with an interval confidence level >7 were ablated followed by pulmonary vein isolation (PVI). For group II, only CFAE sites with continuous electric activity were ablated followed by PVI. For PVI, all 4 PV antra were isolated with confirmed entrance block. Subjects were followed for 1 year with a visit, ECG, and 48-hour Holter every 3 months. Symptoms were confirmed by loop recording. The primary end point was freedom from arrhythmia >30 seconds at 1 year. For both group I and II, CFAE ablation prolonged AF cycle length (25±33 versus 23±33 ms; P=0.78) and resulted in similar rates of AF termination (37% versus 28%; P=0.42). Radiofrequency duration during CFAE ablation was significantly less in group II (23±20 versus 38±20 minutes; P=0.002). At 1-year follow-up, freedom from AF/atrial flutter/atrial tachycardia recurrence was significantly higher in group I versus group II after 1 procedure (50% versus 28%; P=0.03). There were also significantly fewer repeat procedures in group I (13% versus 36%; P=0.021). Conclusions—Continuous electric activity ablation+PVI result in a similar incidence of acute AF termination with significantly less radiofrequency time. However, incidence of repeat procedures and long-term recurrence of AF/atrial flutter/atrial tachycardia are significantly lower using generalized CFAE ablation+PVI. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT00926783

Do Omega-3 fatty acids prevent atrial fibrillation after open heart surgery? A meta-analysis of randomized controlled trials

OBJECTIVES: N-3 polyunsaturated fatty acids have been proposed as a novel treatment for preventing postoperative atrial fibrillation due to their potential anti-inflammatory and anti-arrhythmic effects. However, randomized studies have yielded conflicting results. The objective of this study is to review randomized trials of N-3 polyunsaturated fatty acid use for postoperative atrial fibrillation. METHODS: Using the CENTRAL, PUBMED, EMBASE, and LILACS databases, a literature search was conducted to identify all of the studies in human subjects that reported the effects of N-3 polyunsaturated fatty acids on the prevention of postoperative atrial fibrillation in cardiac surgery patients. The final search was performed on January 30, 2011. There was no language restriction, and the search strategy only involved terms for N-3 polyunsaturated fatty acids (or fish oil), atrial fibrillation, and cardiac surgery. To be included, the studies had to be randomized (open or blinded), and the enrolled patients had to be ≥18 years of age. RESULTS: Four randomized studies (three double-blind, one open-label) that enrolled 538 patients were identified. The patients were predominantly male, the mean age was 62.3 years, and most of the patients exhibited a normal left atrial size and ejection fraction. N-3 polyunsaturated fatty acid use was not associated with a reduction in postoperative atrial fibrillation. Similar results were observed when the open-label study was excluded. CONCLUSIONS: There is insufficient evidence to suggest that treatment with N-3 polyunsaturated fatty acids reduces postoperative atrial fibrillation. Therefore, their routine use in patients undergoing cardiac surgery is not recommended.

Inter- and Intra- observer agreement of FDG-PET/CT image interpretation in patients referred for assessment of Cardiac Sarcoidosis

Recent studies have reported the usefulness of 18F-FDG PET in aiding with the diagnosis and management of patients with cardiac sarcoidosis (CS). However, image interpretation of 18F-FDG PET for CS is sometimes challenging. We sought to investigate the inter- and intraobserver agreement and explore factors that led to important discrepancies between readers. Methods: We studied consecutive patients with no significant coronary artery disease who were referred for assessment of CS. Two experienced readers masked to clinical information, imaging reports, independently reviewed 18F-FDG PET/CT images. 18F-FDG PET/CT images were interpreted according to a predefined standard operating procedure, with cardiac 18F-FDG uptake patterns categorized into 5 patterns: none, focal, focal on diffuse, diffuse, and isolated lateral wall or basal uptake. Overall image assessment was classified as either consistent with active CS or not. Results: One hundred scans were included from 71 patients. Of these, 46 underwent 18F-FDG PET/CT with a no-restriction diet (no-restriction group), and 54 underwent 18F-FDG PET/CT with a low-carbohydrate, high-fat and protein-permitted diet (low-carb group). There was agreement of the interpretation category in 74 of 100 scans. The κ-value of agreement among all 5 categories was 0.64, indicating moderate agreement. For overall clinical interpretation, there was agreement in 93 of 100 scans (κ = 0.85). When scans were divided into the preparation groups, there was a trend toward higher agreement in the low-carb group versus the no-restriction group (80% vs. 67%, P = 0.08). Regarding the overall clinical interpretation, there was also a trend toward greater agreement in the low-carb group versus the no-restriction group (96% vs. 89%, P = 0.08). Conclusion: The interobserver agreement of cardiac 18F-FDG uptake image patterns was moderate. However, agreement was better regarding overall interpretation of CS. Detailed prescan dietary preparation seemed to improve interobserver agreement.

Stroke prevention in patients with atrial fibrillation: The diagnosis and management of hypertension by specialists

BACKGROUND Hypertension is common in patients with atrial fibrillation (AF) and is an important cause of stroke. OBJECTIVES To determine how effectively hypertension is managed among specialist-treated outpatients with AF. METHODS Investigators reviewed the charts of patients with a diagnosis of AF cared for by medical specialists to determine the change in blood pressure, patterns of antihypertensive drug use and the role of the specialist in the management of hypertension. RESULTS Of 209 patients with AF, 118 had a history of hypertension or an office blood pressure greater than 140/90 mmHg. Blood pressure was measured at 73% of all visits. Hypertension was identified as an important problem in 57% of patients and antihypertensive therapy was either initiated or suggested in 77%. One year after the initial specialist visit, systolic blood pressure was significantly lower (140+/-20 mmHg at one year versus 148+/-23 mmHg initially; P=0.015); however, there was no change in diastolic blood pressure (80+/-12 mmHg at one year versus 81+/-16 mmHg initially; P=0.602) and only 50% of patients had a blood pressure less than 140/90 mmHg. In contrast, the percentage of patients receiving warfarin increased from 46% to 78% (P=0.0001). CONCLUSIONS In patients treated by specialists for AF, systolic blood pressure is significantly reduced during follow-up; however, 50% of patients continue to have suboptimal blood pressure control. In many patients, hypertension is not identified as an important comorbid illness and antihypertensive therapy is neither recommended nor initiated by the specialist. Greater specialist involvement in the identification and treatment of hypertension in patients with AF could lead to an important, additional reduction in stroke.

Efficacy and safety of driver-guided catheter ablation for atrial fibrillation: A systematic review and meta-analysis

Targeting localized drivers (electrical rotors or focal impulses) during catheter ablation for atrial fibrillation (AF) has been proposed as a strategy to improve procedural success. However, the strength and quality of the evidence to support this approach is unclear.

Delayed AICD therapy and cardiac arrest resulting from undersensing of ventricular fibrillation in a subject with hypertrophic cardiomyopathy–A case report

Defibrillation testing is no longer routinely performed after automatic implantable cardioverter-defibrillator (AICD) implantation. However, certain subjects undergoing AICD implantation may be at higher risk of undersensing of ventricular arrhythmias resulting in potentially fatal outcomes. We present the case of a 30-year-old woman with hypertrophic cardiomyopathy (HCM; ‘asymmetric septal hypertophy’ morphologic variant) and prophylactic AICD who experienced an out of hospital cardiac arrest. AICD interrogation revealed undersensing as a result of intermittent high amplitude electrograms during an episode of ventricular fibrillation (VF). The subject underwent replacement and repositioning of the AICD lead along with pulse generator replacement (that utilized a different VF sensing algorithm) with appropriate sensing of VF and successful defibrillation testing. The presence of intermittent high amplitude electrograms during episodes of VF in AICDs using the AGC function should be recognized as a situation that may necessitate interventions to prevent undersensing and consequent delay in therapy.