Richard Leather

Standardized Approaches to the Investigation of Syncope: Canadian Cardiovascular Society Position Paper

Syncope is a very common presentation in the emergency department, and the combination of a wide differential diagnosis, a range of prognoses, and infrequent documentation of the faint leads to a high proportion of patients being admitted. These problems are mirrored in the investigation of inpatients with syncope, for which the high proportion of patients with benign outcomes and the profound risk aversion of health care providers make for expensive and inefficient assessment. Difficulties such as this in health services delivery can be improved by standardized approaches, such as guidelines, pathways, and checklists. Accordingly, emergency department decision rules, specialized syncope-monitoring units, and formal diagnostic algorithms have been developed to provide standardized approaches to the investigation of syncope. To provide guidance in the management of syncope, the Canadian Cardiovascular Society commissioned a position paper on standardized approaches to syncope investigation in adults. A primary panel first reviewed the literature systematically, then undertook iterative syntheses of data, and finally took positions with specific recommendations according to the GRADE framework. This paper summarizes the evidence and its quality and makes recommendations on the specific approaches meriting adoption. The position paper was then reviewed by a secondary panel, which provided suggestions for revisions leading to the final document as presented here. Overall, the position group concluded that there is little persuasive evidence that emergency department syncope rules and diagnostic syncope units provide efficient care and improved outcomes but that formal diagnostic algorithms with specialist support show promise.

Multiple accessory pathways in the Wolff-Parkinson-White syndrome as a risk factor for ventricular fibrillation

Abstract Ventricular fibrillation (VF) after atrial fibrillation is the mechanism of sudden death in most patients with Wolff-Parkinson-White (WPW) syndrome. 1–3 Initial data from Duke University 1 suggested that patients who had VF had a shortest RR interval between preexcited beats during atrial fibrillation 4 Several studies 1,5 have also noted the increased frequency of multiple accessory pathways in VF patients with WPW syndrome although other investigators 6 suggested that this was not the case. We sought to determine whether VF occurs more frequently in patients with multiple accessory pathways and whether multiple pathways may be considered as an additional risk factor for this complication.

Cardiac injury after percutaneous catheter ablation for atrial fibrillation

AIMS Small elevations in troponin T levels have been shown with limited radiofrequency (RF) ablation procedures for supraventricular tachycardia, usually to levels below the threshold for ischaemia or infarction. Left atrial catheter ablation for atrial fibrillation (AF) requires far more RF energy, therefore could be expected to have greater elevation in troponin T. We determined troponin T levels before and after ablation in these patients to evaluate the amount of rise with this ablation. METHODS All patients undergoing pulmonary vein isolation (PVI) from May 2004 to October 2004 had troponin T levels measured 4 h following completion of the procedure. The first 30 patients also had a troponin T level measured 1 h prior to PVI to establish a baseline reference. RESULTS Sixty patients were studied, with 81.7% males and a mean age of 54.6 +/- 9.9 years. No patient had underlying structural heart disease. The baseline troponin T level was normal (<0.01 microg/L) in all 30 patients. Post-procedure troponin T levels were elevated in all 60 patients compared with baseline (P < 0.05), with a mean level of 0.85 microg/L and a range of 0.26-1.57 microg/L after an average RF ablation time of 56 +/- 15 min. All levels were above the reference range for diagnosis of acute myocardial infarction (>0.15 microg/L). Troponin T level was not related to the number of RF lesions, RF time, procedure time, or associated external cardioversion. CONCLUSIONS Troponin T elevations occurred in all patients undergoing PVI, to levels at least 20 times the normal concentration, into the range for diagnosis of acute myocardial infarction. Therefore, troponin T would not be specific for ischaemia in the setting of chest pain post-catheter ablation for AF.

Outcome of Apparently Unexplained Cardiac Arrest: Results From Investigation and Follow-Up of the Prospective Cardiac Arrest Survivors With Preserved Ejection Fraction Registry

Background—The Cardiac Arrest Survivors with Preserved Ejection Fraction Registry (CASPER) enrolls patients with apparently unexplained cardiac arrest and no evident cardiac disease to identify the pathogenesis of cardiac arrest through systematic clinical testing. Exercise testing, drug provocation, advanced cardiac imaging, and genetic testing may be useful when a cause is not apparent. Methods and Results—The first 200 survivors of unexplained cardiac arrest from 14 centers across Canada were evaluated to determine the results of investigation and follow-up (age, 48.6±14.7 years, 41% female). Patients were free of evidence of coronary artery disease, left ventricular dysfunction, or evident repolarization syndromes. Advanced testing determined a diagnosis in 34% of patients at baseline, with a diagnosis emerging during follow-up in 7% of patients. Of those who were diagnosed, 28 (35%) had an underlying structural condition and 53 (65%) had a primary electric disease. During a mean follow-up of 3.15±2.34 years, 23% of patients had either a shock or an appropriate antitachycardia pacing from their implantable cardioverter defibrillator, or both. The implantable cardioverter defibrillator appropriate intervention rate was 8.4% at 1 year and 18.1% at 3 years, with no clear difference between diagnosed and undiagnosed subjects, or between those diagnosed with a primary electric versus structural pathogenesis. Conclusions—Obtaining a diagnosis in previously unexplained cardiac arrest patients requires systematic clinical testing and regular follow-up to unmask the cause. Nearly half of apparently unexplained cardiac arrest patients ultimately received a diagnosis, allowing for improved treatment and family screening. A substantial proportion of patients received appropriate implantable cardioverter defibrillator therapy during medium-term follow-up. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT00292032.

Feasibility and safety of outpatient radiofrequency catheter ablation procedures for atrial fibrillation

Introduction Percutaneous catheter ablation for atrial fibrillation (AF) is a procedure performed typically in an inpatient setting. The feasibility and safety of catheter ablation in patients with paroxysmal and persistent AF were evaluated on an outpatient basis. Methods 230 AF ablation procedures were performed in 206 patients (74% male; mean age 56±9 years). Patients were admitted to the hospital outpatient facility in the morning for the AF ablation procedure on the same day. The ablation strategy consisted of wide area circumferential lines around both ipsilateral pulmonary veins. After monitoring in the outpatient service, patients were discharged on the same day, if they were clinically stable. Results Mean procedure time was 201±31 min. Major complications occurred in seven patients (3%). One patient (0.4%) suffered a minor stroke and six patients had pericardial tamponade requiring percutaneous drainage. Patients could be discharged on the same day following 205 (89%) procedures. Among the 148 patients whose clinical outcome was assessed at 6 months, 127 (86%) had a reduction of the total symptomatic AF episodes, compared to pre-ablation, with a complete lack of symptoms in 101 patients (68%). Conclusion Catheter ablation of AF on the day of admission is feasible and safe with a low risk of complications. The vast majority of the patients can be discharged on the same day.

Complete Heart Block Associated With Tricuspid Valve Endocarditis Due to Extended Spectrum β-Lactamase–Producing Escherichia coli

We report a case of complete heart block associated with tricuspid endocarditis due to extended-spectrum β-lactamase-producing Escherichia coli (ESBL E. coli) following a transrectal prostate biopsy. This is the first report of complete heart block associated with tricuspid native valve endocarditis. In addition, this is also the first reported case of ESBL E. coli causing endocarditis of any kind. Prompt antibiotic therapy resulted in a downgrading of the high-grade conduction block and eventual cure of an associated complication, vertebral osteomyelitis, and discitis. The anatomy and microbiology of endocarditis in the context of heart block are presented and discussed.

Cardiac Abnormalities in First-Degree Relatives of Unexplained Cardiac Arrest Victims: A Report From the Cardiac Arrest Survivors With Preserved Ejection Fraction Registry.

Background—Unexplained cardiac arrest (UCA) may be explained by inherited arrhythmia syndromes. The Cardiac Arrest Survivors With Preserved Ejection Fraction Registry prospectively assessed first-degree relatives of UCA or sudden unexplained death victims to screen for cardiac abnormalities. Methods and Results—Around 398 first-degree family members (186 UCA, 212 sudden unexplained death victims’ relatives; mean age, 44±17 years) underwent extensive cardiac workup, including ECG, signal averaged ECG, exercise testing, cardiac imaging, Holter-monitoring, and selective provocative drug testing with epinephrine or procainamide. Genetic testing was performed when a mutation was identified in the UCA survivor or when the diagnostic workup revealed a phenotype suggestive of a specific inherited arrhythmia syndrome. The diagnostic strength was classified as definite, probable, or possible based on previously published definitions. Cardiac abnormalities were detected in 120 of 398 patients (30.2%) with 67 of 398 having a definite or probable diagnosis (17%), including Long-QT syndrome (13%), catecholaminergic polymorphic ventricular tachycardia (4%), arrhythmogenic right ventricular cardiomyopathy (4%), and Brugada syndrome (3%). The detection yield was similar for family members of UCA and sudden unexplained death victims (31% versus 27%; P=0.59). Genetic testing was performed more often in family members of UCA patients (29% versus 20%; P=0.03). Disease-causing mutations were identified in 20 of 398 relatives (5%). The most common pathogenic mutations were RyR2 (2%), SCN5A (1%), and KNCQ1 (0.8%). Conclusions—Cardiac screening revealed abnormalities in 30% of first-degree relatives of UCA or sudden unexplained death victims, with a clear working diagnosis in 17%. Long-QT, arrhythmogenic right ventricular cardiomyopathy, and catecholaminergic polymorphic ventricular tachycardia were the most common diagnoses. Systematic cascade screening and genetic testing in asymptomatic individuals will lead to preventive lifestyle and medical interventions with potential to prevent sudden cardiac death. Clinical Trial Registration—URL: http://www.clinicaltrials.gov. Unique identifier: NCT00292032.

Genetic Testing in the Evaluation of Unexplained Cardiac ArrestCLINICAL PERSPECTIVE: From the CASPER (Cardiac Arrest Survivors With Preserved Ejection Fraction Registry)

Background— Unexplained cardiac arrest may be because of an inherited arrhythmia syndrome. The role of genetic testing in cardiac arrest survivors without a definite clinical phenotype is unclear. Methods and Results— The CASPER (Cardiac Arrest Survivors with Preserved Ejection Fraction Registry) is a large registry of cardiac arrest survivors where initial assessment reveals normal coronary arteries, left ventricular function, and resting ECG. Of 375 cardiac arrest survivors in CASPER from 2006 to 2015, 174 underwent genetic testing. Patients were classified as phenotype-positive (n=72) or phenotype-negative (n=102). Genetic testing was performed at treating physicians’ discretion in line with contemporary guidelines and availability. All genetic variants identified from original laboratory reports were reassessed by the investigators in line with modern criteria. Pathogenic variants were identified in 29 (17%) patients (60% channelopathy-associated and 40% cardiomyopathy-associated genes) and 70 variants of unknown significance were identified in 32 (18%) patients. Prior syncope (odds ratio, 4.0; 95% confidence interval, 1.6–9.7) and a family history of sudden death (odds ratio, 3.2; 95% confidence interval, 1.1–9.4) were independently associated with the presence of a pathogenic variant. In phenotype-negative patients, broad multiphenotype genetic testing led to higher yields (21% versus 8%; P=0.04) but was associated with more variants of unknown significance (55% versus 5%; P<0.01). Conclusions— Genetic testing identifies a pathogenic variant in a significant proportion of unexplained cardiac arrest survivors. Prior syncope and family history of sudden death are predictors of a positive genetic test. Both arrhythmia and cardiomyopathy genes are implicated. Broad, multiphenotype testing revealed the highest frequency of pathogenic variants in phenotype-negative patients. Clinical Trial Registration— https://www.clinicaltrials.gov. Unique Identifier: NCT00292032

Double transseptal puncture for catheter ablation of atrial fibrillation: safety of the technique and its use in the outpatient setting.

Introduction. For pulmonary vein isolation in patients with atrial fibrillation (AF), some centers use the double transseptal puncture technique for catheter access in order to facilitate catheter manipulation within the left atrium. However, no safety data has so far been published using this approach. Method. 269 ablation procedures were performed in 243 patients (mean age 56.6 ± 9.3 years, 75% men) using the double transseptal puncture for catheter access in all cases. Patients were considered for ablation of paroxysmal (80%), persistent (19%), and permanent (1%) AF. 230 procedures were performed on an outpatient basis (85.5%), and 26 were repeat procedures (9.7%). Results. The double transseptal puncture catheter access was successfully achieved in all patients. The procedural success with the endpoint of pulmonary vein isolation was reached in 255 procedures (95%). A total of 1048 out of 1062 pulmonary veins (99%) were successfully isolated. Major complications occurred in eight patients (3.0%). Of these, seven patients (2.6%) had pericardial effusion requiring percutaneous drainage, and one patient (0.4%) suffered a minor reversible stroke. One patient (0.4%) had a minor air embolism with transient symptoms. Conclusion. The double transseptal puncture catheterization technique allows easy catheter manipulation within the left atrium to reach the goal of acute procedural success in AF ablation. Procedure-related complications are rare, and the technique can be used safely for AF ablation in the outpatient setting.

Response to Letter Regarding Article, “Outcome of Apparently Unexplained Cardiac Arrest: Results From Investigation and Follow-Up of the Prospective Cardiac Arrest Survivors With Preserved Ejection Fraction Registry”

We would like to thank Professors Jaimez and Sanchez for their letter of response commenting on our recent summary of evaluation and outcome of our first 200 unexplained cardiac arrest probands.1 We would first like to point out that we excluded patients with a manifest diagnosis, so none of these patients had overt evidence of an ion channelopathy or cardiomyopathy that are typically both readily diagnosed and treated. This is reflected in our empirical strength of diagnosis framework, which is necessary when a classic diagnosis is not forthcoming.2 In addition, registries do not mandate care but rather capture it, and reflect the reality of practice with the vagaries of contextual clinical decision making. In response to the concerns about the incidence of shocks and the inefficacy of medical therapy, it is important to point out the difference between efficacy and effectiveness. Without …