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Using data collected from 2 national atrial fibrillation (AF) primary care physician chart audits (Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation [FREEDOM AF] and Co-ordinated National Network to Engage Physicians in the Care and Treatment of Patients With Atrial Fibrillation [CONNECT AF]), we evaluated the frequency of, and factors associated with, the use of cardiovascular (CV) evidence-based therapies in Canadian AF outpatients with at least 1 CV risk factor or co-morbidity. Of the 11,264 patients enrolled, 9,495 (84.3%) were eligible for one or more CV evidence-based therapies. The proportions of patients with AF receiving all eligible guideline-recommended therapies were 40.8% of patients with coronary artery disease, 48.9% of patients with diabetes mellitus, 40.2% of patients with heart failure, 96.7% of patients with hypertension, and 55.1% of patients with peripheral arterial disease. Factors that were independently associated with nonreceipt of all indicated evidence-based therapies included sinus rhythm rather than AF at baseline and liver disease. In conclusion, although most Canadian outpatients with AF have CV risk factors or co-morbidities, a substantial portion of these patients did not receive all guideline-recommended therapies. These findings suggest that there is an opportunity to improve the quality of care for patients with AF in Canada.

Inherited heart rhythm disorders (IHRDs) are complex and uncommon arrhythmogenic conditions that can lead to sudden unexpected death in seemingly healthy individuals. Multidisciplinary programs can assist in the diagnostic testing of potentially affected individuals and their family members.Patients evaluated in a specialized adult and pediatric IHRD clinic between April 2013 and February 2015 were characterized. The total costs per evaluation and diagnosis were calculated. Patients were divided according to referral indication (primary referral or family member).A total of 618 patients were evaluated (age 36 ± 21 years; 52% male), of which 274 (44%) were primary referrals and 344 (56%) were family members referred for cascade screening. Overall, 47% had at least 1 follow-up visit. Patients had a median of 3 tests; primary referrals required more tests (4 vs 2; P0.01). The median cost per patient was $1340 CAD. Evaluation of the primary referrals was costlier than family members ($3096 vs $983; P0.01). A definite or probable diagnosis was determined in 464 patients (77%), with no difference according to patient type (P = 0.18). The total cost per diagnosis was $4021 in primary referrals compared with $1277 in family members (P0.01).Clinical evaluation of patients with suspected IHRD results in a high diagnostic yield and costs aligned with other complex disorders involving multidisciplinary clinics. Evaluation costs are expectedly higher in primary referrals compared with targeted family screening.

Background Progression from paroxysmal to persistent atrial fibrillation (AF) has important clinical implications and is relevant to the management of patients with AF. Objective The purpose of this study was to define the long-term rate of progression from paroxysmal to persistent AF and the relevant clinical variables. Methods The Canadian Registry of Atrial Fibrillation enrolled patients after a first electrocardiographic diagnosis of paroxysmal AF. Associations between baseline characteristics and clinical outcomes were evaluated using a multivariable Cox proportional hazard model and a competing risk model accounting for death as a competing risk, where appropriate. Results We enrolled 755 patients (61.7% men) aged between 14 and 91 years (mean age 61.2 ± 14.2 years). The median follow-up was 6.35 years (interquartile range 2.93–10.04 years), with a rate of progression to persistent AF at 1, 5, and 10 years was 8.6%, 24.3%, and 36.3%, respectively. All-cause mortality was 30.3% at 10 years. Factors associated with AF progression were increasing age (hazard ratio [HR] 1.40; 95% confidence interval [CI] 1.23–1.60, for each 10-year increment), mitral regurgitation (HR 1.87; 95% CI 1.28–2.73), left atrial dilatation (HR 3.01; 95% CI 2.03–4.47), aortic stenosis (HR 2.40; 95% CI 1.05–5.48), and left ventricular hypertrophy (HR .47; 95% CI 1.04–2.08). Factors associated with a lower rate of progression were a faster heart rate during AF (HR 0.94; 95% CI 0.92–0.96 per 5-beat/min increment) and angina (HR 0.54; 95% CI 0.38–0.77). After accounting for death as a competing risk, left ventricular hypertrophy and aortic stenosis were no longer significant. Conclusion Within 10 years of presenting with paroxysmal AF, >50% of patients will progress to persistent AF or be dead. Increasing age, mitral regurgitation, aortic stenosis, left ventricular hypertrophy, and left atrial dilatation were associated with progression to persistent AF.

Background It is estimated that between 80% and 99% of alarms in the clinical areas are in actionable alarms (Gross, Dahl, & Nielson). Alarm management is one of the Joint Commission's National Patient Safety Goals (2014) because sentinel events have directly been linked to the devices generating these alarms. Purpose At an acute care facility in Boston, a multidisciplinary team consisting of Nursing, Biomedical Engineers, Patient Safety and Providers was formed to conduct a pilot study on the state of telemetry alarms on a surgical floor. Methods An evidence-based approach was taken utilizing Philips Real-time data exporter alarms tracking software to capture all telemetry alarms during a 43-day time span. Likewise, noise meters were placed near telemetry alarm speakers to track decibel levels within the aforementioned timeframe for 21 days. Analysis of the data showed that clinically insignificant Premature Ventricular Contractions (PVC) alarms accounted for more than 40% of all alarms in the unit within the time span, while also contributing to an average noise level of 58.49 dB. In response to the data, the interdisciplinary team approved to permanently default the settings for PAIR PVC, MULTIFORM PVC, and RUN PVC alarms to off. Results The results showed a 54% decrease in the rate of alarms per bed per day, and an average noise reduction of 2.3 dB between the two selected noise measurement areas. Linking Evidence to Action Organizing a multidisciplinary team provides an effective framework toward analyzing and addressing cardiac telemetry alarm fatigue. Looking at quantitative datasets for clinical care areas through various lenses helps identify opportunities for improvement in regards to highlighting alarms that are not actionable. Pilot changes to alarm parameters can be tested for their environmental impact in the care area.

BackgroundVariable expressivity and incomplete penetrance between individuals with identical long QT syndrome (LQTS) causative mutations largely remain unexplained. Founder populations provide a unique opportunity to explore modifying genetic effects. We examined the role of a novel synonymousKCNQ1p.L353L variant on the splicing of exon 8 and on heart rate corrected QT interval (QTc) in a population known to have a pathogenic LQTS type 1 (LQTS1) causative mutation, p.V205M, inKCNQ1-encoded Kv7.1.Methods419 adults were genotyped for p.V205M, p.L353L and a previously described QTc modifier (KCNH2-p.K897T). Adjusted linear regression determined the effect of each variant on QTc, alone and in combination. In addition, peripheral blood RNA was extracted from three controls and three p.L353L-positive individuals. The mutant transcript levels were assessed via qPCR and normalised to overallKCNQ1transcript levels to assess the effect on splicing.ResultsFor women and men, respectively, p.L353L alone conferred a 10.0 (p=0.064) ms and 14.0 (p=0.014) ms increase in QTc and in men only a significant interaction effect in combination with the p.V205M (34.6 ms, p=0.003) resulting in a QTc of ∼500 ms. The mechanism of p.L353L's effect was attributed to approximately threefold increase in exon 8 exclusion resulting in ∼25% mutant transcripts of the totalKCNQ1transcript levels.ConclusionsOur results provide the first evidence that synonymous variants outside the canonical splice sites inKCNQ1can alter splicing and clinically impact phenotype. Through this mechanism, we identified that p.L353L can precipitate QT prolongation by itself and produce a clinically relevant interactive effect in conjunction with other LQTS variants.

Background Physicians treating nonvalvular atrial fibrillation (AF) assess stroke and bleeding risks when deciding on anticoagulation. The agreement between empirical and physician-estimated risks is unclear. Furthermore, the association between patient and physician sex and anticoagulation decision-making is uncertain. Methods We pooled data from 2 national primary care physician chart audit databases of patients with AF (Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation and Coordinated National Network to Engage Physicians in the Care and Treatment of Patients with Atrial Fibrillation Chart Audit) with a combined 1035 physicians (133 female, 902 male) and 10,927 patients (4567 female and 6360 male). Results Male physicians underestimated stroke risk in female patients and overestimated risk in male patients. Female physicians estimated stroke risk well in female patients but underestimated the risk in male patients. Risk of bleeding was underestimated in all. Despite differences in risk assessment by physician and patient sex, > 90% of patients received anticoagulation across all subgroups. There was modest agreement between physician estimated and calculated (ie, CHADS2 score) stroke risk: Kappa scores were 0.41 (0.35-0.47) for female physicians and 0.34 (0.32-0.36) for male physicians. Conclusions Our study is the first to examine the association between patient and physician sex influences and stroke and bleeding risk estimation in AF. Although there were differences in agreement between physician estimated stroke risk and calculated CHADS2 scores, these differences were small and unlikely to affect clinical practice; further, despite any perceived differences in the accuracy of risk assessment by sex, most patients received anticoagulation.

LIA and LinoxIntroduction Medtronic's Lead Integrity Alert (LIA) software algorithm is useful for detecting abnormal parameters across various ICD-lead families. However, its utility in the assessment of the Biotronik Linox™ family of high-voltage (HV) leads is unknown. Methods We conducted a retrospective cohort study to assess the performance of the LIA algorithm to detect abnormalities and lead failure in Linox ICD-leads. All LIA-enabled Medtronic devices connected to an active Linox lead were included. The alerts were adjudicated by 2 blinded electrophysiologists and correlated with clinical data. Results Between 2008 and 2012, data from 208 patients with 564 patient-years of follow-up were available for analysis. The median follow-up duration was 32 (IQR 21–41 months). Twenty-one LIA triggers were noted in 20 different patients. The median delay until a positive LIA was 32 months (IQR 21–41 months) postimplant with a 5-year lead survival free from LIA of 76%. Ninety-five percent (19/20) LIA alerts were true lead failures. The most common LIA triggers were short V–V intervals (85%) and nonsustained ventricular tachycardia (85%). Abrupt changes of the ICD-lead impedance occurred in 5/20 triggers. Inappropriate ICD-shocks were strongly associated with a positive LIA (30% vs. 7.4%; P = 0.006). Of the explanted Linox leads 53% had visible abnormalities. The sensitivity, specificity, and positive predictive value for lead failure in the presence of a LIA trigger were 87%, 99.5%, and 95.2%, respectively. Conclusions A positive LIA trigger in Biotronik Linox ICD-leads is highly predictive of lead failure. LIA is useful in ongoing surveillance of lead performance.

Using data collected from 2 national atrial fibrillation (AF) primary care physician chart audits (Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation [FREEDOM AF] and Co-ordinated National Network to Engage Physicians in the Care and Treatment of Patients With Atrial Fibrillation [CONNECT AF]), we evaluated the frequency of, and factors associated with, the use of cardiovascular (CV) evidence-based therapies in Canadian AF outpatients with at least 1 CV risk factor or co-morbidity. Of the 11,264 patients enrolled, 9,495 (84.3%) were eligible for one or more CV evidence-based therapies. The proportions of patients with AF receiving all eligible guideline-recommended therapies were 40.8% of patients with coronary artery disease, 48.9% of patients with diabetes mellitus, 40.2% of patients with heart failure, 96.7% of patients with hypertension, and 55.1% of patients with peripheral arterial disease. Factors that were independently associated with nonreceipt of all indicated evidence-based therapies included sinus rhythm rather than AF at baseline and liver disease. In conclusion, although most Canadian outpatients with AF have CV risk factors or co-morbidities, a substantial portion of these patients did not receive all guideline-recommended therapies. These findings suggest that there is an opportunity to improve the quality of care for patients with AF in Canada.

Background— Long QT syndrome confers susceptibility to ventricular arrhythmia, predisposing to syncope, seizures, and sudden death. While rare globally, long QT syndrome is ≈15× more common in First Nations of Northern British Columbia largely because of a known mutation in KCNQ1 . However, 2 large multigenerational families were affected, but negative for the known mutation. Methods and Results— Long QT syndrome panel testing was carried out in the index case of each family, and clinical information was collected. Cascade genotyping was performed. Biochemical and myocyte-based assays were performed to evaluate the identified gene variant for loss-of-function activity. Index cases in these 2 families harbored a novel ANK2 c.1937C>T variant (p.S646F). An additional 16 carriers were identified, including 2 with structural heart disease: one with cardiomyopathy resulting in sudden death and the other with congenital heart disease. For all carriers of this variant, the average QTc was 475 ms (±40). Although ankyrin-B p.S646F is appropriately folded and expressed in bacteria, the mutant polypeptide displays reduced expression in cultured H9c2 cells and aberrant localization in primary cardiomyocytes. Furthermore, myocytes expressing ankyrin-B p.S646F lack normal membrane targeting of the ankyrin-binding partner, the Na/Ca exchanger. Thus, ankyrin-B p.S646F is a loss-of-function variant. Conclusions— We identify the first disease-causing ANK2 variant localized to the membrane-binding domain resulting in reduced ankyrin-B expression and abnormal localization. Further study is warranted on the potential association of this variant with structural heart disease given the role of ANK2 in targeting and stabilization of key structural and signaling molecules in cardiac cells.

Background The pharmacologic management of atrial fibrillation (AF), the most common sustained cardiac arrhythmia, has been traditionally dichotomized into control of ventricular rate or re-establishment and maintenance of sinus rhythm. Objective The purpose of this study was to evaluate the use of rate-controlling drugs and antiarrhythmic drugs (AAD) in the Canadian Registry of Atrial Fibrillation (CARAF) over a 16-year period from 1991 through 2007. Methods 1,400 patients with new-onset paroxysmal AF who were enrolled in CARAF were included in this analysis. We assessed trends in ventricular rate-controlling medication use (digoxin, beta-blockers, and calcium channel blockers) and AAD (class IA, IC, and III antiarrhythmic agents) at baseline and follow-up visits as well as by calendar year. Results AAD use increased initially from 1991 to 1994 (peak use 42.5%) before steadily declining. Sotalol use decreased (27% to 6%), whereas amiodarone use increased (1.6% to 17.9%). Rate-controlling medication use decreased from 1991 to 1995 (54.1% to 34.1%) due to declining digoxin use (62.9% to 16.3%). After 1999, there was a continued increase in rate-controlling medication use (peak use 52.5% in 2007) due to increased beta-blocker use (17% to 45.7%). Calcium channel blockers use changed little over the duration of the study. Conclusion The management of AF has undergone significant shifts since 1990, reflecting the influence of drug development, prevailing belief systems, the impact of large clinical trials, and evidence-based recommendations. Monitoring of pharmacotherapy trends will provide insight into the real-world application of evidence-based guidelines as well as allow the opportunity to identify deficiencies and improve patient care.

Background— Atrial fibrillation (AF) is commonly associated with impaired quality of life. There is no simple validated scale to quantify the functional illness burden of AF. The Canadian Cardiovascular Society Severity in Atrial Fibrillation (CCS-SAF) scale is a bedside scale that ranges from class 0 to 4, from no effect on functional quality of life to a severe effect on life quality. This study was performed to validate the scale. Methods and Results— In 484 patients with documented AF (62.2�12.5 years of age, 67% men; 62% paroxysmal and 38% persistent/permanent), the SAF class was assessed and 2 validated quality-of-life questionnaires were administered: the SF-36 generic scale and the disease-specific AFSS (University of Toronto Atrial Fibrillation Severity Scale). There is a significant linear graded correlation between the SAF class and measures of symptom severity, physical and emotional components of quality of life, general well-being, and health care consumption related to AF. Patients with SAF class 0 had age- and sex-standardized SF-36 scores of 0.15�0.16 and −0.04�0.31 (SD units), that is, units away from the mean population score for the mental and physical summary scores, respectively. For each unit increase in SAF class, there is a 0.36 and 0.40 SD unit decrease in the SF-36 score for the physical and mental components. As the SAF class increases from 0 to 4, the symptom severity score (range, 0 to 35) increases from 4.2�5.0 to 18.4�7.8 ( P Conclusions— The CCS-SAF scale is a simple semiquantitative scale that closely approximates patient-reported subjective measures of quality of life in AF and may be practical for clinical use.

Introduction: Radiofrequency ablation (RFA) has become an accepted therapy for atrial fibrillation (AF). The objective of this study was to perform an economic evaluation of RFA versus antiarrhythmic drug therapy (AAD) as first-line treatment of symptomatic paroxysmal AF. Methods: To estimate and compare the costs of RFA versus AAD, a decision analytic model was developed using data on AF recurrence, hospitalization rates, AAD use, and treatment crossover rates derived directly from the Randomized Trial of RFA versus AAD as First-Line Treatment of Symptomatic Atrial Fibrillation (RAAFT). Resource utilization was modeled to reflect Canadian clinical practice in AF management. Unit costs of healthcare interactions were based on available Canadian government resources and published literature. Costs were assessed based on intention-to-treat. Total expected costs were computed to include initial treatment, hospital stay, physician fees, diagnostic tests, and outpatient visits. Sensitivity analyses were performed to account for the uncertainties. The study was conducted from the third party payer's perspective and costs are reported in 2005 Canadian dollars with 3% discount rate used in the analysis. Results: During the 2-month blanking period following therapy selection, total average costs for RFA and AAD were $10,465 and $2,556, respectively; at 1-year follow-up, these were $12,823 and $6,053; and total 2-year cumulative total average costs were $15,303 and $14,392. Sensitivity analyses did not alter the results, suggesting the model is robust. Conclusions: RFA as first-line treatment strategy in patients with symptomatic paroxysmal AF was cost neutral 2 years after the initial procedure compared to AAD.

Objectives Transcatheter aortic valve replacement (AVR) is a promising approach to aortic valve disease. The implications of this new therapy are not entirely known. We describe the potential for the development of new atrioventricular (AV) block. Background Atrioventricular block is a known complication of conventional surgical AVR. Block is presumed to occur as a consequence of surgical trauma to the cardiac conduction tissue during excision of the diseased aortic valve and debridement of the calcified annulus. Whether AV block might occur as a consequence of nonsurgical implantation of an aortic stent valve is unknown. Methods We reviewed our experience with patients undergoing transcatheter AVR using both the percutaneous transarterial and the open-chest direct left ventricular apical ventriculotomy approaches. Patients were considered at high risk for conventional surgery because of comorbidities. Continuous arrhythmia monitoring was performed for at least 48 h after the valve implantation procedure. Patients who developed apparently new, clinically significant AV block were identified. Results Transcatheter AVR was successfully performed in 123 patients. Seventeen of these patients (13.8%) had pre-existing permanent pacemakers. Two patients (1.6%) required pacemaker implantation because of pre-existing intermittent bradycardia. Seven patients (5.7%) developed new and sustained complete AV block requiring pacemaker implantation. An additional 4 patients (3.3%) developed new and sustained left bundle branch block but did not require pacemaker implantation. Conclusions As with conventional AVR surgery, transcatheter AVR may result in impaired atrioventricular conduction. Physicians and patients should be aware of the potential for AV block and pacemaker dependence.

Background Statins have important pleiotropic effects and have been shown to reduce vascular inflammation and the incidence of atrial fibrillation (AF) after cardiac surgery. The role of statins in patients with existing AF is poorly understood. We examined the effect of statins on recurrence of AF in patients after successful cardioversion. Methods Statin use and documented recurrence of AF after successful cardioversion were evaluated in 625 patients with new onset AF who were followed prospectively in the Canadian Registry of Atrial Fibrillation. Logistic regression was used to model the effect of statin use on the recurrence of AF at 1 year while adjusting for potential confounders including concurrent medications. Results In a predominantly male population (62%) with median age 63 years, 12.3% were on statins at baseline. Overall, 32.5% had documented recurrence of AF at 1 year; 23.4% in patients on statins compared to 33.8% in those not on statins ( P = .07). After adjustment for baseline differences and concomitant β-blocker use, statin use was associated with a 74% reduction in AF recurrence, but only in statin users on β-blockers (OR 0.26, 95% CI 0.10-0.66); statin users not on β-blockers (OR 1.07, 95% CI 0.44-2.58). Conclusions In an observational study of patients with new onset AF, statin use was associated with a significant 74% reduction in the odds of recurrent AF, but only in patients also taking β-blockers. Importantly, statin without concomitant β-blocker use was not associated with any changes in AF recurrence.

Study Objective. To determine the risk of bleeding and supratherapeutic international normalized ratios (INRs) associated with use of complementary and alternative medicine (CAM) in patients receiving warfarin. Design. Prospective, longitudinal study. Setting. An acute care, academic and research hospital in Canada. Patients. A total of 171 adults who were prescribed warfarin anticoagulation therapy for an expected duration of at least 4 months after enrollment. Intervention. Patients were asked to complete a 16-week diary by recording bleeding events and exposure to factors previously reported to increase the risk of bleeding and supratherapeutic INRs, including CAM consumption. Measurements and Main Results. Prescription, medical, and laboratory records were reviewed. Risk factors for bleeding events and supratherapeutic INR (at least 0.5 units above the target range) were evaluated longitudinally by using generalized estimating equation (GEE) modeling. Of the 171 patients completing a diary, 87 (51%) reported at least one bleeding event and 36 (21%) had a supratherapeutic INR. Seventy-three patients (43%) indicated they had used at least one CAM product previously reported to interact with warfarin. Warfarin use of less than 3 months' duration was the only statistically significant risk factor identified for supratherapeutic INR. The CAM therapies associated with an increased risk of self-reported bleeding included cayenne, ginger, willow bark, St. John's wort, and coenzyme Q10. Use of more than one CAM while receiving warfarin was also a significant risk factor. Two CAMs were independently associated with an increased risk of self-reported bleeding: coenzyme Q10 (odds ratio [OR] 3.69, 95% confidence interval [CI] 1.88–7.24) and ginger (OR 3.20, 95% CI 2.42–4.24). Other risk factors significantly associated with increased bleeding included high target INR (2.5–3.5), diarrhea, acetaminophen use, increased alcohol consumption, and increased age. Conclusions. The use of CAM by patients receiving warfarin is common, and consumption of coenzyme Q10 or ginger appears to increase the risk of bleeding in this population.

Medtronic's Lead Integrity Alert (LIA) software algorithm is useful for detecting abnormal parameters across various ICD-lead families. However, its utility in the assessment of the Biotronik Linox™ family of high-voltage (HV) leads is unknown.We conducted a retrospective cohort study to assess the performance of the LIA algorithm to detect abnormalities and lead failure in Linox ICD-leads. All LIA-enabled Medtronic devices connected to an active Linox lead were included. The alerts were adjudicated by 2 blinded electrophysiologists and correlated with clinical data.Between 2008 and 2012, data from 208 patients with 564 patient-years of follow-up were available for analysis. The median follow-up duration was 32 (IQR 21-41 months). Twenty-one LIA triggers were noted in 20 different patients. The median delay until a positive LIA was 32 months (IQR 21-41 months) postimplant with a 5-year lead survival free from LIA of 76%. Ninety-five percent (19/20) LIA alerts were true lead failures. The most common LIA triggers were short V-V intervals (85%) and nonsustained ventricular tachycardia (85%). Abrupt changes of the ICD-lead impedance occurred in 5/20 triggers. Inappropriate ICD-shocks were strongly associated with a positive LIA (30% vs. 7.4%; P = 0.006). Of the explanted Linox leads 53% had visible abnormalities. The sensitivity, specificity, and positive predictive value for lead failure in the presence of a LIA trigger were 87%, 99.5%, and 95.2%, respectively.A positive LIA trigger in Biotronik Linox ICD-leads is highly predictive of lead failure. LIA is useful in ongoing surveillance of lead performance.

Background— Social health is a dimension of quality of life, and refers to people’s involvement in, and satisfaction with social roles, responsibilities, and activities. The implantable cardioverter-defibrillator is associated with changes in overall quality of life, but little is known about sex differences in individual trajectories of change in social health. Methods and Results— We prospectively measured changes in 3 subscales of the SF-36v2 generic health questionnaire (role physical, role emotional, and social functioning), 2 Patient-Reported Outcomes Measurement Information System short forms (satisfaction with participation in social roles and satisfaction with participation in discretionary social activities), and the Florida Patient Acceptance Survey before and at 1, 2, and 6 months after implantation. Individual growth models of temporal change were estimated. The scores of the 6 indicators improved with time. The unconditional model demonstrated significant (fixed effects: P P Conclusions— Men and women differed in their trajectories of change in social health, both in terms of their starting points (ie, baseline scores) and their rates of change.

Azimilide hydrochloride (azimilide), an investigational antiarrhythmic drug, has shown variable efficacy in preventing atrial fibrillation (AF). This study was designed to assess its efficacy in maintaining sinus rhythm in patients with paroxysmal AF and heart disease. Patients with symptomatic paroxysmal AF were screened for 1 month by transtelephonic monitoring. After recording 1 episode of AF in the screening period, they were randomized to receive azimilide 125 mg or placebo once daily. Patients were stratified by the presence or absence of congestive heart failure or coronary heart disease (CHF/CHD). A maximum of 220 patients without CHF/CHD were randomized, with the remainder having CHF/CHD. Patients with CHF/CHD were monitored for 3 days during loading. The primary efficacy analysis was the time to the first symptomatic recurrence of AF in the CHF/CHD group. Secondary analyses were the time to the first recurrence in the entire population and the time to the first recurrence in those with significant structural heart disease. The median time to recurrence of AF in the CHF/CHD group was 10 days in the 2 treatment arms. Nonsignificant trends were seen toward efficacy of azimilide in the CHF/CHD group (hazard ratio 1.28, 95% confidence interval 0.97 to 1.70, p=0.087), structural heart disease group (hazard ratio 1.22, 95% confidence interval 0.96 to 1.56, p=0.11), and overall group (hazard ratio 1.22, 95% confidence interval 1.00 to 1.49, p=0.053). No patient died. In conclusion, azimilide showed a nonsignificant trend toward efficacy in maintaining sinus rhythm in patients with AF.

Azimilide dihydrochloride (azimilide) is an investigational antiarrhythmic drug that has been tested in patients with a variety of arrhythmias. In patients with atrial fibrillation, it has shown excellent efficacy in some previous trials and minimal efficacy in others.Patients who had symptomatic atrial fibrillation for48 hours but6 months were eligible for this multicenter, randomized, placebo-controlled clinical trial. Patients were admitted to a hospital and randomly assigned to receive either azimilide 125 mg or a matched placebo twice daily for 3 days and then once daily. Patients who were in sinus rhythm spontaneously or had sinus rhythm restored by electric cardioversion on day 4 were discharged from the hospital. Recurrence of atrial fibrillation was documented by electrocardiogram. In the primary efficacy analysis, time to recurrence in the 2 treatment groups was compared with the log-rank test in the subgroup of patients with structural heart disease. Safety was assessed as deaths, adverse events, and serious adverse events.A total of 446 patients were randomized in the study; 314 were in the subgroup with structural heart disease. The median time to arrhythmia recurrence in both treatment groups with structural heart disease was 13 days, and the difference between treatments was not significant (P = .4596, n = 314). The relative risk for recurrence (placebo:azimilide) was 1.104 (95% CI 0.849-1.436). There was 1 death in the placebo group and 3 in the azimilide group.Azimilide did not demonstrate clinically important or statistically significant efficacy in reducing the risk for arrhythmia recurrence in patients with structural heart disease who were in atrial fibrillation and converted to sinus rhythm.

Canadian atrial fibrillation (AF) guidelines recommend that all AF patients be risk stratified with respect to stroke and bleeding, and that most should receive antithrombotic therapy.As part of the Canadian Facilitating Review and Education to Optimize Stroke Prevention in Atrial Fibrillation (FREEDOM AF) chart audit, data were collected on 4670 patients ≥ 18 years old without significant valvular heart disease from the primary care practices of 474 physicians (February to September, 2011).Physicians did not provide an estimate of stroke and bleeding risk in 15% and 25% of patients, respectively. When risks were provided, they were on the basis of a predictive stroke and bleeding risk index in only 50% and 26% of patients, respectively. There were over- and underestimation of stroke and bleeding risk in a large proportion of patients. Antithrombotic therapy included warfarin (90%); 24% of patients had a time in the therapeutic range (TTR)50%, 9% between 50% and 60%, 11% between 60% and 70%, and 56% had a TTR ≥ 70%.In a large Canadian AF population, primary care physicians did not provide a stroke or bleeding risk in a substantial proportion of their AF patients. When estimates were provided, they were on the basis of a predictive stroke and bleeding risk index in less than half of the patients. Furthermore, there was under- and overestimation of stroke and bleeding risk in a substantial proportion of patients. As many as 1 in 3 patients receiving warfarin have their TTR60%. These findings suggest an opportunity to enhance knowledge translation to primary care physicians.

Atrial fibrillation (AF) is the most common sustained arrhythmia seen in clinical practice, and accounts for most arrhythmia-related emergency room visits and hospital admissions. The present-day management of AF is centred on improving arrhythmia-related symptoms, exercise tolerance, and quality of life, and reducing the morbidity and mortality associated with AF (ie, the prevention of stroke or systemic thromboembolism and tachycardia-induced cardiomyopathy). The contemporary management of AF is centred on the apparently competing strategies of rate and rhythm control, which are more appropriately viewed as complementary. This contemporary review will discuss the rationale underpinning the rate control strategy, and focus on practical aspects of undertaking a rate control strategy.

The effect of left atrial (LA) dimension on the recurrence of atrial fibrillation (AF) has been examined in small studies. We evaluated the effect of LA dimension on the occurrence of AF using 2- and 4-year echocardiographic data in a large cohort of patients with new onset AF.The Canadian Registry of AF (CARAF) enrolled subjects with AF at the first electrocardiographically confirmed diagnosis. Patients were classified at 2 and 4 years as no recurrent AF (No RAF), paroxysmal AF (PAF), or chronic AF (CAF) based on clinical symptoms and electrocardiographic documentation. The association between baseline, 2-, and 4-year LA dimensions with occurrence of AF as determined by echocardiography was evaluated using a multivariate analysis.The No RAF group (n = 176) had a significantly smaller LA dimension (36.9 +/- 6.8 mm) at baseline compared to the CAF group (n = 227) (42.8 +/- 7.5 mm, P.0001). The No RAF and PAF (n = 153) groups did not have a significant change in LA dimension at 2 or 4 years. Only those with CAF had a significant increase in LA dimension at 2 and 4 years, +1.39 mm (95% CI 0.01-2.8) and +3.48 mm (95% CI 1.8-5.2), respectively.A larger baseline LA dimension is associated with progression to CAF. Patients with no or paroxysmal recurrence had no change in LA dimension over a 4-year period. These findings have implications in tailoring modes of therapy in patients with AF.

Background: Of the antiarrhythmic agents currently marketed in Canada, 5 are commonly used to treat atrial fibrillation (AF). The impact of contraindications, warnings and precautions for the use of these drugs in patients with AF is not known. We evaluated the proportion of patients with AF for whom contraindications, warnings and/or precautions might limit the use of these commonly prescribed drugs and the proportion of patients actually receiving antiarrhythmic drugs despite the presence of contraindications and/or warnings. Methods: A total of 723 patients with electrocardiographically confirmed, new-onset paroxysmal AF who were enrolled in the Canadian Registry of Atrial Fibrillation were used in this analysis. The 1996 Compendium of Pharmaceuticals and Specialties was used to obtain contraindications, warnings and precautions for use of 5 antiarrhythmic drugs: flecainide, quinidine, sotalol, amiodarone and propafenone. Proportions of patients with contraindications, warnings and/or precautions for use of any of these drugs owing to comorbid conditions or concomitant drug therapy were calculated, regardless of whether the drugs had been prescribed. We then calculated the proportion of patients taking each antiarrhythmic drug at 3 months despite contraindications and/or warnings. Results: At baseline, when conditions for contraindications and warnings were combined, 414 (57%), 235 (33%), 327 (45%), 285 (39%) and 272 (38%) patients had restrictions for the use of flecainide, quinidine, sotalol, amiodarone and propafenone respectively. Among 465 patients actually taking these medications at 3-month follow-up, 33.3% (2/6), 83.3% (40/48), 36.4% (92/253), 64.1% (25/39) and 34.5% (41/119) respectively had contraindications and/or warnings against their use. The burden of comorbid disease among patients with AF was noteworthy: 404 (56%) had structural heart disease, which included 227 (31%) with ischemic heart disease, 158 (22%) with left ventricular systolic dysfunction and 106 (15%) with heart failure. Interpretation: The high burden of comorbid disease and concomitant drug use in a large proportion of patients with AF limits the suitability of existing antiarrhythmic drugs. Over one-third of patients with new-onset AF received antiarrhythmic drugs despite the presence of contraindications or warnings. Although such restrictions may not preclude the use of these drugs, the results demonstrate the need for new antiarrhythmic drugs with fewer limitations.

Background Malignant ventricular tachyarrhythmia early after cardiac surgery is an uncommon arrhythmic complication but has a negative impact on mortality. The purpose of this study was to evaluate the incidence of new-onset sustained postoperative ventricular tachycardia-ventricular fibrillation and to identify risk factors for the dysrhythmia. Methods Demographic, clinical, operative, and postoperative data, including a variable of postoperative ventricular tachycardia, were prospectively obtained from 4,748 patients undergoing nonemergency coronary artery bypass graft and(or) valve replacement with no history of sustained ventricular tachycardia or sudden death. A detailed analysis was performed to define the risk factors for the ventricular tachycardia and the prognostic impact of the arrhythmia on 30-day mortality was evaluated. Results Forty-five patients (0.95%) had sustained ventricular tachycardia or ventricular fibrillation and the initial episode occurred 3.9 ± 5.2 days (mean ± standard deviation) after surgery. By multivariate analysis, female sex (odds ratio, 1.982), left ventricular ejection fraction ( 50%, 4.771), the presence of pulmonary hypertension (3.066), the presence of systemic hypertension (2.391), and pump time (per 10 minutes, 1.085) were independently associated with the dysrhythmias. Early mortality of patients with the arrhythmia was 28.9%, strikingly higher than that of patients without ventricular tachycardia/ventricular fibrillation (1.9%). Conclusions Left ventricular ejection fraction is the strongest risk factor for new-onset postoperative sustained ventricular tachycardia-ventricular fibrillation; female sex, pump time, pulmonary and systemic hypertension are independent predictors of the dysrhythmias; the arrhythmia is associated with increased 30-day mortality after cardiac surgery.

Background— The Canadian Trial of Physiological Pacing (CTOPP) reported that the risk of stroke or cardiovascular death was similar between patients receiving ventricular versus physiological pacemakers at the end of the original follow-up period of 3 years. However, the occurrence of atrial fibrillation was significantly less frequent with physiological pacemakers. To assess a potential delayed benefit of physiological pacing, follow-up of patients in this study was extended to 6 years. Methods and Results— A total of 1474 patients requiring a pacemaker for symptomatic bradycardia were randomized to receive ventricular and 1094 to physiological pacemakers. The primary outcome was stroke or cardiovascular death. The study was completed in July 1998, and follow-up was extended to July 2001. At a mean follow-up of 6.4 years, there was no difference between treatment groups in the primary outcome of cardiovascular death or stroke. There was no significant difference in total mortality or stroke between groups. There was a significantly lower rate of development of atrial fibrillation in the physiological group, with a relative risk reduction of 20.1% (CI, 5.4 to 32.5; P =0.009). Conclusions— The CTOPP extended study does not show a difference in cardiovascular death or stroke, or in total mortality, or in stroke between patients implanted with ventricular or physiological pacemakers over a mean follow-up of >6 years. However, there is a persistent significant reduction in the development of atrial fibrillation with physiological pacing.

Background: For patients with drug-refractory atrial fibrillation, radiofrequency catheter ablation of the atrioventricular junction and pacemaker implantation is a nonpharmacologic option routinely used nowadays. Few data are available on the long-term survival following the procedure or on evaluation of the risk factors for death in a large study cohort.

Evaluation of: Barrett PM, Komatireddy R, Haaser S et al. Comparison of 24-hour Holter monitoring with 14-day novel adhesive patch electrocardiographic monitoring. Am. J. Med. 127(1), 95.e11–95.e17 (2014). The investigation of cardiac arrhythmias in the outpatient ambulatory setting has traditionally been initiated with the Holter monitor. Using the continuous recording over 24 or 48 h, the Holter monitor permits the detection of baseline rhythm, dysrhythmia and conduction abnormalities, including heart block and changes in the ST segment that may indicate myocardial ischemia. However, apart from the bulkiness and inconvenience of the device itself, the lack of extended monitoring results in a diagnostic yield of typically less than 20%. In this study by Barrett et al., 146 patients referred for the evaluation of cardiac arrhythmia were prospectively enrolled to wear both the 24-h Holter monitor and 14-day adhesive patch monitor (Zio® Patch) simultaneously. The primary outcome was the detection of any one of six arrhythmias: supraventricular tachycardia, atrial fibrillation/flutter, pause >3 s, atrioventricular block, ventricular tachycardia, or polymorphic ventricular tachycardia/fibrillation. The adhesive patch monitor detected more arrhythmia events compared with the Holter monitor over the total wear time (96 vs 61 events; p

OBJECTIVES This study examined the effect of physiologic pacing on the development of chronic atrial fibrillation (CAF) in the Canadian Trial Of Physiologic Pacing (CTOPP). BACKGROUND The role of physiologic pacing to prevent CAF remains unclear. Small randomized studies have suggested a benefit for patients with sick sinus syndrome. No data from a large randomized trial are available. METHODS The CTOPP randomized patients undergoing first pacemaker implant to ventricular-based or physiologic pacing (AAI or DDD). Patients who were prospectively found to have persistent atrial fibrillation (AF) lasting greater than or equal to one week were defined as having CAF. Kaplan-Meier plots for the development of CAF were compared by log-rank test. The effect of baseline variables on the benefit of physiologic pacing was evaluated by Cox proportional hazards modeling. RESULTS Physiologic pacing reduced the development of CAF by 27.1%, from 3.84% per year to 2.8% per year (p = 0.016). Three clinical factors predicted the development of CAF: age ≥74 years (p = 0.057), sinoatrial (SA) node disease (p < 0.001) and prior AF (p < 0.001). Subgroup analysis demonstrated a trend for patients with no history of myocardial infarction or coronary disease (p = 0.09) as well as apparently normal left ventricular function (p = 0.11) to derive greatest benefit. CONCLUSIONS Physiologic pacing reduces the annual rate of development of chronic AF in patients undergoing first pacemaker implant. Age ≥74 years, SA node disease and prior AF predicted the development of CAF. Patients with structurally normal hearts appear to derive greatest benefits.

Background —A recently completed trial, the Canadian Trial of Physiological Pacing (CTOPP), showed that physiological pacing did not significantly reduce mortality, stroke, or heart failure hospitalization, but it did show that atrial fibrillation occurred less frequently in patients with physiological pacing. Many pacemaker patients experience only transient bradyarrhythmias with an adequate unpaced heart rate (UHR) and are not pacemaker-dependent. The purpose of the present analysis was to determine if pacemaker-dependent patients have an increased benefit from physiological pacing compared with non–pacemaker-dependent patients. Methods and Results —Of 2568 patients included in the CTOPP trial, 2244 patients had a pacemaker dependency test performed at the first follow-up visit. The yearly event rate of cardiovascular death or stroke steadily increased with decreasing UHR in the ventricular pacing group, but it remained constant in the physiological pacing group. When the patients were subdivided to UHR ≤60 bpm or >60 bpm, there was an interaction between pacing mode treatment and UHR subgroup. The Kaplan-Meier plot confirmed a physiological pacing advantage only in the UHR ≤60 bpm subgroup. This differential effect was also present for the outcomes of cardiovascular death and total mortality. Conclusions —This study demonstrated that UHR at first follow-up has an important influence on how pacing mode selection affects cardiovascular death and total mortality. Pacemaker-dependent patients with low UHR will probably be paced frequently and will likely benefit from physiological pacing. In contrast, non–pacemaker-dependent patients will likely be paced infrequently and may not benefit from physiological pacing.

The circadian variation of paroxysmal atrial fibrillation (AF) was studied in 67 patients who received a dual-chamber pacemaker 3 months before a planned atrioventricular node ablation. A distinct circadian variation of AF was observed with 2 time peaks in initiation (1 in the early morning and 1 in the early evening hours), which was modulated by atrial pacing, the duration of AF, and the use of beta-adrenergic blocking agents.

Aims In the era of increasing implantable cardioverter defibrillator (ICD) complexity, the ICD patient alert is deemed to be an important feature in the early detection of ICD system malfunction and is either an audible or a vibratory alert. We sought to evaluate the patient's ability to detect these ICD alerts in the device clinic setting as a surrogate endpoint of clinical utility. Methods and results From 1 November 2006 to 31 March 2008, 563 patients with an ICD equipped with either an audible patient alert (APA, Medtronic and Guidant; n = 485) or a vibratory monitoring alert ([VMA, St Jude Medical; n = 78) had their alarm demonstrated in the quiet clinic setting. The ability to recognize the alert was analysed and then stratified by gender, age, manufacturer, type of alert, and pocket location. The average patient age was 63.3 (±13.6) years and 82.8% of patients were male. Implantable cardioverter defibrillator manufacturers were Medtronic ( n = 464), Boston Scientific ( n = 21), and SJM ( n = 78). The APA was heard in 86.0% of patients. This was less likely in patients who were older, male, and where the device was placed in the submuscular position. Every patient with a VMA sensed their alert. Conclusion In the current ICD alert technology, the ability to sense the ICD alert in the device clinic appears to be higher for the VMA than for the APA. In particular, older patients and male patients are less likely to sense the APA.

Background —Some clinical data suggest that atrial-based pacing prevents paroxysmal atrial fibrillation (AF). This study tested the hypothesis that DDDR pacing compared with VDD pacing prevents AF after atrioventricular (AV) junction ablation. Methods and Results —Patients were randomized to DDDR pacing (n=33) or to VDD pacing (n=34) after AV junction ablation and followed every 2 months for 6 months. Patients then crossed over to the alternate pacing mode and were followed for an additional 6 months. Primary analysis included the time to first recurrence of sustained AF (duration >5 minutes), total AF burden, and the development of permanent AF. The time to first episode of AF was similar in the DDDR group (0.37 days, 95% CI 0.1 to 1.3 days) and the VDD pacing group (0.5 days, 95% CI 0.2 to 1.7 days, P =NS). AF burden increased over time in both groups ( P P =NS). Twelve (35%) patients in the DDDR group and 11 (32%) patients in the VDD group had permanent AF within 6 months of ablation. Within 1 year of follow-up, 43% of patients had permanent AF. Conclusions —DDDR pacing compared with VDD pacing does not prevent paroxysmal AF over the long term in patients in the absence of antiarrhythmic drug therapy after total AV junction ablation. Many patients have permanent AF within the first year after ablation.

Background Evidence suggests that physiologic pacing (dual-chamber or atrial) may be superior to single-chamber (ventricular) pacing because it is associated with lower risks of atrial fibrillation, stroke, and death. These benefits have not been evaluated in a large, randomized, controlled trial. Methods At 32 Canadian centers, patients without chronic atrial fibrillation who were scheduled for a first implantation of a pacemaker to treat symptomatic bradycardia were eligible for enrollment. We randomly assigned patients to receive either a ventricular pacemaker or a physiologic pacemaker and followed them for an average of three years. The primary outcome was stroke or death due to cardiovascular causes. Secondary outcomes were death from any cause, atrial fibrillation, and hospitalization for heart failure. Results A total of 1474 patients were randomly assigned to receive a ventricular pacemaker and 1094 to receive a physiologic pacemaker. The annual rate of stroke or death due to cardiovascular cause...

Current recommendations in favor of dual-chamber over single-chamber ventricular pacing for patients with sinus node dysfunction or AV conduction disorders were made largely based on observational data and expert opinions. The first randomized pacing mode selection study was relatively small and suggested survival advantage with physiologic pacing only after an extended follow-up duration of 5.5 years. Preliminary results of the first large-scale multicenter randomized pacing mode selection trial revealed only modest reduction in atrial fibrillation without survival advantage after 3 years of physiologic pacing. Two other large-scale multicenter randomized trials comparing physiologic versus ventricular pacing are currently ongoing. They may provide further scientific evidence based on which more objective recommendations can be made with respect to pacing mode selection.

There is a relative paucity of data linking inappropriate implantable cardioverter-defibrillator (ICD) shocks to adverse clinical outcomes.To examine the association between inappropriate ICD shocks and mortality or heart transplantation in a large population cohort.A cohort study which included all subjects who underwent ICD implantation between 1998 and 2008 and were followed up at our institution.Multivariable Cox regression analyses were conducted to investigate the effect of inappropriate shocks on the risk of death and heart transplantation. Appropriate and inappropriate ICD therapies were modelled as time-dependent covariates.A total of 1698 patients were included. During a median follow-up of 30 months, there were 246 (14.5%) deaths and 42 (2.5%) heart transplants. The incidence of inappropriate shocks was 10% at 1 year and 14% at 2 years. In the adjusted model, inappropriate shocks were not associated with death or transplantation (HR=0.97, 95% CI 0.70 to 1.36, p value=0.873). In contrast, appropriate shocks were associated with adverse outcomes (HR=3.11, 95% CI 2.41 to 4.02, p value0.001). The lack of association between inappropriate shocks and outcomes persisted for those with severely impaired left ventricular function (ejection fraction30%) and for those receiving multiple inappropriate treatments.In this study, we observed no association between inappropriate ICD shocks and increased mortality or heart transplantation, even among those with severely impaired cardiac function. These findings question whether inappropriate ICD shocks lead to adverse outcomes.

This report presents the outcome of a cohort of 94 patients with atrial fibrillation from the Canadian Registry of Atrial Fibrillation, in which we paid particular attention to the probability of stroke and death. We also evaluated warfarin use over time and compared left atrial dimensions in patients with atrial flutter with those with atrial fibrilliation.

Background Catheter ablation of the atrioventricular (AV) node with radiofrequency current (RFC) is associated with the short-term onset of a junctional escape rhythm (JER) in nearly all patients. However, the origin of the JER and short-term thermal effects of RFC on this junctional pacemaker activity are ill defined. Methods and Results Short-term and noninvasive long-term follow-up studies were performed to examine the electrophysiological characteristics of the underlying JER in 45 patients who had undergone AV nodal ablation with RFC. Baseline characteristics and responses to overdrive ventricular pacing and intravenous atropine followed by an incremental isoproterenol infusion were determined. Short- and long-term responses were compared. HV intervals before and after ablation were 49±9 and 48±9 milliseconds, respectively ( P =NS). Follow-up was 11±8.3 months. JER cycle length was 1526±298 milliseconds in the short-term setting and was present in 44 patients (98%) in the long-term setting, measuring 1426±223 milliseconds ( P P =NS), and 20.6±12.1% versus 24.8±9.1% with 4 μg/min ( P Conclusions Radiofrequency ablation of the AV node is associated with development of a JER that is stable in the long-term setting. The lack of change in HV interval after ablation locates the junctional pacemaker proximal to the central fibrous body. The pattern of drug responses suggests an origin within the proximal His bundle at its junction with the AV node rather than the AV node itself. The overall similarity between short- and long-term characteristics of junctional pacemaker activity mitigates against any reversible thermal effects of RFC on this pacemaker focus.

The modulation of quinidine's effect by pacing cycle lengths was assessed over an isthmus of atrial myocardium, simulating the Wolff-Parkinson-White syndrome. Isolated rabbit atria were dissected so that two tissue blocks, A and B, were linked by an isthmus, 1 mm in width. Effective refractory period in the tissue blocks and over the isthmus was measured at cycle lengths of 1000, 600, and 400 ms, and the minimum cycle length to sustain 1:1 conduction over the isthmus was measured before treatment, during quinidine superfusion (4 mg/L), and after washout. Longitudinal velocity over the isthmus was also measured. The increment in the effective refractory period in the tissue blocks by quinidine appeared to be similar, about 10% at three pacing cycle lengths (p > 0.05). However, the increment of the effective refractory period over the isthmus was modulated by pacing cycle lengths: greater increase at shorter cycle lengths (p

BACKGROUND: Patients with PMs or ICDs may be exposed to significant electromagnetic fields (EMF) from high voltage transmission lines (HVTL), which may interact with their device. To our knowledge, the rate of electromagnetic interference (EMI) has not been quantified nor have the circumstances of these EMIs. These were the objectives of the current registry. METHOD: Between February 2012 and March 2014, 18 296 device interrogations from patient visits to the PM/ICD clinic were reviewed (11 640 from PMs and 6 656 from ICDs). Fifty patients were recruited after noise episodes were seen during a routine follow-up interrogation. Only 10% of patients with noise episodes refused recruitment in the registry. Recruited patients were asked to keep a detailed log of their activities and travels. Their devices were then re-interrogated after 1, 4 and 12 weeks. Noise events registered on the devices interrogated in the PM/ICD clinic were correlated with a geographical map of the EMFs created by HVTLs, provided by Hydro-Quebec, the province of Quebec’s hydroelectric producer. RESULTS: Two patients were lost to follow-up. Of the remaining 48, 25 had further interference episodes for a total number of 1,080 episodes. Of these, 985 (91.2%) took place at home, 76 (7.1%), during an unknown activity (no activity recorded in the patient log at the time of the interference) and 19 (1.8%), during travels where a HVTL was identified in the vicinity. All of these travels, but one, were in motor vehicles which acted as a Faraday cage and shielded the patients and device from the electric field generated by the HVTLs. No episode was associated with a movement directly under a HVTL, on foot. There was no difference in the morphology of the noise signals based on the type of activity. A single inappropriate mode switch was noted as a result of the noise episodes. There was no relation between patient reported symptoms and the noise episodes. CONCLUSION: The overall rate of EMI is very low (0.3%) and the majority of episodes occur in the home environment. Despite the large number of patients sampled, there were no episodes of EMI linked to passage under a HVTL, which is reassuring from a public safety standpoint.

Defibrillation Testing at ICD Implantation.Background: There is uncertainty about the proper role of defibrillation testing (DT) at the time of implantable cardioverter defibrillator (ICD) insertion. Methods: A prospective registry was conducted at 13 sites in Canada between January 2006 and October 2007. Objectives: To document the details of DT, the reasons for not conducting DT, and the costs and complications associated with DT. Results: DT was conducted at implantation in 230 of 361 patients (64%). DT was more likely to be conducted for new implants compared with impulse generator replacements (71% vs 32%, P = 0.0001), but was similar for primary and secondary prevention indications (64% vs 63%, P = NS). Among patients not having DT, the reason(s) given were: considered unnecessary (44%); considered unsafe, mainly due to persistent atrial fibrillation (37%); lack of an anesthetist (20%); and, patient or physician preference (6%). When performed, DT consisted of a single successful shock ≥ 10J below maximum device output in 65% of cases. A 10J safety-margin was met by 97% of patients, requiring system modification in 2.3%. Major perioperative complications occurred in 4.4% of patients having DT versus 6.6% of patients not having DT (P = NS). ICD insertion was $844 more expensive for patients having DT (P = 0.16), largely due to increased costs ($28,017 vs $24,545) among patients having impulse generator replacement (P = 0.02). Conclusions: DT was not performed in a third of ICD implants, usually due to a perceived lack of need or relative contraindication. (J Cardiovasc Electrophysiol, Vol. 21, pp. 177-182, February 2010)