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Pulmonary vein isolation (PVI) using radiofrequency catheter ablation is a widely accepted therapy for drug-refractory atrial fibrillation patients. Elimination of the negative component of the local unipolar electrogram (UEGM) during PVI is a marker of transmural lesion formation. The ablation index (AI) can predict the quality of ablation lesion. Combining these two parameters could make PVI safer and efficient. The purpose of this pilot study was to examine the correlation between UEGM modification characteristics of the different target areas of left atrium and the associated AI values during PVI.We analyzed 10 patients who underwent PVI using radiofrequency energy. The local electrophysiological properties and ablation parameters of 15 designated areas of interest in the left atria targeted by radiofrequency catheter ablation were collected.Out of the 10 patients, six were men (mean age 66 years) and 80% had paroxysmal AF. The mean time to achieve the UEGM modification in the posterior wall was shorter than that of the anterior wall (8.9 seconds vs. 11.1 s, respectively). The UEGM modification for every lesion was achieved at significantly lower AI values than conventional AIs (p .001).During PVI, the AIs deduced according to the local UEGM modification are markedly shorter than those generally recommended AIs in contemporary practice. This indicates that conventionally recommended AIs could be safely reduced while ensuring the efficacy and quality of radiofrequency ablation during PVI. This approach would probably reduce to risk of collateral thermal injuries.

Adherence to oral anticoagulants (OACs) in patients with atrial fibrillation (AF) is important in preventing stroke. The dominance of retrospective studies using administrative data has led to a lack of data on psychosocial determinants of adherence and prevented comparison of adherence between OAC drug classes. OAC switching is another aspect of adherence that is unexplored.A prospective design was utilized to measure AF patients' self-reported adherence and OAC switching, and to identify their clinical, demographic, and psychosocial determinants. Participants were recruited from specialized AF clinics in Canada and followed for up to 2 years. Data were collected via telephone every 3-4 months using a structured survey. Adherence was measured using the Morisky Medication Adherence scale (©MMAS-8).The included participants (N = 306) were followed for a median follow up time of 14.1 months and had an average of 3.2(SD 1.4) study visits. The mean self-reported adherence on the ©MMAS-8 was 7.28(SD 0.71) for patients receiving care at specialized AF clinics. Older age, experiencing a bleed, and higher satisfaction with the burden of medications were significantly associated with higher adherence. Drug class did not have any significant impact on adherence. 7.8% of the cohort experienced a switch with most of them being from warfarin to DOAC. Taking warfarin as the index medication, experiencing a bleed and older age were significantly associated with higher odds of switching.Patients with AF reported high adherence to their OAC therapy however being on DOAC may not translate to better adherence compared to VKA. Improving satisfaction with the burden of therapy is important in improving adherence.

Atrial fibrillation (AF) is a common chronic and progressive heart rhythm disorder. For those in whom sinus rhythm is desired, contemporary clinical practice guidelines recommend antiarrhythmic drugs (AADs) as the initial therapy. However, these medications have modest efficacy and are associated with significant adverse effects.The current article reviews the evidence surrounding first-line catheter ablation, particularly the emerging evidence surrounding the use of cryoballoon ablation as a first-line therapy. The focus of the review is on the outcomes of arrhythmia freedom, quality of life, health-care utilization, and safety. In addition, the article will review novel cryoablation systems.Recent evidence suggests that cryoballoon ablation significantly improves arrhythmia outcomes (e.g. freedom from any atrial tachyarrhythmia or symptomatic atrial tachyarrhythmia, reduction in arrhythmia burden), patient-reported outcomes (e.g. symptoms and quality of life), and health-care resource utilization (e.g. hospitalization), without increasing the risk of adverse events. These findings are relevant to patients, providers, and health-care systems, as they help inform the decision-making regarding the initial choice of rhythm-control therapy in patients with treatment-naive AF.

Aims Hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease. Insertable cardiac monitors (ICMs) are increasingly used in this population to provide closer monitoring, with the potential for notification systems. However, little is known regarding the psychological impact this information may have on patients. The Abbott Confirm Rx™ ICM has the capability of connecting to the patient’s smartphone to enable active participation in their care, as well as two-way communication between the patient and their care providers. This study aimed to explore individuals’ experiences of having a smartphone-enabled ICM to monitor for arrhythmias in HCM. Methods and results Semi-structured interviews were conducted with 10 participants. Utilizing a grounded theory approach, the interview guide was modified based on emerging themes throughout the study. Reflexive thematic analysis was applied to categorize interview data into codes and overacting themes, with each interview independently coded by two study members. Analysis revealed three key themes: (i) psychological impact, (ii) educational needs, and (iii) technology expectations. Participants reported that receiving feedback from ICM transmissions resulted in improved symptom clarity, providing reassurance, and aiding implantable cardioverter defibrillator decision-making. Some participants reported uncertainty regarding when to send manual transmissions. Lastly, participants reported the app interface did not meet expectations with regard to the amount of data available for patients. Conclusion Overall, utilizing a smartphone app to facilitate two-way communication of ICM transmissions was well accepted. Future directions include addressing gaps in educational needs and improvements in the patient interface with increased access to data.

Atrial fibrillation is a chronic, progressive disorder, and persistent forms of atrial fibrillation are associated with increased risks of thromboembolism and heart failure. Catheter ablation as initial therapy may modify the pathogenic mechanism of atrial fibrillation and alter progression to persistent atrial fibrillation.We report the 3-year follow-up of patients with paroxysmal, untreated atrial fibrillation who were enrolled in a trial in which they had been randomly assigned to undergo initial rhythm-control therapy with cryoballoon ablation or to receive antiarrhythmic drug therapy. All the patients had implantable loop recorders placed at the time of trial entry, and evaluation was conducted by means of downloaded daily recordings and in-person visits every 6 months. Data regarding the first episode of persistent atrial fibrillation (lasting ≥7 days or lasting 48 hours to 7 days but requiring cardioversion for termination), recurrent atrial tachyarrhythmia (defined as atrial fibrillation, flutter, or tachycardia lasting ≥30 seconds), the burden of atrial fibrillation (percentage of time in atrial fibrillation), quality-of-life metrics, health care utilization, and safety were collected.A total of 303 patients were enrolled, with 154 patients assigned to undergo initial rhythm-control therapy with cryoballoon ablation and 149 assigned to receive antiarrhythmic drug therapy. Over 36 months of follow-up, 3 patients (1.9%) in the ablation group had an episode of persistent atrial fibrillation, as compared with 11 patients (7.4%) in the antiarrhythmic drug group (hazard ratio, 0.25; 95% confidence interval [CI], 0.09 to 0.70). Recurrent atrial tachyarrhythmia occurred in 87 patients in the ablation group (56.5%) and in 115 in the antiarrhythmic drug group (77.2%) (hazard ratio, 0.51; 95% CI, 0.38 to 0.67). The median percentage of time in atrial fibrillation was 0.00% (interquartile range, 0.00 to 0.12) in the ablation group and 0.24% (interquartile range, 0.01 to 0.94) in the antiarrhythmic drug group. At 3 years, 8 patients (5.2%) in the ablation group and 25 (16.8%) in the antiarrhythmic drug group had been hospitalized (relative risk, 0.31; 95% CI, 0.14 to 0.66). Serious adverse events occurred in 7 patients (4.5%) in the ablation group and in 15 (10.1%) in the antiarrhythmic drug group.Initial treatment of paroxysmal atrial fibrillation with catheter cryoballoon ablation was associated with a lower incidence of persistent atrial fibrillation or recurrent atrial tachyarrhythmia over 3 years of follow-up than initial use of antiarrhythmic drugs. (Funded by the Cardiac Arrhythmia Network of Canada and others; EARLY-AF ClinicalTrials.gov number, NCT02825979.).

Atrial fibrillation (AF), the most common sustained arrhythmia observed in clinical practice, is a chronic and progressive disorder characterized by exacerbations and remissions. Guidelines recommend antiarrhythmic drugs as the initial therapy for the maintenance of sinus rhythm; however, antiarrhythmic drugs have modest efficacy to maintain sinus rhythm and can be associated with significant adverse effects. An initial treatment strategy of cryoballoon catheter ablation in patients with treatment-naive AF has been shown to significantly improve arrhythmia outcomes (freedom from any, or symptomatic atrial tachyarrhythmia), produce clinically meaningful improvements in patient-reported outcomes (symptoms and quality of life), and significantly reduce subsequent health care resource use (hospitalization), and it does not increase the risk of serious or any adverse events compared with initial antiarrhythmic drug therapy. These findings are relevant to inform patients, providers, and health care systems regarding the initial choice of rhythm-control therapy in patients with treatment-naive AF.

Background: Satisfaction with treatment has been identified as an important contributing factor to adherence with oral anticoagulant (OAC) therapy in patients with atrial fibrillation (AF). We aimed to evaluate the satisfaction level of patients with AF regarding OAC use over time, using validated patient-reported outcome instruments, and to identify associated patient characteristics. Methods: Participants were recruited from specialized AF clinics in Canada. Eligible AF patients who were prescribed OACs were followed for up to 2 years. Participants were interviewed via telephone every 3-4 months using a structured survey. The Treatment Satisfaction Questionnaire for Medication (TSQM II) and the Anti-Clot Treatment Scale (ACTS) were used to measure satisfaction over time. Results: Among the 306 participants, satisfaction scores on the TSQM II and ACTS instruments were high. Unadjusted analyses showed significantly greater satisfaction with the burden of therapy with direct OACs (DOACs) compared to that with warfarin (small-magnitude effect) and greater satisfaction with the convenience of rivaroxaban, compared with that of all other OACs (moderate-magnitude effect). After adjustment for all other variables, vitamin K antagonist therapy was associated with greater global satisfaction than was DOAC treatment. Satisfaction with benefit and burden as measured by the ACTS scale, and global satisfaction on the TSQM II scale, tended to increase over time. Patient factors that were somewhat consistently associated with greater satisfaction were female sex and younger age. Conclusions: Patients with AF were highly satisfied with their therapy, with few differences among OAC classes and individual OACs. Individual patients may or may not be more satisfied with DOAC than VKA therapy, and regardless of the OAC prescribed, the may require significant support to maintain therapy adherence. Résumé: Contexte: La satisfaction à l’égard du traitement a été désignée comme un facteur important contribuant à l’adhésion au traitement par anticoagulants oraux (ACO) chez les patients atteints de fibrillation auriculaire (FA). Notre objectif était d’évaluer le degré de satisfaction des patients atteints de FA concernant l’utilisation des ACO au fil du temps, à l’aide d’instruments validés mesurant les résultats signalés par les patients, et de déterminer les caractéristiques connexes des patients. Méthodologie: Les participants ont été recrutés dans des cliniques spécialisées en FA au Canada. Les patients admissibles atteints de FA qui se sont fait prescrire des ACO ont été suivis pendant une période allant jusqu’à 2 ans. Les participants ont été interrogés par téléphone tous les 3 ou 4 mois à l’aide d’une enquête structurée. Le questionnaire Treatment Satisfaction Questionnaire for Medication – Version II (TSQM II) et l’échelle Anti-Clot Treatment Scale (ACTS) ont été utilisés pour mesurer la satisfaction au fil du temps. Résultats: Parmi les 306 participants, les taux de satisfaction indiqués par les instruments TSQM II et ACTS étaient élevés. Les analyses non corrigées ont montré une satisfaction liée au fardeau du traitement significativement plus élevée avec les ACO directs qu’avec la warfarine (effet de faible ampleur) et une plus grande satisfaction concernant la commodité du rivaroxaban par rapport à celle de tous les autres ACO (effet de moyenne ampleur). Après ajustement pour tenir compte de toutes les autres variables, le traitement par antivitamines K (AVK) était associé à une plus grande satisfaction globale que le traitement par ACO direct. La satisfaction à l’égard des avantages et du fardeau, mesurée par l’échelle ACTS, et la satisfaction globale sur l’échelle TSQM II, ont eu tendance à augmenter avec le temps. Les facteurs liés aux patients qui ont été associés de manière assez constante à une plus grande satisfaction étaient le sexe féminin et un âge plus jeune. Conclusions: Les patients atteints de FA étaient très satisfaits de leur traitement, et peu de différences existaient entre les classes d’ACO et les ACO individuels. Chaque patient peut être ou non plus satisfait du traitement par ACO direct que par AVK et, quel que soit l’ACO prescrit, il peut avoir besoin d’un soutien important pour maintenir l’adhésion au traitement.

Evidence has accumulated over the last century of the importance of a critical electrical mass in sustaining atrial fibrillation (AF). AF ablation certainly reduces electrically contiguous atrial mass, but this is not widely accepted to be an important part of its mechanism of action. In this article, we review data showing that atrial size is correlated in many settings with AF propensity. Larger mammals are more likely to exhibit AF. This is seen both in the natural world and in animal models, where it is much easier to create a goat model than a mouse model of AF, for example. This also extends to humans—athletes, taller people, and obese individuals all have large atria and are more likely to exhibit AF. Within an individual, risk factors such as hypertension, valvular disease and ischaemia can enlarge the atrium and increase the risk of AF. With respect to AF ablation, we explore how variations in ablation strategy and the relative effectiveness of these strategies may suggest that a reduction in electrical atrial mass is an important mechanism of action. We counter this with examples in which there is no doubt that mass reduction is less important than competing theories such as ganglionated plexus ablation. We conclude that, when considering future strategies for the ablative therapy of AF, it is important not to discount the possibility that contiguous electrical mass reduction is the most important mechanism despite the disappointing consequence being that enhancing success rates in AF ablation may involve greater tissue destruction.

Background: Whether advances in identification and management of atrial fibrillation and atrial flutter (collectively, AF) have led to improved outcomes is unclear. We sought to study trends in clinical outcomes selected as quality indicators for nonvalvular AF in Canada. Methods: We identified hospitalized patients with a first diagnosis of nonvalvular AF between April 2006 and March 2015, in all of Canada except Quebec. We assessed trends in 1-year incidence of stroke/systemic embolism (SSE), major bleeding, and initial heart failure (HF) hospitalization. Results: The cohort included 466,476 patients. The median age was 77 years (interquartile range, 68-84 years), 46% were female, and 68% had a Congestive Heart Failure, Hypertension, Age (≥75 years), Diabetes, Stroke/Transient Ischemic Attack, Vascular Disease, Age (65-74 years), Sex (Female) (CHA2DS2-VASc) score > 3. Within 1 year of discharge, 3.5% were hospitalized for stroke or SSE, 1.6% for major bleeding, and 8.6% for new HF. Over the study period, the crude rate of SSE declined from 3.6% to 3.3% (P = 0.002), whereas the rates of hospitalization for new HF and for major bleeding did not significantly change. After adjustment for CHA2DS2-VASc score, the yearly rates of incident SSE (risk ratio, 0.99; 95% confidence interval [CI], 0.98-0.99; P = 0.002) and HF (risk ratio, 0.99; 95% CI, 0.99-1.00; P = 0.001) declined ≤ 1% absolute, whereas major bleeding remained unchanged (risk ratio, 1.00; 95% CI, 0.99-1.00; P = 0.28). Conclusions: Among hospitalized patients with nonvalvular AF in Canada, the rate of SSE and new HF decreased modestly over a 10-year period, with no significant change in major bleeding. Efforts to study process-based quality indicators, with increased focus on HF prevention, are needed. Résumé: Contexte: On ne sait pas si les avancées en matière de détection et de prise en charge de la fibrillation auriculaire et du flutter auriculaire (collectivement appelés « FA » ci-après) ont permis d’améliorer les résultats pour les patients. Nous avons donc étudié les tendances à l’égard de résultats cliniques particuliers pris comme indicateurs de qualité relatifs à la FA non valvulaire au Canada. Méthodologie: Nous avons recensé les patients hospitalisés au Canada (sauf au Québec) entre avril 2006 et mars 2015 en raison d’une FA non valvulaire nouvellement diagnostiquée. Nous avons évalué les tendances quant à la survenue d’un accident vasculaire cérébral ou d’une embolie systémique (AVC/ES), d’une hémorragie majeure et d’une première hospitalisation pour insuffisance cardiaque. Résultats: La cohorte comprenait 466 476 patients, dont l’âge médian était de 77 ans (intervalle interquartile : 68 à 84 ans); 46 % des patients étaient des femmes, et 68 % avaient un score CHA2DS2-VASc (Congestive Heart Failure [insuffisance cardiaque congestive], hypertension, âge [≥ 75 ans], diabète, Stroke/Transient Ischemic Attack [AVC/accident ischémique transitoire] – maladie vasculaire, âge [65-74 ans], sexe [femmes]) supérieur à 3. Dans l’année suivant la sortie de l’hôpital, 3,5 % des patients ont été hospitalisés en raison d’un AVC ou d’un AVC/ES, 1,6 %, en raison d’une hémorragie majeure et 8,6 %, en raison d’une nouvelle insuffisance cardiaque. Au cours de la période étudiée, le taux brut d’AVC/ES est passé de 3,6 % à 3,3 % (p = 0,002), tandis que les taux d’hospitalisation en raison d’une nouvelle insuffisance cardiaque ou d’une hémorragie majeure n’ont pas changé de manière significative. Après correction pour tenir compte du score CHA2DS2-VASc, les taux annuels de survenue d’un AVC/ES (rapport des risques de 0,99; intervalle de confiance [IC] à 95 % : de 0,98 à 0,99; p = 0,002) et d’une insuffisance cardiaque (rapport des risques de 0,99; IC à 95 % : de 0,99 à 1,00; p = 0,001) ont diminué de ≤ 1 % en valeur absolue, tandis que le taux de survenue d’une hémorragie majeure n’a pas changé (rapport des risques : 1,00; IC à 95 % : de 0,99 à 1,00; p = 0,28). Conclusions: Parmi les patients hospitalisés au Canada en raison d’une FA non valvulaire, les taux d’AVC/ES et de nouvelle insuffisance cardiaque ont affiché une réduction modeste sur une période de 10 ans, tandis que le taux d’hémorragie majeure n’a pas changé de manière significative. D’autres études évaluant les indicateurs de qualité fondés sur les procédés, notamment en matière de prévention de l’insuffisance cardiaque, s’imposent.

Background This is a rare and challenging case of Wolff–Parkinson–White syndrome due to a posteroseptal accessory pathway located in the coronary sinus diverticulum. It is often difficult to precisely locate this type of accessory pathway, and the ablation procedure could be associated with collateral damage to the neighbouring coronary arteries. Case Presentation The patient was a 49-year-old female with Wolff–Parkinson–White syndrome who was referred for catheter ablation. She had had a previous unsuccessful attempt at ablation and had remained symptomatic despite drug therapy. The pre-procedural cardiac computed tomography scan revealed the presence of a diverticulum in the proximal coronary sinus. Using an advanced three-dimensional cardiac mapping system, the electroanatomic map of the diverticulum was created. The accessory pathway potential was identified within the diverticulum preceding the ventricular insertion. The accessory pathway was then successfully ablated using radiofrequency energy. Conclusion We have demonstrated that the advanced three-dimensional cardiac mapping system plays a very important role in guiding clinicians in order to precisely locate and safely ablate this type of challenging accessory pathway.

Background Guidelines recommend a trial of one or more antiarrhythmic drugs before catheter ablation is considered in patients with atrial fibrillation. However, first-line ablation may be...

Aims Same-day discharge is increasingly common after catheter ablation for atrial fibrillation (AF). However, the impact of same-day discharge on healthcare utilization after ablation and whether this differs by ablation modality remains uncertain. We examined the safety, efficacy, and subsequent healthcare utilization of a same-day discharge protocol for AF ablation, including radiofrequency (RF) and cryoballoon ablation, in a contemporary cohort. Methods and results All consecutive patients for whom full healthcare utilization data were available at two centres and who underwent AF ablation from 2018 to 2019 were included. Same-day discharge was the default strategy for all patients. The efficacy and safety outcomes were proportions of same-day discharge and readmission/emergency room (ER) visits, and post-discharge complications, respectively. Of the 421 patients who underwent AF ablation (mean 63.3 ± 10.2 years, 33% female), 90.5% (381/421) achieved same-day discharge with no difference between RF and cryoballoon ablation (89.8 vs. 95.1%, adjusted P = 0.327). Readmission ≤30 days occurred in 4.8%, with ER visits ≤30 days seen in 26.1% with no difference between ablation modalities (P = 0.634). Patients admitted overnight were more likely to present to the ER (40.0 vs. 24.7% with same-day discharge, P = 0.036). The overall post-discharge complication rate was low at 4/421 (1.0%), with no difference between ablation modality (P = 0.324) and admission/same-day discharge (P = 0.485). Conclusion Same-day discharge can be achieved in a majority of patients undergoing RF or cryoballoon ablation for AF. Healthcare utilization, particularly ER visits, remains high after AF ablation, regardless of ablation modality or same-day discharge.

The role of cardiac magnetic resonance (CMR) in the evaluation and management of patients with frequent premature ventricular complexes (PVCs) of unknown etiology remains unclear.This study evaluated the prevalence and prognostic significance of myocardial abnormalities detected with CMR among patients with frequent PVCs and no known structural heart disease.This prospective cohort study included consecutive patients with frequent PVCs and a negative initial diagnostic work-up who underwent CMR with late gadolinium enhancement imaging. The clinical outcome was a composite of mortality, ventricular fibrillation, sustained ventricular tachycardia, or reduction in left ventricular ejection fraction of ≥10%.A total of 255 patients were included, of whom 35 (13.7%) had evidence of myocardial abnormality on CMR. Age ≥60 years (odds ratio [OR]: 6.96; 95% CI: 1.30-37.18), multifocal PVCs (OR: 10.90; 95% CI: 3.21-36.97), and non-outflow tract left ventricular PVC origin (OR: 3.00; 95% CI: 1.00-8.95) were independently associated with the presence of a myocardial abnormality on CMR. After a median follow-up of 36 months, the composite outcome occurred in 15 (5.9%) patients. The presence of a myocardial abnormality on CMR was independently associated with the composite outcome (HR: 4.35; 95% CI: 1.34-14.15; P = 0.014).One in 7 patients with frequent PVCs with no known structural heart disease had myocardial abnormality detected on CMR, and these abnormalities were associated with adverse clinical outcomes. These findings highlight the important role of CMR in the evaluation of patients with frequent PVCs.

AimsAtrial tachyarrhythmia recurrence ≥30 s remains the primary endpoint of clinical trials; however, this definition has not been correlated with clinical outcomes or pathophysiological processes. This study sought to determine the atrial tachyarrhythmia duration and burden associated with meaningful clinical outcomes.Methods and resultsThe time and duration of every atrial tachyarrhythmia episode recorded on implantable cardiac monitor were evaluated. Healthcare utilization and quality of life in the year following ablation were prospectively collected. Three hundred and forty-six patients provided 126 110 monitoring days. One-year freedom from recurrence increased with arrhythmia duration thresholds, from 52.6 (182/346) to 93.3% (323/346; P < 0.0001). Patients with atrial fibrillation (AF) recurrence limited to durations ≤1 h had rates of healthcare utilization comparable with patients free of recurrence, while patients with AF recurrences lasting >1 h had a relative risk for emergency department consultation of 3.2 [95% confidence interval (CI) 2.0–5.3], hospitalization of 5.3 (95% CI 2.9–9.6), and repeat ablation of 27.1 (95% CI 10.5–71.0). Patients with AF burden of ≤0.1% had rates of healthcare utilization comparable with patients free of recurrence, while patients with AF burden of >0.1% had a relative risk for emergency department consultation of 2.4 (95% CI 1.9–3.9), hospitalization of 6.8 (95% CI 3.6–13.0), cardioversion of 9.1 (95% CI 3.3–25.6), and repeat ablation of 21.8 (95% CI 9.2–52.2). Compared with patients free of recurrence, the disease-specific quality of life was significantly impaired with AF episode durations >24 h, or AF burdens >0.1%.ConclusionAF recurrence, as defined by 30 s of arrhythmia, lacks clinical relevance. AF episode durations >1 h or burdens >0.1% were associated with increased rates of healthcare utilization.

Objectives This study sought to evaluate sex-specific differences in atrial fibrillation (AF) presentation and catheter ablation outcomes in the prospective, multicenter, randomized CIRCA-...

Current guidelines recommend 4 weeks of private driving restriction after implantation of a primary-prevention implantable cardioverter-defibrillator (ICD). These driving restrictions result in significant inconvenience and social implications. Advances in medical treatment and ICD programming have lowered the overall rate of device therapies. The objective of this study was to assess the incidence of ICD therapies at 30, 60, and 180 days after implantation.Driving Restrictions and Early Arrhythmias in Patients Receiving a Primary-Prevention Implantable Cardioverter-Defibrillator (DREAM-ICD) was a retrospective cohort study conducted at 2 Canadian university centres enrolling patients with new implantation of a primary-prevention ICD. Device programming was standardised according to current guidelines. A total of 803 patients were enrolled.The cumulative rates of appropriate ICD therapies at 30, 60, and 180 days were 0.12%, 0.50%, and 0.75%, respectively. There was no syncope during the first 6 months. The median duration to the first appropriate ICD therapy was 208 (range 23-1109) days after implantation. The rate of inappropriate ICD therapies at 30 days was only 0.2%. Overall,13.6% of all appropriate ICD therapies occurred within the first 6 months after implantation.The rate of appropriate ICD therapies within the first 30 days after device insertion is extremely low in contemporary primary prevention cohorts with guideline-concordant device programming. There was no increased risk for ventricular arrhythmia early after ICD insertion. The results of DREAM-ICD suggest the need for a revision of the existing driving restrictions for primary-prevention ICD recipients.

ObjectiveDespite the widespread and increasing use of ambulatory electrocardiography (ECG), there is no consensus on reference ranges for ambulatory electrocardiogram parameters to guide interpretation. We sought to determine population distribution-based reference ranges for parameters measured during ambulatory electrocardiogram in healthy adults, based on existing literature.MethodsWe searched multiple databases from 1950 to 2020. Articles reporting original data from ≥24-hour ambulatory electrocardiogram monitoring in healthy adults were included. Data extraction and synthesis were performed according to Meta-analysis of Observational Studies in Epidemiology guidelines. The prevalence/mean and SD for common parameters (sinus pauses, conduction abnormalities and ectopy) were extracted by age group (18–39, 40–59, 60–79 and 80+ years).ResultsWe identified 33 studies involving 6466 patients. Sinus pauses of >3 s were rare (pooled prevalence 1000/24 hours increased with age, from 0% (95% CI 0% to 0%) in those aged 18–39 years to 6% (95% CI 0% to 17%) in those aged 60–79 years. Episodes of supraventricular tachycardia increased from 3% (95% CI 1% to 6%) in those aged 18–39 years to 28% (95% CI 9% to 52%) in those aged 60–79 years. Ventricular ectopy of >1000/24 hours also increased with age, from 1% (95% CI 0% to 2%) in those aged 18–39 years to 5% (95% CI 1% to 10%) in those aged 60–79 years. Episodes of non-sustained ventricular tachycardia ranged from 0% (95% CI 0% to 1%) in those aged 18–39 years to 2% (95% CI 0% to 5%) in those aged 60–79 years.ConclusionDespite the limitations of existing published data, this meta-analysis provides evidence-based reference ranges for ambulatory electrocardiogram parameters and highlights significant age-dependent differences that should be taken into account during interpretation.

Purpose Ventricular tachycardia (VT) is a rapid, abnormal heart rhythm that can lead to sudden cardiac death. Current treatment options include antiarrhythmic drug therapy and catheter ablation, both of which have only modest efficacy and have potential complications. Cardiac radiosurgery has the potential to be a noninvasive and efficient treatment option for VT. Cardiac motion, however, must be accounted for to ensure accurate dose delivery to the target region. Cardiac synchronized volumetric modulated arc therapy (CSVMAT) aims to minimize the dose delivered to normal tissues by synchronizing beam delivery with a cardiac signal, irradiating only during the quiescent intervals of the cardiac cycle (when heart motion is minimal) and adjusting the beam delivery speed in response to heart rate changes. Methods A CSVMAT plan was adapted from a conventional VMAT plan and delivered on a Varian TrueBeam linear accelerator. The original VMAT plan was divided into three interleaved CSVMAT phases, each consisting of alternating beam-on and beam-off segments synchronized to a sample heart rate. Trajectory log files were collected for the original VMAT and CSVMAT deliveries and the dose distributions were measured with Gafchromic EBT-XD film. Results Analysis of the trajectory log files showed successful synchronization with the sample cardiac signal. Film analysis comparing the original VMAT and CSVMAT dose distributions returned a gamma passing rate of 99.14% (2%/2 mm tolerance). Conclusions The film results indicated excellent agreement between the dose distributions of the original and cardiac synchronized beam deliveries. This study demonstrates a proof of principle cardiac synchronization strategy for precise radiation treatment plan delivery and adjustment to a variable heart rate. The cardiac synchronized technique may be advantageous in radioablation for VT.

Use of intraprocedural observation and pharmacologic challenges have been proposed as means to differentiate permanent pulmonary vein (PV)-left atrial conduction block from inadequate ablation lesions.The purpose of this study was to determine the prevalence and clinical impact of spontaneous and adenosine-provoked reconnection using contemporary atrial fibrillation (AF) ablation technologies.The CIRCA-DOSE (Cryoballoon vs. Irrigated Radiofrequency Catheter Ablation: Double Short vs. Standard Exposure Duration) study enrolled 346 patients with paroxysmal AF and randomized them to contact force-guided radiofrequency ablation (CF-RF) or cryoballoon ablation. Patients underwent provocative testing with adenosine after a 20-minute observation period. All patients received an implantable cardiac monitor for arrhythmia monitoring.Spontaneous reconnection was observed in 5.4% of PVs (71/1318) during the 20-minute postprocedure observation period, and dormant conduction was elicited in 5.7% of PVs (75/1318). Both spontaneous reconnection and dormant conduction were more common after CF-RF compared to cryoballoon ablation (P = .03 and P.0001, respectively). Acute PV reconnection (spontaneous or adenosine-provoked) was associated with a significantly higher incidence of recurrent atrial tachyarrhythmia in the cryoballoon group (hazard ratio [HR] 2.39; 95% confidence interval [CI] 1.44-3.96; P = .0007) but not in the CF-RF group (HR 1.47; 95% CI 0.84-2.58; P = .16). In the absence of acute reconnection, the freedom from recurrent arrhythmia did not differ between groups (HR 0.95; 95% CI 0.6057-1.495; P = .83).Patients without spontaneous or adenosine-provoked reconnection had better outcomes compared to those with acute PV reconnection, suggesting that efforts should be directed toward ensuring an ideal ablation lesion at the first attempt in order to achieve durable PV isolation.

This Canadian Cardiovascular Society position statement is focused on the management of sustained ventricular tachycardia (VT) and ventricular fibrillation (VF) that occurs in patients with structural heart disease (SHD), including previous myocardial infarction, dilated cardiomyopathy, and other forms of nonischemic cardiomyopathy. This patient population is rapidly increasing because of advances in care and improved overall survival of patients with all forms of SHD. In this position statement, the acute and long-term management of VT/VF are outlined, and the many unique aspects of care in this population are emphasized. The initial evaluation, acute therapy, indications for chronic suppressive therapy, choices of chronic suppressive therapy, implantable cardioverter-defibrillator programming, alternative therapies, and psychosocial care are reviewed and recommendations for optimal care are provided. The target audience for this statement includes all health professionals involved in the continuum of care of patients with SHD and VT/VF.

Contemporary guidelines recommend that atrial fibrillation (AF) be classified into paroxysmal and persistent AF based on clinical assessment, with these categorizations forming the basis of therapeutic recommendations. While pragmatic, clinical assessment may introduce misclassification errors, which may impact treatment decisions. We sought to determine the relationship between AF classification, baseline AF burden, and post-ablation arrhythmia outcomes.The current study is a sub-analysis of a prospective, parallel-group, multicenter, single-blinded randomized clinical trial. All 346 patients enrolled in CIRCA-DOSE received an implantable cardiac monitor a median of 72 days prior to ablation. AF was classified as low burden paroxysmal, high burden paroxysmal, or persistent based on clinical assessment prior to device implantation. Prior to ablation patients were re-classified using the same definitions based on device monitoring data. Correlation between classifications, AF burden, and post-ablation arrhythmia outcomes were assessed.There was poor agreement between clinical and device-based AF classification (Cohen's kappa: 0.192). AF classification derived from pre-ablation continuous monitoring reflected baseline and post-ablation AF burden with greater accuracy and with less overlap between the AF classes (P 0.01 for all categorical comparisons). Patients objectively classified as "Low Burden" paroxysmal by continuous monitoring data had significantly greater freedom from recurrent AF/AT/AFL compared to those classified as "High Burden" paroxysmal (hazard ratio [HR] 0.57 for AF/AT/AFL recurrence) or persistent AF (HR 0.19 for AF/AT/AFL recurrence).Classification of AF pattern based on pre-ablation continuous cardiac rhythm monitoring better predicted AF burden and freedom from recurrent AF post ablation. Despite the use of standardized definitions, classification of AF based on clinical assessment did not predict baseline AF burden, post ablation AF burden, or freedom from recurrent AF post ablation.ClinicalTrials.govNCT01913522.

This study sought to determine, in patients with new-onset persistent left bundle branch block (NOP-LBBB) after transcatheter aortic valve implantation (TAVI), the incidence and factors associated with (i) LBBB recovery and (ii) permanent pacemaker implantation (PPI) at 1-year follow-up. This was a multicenter study including 153 patients (mean age: 81 ± 5 years, 56% of women) with NOP-LBBB post-TAVI (balloon-expandable valve in 112 patients). Delta PR (ΔPR) and delta QRS (ΔQRS) were defined as the difference in PR and QRS length between baseline and hospital discharge ECG, and the relative ΔPR and ΔQRS as absolute ΔPR and ΔQRS divided by baseline PR and QRS length, respectively. The patients had a clinical visit and 12-lead ECG at 1-year follow-up. LBBB recovery was observed in 50 patients (33%), and 14 patients (9%) had advanced conduction disturbances requiring PPI during the follow-up period. No clinical or ECG variables were associated with LBBB recovery, including prosthesis type (self- or balloon-expandable valve, p = 0.563), QRS width at baseline/discharge or absolute/relative ΔQRS (p >0.10 for all). The presence of atrial fibrillation at baseline (0.026), a longer PR interval at discharge (0.009), and a longer absolute and relative ΔPR (p = 0.002 and p = 0.004, respectively) were associated with an increased risk of PPI at 1-year follow-up. In conclusion, NOP-LBBB post-TAVI resolved in one-third of patients at 1-year follow-up, but no clinical or ECG variables were associated with LBBB recovery. Conversely, a nonsinus rhythm at baseline and a longer ΔPR were associated with an increased risk of PPI within the year after TAVI.

The Cryoballoon vs Irrigated Radiofrequency Catheter Ablation: Double Short vs Standard Exposure Duration (CIRCA-DOSE) study was a multicentre, randomised, single-blinded trial that compared contact-force radiofrequency ablation and two different regimens of cryoballoon ablation. All patients received an implantable cardiac monitor for the purpose of continuous rhythm monitoring, with all arrhythmia events undergoing independent adjudication by a committee blinded to treatment allocation. The study demonstrated there were no significant differences between contact-force radiofrequency ablation and cryoballoon ablation with respect to recurrence of any atrial tachyarrhythmia, symptomatic atrial tachyarrhythmia, asymptomatic AF, symptomatic AF or AF burden. While the results of the CIRCA-DOSE study are reviewed here, this article focuses on considerations around the design of the study and places the observed outcomes in context.

Background: Regulatory authorities of most industrialized countries recommend 6 months of private driving restriction after implantation of a secondary prevention implantable cardioverter-defibrillator (ICD). These driving restrictions result in significant inconvenience and social implications. This study aimed to assess the incidence rate of appropriate device therapies in contemporary recipients of a secondary prevention ICD. Methods: This retrospective study at 3 Canadian tertiary care centers enrolled consecutive patients with new secondary prevention ICD implants between 2016 and 2020. Results: For a median of 760 days (324, 1190 days), 721 patients were followed up. The risk of recurrent ventricular arrhythmia was highest during the first 3 months after device insertion (34.4%) and decreased over time (10.6% between 3 and 6 months, 11.7% between 6 and 12 months). The corresponding incidence rate per 100 patient-days was 0.48 (95% CI, 0.35–0.64) at 90 days, 0.28 (95% CI, 0.17–0.45) at 180 days, and 0.21 (95% CI, 0.13–0.33) between 181 and 365 days after ICD insertion ( P P Conclusions: The incidence rate of appropriate therapies resulting in sudden cardiac incapacitation in contemporary recipients of a secondary prevention ICD is much lower than previously reported and declines significantly after the first 3 months. Lowering driving restrictions to 3 months after the index cardiac event seems safe, and revision of existing guidelines should be considered in countries still adhering to a 6-month period. Existing restrictions for private driving after implantation of a secondary prevention ICD should be reconsidered.

Key Points Question What proportion of patients with left ventricular dysfunction identified during hospitalization for acute myocardial infarction have follow-up assessment of left ventricular ejection fraction (LVEF)? Findings In this cohort study of 501 patients, 303 patients had undergone LVEF reassessment by 6 months, with significant variability according to patient-level and site-level characteristics. Meaning These findings suggest that programs to improve the quality of post–myocardial infarction care should include measures to ensure that indicated repeat cardiac imaging is performed., This cohort study assesses adherence with guideline-recommended left ventricular ejection fraction (LVEF) reassessment after myocardial infarction and studies the evolution of LVEF over 6 months of follow-up in the Acute Myocardial Infarction Quality Assurance (AMIQA) Canada study., Importance Persistently depressed left ventricular ejection fraction (LVEF) after myocardial infarction (MI) is associated with adverse prognosis and directs the use of evidence-based treatments to prevent sudden cardiac death and/or progressive heart failure. Objective To assess adherence with guideline-recommended LVEF reassessment and to study the evolution of LVEF over 6 months of follow-up. Design, Setting, and Participants This was a multicenter cohort study at Canadian academic and community hospitals with on-site cardiac catheterization services. Patients with type 1 acute MI and LVEF less than or equal to 45% during the index hospitalization were enrolled between January 2018 and August 2019 and were followed-up for 6 months. Data analysis was performed from May 2020 to September 2021. Exposures Baseline clinical factors, in-hospital care and LVEF, and site-specific features. Main Outcomes and Measures The main outcomes were receipt of repeat LVEF assessment by 6 months and the presence of a persistent LVEF reduction at 2 thresholds: LVEF less than or equal to 40%, prompting consideration of additional medical therapy for heart failure, or LVEF less than or equal to 35%, prompting referral for implanted cardioverter defibrillator in addition to medical therapy. Results This study included 501 patients (mean [SD] age, 63.3 [13.0] years; 113 women [22.6%]). Overall, 370 patients (73.4%) presented with STEMI, and 454 (90.6%) had in-hospital revascularization. The median (IQR) baseline LVEF was 40% (34%-43%). Of 458 patients (91.4%) who completed the 6-month follow-up, 303 (66.2%; 95% CI, 61.7%-70.5%) had LVEF reassessment, with a range of 46.7% to 90.0% across sites (χ213 = 19.6; P = .11). Participants from community hospitals were more likely than those from academic hospitals to undergo LVEF reassessment (73.6% vs 63.2%; χ21 = 4.50; P = .03), as were those with worse LVEF at baseline. Follow-up LVEF improved by an absolute median (IQR) of 8% (3%-15%). However, 103 patients (34.1%) met the definitions of clinically relevant LVEF reduction, including 52 patients (17.2%) with LVEF less than or equal to 35% and 51 patients (16.9%) with LVEF of 35.1% to 40.0%. Conclusions and Relevance In this cohort study, approximately 1 in 3 patients with at least mild LVEF reduction after acute MI did not undergo indicated LVEF reassessment within 6 months, suggesting that programs to improve the quality of post-MI care should include measures to ensure that indicated repeat cardiac imaging is performed. In those with follow-up imaging, clinically relevant persistent LVEF reduction was identified in more than one-third of patients.

Background: Various noninvasive intermittent rhythm monitoring strategies have been used to assess arrhythmia recurrences in trials evaluating pharmacological and invasive therapeutic interventions for atrial fibrillation (AF). We determined whether a frequency and duration of noninvasive rhythm monitoring could be identified that accurately detects arrhythmia recurrences and approximates the AF burden derived from continuous monitoring using an implantable cardiac monitor (ICM). Methods: The rhythm history of 346 patients enrolled in the CIRCA-DOSE trial (Cryoballoon Versus Contact-Force Irrigated Radiofrequency Catheter Ablation) was reconstructed. Using computer simulations, we evaluated event-free survival, sensitivity, negative predictive value, and AF burden of a range of noninvasive monitoring strategies, including those used in contemporary AF ablation trials. Results: A total of 126 290 monitoring days were included in the analysis. At 12 months, 164 patients experienced atrial arrhythmia recurrence as documented by the ICM (1-year event-free survival, 52.6%). Most noninvasive monitoring strategies used in AF ablation trials had poor sensitivity for detecting arrhythmia recurrence. Sensitivity increased with the intensity of monitoring, with serial (3) short-duration monitors (24-/48-hour ECG monitors) missing a substantial proportion of recurrences (sensitivity, 15.8% [95% CI, 8.9%–20.7%] and 24.5% [95% CI, 16.2%–30.6%], respectively). Serial (3) longer-term monitors (14-day ECG monitors) more closely approximated the gold standard ICM (sensitivity, 64.6% [95% CI, 53.6%–74.3%]). AF burden derived from short-duration monitors significantly overestimated the true AF burden in patients with recurrences. Increasing monitoring duration resulted in improved correlation and concordance between noninvasive estimates of the invasive AF burden ( R 2 = 0.85 and interclass correlation coefficient = 0.91 for serial [3] 14-day ECG monitors versus ICM). Conclusions: The observed rate of postablation atrial tachyarrhythmia recurrence is highly dependent on the arrhythmia monitoring strategy employed. Between-trial discrepancies in outcomes may reflect different monitoring protocols. On the basis of measures of agreement, serial long-term (7–14 day) intermittent monitors accumulating at least 28 days of annual monitoring provide estimates of AF burden comparable with ICM. However, ICMs outperform intermittent monitoring for arrhythmia detection, and should be considered the gold standard for clinical trials. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT01913522.