Comparison of anterior mitral line and mitral isthmus line for ablation of mitral annular flutter.

BACKGROUND: Mitral annular flutter (MAF) is the most common left atrial macro-reentrant arrhythmia following catheter ablation of atrial fibrillation (AF). The best ablation approach for this arrhythmia remains unclear. METHODS: This single-center, retrospective study sought to compare the acute and long-term outcomes of patients with MAF treated with an anterior mitral line (AML) versus a mitral isthmus line (MIL). Acute ablation success, complication rates, and long-term arrhythmia recurrence were compared between the two groups. RESULTS: Between 2015 and 2021, a total of 81 patients underwent ablation of MAF (58 with an AML and 23 with a MIL). Acute procedural success defined as bidirectional block was achieved in 88% of the AML and 91% of the MIL patients respectively (p = 1.0). One year freedom from atrial arrhythmias was 49.5% versus 77.5% and at 4 years was 24% versus 59.6% for AML versus MIL, respectively (hazard ratio [HR]: 0.38, confidence interval [CI]: 0.17-0.82, p = .009). Fewer patients in the MIL group had recurrent atrial flutter when compared to the AML group (HR: 0.32, CI: 0.12-0.83, p = .009). The incidence of recurrent AF, on the other side, was not different between both groups (21.7% vs. 18.9%; p = .76). There were no serious adverse events in either group. CONCLUSION: In this retrospective study of patients with MAF, a MIL compared to AML was associated with a long-term reduction in recurrent atrial arrhythmias driven by a reduction in macroreentrant atrial flutters.

Right atrial collision time (RACT): A novel marker of propensity for typical atrial flutter.

INTRODUCTION: The risk of typical atrial flutter (AFL) is increased proportionately to right atrial (RA) size or right atrial scarring that results in reduced conduction velocity. These characteristics result in propagation of a flutter wave by ensuring the macro re-entrant wave front does not meet its refractory tail. The time taken to traverse the circuit would take account of both of these characteristics and may provide a novel marker of propensity to develop AFL. Our goal was to investigate right atrial collision time (RACT) as a marker of existing typical AFL. METHODS: This single-centre, prospective study recruited consecutive typical AFL ablation patients that were in sinus rhythm. Controls were consecutive electrophysiology study patients >18 years of age. While pacing the coronary sinus (CS) ostium at 600 ms, a local activation time map was created to locate the latest collision point on the anterolateral right atrial wall. This RACT is a measure of conduction velocity and distance from CS to a collision point on the lateral right atrial wall. RESULTS: Ninety-eight patients were included in the analysis, 41 with atrial flutter and 57 controls. Patients with atrial flutter were older, 64.7 ± 9.7 versus 52.4 ± 16.8 years (<.001), and more often male (34/41 vs. 31/57 [.003]). The AFL group mean RACT (132.6 ± 17.3 ms) was significantly longer than that of controls (99.1 ± 11.6 ms) (p < .001). A RACT cut-off of 115.5 ms had a sensitivity and specificity of 92.7% and 93.0%, respectively for diagnosis of atrial flutter. A ROC curve indicated an AUC of 0.96 (95% CI: 0.93-1.0, p < .01). CONCLUSION: RACT is a novel and promising marker of propensity for typical AFL. This data will inform larger prospective studies.

Electrocardiographic predictors of atrial fibrillation in patients with cryptogenic stroke.

BACKGROUND: Empiric anticoagulation is not routinely indicated in patients with cryptogenic stroke without documentation of atrial fibrillation (AF). Therefore, identification of patients at increased risk of AF from this vulnerable group is vital. OBJECTIVES: To identify electrocardiographic (ECG) predictors of AF in patients with cryptogenic stroke or transient ischemic attack (TIA) undergoing insertion of an implantable cardiac monitor (ICM). METHODS: In this single-center study, 48 patients with cryptogenic stroke or TIA had an ICM implanted for detection of AF between January 2013 and September 2019. Patients with and without AF were compared in terms of p-wave duration and a novel index (MVP score). RESULTS: During a mean follow-up of 16 ± 14 months, AF was detected in seven patients (15%). Diagnosis of AF was made after a mean of 10 ± 14 months, with time to first AF detection ranging between 1 and 40 months. Patients with AF had a longer p-wave duration (136 ± 9 ms vs. 116 ± 10 ms; p = .0001) and a higher MVP score (4.5 ± 1.2 vs. 2.0 ± 0.9, p = .0001) than those without AF. Advanced interatrial block (IAB) was observed in 43% of patients with ICM evidence of AF and 0% of those without AF (p = .002). Age, LA size or LVEF were not predictors of AF. CONCLUSION: An increased p-wave duration, advanced IAB and high MVP score are associated with AF occurrence in patients with cryptogenic stroke. Identifying patients with these markers may be helpful as they may benefit from more exhaustive and prolonged monitoring.

Perturbations in cardiac metabolism in a human model of acute myocardial ischaemia.

INTRODUCTION: Acute myocardial ischaemia and the transition from reversible to irreversible myocardial injury are associated with abnormal metabolic patterns. Advances in metabolomics have extended our capabilities to define these metabolic perturbations on a metabolome-wide scale. OBJECTIVES: This study was designed to identify cardiac metabolic changes in serum during the first 5 min following early myocardial ischaemia in humans, applying an untargeted metabolomics approach. METHODS: Peripheral venous samples were collected from 46 patients in a discovery study (DS) and a validation study (VS) (25 for DS, 21 for VS). Coronary sinus venous samples were collected from 7 patients (4 for DS, 3 for VS). Acute myocardial ischaemia was induced by transient coronary occlusion during percutaneous coronary intervention (PCI). Plasma samples were collected at baseline (prior to PCI) and at 1 and 5 min post-coronary occlusion. Samples were analyzed by Ultra Performance Liquid Chromatography-Mass Spectrometry in an untargeted metabolomics approach. RESULTS: The study observed changes in the circulating levels of metabolites at 1 and 5 min following transient coronary ischaemia. Both DS and VS identified 54 and 55 metabolites as significant (P < 0.05) when compared to baseline levels, respectively. Fatty acid beta-oxidation and anaerobic respiration, lysoglycerophospholipids, arachidonic acid, docosahexaenoic acid, tryptophan metabolism and sphingosine-1-phosphate were identified as mechanistically important. CONCLUSION: Using an untargeted metabolomics approach, the study identified important cardiac metabolic changes in peripheral and coronary sinus plasma, in a human model of controlled acute myocardial ischaemia. Distinct classes of metabolites were shown to be involved in the rapid cardiac response to ischemia and provide insights into diagnostic and interventional targets.

Treating Lyme carditis high-degree AV block using a temporary-permanent pacemaker.

A 28-year-old previously healthy male presented with nonprodromal syncope and a 4-day history of chest pain, shortness of breath, and malaise. His ECG showed rapidly progressive high-degree AV block. His Suspicious Index in Lyme Carditis (SILC) score was 8, indicating high risk for Lyme carditis. Lyme serology revealed to be positive (anti-Lyme IgM). During the second day of hospitalization, the patient deteriorated his AV conduction, and a temporary-permanent pacemaker was implanted allowing ambulating in hospital the very same day. Temporary-permanent pacemakers for the management of transient high-degree heart block associated with Lyme carditis were only occasionally used in the past.

Ambulatory ECG predictors of atrial fibrillation are ineffective in severe sleep apnea.

BACKGROUND: Obstructive sleep apnea (OSA) is strongly associated with atrial fibrillation (AF). Long-term ECG monitoring with implantable loop recorders facilitates the identification of undiagnosed AF in 20% of severe OSA cases. However, ambulatory ECG (AECG) monitoring is less resource intensive, and various parameters have been shown to predict AF. The aim of this study was to assess the efficacy of such AECG-based AF predictors in identifying patients with severe OSA most at risk. METHODS: Prospective observational study including patients with severe OSA and no history of AF. Patients had two 24-h AECG recordings, and if no AF was detected, implanted with a loop recorder (maximum 3 years). RESULTS: Of 25 patients implanted, AF ≥ 10 s was detected in 5 patients. None of the parameters from the AECG recordings were significantly different between patients who did and did not develop AF. CONCLUSIONS: AECG-based parameters were not effective for the prediction of AF in this severe OSA cohort.

Half-Normal Saline vs Normal Saline for Cavotricuspid Isthmus-Dependent Atrial Flutter Ablation.

Background: Cavotricuspid isthmus (CTI) ablation requires permanent bidirectional block to prevent recurrence of typical atrial flutter (AFL). Catheter irrigation with half-normal saline (HNS) produces larger and deeper lesions in experimental models compared with normal saline (NS). This study was performed to compare the clinical efficacy and safety of HNS vs NS irrigation for typical AFL ablation. Methods: Sixty patients undergoing catheter ablation of typical AFL were randomized 1:1 to NS or HNS irrigation. Endpoints included time to CTI block, acute reconnection, incidence of steam pops, and recurrence of AFL during follow-up. Results: Baseline characteristics were comparable between both arms. The mean age of the patients was 68.5 ± 8.2 years, 20% were female, and 32% had atrial fibrillation before being enrolled. Bidirectional CTI block was obtained in all patients with no difference in time to CTI block between groups (6.4 ± 4.4 minutes vs 7.6 ± 4.5 minutes, respectively; P = 0.15). There was a trend to less acute reconnection in the HNS group compared with NS (13.3% vs 26.6%; P = 0.46). Steam pops occurred in 4 patients using HNS vs none in the NS group, but no major complications were observed. During the follow-up, rate of AFL recurrence was similar between groups (6.7% with HNS vs 10% with NS; P = 0.5). There was no difference in time to recurrence (7.6 ± 6.9 vs 4.9 ± 4.5 months; P = 0.6). Conclusions: In this small pilot randomized controlled trial, there was no significant difference between HNS and NS for CTI ablation; however, HNS may increase the incidence of steam pops.

Contexte: Pour prévenir la récurrence d'un flutter auriculaire (flutter) typique, l'ablation de l'isthme cavotricuspidien exige un bloc de conduction bidirectionnel permanent. Dans des modèles expérimentaux, l'irrigation par cathéter au moyen d'un soluté demi-salin produit des lésions plus larges et plus profondes, comparativement à un soluté physiologique salin. La présente étude a été réalisée dans le but de comparer l'efficacité clinique et l'innocuité de l'irrigation au moyen d'un soluté demi-salin à celles de l'irrigation par un soluté physiologique salin dans les cas d'ablation d'un flutter. Méthodologie: Soixante patients soumis à une ablation d'un flutter typique par cathéter ont été répartis au hasard dans un rapport de 1:1 en deux groupes d'irrigation, soit par soluté demi-salin, soit par soluté physiologique salin. Les critères d'évaluation de l'étude étaient les suivants : temps écoulé jusqu'au bloc de l'isthme cavotricuspidien, reconnexion aiguë, jet de vapeur sonore (steam pop) et récidive de flutter durant le suivi. Résultats: Les caractéristiques initiales étaient comparables dans les deux groupes. Les patients avaient une moyenne d'âge de 68,5 ± 8,2 ans, 20 % étaient des femmes et 32 % présentaient une fibrillation auriculaire avant leur admission à l'étude. Un bloc bidirectionnel dans l'isthme cavotricuspidien a été obtenu chez tous les patients, sans différence entre les groupes en ce qui a trait au temps écoulé jusqu'à l'obtention du bloc isthmique (6,4 ± 4,4 minutes vs 7,6 ± 4,5 minutes, respectivement; p = 0,15). Une tendance vers un nombre plus faible de cas de reconnexion aiguë a été notée dans le groupe d'irrigation par soluté demi-salin, comparativement au soluté physiologique salin (13,3 % vs 26,6 %; p = 0,46). Un jet de vapeur sonore est survenu chez 4 patients recevant un soluté demi-salin contre aucun dans le groupe sous soluté physiologique salin, mais aucune complication importante n'a été relevée. Durant le suivi, le taux de récidive de flutter a été similaire dans les deux groupes (6,7 % sous soluté demi-salin vs 10 % sous soluté physiologique salin; p = 0,5). Aucune différence n'a été notée pour ce qui est du temps écoulé jusqu'à la survenue d'une récidive (7,6 ± 6,9 vs 4,9 ± 4,5 mois; p = 0,6). Conclusions: Dans cette petite étude pilote contrôlée et avec répartition aléatoire, aucune différence significative n'a été observée entre le soluté demi-salin et le soluté physiologique salin pour l'ablation de l'isthme; toutefois, le soluté demi-salin augmenterait la fréquence des cas de jet de vapeur sonore.

Metabolomics Work Flow and Analytics in Systems Biology.

Metabolomics is an omics approach of systems biology that involves the development and assessment of large-scale, comprehensive biochemical analysis tools for metabolites in biological systems. This review describes the metabolomics workflow and provides an overview of current analytic tools used for the quantification of metabolic profiles. We explain analytic tools such as mass spectrometry (MS), nuclear magnetic resonance (NMR) spectroscopy, ionization techniques, and approaches for data extraction and analysis.

Pacemaker Explantation in Patients With Lyme Carditis.

Early recognition of Lyme carditis is critical to preventing unnecessary pacemaker implantation for conduction abnormalities associated with this tick-born infection. Patients who do receive a pacemaker should be considered for device extraction after the completion of their antibiotic therapy if they recover normal atrioventricular node conduction. (Level of Difficulty: Intermediate.).

Long-term Outcomes in Treated Lyme Carditis.

Lyme disease is the most reported tick-borne illness in North America. Lyme carditis (LC) is an early-disseminated manifestation of Lyme disease, most commonly presenting as symptomatic high-degree atrioventricular block (AVB) which resolves with appropriate antibiotic therapy. However, long-term outcomes of treated LC have not previously been described. We present a series of 7 patients (median 28 years, 6 male) with serologically confirmed LC treated with a standard protocol developed at our center including antibiotics and pre-discharge stress test to assess AV node stability. At a mean follow-up of 20.8 months, all patients were asymptomatic, had resumed normal activities, and were free of conduction abnormalities. None required permanent pacing. Our study supports avoidance of permanent pacing for LC if conduction is stable at discharge.

Activation of Pak1/Akt/eNOS signaling following sphingosine-1-phosphate release as part of a mechanism protecting cardiomyocytes against ischemic cell injury.

We investigated whether plasma long-chain sphingoid base (LCSB) concentrations are altered by transient cardiac ischemia during percutaneous coronary intervention (PCI) in humans and examined the signaling through the sphingosine-1-phosphate (S1P) cascade as a mechanism underlying the S1P cardioprotective effect in cardiac myocytes. Venous samples were collected from either the coronary sinus (n = 7) or femoral vein (n = 24) of 31 patients at 1 and 5 min and 12 h, following induction of transient myocardial ischemia during elective PCI. Coronary sinus levels of LCSB were increased by 1,072% at 1 min and 941% at 5 min (n = 7), while peripheral blood levels of LCSB were increased by 579% at 1 min, 617% at 5 min, and 436% at 12 h (n = 24). In cultured cardiac myocytes, S1P, sphingosine (SPH), and FTY720, a sphingolipid drug candidate, showed protective effects against CoCl induced hypoxia/ischemic cell injury by reducing lactate dehydrogenase activity. Twenty-five nanomolars of FTY720 significantly increased phospho-Pak1 and phospho-Akt levels by 56 and 65.6% in cells treated with this drug for 15 min. Further experiments demonstrated that FTY720 triggered nitric oxide release from cardiac myocytes is through pertussis toxin-sensitive phosphatidylinositol 3-kinase/Akt/endothelial nitric oxide synthase signaling. In ex vivo hearts, ischemic preconditioning was cardioprotective in wild-type control mice (Pak1(f/f)), but this protection appeared to be ineffective in cardiomyocyte-specific Pak1 knockout (Pak1(cko)) hearts. The present study provides the first direct evidence of the behavior of plasma sphingolipids following transient cardiac ischemia with dramatic and early increases in LCSB in humans. We also demonstrated that S1P, SPH, and FTY720 have protective effects against hypoxic/ischemic cell injury, likely a Pak1/Akt1 signaling cascade and nitric oxide release. Further study on a mouse model of cardiac specific deletion of Pak1 demonstrates a crucial role of Pak1 in cardiac protection against ischemia/reperfusion injury.

Diathermy-induced Ventricular Fibrillation.

Diathermy is extensively used in patients for intracardiac device implant and extraction. While diathermy helps with adequate hemostasis, it may rarely be associated with fatal dysrhythmias. We report a case of diathermy-induced ventricular fibrillation during device extraction. The case highlights the importance and supports the involvement of a defibrillation facility during pacemaker revisions requiring diathermy.

Acute heart failure in pregnancy: importance of a timely multidisciplinary approach to recognition and management.

Increased cardiovascular demands of pregnancy may unmask occult diseases, such as dilated cardiomyopathy or valvular stenosis, or precipitate peripartum cardiomyopathy. We report a case of the emergency management and delivery of a young pregnant woman who presented with acute decompensated heart failure that was not immediately recognized. An emergency transfer to a tertiary care institution was arranged. Once diagnosed, the patient received multidisciplinary care shared between cardiologists, obstetricians, cardiac anesthetists, a neonatologist, and a midwife, resulting in good maternal and fetal outcomes.

Close-coupled pacing to identify the "functional" substrate of ventricular tachycardia: Long-term outcomes of the paced electrogram feature analysis technique.

BACKGROUND: The conduction delay and block that compose the critical isthmus of macroreentrant ventricular tachycardia (VT) is partly "functional" in that they only occur at faster cycle lengths. Close-coupled pacing stresses the myocardium's conduction capacity and may reveal late potentials (LPs) and fractionation. Interest has emerged in targeting this functional substrate. OBJECTIVE: The purpose of this study was to assess the feasibility and efficacy of a functional substrate VT ablation strategy. METHODS: Patients with scar-related VT undergoing their first ablation were recruited. A closely coupled extrastimulus (ventricular effective refractory period + 30 ms) was delivered at the right ventricular apex while mapping with a high-density catheter. Sites of functional impaired conduction exhibited increased electrogram duration due to LPs/fractionation. The time to last deflection was annotated on an electroanatomic map, readily identifying ablation targets. RESULTS: A total of 40 patients were recruited (34 [85%] ischemic). Median procedure duration was 330 minutes (interquartile range [IQR] 300-369), and ablation time was 49.4 minutes (IQR 33.8-48.3). Median functional substrate area was 41.9 cm2 (IQR 22.1-73.9). It was similarly distributed across bipolar voltage zones. Noninducibility was achieved in 34 of 40 patients (85%). Median follow-up was 711 days (IQR 255.5-972.8), during which 35 of 39 patients (89.7%) did not have VT recurrence, and 3 of 39 (7.5%) died. Antiarrhythmic drugs were continued in 53.8% (21/39). CONCLUSION: Functional substrate ablation resulted in high rates of noninducibility and freedom from VT. Mapping times were increased considerably. Our findings add to the encouraging trend reported by related techniques. Randomized multicenter trials are warranted to assess this next phase of VT ablation.

A meta-analysis of the prognostic significance of atrial fibrillation in chronic heart failure.

AIMS: Atrial fibrillation (AF) is one of the commonest sustained arrhythmias in chronic heart failure (CHF), although the prognostic implications of the presence of AF in CHF remain controversial. We have therefore performed this meta-analysis to study the effects of the presence of AF on mortality in CHF patients. METHODS AND RESULTS: A systematic MEDLINE search for all randomized trials and observational studies in which the influence of AF on CHF mortality was investigated and meta-analysis of the mortality data was performed. A total of 16 studies were identified of which 7 were randomized trials and 9 were observational studies including 30,248 and 23,721 patients, respectively. An adjusted meta-analysis of the data revealed that the presence of AF is associated with an adverse effect on total mortality with an odds ratio (OR) of 1.40 [95% confidence interval (CI) 1.32-1.48, P < 0.0001] in randomized trials and an OR of 1.14 (95% CI 1.03-1.26, P < 0.05) in observational studies. This increase in mortality associated with the presence of AF was observed in subgroups of CHF patients with both preserved and impaired left ventricular (LV) systolic function. CONCLUSION: In conclusion, meta-analysis of 16 studies involving 53,969 patients suggests that the presence of AF is associated with an adverse prognosis in CHF irrespective of LV systolic function.

Deactivation of Implantable Cardioverter Defibrillator in Patients With Terminal Diagnoses.

Implantable cardioverter defibrillators (ICDs) prevent sudden cardiac death. However, in patients with terminal illnesses, these devices may disrupt the dying process. This study was undertaken to review our current strategies surrounding device deactivation. A retrospective chart review was performed at Kingston Health Sciences Centre of patients with an ICD who died from 2015 to 2018. Data collected included patient demographics, clinical details surrounding device implantation, patient co-morbidities leading to deactivation, time to deactivation, physical place of deactivation, and device programming information. Ethics approval was obtained from the Queen's University Health Sciences Research Ethics Board. A total of 49 patients were included for analysis. Mean age at the time of death was 77.5 years (range: 57 to 94 years) and 12.2% (6/49) were women. The indications for ICD implantation were primary prevention of sudden cardiac death in 69.4% (34/49) and secondary prevention in 30.6% (15/49). Deactivation as part of end-of-life care was performed in 32.7% of patients (16/49). Deactivations occurred in clinic in 6.1% (3/49) of patients, on hospital inpatient wards in 12.2% (6/49) of patients, and in critical care settings in 14.2% (7/49) of patients. The remaining 67.3% (33/49) of patients died with fully functioning devices in place. The most prevalent terminal diagnoses were metastatic cancer (22.4%) and end-stage congestive heart failure (20.4%). On average, patients had their devices deactivated 13 months (range: 0 to 62 months) after their terminal diagnosis was established. Once a patient was documented as Do Not Resuscitate (DNR), deactivation was discussed and carried out within a mean time of 38 days (range: 0 to 400 days). Seven patients had their device active for more than 1 month after being documented as DNR. Ten patients (20.4%) received ICD shocks after their terminal diagnosis, 9 received shocks in the month before death, and 2 received shocks after formal DNR orders were in place. Approximately one-third of patients with ICDs received deactivation of their cardioversion/defibrillation therapies as part of their end-of-life care plan. A relatively high proportion of patients (20%) received an ICD shock in the last month of life. In conclusion, addressing device programming needs, including deactivation of cardioversion/defibrillation therapies, should be considered in the context of a patient's goals of care in every patient with an ICD who has a co-existing life-limiting diagnosis.

Radiotherapy for patients with cardiovascular implantable electronic devices: an 11-year experience.

PURPOSE: As cardiovascular implantable electronic devices (CIEDs) are increasingly indicated in older patients, and the burden of cancer is rising with the aging population, the management of patients with CIEDs who require radiotherapy (RT) is a timely concern. The objective of the study was to evaluate the management of, and malfunctions in, patients with CIEDs undergoing RT. METHODS: A retrospective study of patients with CIEDs receiving RT at Kingston Health Sciences Center from March 2007-April 2018 was conducted. Data on demographics, RT, devices, and management were compared for the primary outcome of device malfunction. RESULTS: Of the 189 patients with CIEDs receiving a total of 297 courses of RT, 4 patients (2.1%) experienced device malfunctions. Higher beam energy was associated with a malfunction (p < 0.05). Patients with malfunctions received a lower dose of radiation per fraction (267 ± 93 cGy vs. 477 ± 282 cGy; p < 0.05) and were significantly younger (71.4 ± 2.2 years vs. 77.8 ± 9.8 years; p < 0.01) compared to patients without malfunctions. CONCLUSION: RT-induced device malfunctions are rare, but given the potential complications, a better understanding of the potential predictors of malfunction and the development of evidence-based guidelines will help optimize patient safety.

Prevalence, characteristics and outcomes of people aged 65 years and over with an incidental rise in cardiac troponin I. An observational prospective cohort study.

BACKGROUND: Cardiac troponin I (cTnI) is a sensitive and specific marker of acute cardiac damage. We examined the prevalence, characteristics and outcome of incidental cTnI rises in older patients. METHODS: One hundred and eighty-seven consecutive patients aged 65 years or over with a raised cTnI on admission at least 8 h after symptom onset were categorised into: (1) ST-elevation myocardial infarction, (2) other acute coronary syndromes (ACS), (3) other recognised non-ACS causes of cTnI rise and (4) non-ACS with no other identifiable cause (an incidental finding). The number of readmissions and deaths for each group was measured at 30 and 90 days. RESULTS: Age range = 65-98 years. Male = 55.6%. Fifty-four percent had a raised cTnI due to non-ACS illnesses, whilst in 18% it was an incidental finding. The latter group was relatively older and had a significantly lower degree of cTnI rise (U = 1718.5, p = 0.002), but a higher readmission and mortality rate compared to the other groups (categories 1-3) for both follow-up periods. CONCLUSIONS: Incidental cTnI rise is common in older patients and is associated with a poorer prognosis compared to ACS or a recognised non-ACS condition. Future research should attempt to evaluate the significance of such incidental rises in elderly patients.