Sustained Supraventricular Tachycardia Research Articles

Incidental Arrhythmias During Atrial Fibrillation Screening With Repeat 7-Day Holter ECGs in a Hospital-Based Patient Population.

Screening for atrial fibrillation (AF) may reveal incidental arrhythmias of relevance. The aim of this study was to describe incidental arrhythmias detected during screening for AF in the STAR-FIB (Predicting SilenT AtRial FIBrillation in Patients at High Thrombembolic Risk) cohort study. In the STAR-FIB cohort study, we screened hospitalized patients for AF with 3 repeat 7-day Holter ECGs. We analyzed all Holter ECGs for the presence of the following incidental arrhythmias: (1) sinus node dysfunction, defined as sinus pause of ≥3 seconds' duration; (2) second-degree (including Wenckebach) or higher-degree atrioventricular block (AVB); (3) sustained supraventricular tachycardia of ≥30 seconds' duration; and (4) sustained ventricular tachycardia of ≥30 seconds' duration. We furthermore report treatment decisions because of incidental arrhythmias. A total of 2077 Holter ECGs were performed in 794 patients (mean age, 74.7 years; 49% women), resulting in a mean cumulative duration of analyzable ECG signal of 414±136 hours/patient. We found incidental arrhythmias in 94 patients (11.8%). Among these were sinus node dysfunction in 14 patients (1.8%), AVB in 41 (5.2%), supraventricular tachycardia in 42 (5.3%), and ventricular tachycardia in 2 (0.3%). Second-degree AVB was found in 23 patients (2.9%), 2:1 AVB in 10 (1.3%), and complete AVB in 8 (1%). Subsequently, 8 patients underwent pacemaker implantation, 1 for sinus node dysfunction (post-AF conversion pause of 9 seconds) and 7 for advanced AVB. One patient had an implantable cardioverter-defibrillator implanted for syncopal ventricular tachycardia. Incidental arrhythmias were frequently detected during screening for AF in the STAR-FIB study and resulted in device therapy in 1.1% of our cohort patients.

Cardiac Magnetic Resonance in Patients with Suspected Tachycardia-Induced Cardiomyopathy: The Impact of Late Gadolinium Enhancement and Epicardial Fat Tissue.

Tachycardia-induced cardiomyopathy (TIC) is a reversible subtype of dilated cardiomyopathy (DCM) resulting from sustained supraventricular or ventricular tachycardia and diagnosed by the normalization of left ventricular ejection fraction (LVEF) after stable sinus rhythm restoration. The aim of this study was to determine the contribution of cardiac magnetic resonance (CMR) to the differential diagnosis of TIC and DCM with persistent atrial arrythmias in patients hospitalized for the first time with heart failure (HF) with reduced LVEF of nonischemic origin. A total of 29 patients (age: 58.2 ± 16.9 years; males: 65.5%; average EF: 37.0 ± 9.5%) with persistent atrial tachyarrhythmia and first decompensation of HF without known coronary artery diseases were included in this study. The patients successfully underwent cardioversion and were observed for 30 days. The study population was divided into groups of responders (TIC patients; N = 16), which implies achieving FF > 50% or its increase > 10% in 30 days of TIC, and non-responders (N = 13). The increase in left ventricle (LV) volumes measured using CMR was significantly higher in the non-responder group when compared with the responders (114.8 mL ± 25.1 vs. 68.1 mL ± 10.5, respectively, p < 0.05). Non-responders also demonstrated decreased interventricular septum thickness (9.1 ± 0.8 vs.11.5 ± 1.3, respectively, p < 0.05). Late gadolinium enhancement (LGE) was observed in 12 patients (41.4%). The prevalence of LGE was increased in the non-responder group (25.0% vs. 65.1%, respectively, p = 0.046). Notably, a septal mid-wall LGE pattern was found exclusively in the non-responders. Epicardial adipose tissue thickness was decreased in the non-responder group versus the TIC patients. Conclusion: Patients with TIC were found to have smaller atrial and ventricular dimensions in comparison to patients with DCM. In addition, LGE was more common in DCM patients.

Localization and characterization of atrial depolarization waves on the surface electrocardiogram in dogs with rapid supraventricular tachycardia.

Supraventricular tachycardias (SVTs), despite having various anatomical substrates and pathophysiological mechanisms, frequently show similar electrocardiographic presentations. To locate and characterize atrial deflections (ADs) on 12-lead electrocardiograms in dogs with sustained rapid SVT and assess the utility of different electrocardiographic variables in differentiating types of tachycardia. Ninety-two dogs with orthodromic atrioventricular reciprocating tachycardia, 17 with atrial flutter, 33 with focal atrial tachycardia recorded and confirmed by electrophysiological study, and 40 dogs with sinus tachycardia. Atrial deflection position on the 12-lead surface electrocardiogram was assessed according to the sequence of intracardiac activation. Its features were evaluated together with the relationship between AD and QRS complex interval (AD-R) and QRS complex and AD interval (R-AD). Orthodromic atrioventricular reciprocating tachycardia was characterized by an AD-AD interval of 213 ± 30 ms, mean electrical axis (MEA) of AD of -90 (-90/-78)°, R-AD interval of 75 (65-80) ms, and R-AD/AD-R of 0.54 (0.45-0.64). Atrial flutter was characterized by an AD-AD interval of 199 ± 57 ms, MEA of 76° (72/81), R-AD of 120 (72-144) ms, and R-AD/AD-R of 0.81 (0.63-1.13). Focal atrial tachycardia was characterized by an AD-AD interval of 270 ± 38 ms, MEA of 49 (-72/76)°, R-AD of 160 (120-200) ms, and R-AD/AD-R of 1.45 (0.92-1.67). Sinus tachycardia was characterized by an AD-AD interval of 292 ± 31 ms, MEA of 66° (52/73), R-AD of 215 (192-222) ms, and R-AD/AD-R of 2.68 (2.25-3.08). Analyzing AD on 12-lead electrocardiogram is helpful in differentiating the most common SVTs in dogs.

Predictors of arrhythmia during pregnancy in adults with congenital heart disease

BackgroundRisk prediction of arrhythmia during pregnancy in adult congenital heart disease (ACHD) patients is currently lacking, and the impact of preconception catheter ablation on future antepartum arrhythmia has not been studied. MethodsWe conducted a single-center, retrospective cohort study of pregnancies in ACHD patients. Clinically significant arrhythmia events during pregnancy were described, predictors of arrhythmia were analyzed, and a risk score devised. The impact of preconception catheter ablation on antepartum arrhythmia was assessed. ResultsThe study included 172 pregnancies in 137 patients. Arrhythmia events occurred in 25 (15%) of pregnancies, with 64% of events occurring in the second trimester and sustained supraventricular tachycardia being the most common rhythm. Univariate predictors of arrhythmia were history of tachyarrhythmia (OR 20.33, 95% CI 6.95–59.47, p < 0.001, Fontan circulation (OR 11.90, 95% CI 2.60–53.70, p < 0.001), baseline physiologic class C/D (OR 3.72, 95% CI 1.54–9.01, p = 0.002) and history of multiple valve interventions (OR 3.10, 95% CI 1.20–8.20, p = 0.017). Three risk factors (excluding multiple valve interventions) were used to formulate a risk score, with a cutoff of ≥2 points predicting antepartum arrhythmia with sensitivity and specificity of 84%. While recurrence of the index arrhythmia was not observed following successful catheter ablation, preconception ablation did not impact odds of antepartum arrhythmia. ConclusionsWe provide a novel risk stratification scheme for predicting antepartum arrhythmia in ACHD patients. The role of contemporary preconception catheter ablation in risk reduction needs further refinement with multicenter investigation.

10-year single center experience of catheter ablation of focal atrial tachycardia.

Focal atrial tachycardias (ATs) represent 5-15% of sustained supraventricular tachycardias (SVTs). Characteristic distribution of sites of origin and detailed electrophysiologic characterization of AT from specific sites of origin (SOO) have been described. Acute success and recurrence are less favorable than for other SVTs. In this series, we present our experience of focal AT ablation over a 10-year period. We undertook a retrospective review of an electronically maintained database of all patients undergoing AT ablation at our institution between January 2011 and December 2020. Demographic, procedural, and outcomes data were reviewed. A total of 293 distinct atrial tachycardias were treated during 279 procedures in 256 patients, including 207 first AT ablations. Acutely successful AT suppression was achieved in 91% of first-time ablations. Acute success was dependent on SOO of AT with lowest rates of acute suppression in the para-Hisian region and the crista terminalis (CT). The most common reason for failure to acutely suppress the AT was proximity to a critical structure (phrenic nerve, sinus node, and AV node). 8.9% of patients in this series presented with a tachycardia-mediated cardiomyopathy (TCM). 48% of TCM patients underwent an ablation attempt during an acute medical admission. Among the TCM group, median LV ejection fraction increased from 25% (range 10-50%) to 55% (range 35-65%) with successful treatment of AT. Five patients undergoing a repeat procedure had planned pericardial access for displacement of the phrenic nerve to permit ablation of the AT, which was successful in all cases. Among patients without a pre-existing diagnosis of AF, peri-procedural AF was not associated with a higher incidence of a subsequent diagnosis of AF (odds ratio 1.169, 95% CI 0.4058-3.475, p = 0.7628). Median duration of follow-up was 832days. By Kaplan-Meier estimate, recurrence-free survival was 78% (95% CI 67-88%). In this series, focal AT ablation is associated with good acute results and a low rate of complications, but outcomes remain less favorable than previously reported for other forms of SVT.

Abstract 14295: Asymptomatic Frequent Atrial Ectopy in Healthy Children and Adolescents

Introduction: Premature atrial complexes (PACs) in pediatric patients with a structurally normal heart are usually presumed to be benign and self-resolving. On the contrary, adults with frequent PACs are at increased risk of multiple cardiovascular conditions. This study aims to evaluate a group of asymptomatic pediatric subjects with frequent PACs over time. Hypothesis: We hypothesized that, while most pediatric patients with frequent APCs have a benign prognosis there may be a subset that could progress to supraventricular arrhythmias Methods: Records for 343 pediatric patients (1-21 yrs) with asymptomatic frequent premature atrial complexes (&gt;50/24 hours) were selected from 6902 pediatric patients that underwent Holters over a 10 year period. Demographics, pertinent clinical characteristics and results of cardiac investigations were tabulated. Comparisons were made between Holter results at presentation and follow-up. Patients were classified into two groups on follow-up, those with a significant (&gt;20%) reduction in burden of atrial ectopy versus those with an insignificant (&lt;20%) reduction or increase in burden of atrial ectopy. Results: The median age at initial Holter was 8.26 (1.3-20.9) years with a comparable male to female ratio. An irregular heart rate was the most common reason for a Holter. The most common preexisting medical condition was attention deficit disorder, followed by asthma. Follow-up Holters were performed on 188(54.8%) patients at a median of 2.2 (0.5-8) yrs after the first Holter. Overall there was a significant decrease in atrial ectopy burden on repeat Holter examinations; median 3.6% (0.03-18.7) to 0.5% (0-19) with 166 (88.3%) patients demonstrating a decrease in atrial ectopy by over 20% of baseline. Ten (5.3%) patients had an increase in the ectopy burden over time and 12(6.3%) had an insignificant change. Non sustained supraventricular tachycardia was noted in three patients on the initial Holter but none on subsequent evaluations. Multivariate analysis identified a higher initial burden of PACs as a strong independent predictor for reduction in burden of ectopy with time (p&lt;0.005). Conclusions: Asymptomatic childhood PACs in the setting of a structurally normal heart are rare and tend to resolve with time.

Postnatal Outcomes in Infants WithaHistory of Fetal SupraventricularTachycardia.

Fetal supraventricular tachycardia (SVT) is rare and proposed predictors of postnatal outcomes in fetal SVT have not been validated. Valid predictors can guide postnatal management. The authors correlated fetal characteristics to the incidence of postnatal SVT and compared SVT outcomes in infants with and without a history of fetal SVT. Mother-fetus dyads with fetal SVT and a structurally normal heart were described and compared with a second cohort of infants with a postnatal diagnosis of SVT. SVT was observed in 78 fetuses and 76 survived to delivery. Maternally administered transplacental antiarrhythmics were used in 49 mother-fetus dyads. Rhythm control was achieved in 37 of 49 (76%). Among fetuses with intermittent SVT, there was no ventricular dysfunction or hydrops. Postnatal SVT occurred in one-half of infants (37 of 76), and 94% presented within the first 2days of life. The following fetal characteristics were associated with postnatal SVT on univariable analysis: sustained SVT (87% vs 56%), ventricular dysfunction (41% vs 15%), lack of conversion to sinus rhythm (49% vs 10%), and earlier gestational age at delivery (37.6weeks vs 38.9weeks; P≤ 0.01 for each comparison). Compared with infants with a postnatal diagnosis of SVT, infants with a fetal diagnosis presented earlier (median age 0days vs 17days; P&lt; 0.01) and had a lower incidence ventricular dysfunction at presentation (5% vs 42%; P&lt; 0.01). One-half of infants with fetal SVT had postnatal SVT, nearly all within 2days of life. These data and predictors of postnatal SVT may influence parental counseling and postnatal clinical decision-making.

When adenosine is not enough.

For pediatric patients who present with sustained supraventricular tachycardia (SVT), adenosine is the drug of choice for initial treatment.1 For those patients with adenosine refractory SVT, treatment options are limited. Additionally, this has been identified as a knowledge gap in the 2020 American Heart Association Guidelines for pediatric life support.1 Our study sought to describe our experience with intravenous (IV) sotalol for pediatric patients with adenosine refractory reentrant SVT.

Assessment of New Onset Arrhythmias After Transcatheter Aortic Valve Implantation Using an Implantable Cardiac Monitor.

BackgroundTranscatheter aortic valve implantation (TAVI) is associated with new onset brady- and tachyarrhythmias which may impact clinical outcome.AimsTo investigate the true incidence of new onset arrhythmias within 12 months after TAVI using an implantable cardiac monitor (ICM).MethodsOne hundred patients undergoing TAVI received an ICM within 3 months before or up to 5 days after TAVI. Patients were followed-up for 12 months after discharge from TAVI for the occurrence of atrial fibrillation (AF), bradycardia (≤30 bpm), advanced atrioventricular (AV) block, sustained ventricular and supraventricular tachycardia.ResultsA previously undiagnosed arrhythmia was observed in 31 patients (31%) and comprised AF in 19 patients (19%), advanced AV block in 3 patients (3%), and sustained supraventricular and ventricular tachycardia in 10 (10%) and 2 patients (2%), respectively. Three patients had a clinical diagnosis of sick-sinus-syndrome. A permanent pacemaker (PPM) was implanted in six patients (6%). The prevalence of pre-existing AF was 28%, and 47% of the patients had AF at the end of the study period. AF burden was significantly higher in patients with pre-existing [26.7% (IQR 0.3%; 100%)] compared to patients with new-onset AF [0.0% (IQR 0.0%; 0.06%); p = 0.001]. Three patients died after TAVI without evidence of an arrhythmic cause according to the available ICM recordings.ConclusionsRhythm monitoring for 12 months after TAVI revealed new arrhythmias, mainly AF, in almost one third of patients. Atrial fibrillation burden was higher in patients with prevalent compared to incident AF. Selected patients may benefit from short-term remote monitoring.Trial Registrationhttps://clinicaltrials.gov/: NCT02559011.

Ambulatory Cardiac Monitoring in Infants with Supraventricular Tachycardia.

Supraventricular tachycardia (SVT) is a frequent cause of tachyarrhythmia in infants < 1year of age and ambulatory cardiac monitoring is an important tool for diagnosis and follow-up of these patients. We retrospectively reviewed 594 infants (mean age 4.05months, SD 3.55; 54% M) who underwent ambulatory cardiac monitoring (69% 24h Holter, 31% extended monitor) through the Pocket ECG system (MediLynx) between January 2016 and July 2020. 170 patients who had the ICD-10 code I47.1 for SVT used at enrollment were analyzed separately. 49 (8.3%) patients had sustained SVT or non-sustained SVT (nSVT) during the study period, including 20 patients (11.8%) who had the ICD-10 code I47.1 at enrollment. Extended ambulatory cardiac monitors detected 61% of all patients with nSVT or SVT and was superior when compared to 24h Holter (p < 0.0001). In the overall group, the first episode of SVT or nSVT was detected within 24h of monitoring in 40/49 patients (82%). 48/49 patients (98%) were diagnosed within a week of monitoring and the single remaining patient was diagnosed with nSVT at day 15 of monitoring. There was no significant difference in minimal, maximal, and average heart rate between patients with and without ICD-10 code I47.1 at enrollment or between patients with and without SVT or nSVT. Despite their low yield, ambulatory cardiac monitors are an important diagnostic tool. The ideal length of monitoring in patients with known or suspected SVT has yet to be defined, although all patients in our cohort were identified by day 15 of monitoring.

Fetal Tachyarrhythmia Management from Digoxin to Amiodarone-A Review.

Sustained fetal tachycardias are rare but represent a high risk of mortality and morbidity. Consensus has yet to be found regarding their optimal management. The aim of this narrative review is to summarize the data available in the current literature regarding the efficacy and safety of medications used in the management of intrauterine tachyarrhythmias and to provide possible treatment protocols. In this review, we would like to emphasize the importance of a thorough evaluation of both the fetus and the mother, prior to transplacental antiarrhythmic drug initiation. Factors such as the hemodynamic status of the fetus, possible mechanisms of fetal arrhythmia, and concomitant maternal conditions are of primordial importance. As a possible treatment protocol, we would like to recommend the following: due to the risk of sustained supraventricular tachycardia (SVT), fetuses with frequent premature atrial beats should be evaluated more frequently by echocardiography. A careful hemodynamic evaluation of a fetus with tachycardia is primordial in forestalling the appearance of hydrops. In the case of atrial flutter (AFL), sotalol therapy could represent a first choice, whereas when dealing with SVT patients, flecainide should be considered, especially for hydropic patients. These data require consolidation through larger scale, non-randomized studies and should be handled with caution.

Prospective arrhythmia surveillance after a COVID-19 diagnosis

BackgroundCardiac arrhythmias have been observed among patients hospitalised with acute COVID-19 infection, and palpitations remain a common symptom among the much larger outpatient population of COVID-19 survivors in the convalescent...

Cardioversion of supraventricular tachycardia in a cat with suspected Wolff–Parkinson–White syndrome in the absence of structural cardiac disease

AbstractThe objective of this publication is to provide the clinical presentation, electrocardiographic findings and therapy for management of suspected Wolff–Parkinson–White syndrome in a cat without evidence of underlying cardiomyopathy or systemic disease. A 2‐year‐old male neutered domestic shorthair cat was presented for continued investigations following recent transient loss of consciousness episodes. Electrocardiography showed a sustained supraventricular tachycardia, which was successfully converted to sinus rhythm with intravenous diltiazem administration. Ventricular pre‐excitation was presumed during the electrocardiogram postconversion and oral diltiazem was instituted. Cardiac troponin I was measured, conversely to prior reports, which was significantly high on presentation and decreased after treatment. The new information provided by this case report is that it represents an original description of Wolff–Parkinson–White syndrome in a cat without any obvious underlying cardiomyopathy, and treatment protocol resulted in a successful outcome to date.

Supraventricular Tachycardia Causing Left Ventricular Dysfunction

There is limited evidence on characterization and natural history of supraventricular tachycardia (SVT)-induced left ventricular (LV) dysfunction. The aim of this work was to characterize clinical features and long-term evolution of SVT-induced LV dysfunction. Patients consecutively admitted with sustained SVT and heart rate >100 bpm as the only known cause of a new onset LV systolic dysfunction (i.e., LV ejection fraction [EF] <50%) were analyzed. Patients were then revaluated periodically. Recovered LVEF (i.e., ≥50%) and a composite of death, heart transplant or first episode of major ventricular arrhythmias were evaluated as study end-points. We enrolled 83 patients. After SVT therapy, 56 (67%) showed a recovered LVEF at the last follow-up of median 54 (interquartile range 36 to 87) months. Seventeen (30%) of those patients had a temporary new drop in LVEF during follow-up associated to high-rate SVT relapse. At presentation, patients with recovered LVEF were younger (52 vs 67 years respectively, p <0.001) and had higher LVEF (34% vs 27% respectively, p=0.005) compared to non-recovered LVEF patients. Finally, 4% of recovered LVEF patients vs 26% of nonrecovered LVEF patients experienced death/heart transplant/major ventricular arrhythmias during follow-up (p=0.004). In conclusion, after almost 5 years of follow-up, two-thirds of patients with high-rate SVT causing a newly diagnosed LV systolic dysfunction recovered and maintained normal LV function after SVT control, with a subsequent benign outcome. Long term individual surveillance is required in those patients, as arrhythmic recurrences and new drops in LVEF are common in the long term.

Managing athletes with palpitations of unknown origin with an external loop recorder: a cohort study.

Palpitations in athletes are usually benign, but the presence of major cardiac arrhythmias should be ruled out despite the infrequent appraisal of symptoms. External loop recorders (ELR) are promising to identify arrhythmias in these circumstances, but experiences in athletes are lacking. We aimed to investigate the feasibility and diagnostic yield of an ELR in athletes with unexplained palpitations in a cohort study. One hundred twenty-two consecutive subjects (61 athletes and 61 sedentary controls) with sporadic palpitations and inconclusive diagnosis were enrolled and equipped with an ELR. Findings were categorized as major and minor arrhythmic findings, non-arrhythmic findings or negative monitoring. Long-term ELR monitoring was feasible in all subjects, with median duration of 12 (11; 15) days. Major arrhythmic events during palpitations were found in 9 (14.8%) athletes: 7 experienced sustained paroxysmal supraventricular tachycardia, and 2 had non sustained ventricular tachycardia. Minor arrhythmic events (premature supraventricular or ventricular beats) were observed in 13 athletes (21.3%). Non-arrhythmic findings (i.e., sinus rhythm or sinus tachycardia) were recorded in 28 athletes (45.9%), whereas 11 (18%) had negative monitoring. In the sedentary group, arrhythmic events were similar for types and frequency to athletes. The diagnostic yield of loop monitoring was 82.8% in the overall population and 82.0% in the athlete's group. In the management of an athlete symptomatic with unexplained palpitations after 24-hour ECG monitoring and stress test, ELR is an efficient tool to identify major arrhythmic events, which can be present in up to 10% of symptomatic athletes during practice and competition.

Usefulness of Left Ventricular Myocardial Deformation in Children Hospitalized for Acute Myocarditis who Develop Arrhythmias

Cardiac arrhythmias occur in 3-40% of patients with acute myocarditis and cause significant morbidity and mortality. Myocardial injury also results in abnormal myocardial deformation. The relationship between left ventricular (LV) deformation, measured by two-dimensional speckle tracking echocardiography (2D-STE), and arrhythmia in pediatric myocarditis is unknown. We evaluated the association between 2D-STE and arrhythmias in children hospitalized with acute myocarditis. We reviewed patients ≤ 18 years hospitalized for acute myocarditis from 2008 to 2018. Arrhythmias were defined as 1) non-sustained or sustained ventricular tachycardia or ventricular fibrillation, 2) sustained supraventricular tachycardia (SVT), 3) high-grade or complete heart block, and 4) any arrhythmia treated with an antiarrhythmic medication. Systolic LV strain values (including LV global longitudinal strain (GLS), global circumferential strain (GCS), and six segments of LV regional long axis strain) were obtained from initial echocardiograms during hospitalization. Of 66 patients hospitalized, 23 (35%) had arrhythmias. SVT was the predominant arrhythmia (74%). Global and regional strain indices were reduced in the arrhythmia group: LV GLS [-8.9 (IQR -13.6, -6.1) vs. -13.7 (IQR -16.9, -9.7), p=0.038]; basal inferior/septal [-10.7 (IQR -15.5, -7.8) vs. -16.4 (IQR -18, -11.8), p=0.009]; basal anterior/lateral [-7.1 (IQR -12.8, -4.7) vs. -9.4 (IQR -16.7, -7.4), p=0.025]; and mid inferior/septal segments [-9 (IQR -13, -7.7) vs. -14.1 (IQR -22.5, -10.7), p=0.007]. After controlling for age, reductions in GLS and segmental strain in the two basal and two mid-segments were associated with increased arrhythmia occurrence (p <0.05). Our findings suggest that echocardiographic LV deformation by 2D-STE may be useful in identifying pediatric patients with acute myocarditis at risk for arrhythmias.

Incidence and type of arrhythmias recorded by one-month continuous ECG monitoring in stroke patients

Abstract Funding Acknowledgements Type of funding sources: None. BACKGROUND The incidence of atrial fibrillation (AF) following stroke has been studied with implantable loop recorders. However, these devices do not record short lasting AF episodes (&amp;lt;30-120 seconds [s]). In addition, the incidence and type of other clinically relevant arrhythmias is poorly understood in this clinical setting. PURPOSE To evaluate the incidence, type and clinical relevance of arrhythmias detected by one-month continuous ECG monitoring in patients after cryptogenic stroke. MATERIAL AND METHODS Consecutive patients (p) with stroke and no previous AF or other cardioembolic or atheroembolic causes were prospectively enrolled in the study. An external wearable 2-lead ECG monitoring system (NUUBO) was used for 30 days (d) in all of them after the acute phase of the stroke. In the absence of documented AF, a parafibrillatory status was defined as &amp;gt;3000 atrial ectopic beats/d or &amp;gt;2 "micro AF" episodes (fibrillatory burst &amp;lt;30 s)/d or ≥1 episode of "micro AF" &amp;gt;14 s. RESULTS 130 p. were included in the study (age 73 ± 12, 57% males, 19% previous stroke, 7% ischemic cardiopathy, CHA2DSVA2Sc pre-stroke 3.1 ± 1.7). 3 were withdrawn from the study due to inadequate use (recording time &amp;lt;14 d) and 1 due to stroke during SARS-CoV2 infection. Total recording time was 28 ± 3 d, total analyzable ECG time was 23 ± 5 d. ECG monitoring was repeated in 12 (9.5%) p due to poor ECG quality in 6 p or high suspicion of AF despite an initial negative result in 6 p. AF &amp;gt;30 s was detected in a total of 27 (21.4%) p, average AF duration was 52 hours (range 30 s-22 d). AF &amp;gt;30s was detected in 2 (17%) p with repeated monitoring. All these patients were placed on anticoagulation. Sustained paroxysmal supraventricular tachycardia (SVT) was documented in 4 (4.4%) p without AF. All episodes of AF and SVT were asymptomatic. Mobitz I second degree AV block in 4 (3.2%) p. 3 (2.4%) p had a pacemaker implanted: 2 for severe sinus dysfunction and 1 for AV block. High-density ventricular ectopy (&amp;gt;3000/d) was present in 7 (6%) p and ≥1 episode of non-sustained ventricular tachycardia was detected in 26 (21%) p. A parafibrillatory status was identified in 27 (21%) p with no AF &amp;gt;30 s. At 1-year follow up 4/22 (18%) of patients with parafibrillatory status and 3/59 (5%) without parafibrillatory status suffered a new stroke (p = 0.08). CONCLUSIONS AF and other potentially relevant arrhythmias are frequent after stroke and easily detectable with one-month non-invasive continuous ECG monitoring. Patients with a parafibrillatory status could benefit from longer monitoring time to detect AF.

Design and Preliminary Results of Sensing and Detection for an Extravascular Implantable Cardioverter-Defibrillator.

This study reports the sensing and arrhythmia detection performance of a novel extravascular (EV) implantable cardioverter-defibrillator (ICD) in a first-in-human pilot study. The EV ICD lead is implanted in the substernal space, resulting in novel sensing and detection challenges. It uses a programmable sensing profile with new or modified discrimination of oversensing and of ventricular tachycardia (VT) from supraventricular tachycardia (SVT). Electrograms were post-processed from induced ventricular fibrillation (VF) at implant to determine virtual detection times for each programmable sensitivity and the least-sensitive safe sensitivity setting. In ambulatory patients, programmed sensitivity provided at least a twofold safety margin for detecting induced VF. Noise discrimination was stress tested, and the effects of source, posture, and lead maturation were determined on electrogram amplitude. Telemetry Holter monitors were used to quantify undersensing and oversensing. In 20 patients at implant, the least-sensitive safe sensitivity for VF detection ranged from 0.1 to 0.6mV. Seventeen patients were followed up for a total of 16.6 patient-years. Electrogram amplitudes were stable over time, but there were significant differences among postures and sensing vectors. For the primary sensing vector, the weighted oversensing and undersensing rates were 1.03% and 0.40% respectively, on a beat-to-beat basis. Oversensing did not cause inappropriate therapy in patients with in situ leads. Oversensing discriminators withheld VF detection in 4 of 5 spontaneous, sustained oversensed episodes. SVT-VT discriminators correctly classified 93% of 128 sustained SVTs in monitor zones. In the EV ICD pilot study, oversensing did not cause inappropriate therapy during ambulatory follow-up of stable leads.

The Effect of Accessory Pathway Location on Cardiac Function in Adult Patients with Wolff-Parkinson-White Syndrome.

Introduction The relationship between ventricular pre-excitation and left ventricular dysfunction has been described in the absence of sustained supraventricular tachycardia in a series of case reports. However, there have been no systematic studies about the effect of ventricular pre-excitation on cardiac function in adult patients with different accessory pathway locations. Methods and Results Patients were divided into four groups based on the type and location of their accessory pathway: septal, right free wall, left free wall, and concealed. N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels, electrocardiogram recordings, electrophysiological properties, and transthoracic echocardiographic data (septal-to-posterior wall motion delay (SPWMD) and interventricular mechanical delay (IVMD) indicating intraventricular and interventricular dyssynchrony) were compared before and after successful ablation. Before radiofrequency catheter ablation, left ventricular ejection fraction (LVEF) was significantly lower in patients with septal and right free wall accessory pathways. Within three months after radiofrequency catheter ablation, NT-proBNP levels decreased, left ventricular function improved, and intraventricular left ventricular dyssynchrony disappeared. There was a negative correlation between initial LVEF with initial QRS duration and initial SPWMD. Notably, SPWMD had a stronger correlation with LVEF than initial QRS duration. Conclusions Anterograde conduction with a septal or right free wall accessory pathway may cause left ventricular dyssynchrony and impair left ventricular function. Intraventricular left ventricular dyssynchrony seems to be responsible for the pathogenesis of left ventricular dysfunction. Radiofrequency catheter ablation results in decreased NT-proBNP levels, normalized QRS duration, mechanical resynchronization, and improved left ventricular function.

Update on Etripamil Nasal Spray for the At-home Treatment of Acute Paroxysmal Supraventricular Tachycardia.

The current treatment of sustained paroxysmal supraventricular tachycardia (PSVT) often requires attendance at a medical facility. This burden is driven by the lack of an effective self-administered treatment for PSVT. Etripamil (Milestone Pharmaceuticals, Saint-Laurent, QC, Canada) is a novel intra-nasal preparation of a rapidly effective but short-acting calcium-channel blocker, which shows promise in offering out-of-hospital treatment for patients with PSVT. Studies, to date, have demonstrated good tolerability and potential efficacy, with a safety profile that is acceptable for unsupervised self-administration. This article reviews the current epidemiology and international guidelines for the treatment of acute PSVT, the pharmacology and clinical trial evidence behind the novel agent etripamil, and considers its potential role in the management of patients with PSVT.