The effect of long-term use of methylphenidate on cardiac autonomic functions and ventricular arrhythmogenesis: a prospective case-control study.

OBJECTIVE: We aimed to assess cardiac autonomic balance with heart rate variability by using 24-hour Holter electrocardiography and also to assess susceptibility to ventricular arrhythmias by using microvolt T wave alternance in children with attention deficit hyperactivity disorder. METHOD: This study was conducted with age- and gender-matched groups of 40 patients taking long-acting methylphenidate for more than a year and 55 healthy controls. Heart rate variability analysis for cardiac autonomic functions and microvolt T wave alternance measurements for susceptibility to ventricular arrhythmias were evaluated by 24-hour Holter electrocardiography. RESULTS: The mean age 10.9 ± 2.7 years, mean duration of therapy 22.76 months, and mean methylphenidate doses were 37.64 mg/day. The study group had considerably higher rMSSD, higher HF, and a lower LF/HF ratio (respectively, p : 0.02, p : 0.001 and p : 0.01). While parasympathetic activity parameters were elevated, sympathetic activity parameters were low during the sleep period. Increase in the microvolt T wave alternance values of the study group was not found to be statistically significant (p > 0.05). CONCLUSION: In children taking long-acting methylphenidate, the autonomic balance was shown to be in favour of the parasympathetic system. Determination of the vulnerability to life-threatening ventricular arrhythmias has been evaluated for the first time in children with attention deficit hyperactivity disorder. Accordingly, microvolt T-wave alternance values give the notion that drug use is safe.

Holter Electrocardiographic Approach to Predicting Outcomes of Pediatric Patients With Long QT Syndrome.

BACKGROUND: This study was performed to clarify the clinical findings of pediatric patients diagnosed with long QT syndrome (LQTS) through electrocardiographic screening programs and to predict their outcome using Holter electrocardiographic approaches.Methods and Results: This retrospective study included pediatric patients with a Schwartz score of ≥3.5 who visited the National Hospital Organization Kagoshima Medical Center between April 2005 and March 2019. Resting 12-lead and Holter electrocardiograms were recorded at every visit. The maximum resting QTc and maximum Holter QTc values among all recordings were used for statistical analyses. To test the prognostic value of QTc for the appearance of cardiac events after the first hospital visit, receiver operating characteristic curves were used to calculate the area under the curve (AUC). Among 207 patients, 181 (87%) were diagnosed through screening programs. The prevalence of cardiac events after the first hospital visit was 4% (8/207). Among QTc at diagnosis, maximum resting QTc, and maximum Holter QTc, only maximum Holter QTc value was a predictor (P=0.02) of cardiac events after the hospital visit in multivariate regression analysis. The AUC of the maximum Holter QTc was significantly superior to that of maximum resting QTc. CONCLUSIONS: The maximum Holter QTc value can be used to predict the appearance of symptoms in pediatric patients with LQTS.

Recent progress of Holter-based late potential for predicting serious cardiac events and its implications and future challenges.

Late potential (LP) has recently been measured using Holter electrocardiogram (H-LP), and accumulating evidence suggests that it is a useful approach for detecting lethal arrhythmias and sudden cardiac death, especially in cases of ischemic heart disease. In this review, our primary objective was to advance the understanding and utilization of H-LP by elucidating the existing unresolved aspects, thereby serving as a guide for future research in this domain. Particularly, the combination of H-LP with non-sustained ventricular tachycardia, rather than LP alone, may improve the accuracy of the test. H-LP parameters show diurnal variations in both patients with cardiac disease and healthy individuals. Although H-LP shows promise as the future mainstream LP test, there are several problems; specifically, handling noise levels when H-LP is performed in unrestricted daily activities. Additionally, a reference value that considers diurnal variations has not yet been established. These challenges need to be addressed to improve the viability and clinical use of H-LP. By incorporating H-LP into routine assessments, healthcare practitioners can gain valuable insights into the cardiovascular health of their patients, facilitating timely interventions and better disease management.

Prediction model for the new onset of atrial fibrillation combining features of 24-hour Holter electrocardiogram with 12-lead electrocardiogram.

Background: Several factors that predict new-onset atrial fibrillation (AF) have been investigated using the 24-hour Holter electrocardiogram (ECG) and 12-lead ECG; however, these have been based on each test independently. The aim of this study was to combine findings from the two tests to create a comprehensive, easy-to-use score and to examine its validity. Methods and Results: A total of 502 patients underwent 24-hour Holter ECG and 12-lead ECG were followed up for 6.2 ± 3.5 years, and 66 patients developed new-onset AF. Multivariate Cox regression analyses revealed that total number of supraventricular extrasystoles (SVEs) ≥ 100 beats/day and SVE's longest run ≥ 3 beats on 24-hour Holter ECG and PR interval ≥ 185 ms, amplitude ratio of P wave (aVR/V1) < 1.0 and amplitude of RV5 + SV1 ≥ 2.2 mV on 12-lead ECG were significant independent predictors for developing AF (all p < 0.01). Using these cut-off points, the PAAFS (acronym for risk factors) score was constructed by adding one point for each parameter if the patient met each of the criteria. The area under the curve (AUC) of the PAAFS score was 0.80, compared to the AUCs of 24-hour Holter ECG-only factors (0.73) and 12-lead ECG-only factors (0.72), indicating an improvement in score. The annual incidence of AF for each PAAFS score were 0.0%, 0.2%, 0.7%, 1.9%, 5.6%, and 11.1%/year for scores 0 to 5, respectively. Conclusion: The PAAFS score, which combines findings from 24-hour Holter ECG and 12-lead ECG, was superior to 24-hour Holter ECG and 12-lead ECG alone in predictive accuracy for new-onset AF.

[Evaluation of Disopyramide Efficacy for Refractory Syncope in Heart Failure with Preserved Ejection Fraction Using Holter Electrocardiography: A Case Report].

The management of syncope is clinically important for heart failure (HF) patients. We herein describe a case on the efficacy of disopyramide for refractory syncope in HF with preserved ejection fraction (HFpEF). An 82-year-old man was hospitalized for respiratory distress and lower limb edema and was subsequently diagnosed with HFpEF. The use of diuretics improved HF symptoms; however, on day 10 after hospitalization, a rapid decrease in blood pressure and transient loss of consciousness developed. After neurologic examination, he was diagnosed with pure autonomic failure. Although he was administered midodrine 8 mg/d, fludrocortisone 0.1 mg/d, and droxidopa 300 mg/d, syncope was observed once a day on average. According to the Holter electrocardiogram, the patient's heart rate and coefficient of variation of R-R intervals (CVRR) during the day were unstable. In addition, high frequency power (parasympathetic nerve activity) was significantly higher than low frequency power (both sympathetic and parasympathetic nerves activity), suggesting that the parasympathetic nerves may have been highly active while the sympathetic nerves would have been blocked. On day 29, a pharmacist proposed disopyramide 300 mg/d, which blocks parasympathetic nerves and improves neural-mediated syncope, to the attending doctor. After the initiation of disopyramide, transient loss of consciousness was not observed. Furthermore, the diurnal variation in the heart rate and CVRR completely disappeared. In conclusion, disopyramide would be effective for refractory syncope in patients with HFpEF, and the Holter electrocardiogram may be a useful tool for the assessment of drug efficacy by pharmacists.

Variation in heart rate range by 24-h Holter monitoring predicts heart failure in patients with atrial fibrillation.

AIMS: The analysis of heart rate (HR) changes, such as the HR variability or HR turbulence, has been reported as a marker of cardiovascular events during sinus rhythm; however, those relationships during atrial fibrillation (AF) remain controversial, and those parameters are not commonly used in AF patients. We sought to investigate the relationship between a simple index focused on the HR and heart failure (HF) events in patients with permanent AF. METHODS AND RESULTS: We enrolled 198 patients with permanent AF and evaluated the HR range, defined as the maximum HR minus the minimum HR on 24-h Holter electrocardiogram recordings. The patients were divided into two groups, i.e., the larger (n = 101) and smaller (n = 97) HR range (HRR) groups, determined by the median value. The HF events were defined as hospitalizations for HF or urgent hospital visits due to exacerbations of one's HF status. The observation period of this study was set at 5 years from registration. The median age was 73 (68-77) years, and 29% were female. The median HRR was 84 (63-118) beats per minutes (bpm). During the observational period of 1825 days (median), HF events occurred in 37 (0.047 per patient-year) patients. In a log-rank test, the larger HRR group had more frequent HF events than the smaller HRR group (P = 0.0078). In the adjusted Cox proportional hazards model using the significantly different factors from the univariate analysis (Model 1) and factors and medications associated with HF (Model 2), the larger HRR group had a higher prevalence of HF events than the smaller HRR group for both models [Model 1, adjusted hazard ratio = 3.21, 95% confidence interval (CI) 1.593-6.708, P = 0.0009; Model 2, adjusted hazard ratio = 3.12, 95% CI 1.522-6.685, P = 0.002]. When analysed using the time-dependent Cox proportional hazards model, the HRR was associated with HF with a statistically significant difference in both the univariate and multivariate analyses [hazard ratio = 1.01, 95% CI 1.006-1.020, P = 0.0002; Model 1, adjusted hazard ratio = 1.02, 95% CI 1.011-1.027, P < 0.0001; Model 2, adjusted hazard ratio = 1.01, 95% CI 1.008-1.021, P = 0.0003). There was no significant difference in the chronotropic medications between the two groups. CONCLUSIONS: In patients with permanent AF, a larger HRR was associated with HF events.

Predictores de fibrilación auricular en pacientes con ictus embólico de origen indeterminado / Atrial fibrillation predictors in patients with embolic stroke of undetermined source

Antecedentes y objetivos: En el accidente cerebrovascular embólico de origen indeterminado (ESUS) la detección de fibrilación auricular (FA) conlleva un cambio de tratamiento y una reducción drástica en la incidencia de nuevos ictus. Es necesario determinar qué pacientes se benefician en mayor medida de una monitorización electrocardiográfica prolongada. Nuestro objetivo fue la búsqueda de predictores electrocardiográficos y ecocardiográficos de FA en pacientes con ESUS.Materiales y métodosSe diseñó un estudio observacional de cohortes en el que se incluyeron 95 pacientes consecutivos que ingresaron por ESUS en un hospital terciario. A todos se les realizó un electrocardiograma (ECG), un Holter electrocardiograma (Holter-ECG) de 24h y un ecocardiograma durante el ingreso. Se realizó un seguimiento presencial durante 2años mediante Holter-ECG de 24h, trimestral durante el primer año y semestral durante el segundo.ResultadosDurante el seguimiento se detectó FA en 11 pacientes (11,6%), siendo la tasa detección del 3,2% a los 6meses, del 7,4% a los 12meses y del 11,6% a los 18 y a los 24meses. Las variables que se relacionaron de forma independiente con el desarrollo de FA fueron la dilatación en grado moderado o severo de la aurícula izquierda (AI) (p=0,02), el bloqueo interauricular avanzado (BIA-A) (p=0,04) y la presencia de más de 1.000 extrasístoles auriculares (EA) en Holter-ECG de 24h (p=0,01).ConclusionesLa dilatación en un grado moderado o severo de AI, el BIA-A y la presencia de más de 1.000 EA en Holter-ECG de 24h se comportan como predictores independientes de FA en pacientes con ESUS. (AU)

Background and objectives: Atrial fibrillation (AF) detection in patients with embolic stroke of underdetermined source (ESUS) entails a change of medical treatment and a significant decrease in the incidence of new strokes. It is necessary to determine which patients would benefit more from prolonged electrocardiographic monitoring. Our aim was to find electrocardiographic and echocardiographic AF predictors in patients with ESUS.MethodsWe performed a cohort study that included 95 consecutive patients admitted to the hospital because of an ESUS. An electrocardiogram, each subject in the study underwent a 24-hour Holter-electrocardiogram (Holter-ECG) and an echocardiogram. A 2-year follow up was also conducted, with a 24-hour Holter-ECG every 3months for the first year, and every 6months during the second one.ResultsDuring the follow-up, AF was detected in 11 patients (11.6%), with a detection rate of 3.2% at 6months, 7.4% at 12months, and 11.6% at 18months as well as at 24months. The variables that were independently related to AF detection included moderate or severe left atrium dilation (P=.02), interatrial advanced block (P=.04) and more than 1000 premature atrial beats on 24-hour Holter-ECG (P=.01).ConclusionsModerate or severe atrial dilation, interatrial advanced block, and the presence of more than 1000 premature atrial beats on 24-hour Holter-ECG behave as AF predictors in patients with ESUS. (AU)

Correlation of heart rate recovery and heart rate variability with atrial fibrillation progression.

OBJECTIVE: To examine the combination of heart rate recovery (HRR) and heart rate variability (HRV) in predicting atrial fibrillation (AF) progression. METHODS: Data from patients with a first detected episode of AF who underwent treadmill exercise testing and 24-h Holter electrocardiography were retrospectively analysed. Autonomic dysfunction was verified using HRR values. Sympathetic and parasympathetic modulation was analysed by HRV. AF progression was defined as transition from the first detected paroxysmal episode to persistent/permanent AF. RESULTS: Of 306 patients, mean LF/HF ratio and HRR did not differ significantly by AF progression regardless of age (< or ≥65 years). However, when the LF/HF ratio was divided into tertiles, in patients aged <65 years, the mid LF/HF (1.60-2.40) ratio was significantly associated with lower AF progression rates and longer maintenance of normal sinus rhythm. For patients aged <65 years, less metabolic equivalents were related to higher AF progression rates. For patients aged ≥65 years, a low HRR was associated with high AF progression rates. CONCLUSION: In relatively younger age, high physical capacity and balanced autonomic nervous system regulation are important predictors of AF progression. Evaluation of autonomic function assessed by age could predict AF progression.

Neurological complications in COVID-19 - a diagnostic challenge.

With the exponential growth of COVID-19 cases, the neurological complications reported during or after the infection became more common. There is limited knowledge regarding the pathophysiological mechanisms that are responsible for these complications. Recent data provides compelling evidence for the neurotropic nature of SARS-CoV-2, based on neurological manifestations reported during the current pandemic, as well as on previous experience with other coronaviruses. We present the case of a patient who developed headaches, motor deficit and dysphasia after respiratory COVID-19. Imaging tests showed heterogeneous central nervous system lesions (multiple subarachnoid hemorrhages and two ischemic strokes). Given the plethora of atypical neurological complications of COVID-19 described in the current literature, establishing a positive diagnosis and deciding on a treatment plan proved to be particularly challenging. We set to discuss some of the possible pathologies, hypothesized to be associated with COVID-19, that could lead to concomitant neurological lesions, similar to those noticed in our patient.

Utility of cyclic variation of heart rate score as a screening tool for sleep-disordered breathing in patients with heart failure.

STUDY OBJECTIVES: Patients with sleep-disordered breathing have cyclic variation of heart rate (CVHR) in response to respiratory events. However, limited data are available regarding the utility of CVHR as a screening tool for sleep-disordered breathing in patients with mixed heart failure (HF) and those without HF. METHODS: We enrolled consecutive patients with and without HF who underwent full polysomnographies with simultaneous Holter electrocardiogram monitoring. We determined the temporal position of the individual dips comprising the CVHR score using time-domain methods. RESULTS: The data of 101 patients, including 70 with and 31 without HF, were analyzed. The CVHR score was significantly correlated with the apnea-hypopnea index (r = .667, P < .001) and limits of agreement between the apnea-hypopnea index and CVHR score were -21.8 to 35.2. The receiver operating characteristic analysis demonstrated that the CVHR score (best cut-off of 23.5 events/h) identified severe sleep-disordered breathing with a sensitivity of 83.3%, specificity of 79.5%, and the area under the curve of 0.856. In addition, there was no interaction between the presence or absence of HF and the apnea-hypopnea index-CVHR score relationship (P = .323). CONCLUSIONS: The CVHR score, determined by Holter electrocardiogram monitoring, is a useful tool for evaluating sleep-disordered breathing even in patients with mixed HF and patients without HF. CITATION: Yatsu S, Kasai T, Naito R, et al. Utility of cyclic variation of heart rate score as a screening tool for sleep-disordered breathing in patients with heart failure. J Clin Sleep Med. 2021;17(11):2187-2196.

[Atrial fibrillation predictors in patients with embolic stroke of undetermined source]. / Predictores de fibrilación auricular en pacientes con ictus embólico de origen indeterminado.

BACKGROUND AND OBJECTIVES: Atrial fibrillation (AF) detection in patients with embolic stroke of underdetermined source (ESUS) entails a change of medical treatment and a significant decrease in the incidence of new strokes. It is necessary to determine which patients would benefit more from prolonged electrocardiographic monitoring. Our aim was to find electrocardiographic and echocardiographic AF predictors in patients with ESUS. METHODS: We performed a cohort study that included 95 consecutive patients admitted to the hospital because of an ESUS. An electrocardiogram, each subject in the study underwent a 24-hour Holter-electrocardiogram (Holter-ECG) and an echocardiogram. A 2-year follow up was also conducted, with a 24-hour Holter-ECG every 3months for the first year, and every 6months during the second one. RESULTS: During the follow-up, AF was detected in 11 patients (11.6%), with a detection rate of 3.2% at 6months, 7.4% at 12months, and 11.6% at 18months as well as at 24months. The variables that were independently related to AF detection included moderate or severe left atrium dilation (P=.02), interatrial advanced block (P=.04) and more than 1000 premature atrial beats on 24-hour Holter-ECG (P=.01). CONCLUSIONS: Moderate or severe atrial dilation, interatrial advanced block, and the presence of more than 1000 premature atrial beats on 24-hour Holter-ECG behave as AF predictors in patients with ESUS.

The Burden of Ventricular Premature Complex Is Associated With Cardiovascular Mortality.

BACKGROUND: Ventricular premature complex (VPC) is one of the most common ventricular arrhythmias. The presence of VPC is associated with an increased risk of heart failure (HF). METHOD: We designed a single-center, retrospective, and large population-based cohort to clarify the role of VPC burden in long-term prognosis in Taiwan. We analyzed the database from the National Cheng Kung University Hospital-Electronic Medical Record (NCKUH-EMR) and NCKUH-Holter (NCKUH-Holter). A total of 19,527 patients who underwent 24-h Holter ECG monitoring due to palpitation, syncope, and clinical suspicion of arrhythmias were enrolled in this study. RESULTS: The clinical outcome of interests involved 5.65% noncardiovascular death and 1.53% cardiovascular-specific deaths between 2011 and 2018. Multivariate Cox regression analysis, Fine and Gray's competing risk model, and propensity score matching demonstrated that both moderate (1,000-10,000/day) and high (>10,000/day) VPC burdens contributed to cardiovascular death in comparison with a low VPC burden (<1,000/day). CONCLUSION: A higher VPC burden via Holter ECG is an independent risk factor of cardiovascular mortality.

Predictive value of premature atrial complex characteristics in pulmonary vein isolation for patients with paroxysmal atrial fibrillation.

BACKGROUND: Premature atrial complexes from pulmonary veins are the main triggers for atrial fibrillation in the early stages. Thus, pulmonary vein isolation is the cornerstone of catheter ablation for paroxysmal atrial fibrillation. However, the success rate remains perfectible. AIM: To assess whether premature atrial complex characteristics before catheter ablation can predict pulmonary vein isolation success in paroxysmal atrial fibrillation. METHODS: We investigated consecutive patients who underwent catheter ablation for paroxysmal atrial fibrillation from January 2013 to April 2017 in two French centres. Patients were included if they were treated with pulmonary vein isolation alone, and had 24-hour Holter electrocardiogram data before catheter ablation available and a follow-up of≥6 months. Catheter ablation success was defined as freedom from any sustained atrial arrhythmia recurrence after a 3-month blanking period following catheter ablation. RESULTS: One hundred and three patients were included; all had an acute successful pulmonary vein isolation procedure, and 34 (33%) had atrial arrhythmia recurrences during a mean follow-up of 30±15 months (group 1). Patients in group 1 presented a longer history of atrial fibrillation (71.9±65.8 vs. 42.9±48.4 months; P=0.008) compared with those who were "free from arrhythmia" (group 2). Importantly, the daily number of premature atrial complexes before catheter ablation was significantly lower in group 1 (498±1413 vs. 1493±3366 in group 2; P=0.028). A daily premature atrial complex cut-off number of<670 predicted recurrences after pulmonary vein isolation (41.1% vs. 13.3%; sensitivity 88.2%; specificity 37.7%; area under the curve 0.635; P=0.017), and was the only independent predictive criterion in the multivariable analysis (4-fold increased risk). CONCLUSION: Preprocedural premature atrial complex analysis on 24-hour Holter electrocardiogram in paroxysmal atrial fibrillation may improve patient selection for pulmonary vein isolation.

Nonlinear relationship between serum total bilirubin levels and initial ischemic stroke in patients with non-valvular atrial fibrillation.

OBJECTIVE: This study aimed to examine the relationship between total bilirubin levels and initial ischemic stroke in patients with non-valvular atrial fibrillation. METHODS: This was a retrospective study. Atrial fibrillation was diagnosed by 24-hour Holter electrocardiography and serum total bilirubin levels were divided into quintiles. Ischemic stroke was diagnosed by symptoms, signs, and a medical image examination. The multivariate Cox proportional hazards model and survival analysis were used to estimate the association of total bilirubin with initial ischemic stroke. RESULTS: We studied 316 patients with non-valvular atrial fibrillation. During follow-up, there were 42 (13.29%) first ischemic strokes. After multivariate adjustment, for each 1 µmol/L increase in total bilirubin, the risk of first ischemic stroke increased by 4% (95% confidence interval [CI]: 1.01, 1.07). When using the first quintile as the reference, from the second to fifth quintiles, the risks of first ischemic stroke were 0.52 (95% CI: 0.17, 1.65), 0.23 (95% CI: 0.06, 0.87), 0.92 (95% CI: 0.32, 2.67), and 1.33 (95% CI: 1.09, 4.41), respectively. The optimal cut-off point of total bilirubin for the lowest risk of ischemic stroke was 17.0 µmol/L. CONCLUSIONS: Total bilirubin levels are nonlinearly associated with initial ischemic stroke in patients with non-valvular atrial fibrillation.

Reference values for a novel ambulatory-based frequency domain T-wave alternans in subjects without structural heart disease.

BACKGROUND: Conventional frequency domain T wave alternans (FD-TWA) is a noninvasive risk stratification marker for identifying arrhythmic sudden cardiac death, but the conventional FD-TWA device that was considered the gold standard device has been discontinued commercially. Recently, a newly developed ambulatory electrocardiogram (AECG) device that can detect FD-TWA continuously for 24 hours is available in clinical settings. However, information on the normal values using the novel AECG-based frequency domain TWA (FD-TWA) is lacking. METHODS: FD-TWA for AECG was examined in 312 subjects without heart disease (Sb-wHD) (range 20-89 years, 146 men) and 30 heart disease patients (HD-P) (mean age 57±17 years, 24 men). The maximum FD-TWA amplitude over 24 hours was measured with manual editing. The upper limit of local noise levels for measurement of FD-TWA was set to both <10 µV and <20 µV (acceptable noise level <10 µV and <20 µV). RESULTS: The reference values (95th percentiles) of FD-TWA in Sb-wHD were 19.9 µV for the acceptable noise level <10 µV and 23.6 µV for the acceptable noise level <20 µV. The 75th percentile of FD-TWA amplitude in HD-P was 19.5 µV at an acceptable noise level <10 µV and 21.5 µV at an acceptable noise level <20 µV. FD-TWA amplitude without heart disease was significantly affected by heart rate when the maximum FD-TWA was measured (ß = 0.274 p < 0.001 for the acceptable noise level <10 µV; ß = 0.263, p < 0.001 for the acceptable noise level <20 µV) and age (ß = 0.204, p = 0.004 for the acceptable noise level <10 µV; ß = 0.149, p = 0.034 for the acceptable noise level <20 µV). CONCLUSIONS: In the present study, the reference values for a novel FD-TWA in Sb-wHD and the distribution of TWA values in HD-P were established. In future research, the cut-off values of FD-TWA in HD-P will need to be examined.

Optimal length of R-R interval segment window for Lorenz plot detection of paroxysmal atrial fibrillation by machine learning.

BACKGROUND: Heartbeat interval Lorenz plot (LP) imaging is a promising method for detecting atrial fibrillation (AF) in long-term monitoring, but the optimal segment window length for the LP images is unknown. We examined the performance of AF detection by LP images with different segment window lengths by machine learning with convolutional neural network (CNN). LP images with a 32 × 32-pixel resolution of non-overlapping segments with lengths between 10 and 500 beats were created from R-R intervals of 24-h ECG in 52 patients with chronic AF and 58 non-AF controls as training data and in 53 patients with paroxysmal AF and 52 non-AF controls as test data. For each segment window length, discriminant models were made by fivefold cross-validation subsets of the training data and its classification performance was examined with the test data. RESULTS: In machine learning with the training data, the averages of cross-validation scores were 0.995 and 0.999 for 10 and 20-beat LP images, respectively, and > 0.999 for 50 to 500-beat images. The classification of test data showed good performance for all segment window lengths with an accuracy from 0.970 to 0.988. Positive likelihood ratio for detecting AF segments, however, showed a convex parabolic curve linear relationship to log segment window length and peaked at 85 beats, while negative likelihood ratio showed monotonous increase with increasing segment window length. CONCLUSIONS: This study suggests that the optimal segment window length that maximizes the positive likelihood ratio for detecting paroxysmal AF with 32 × 32-pixel LP image is 85 beats.

Comparison of the Transdermal Bisoprolol Patch with Oral Bisoprolol Fumarate Administration as a Therapeutic Agent for Idiopathic Frequent Premature Ventricular Contractions.

The transdermal bisoprolol patch (TB) was designed to maintain a sustained concentration of bisoprolol in plasma by a higher trough concentration than oral bisoporolol (OB). We compared the efficacy between TB and OB in patients with idiopathic premature ventricular contractions (PVCs) while considering their duration of action.A total of 78 patients with a PVC count of ≥ 3,000 beats/24 hours were divided into groups treated with TB 4 mg (n = 43) or OB 2.5 mg (n = 35). PVCs were divided into positive heart rate (HR) -dependent PVCs (P-PVCs) and non-positive HR-dependent PVCs (NP-PVCs) based on the relationship between the hourly PVC density and hourly mean HR. Twenty-four-hour Holter electrocardiograms were performed before and 1 to 3 months after the initiation of therapy.There were no significant between-group differences in the baseline characteristics. Both the TB (from 14.6 [9.9-19.2] to 7.6 [1.7-15.8]%, P < 0.001) and OB (from 13.2 [7.6-21.9] to 4.6 [0.5-17.0]%, P = 0.0041) significantly decreased the PVC density, and there was no significant difference between the two groups (P = 0.73). Compared to OB, the TB had similar effects in reducing the PVC density for P-PVCs (P = 0.96), and NP-PVCs (P = 0.71). The TB significantly decreased the P-PVC density from baseline not only during day-time (P < 0.001) but also night-time (P = 0.0017), while the OB did not significantly decrease the P-PVC density from baseline during night-time (P = 0.17).Compared to OB, the TB could be used with the same efficacy of reducing idiopathic PVCs. The TB may be a more useful therapeutic agent than OB for P-PVCs during a 24-hour period.

A novel signal-averaged electrocardiogram and an ambulatory-based signal-averaged electrocardiogram show strong correlations with conventional signal-averaged electrocardiogram in healthy subjects: A validation study.

BACKGROUND: A novel signal-averaged electrocardiogram (SAECG) device and a novel ambulatory SAECG device are clinically available, but reference values have not been established. This study aimed to validate the novel SAECG and the novel ambulatory-based SAECG devices by comparison with the conventional SAECG device. METHODS AND RESULTS: High-resolution SAECGs were recorded consecutively in 83 healthy volunteers using the 3 devices. A novel ambulatory SAECG device was used as real-time recording within 15 min for validation study (15 min ambulatory-based SAECG). We examined the concordance of positive results (at least 2/3 abnormal SAECG parameters) and negative results (0 or 1/3 abnormal parameters), as well as the correlations between SAECG parameters (filtered QRS duration [fQRS]); duration of low-amplitude signals < 40 µV in the terminal filtered QRS complex [LAS40]; root mean square voltage of the terminal 40 ms of the filtered QRS complex [RMS40]). Qualitative analysis showed excellent concordance among the novel SAECG, the 15 min ambulatory-based SAECG, and the conventional SAECG methods (novel SAECG vs. conventional SAECG = 94%; 15 min ambulatory-based SAECG vs. conventional SAECG = 91.6%; p = 0.755), while quantitative analysis indicated strong correlations between the novel SAECG and the conventional SAECG values for fQRS, LAS40, and LnRMS40 (r = 0.838-0.805, p < 0.0001, respectively). Strong correlations were also seen between 15 min ambulatory-based SAECG and conventional SAECG values for fQRS, LAS40, and RMS40 (r = 0.943-0.888, p < 0.0001, respectively). However, Bland-Altman quantitative analysis showed better agreement in fQRS and LnRMS40 measured by the 15 min ambulatory-based SAECG and the conventional SAECG than those by the novel SAECG and the conventional SAECG (fQRS, Lin's rho_c = 0.923 vs. 0757; RMS40, Lin's rho_c = 0.932 vs. 0.818, respectively). CONCLUSION: In healthy subjects, the parameters of either the novel SAECG or the 15 min ambulatory-based SAECG and those of the conventional SAECG were strongly correlated. Relatively good agreements were observed among 3 SAECGs, especially better between the 15 min ambulatory-based SAECG and the conventional SAECG probably due to similar measurement system of 2 methods.

Effects of cilostazol on the heart rate in healthy dogs.

Appropriate dosages of cilostazol have not been studied in veterinary patients, and the degrees of heart rate (HR) increase have not been studied in dogs administered cilostazol. Therefore, this study aimed to investigate the degrees of HR increase in healthy dogs administered cilostazol. Thirty healthy beagle dogs (15 males and 15 females; age, 5-8 years) were divided into 3 groups of 10 dogs each and orally administered 2.5, 5, or 10 mg/kg cilostazol (twice a day at 8:00 AM and 8:00 PM for 10 days). Higher HR increases were seen in the 5 mg/kg group than in the 2.5 mg/kg group at all time points except 7:00 AM, 9:00 AM, 1:00 PM, and 4:00 PM (P<0.01). Higher HR increases were also observed in the 10 mg/kg group than in the 2.5 mg/kg group at all time points except 4:00 PM (P<0.01). The 10 mg/kg group showed higher HR increases than the 5 mg/kg group at all time points except 6:00 AM, 7:00 AM, 6:00 PM, and 7:00 PM (P<0.05 for 4:00 PM and 5:00 PM; P<0.01 for the other time points). These results together show that the HR of healthy dogs increased in a dose-dependent manner after cilostazol administration twice a day at doses of 5 to 10 mg/kg. These results provide a useful basis for choosing cilostazol in the treatment of bradyarrhythmia in dogs.

Coronary Artery Dominance May Predict Future Risk of Atrial Fibrillation.

BACKGROUND: Ischemia of the atria and conductive system of the heart results in greater atrial electrophysiological changes and propensity for atrial fibrillation. P wave duration and dispersion have been proposed to be useful for the prediction of paroxysmal atrial fibrillation (PAF). This study aimed to investigate the effect of coronary artery dominance on P wave duration and dispersion. METHODS: The study population included 194 patients with left dominant circulation (LDC) and 200 age- and gender-matched controls with right dominant circulation (RDC) and without coronary artery disease based on invasive coronary angiography findings. P wave dispersion (PWD) was defined as the difference between the maximum and minimum P wave duration. Arrhythmias were identified by 24-hour Holter electrocardiogram at 3 years of follow-up. RESULTS: PWD was significantly prolonged in the patients with LDC compared to the controls with RDC (p = 0.001). There were positive correlations between PWD and age (r: 0.502, p = 0.009), left ventricular mass (LVM) (r: 0.614, p = 0.001), LVM index (r: 0.727, p < 0.001) and left atrium (LA) diameter (r: 0.558, p = 0.003) in the LDC group. Multivariate logistic regression analysis showed that age, LVM index, LA diameter and LDC were independent predictors of prolonged PWD. At 3 years of follow-up, 7 (3.9%) patients with LDC and 1 (0.5%) patient with RDC had PAF in Holter electrocardiogram (p < 0.001). CONCLUSIONS: LDC could lead to an increased risk of atrial fibrillation through prolonged PWD. We recommend following up these patients to assess the development of atrial fibrillation.