Implicit HbA1c Achieving 87% Accuracy within 90 Days in Non-Invasive Fasting Blood Glucose Measurements Using Photoplethysmography.

To reduce the error induced by overfitting or underfitting in predicting non-invasive fasting blood glucose (NIBG) levels using photoplethysmography (PPG) data alone, we previously demonstrated that incorporating HbA1c led to a notable 10% improvement in NIBG prediction accuracy (the ratio in zone A of Clarke's error grid). However, this enhancement came at the cost of requiring an additional HbA1c measurement, thus being unfriendly to users. In this study, the enhanced HbA1c NIBG deep learning model (blood glucose level predicted from PPG and HbA1c) was trained with 1494 measurements, and we replaced the HbA1c measurement (explicit HbA1c) with "implicit HbA1c" which is reversely derived from pretested PPG and finger-pricked blood glucose levels. The implicit HbA1c is then evaluated across intervals up to 90 days since the pretest, achieving an impressive 87% accuracy, while the remaining 13% falls near the CEG zone A boundary. The implicit HbA1c approach exhibits a remarkable 16% improvement over the explicit HbA1c method by covering personal correction items automatically. This improvement not only refines the accuracy of the model but also enhances the practicality of the previously proposed model that relied on an HbA1c input. The nonparametric Wilcoxon paired test conducted on the percentage error of implicit and explicit HbA1c prediction results reveals a substantial difference, with a p-value of 2.75 × 10-7.

Association between corrected QT interval and long-term cardiovascular outcomes in elderly patients who had undergone endovascular therapy for lower extremity arterial disease.

Background: Population-based studies have reported the association between prolonged corrected QT (QTc) intervals and an increased risk of adverse cardiovascular events. Data regarding the association between longer QTc intervals and incident cardiovascular outcomes in patients with lower extremity arterial disease (LEAD) are scarce. Objective: To examine the impact of QTc interval on long-term cardiovascular outcomes in elderly patients with symptomatic LEAD. Methods: This cohort study extracted data from the Tzu-chi Registry of ENDovascular Intervention for Peripheral Artery Disease (TRENDPAD) and enrolled 504 patients aged ≥ 70 treated with endovascular therapy for atherosclerotic LEAD from July 1, 2005, to December 31, 2019. The main outcomes of interest were all-cause mortality and major adverse cardiovascular events (MACE). Multivariate analysis was conducted using the Cox proportional hazard model to determine independent variables. We performed interaction analysis between corrected QT and other covariates and Kaplan-Meier analysis to compare the outcome of interest among the groups stratified by the tercile of QTc intervals. Results: A total of 504 patients [235 men (46.6%); mean age, 79.9 ± 6.2 years; mean QTc interval, 459 ± 33 msec] entered the final data analysis. We categorized the baseline patient characteristics according to terciles of QTc intervals. During the median follow-up time of 3.15 (interquartile ranges, 1.65-5.42) years, we noted 264 deaths and 145 MACEs. The 5-year rates of freedom from all-cause mortality (71% vs. 57% vs. 31%, P < 0.001) and MACEs (83% vs. 67% vs. 46%, P < 0.001) were significantly different among the tercile groups. Multivariate analysis showed that a 1-SD increase in the QTc interval increased the risk of all-cause mortality [hazard ratio (HR) 1.49, P < 0.001] and MACEs (HR 1.59, P < 0.001) after adjusting for other covariates. The interaction analysis showed that QTc interval and C-reactive protein levels were most strongly associated with death (HR = 4.88, 95% CI 3.09-7.73, interaction P < 0.001) and MACEs (HR = 7.83, 95% CI 4.14-14.79, interaction P < 0.001). Conclusions: In elderly patients with symptomatic atherosclerotic LEAD, a prolonged QTc interval is associated with advanced limb ischemia, multiple medical comorbidities, increased risk of MACEs, and all-cause mortality.

Repetition of Paclitaxel-Coated Devices for the Treatment of Lower Extremity Artery Disease: Mortality Outcomes and Predictors.

Background: A recent meta-analysis reported late excess mortality in patients treated with paclitaxel-coated devices (PCDs) for symptomatic femoropopliteal disease. However, this finding is controversial. Objectives: To investigate the impact on mortality and predictors of repeat exposure to PCDs in patients with lower extremity peripheral arterial disease (LE-PAD). Methods: We analyzed registry patient-level data from two centers. A total of 214 patients were enrolled, and stratified based on terciles of cumulative dose of paclitaxel. We treated 134 patients with a single PCD exposure and 80 with multiple PCD exposures. We used the follow-up index (FUI) in Kaplan-Meier survival estimates to minimize potential selection bias. We used Cox proportional hazard and splines models to determine the predictors of mortality and assess their relationships with mortality. Results: The mean cumulative dose of paclitaxel was significantly different among groups (6.40 mg vs. 15.06 mg vs. 38.57 mg, p < 0.001). The 5-year FUI (0.93 ± 0.19 vs. 0.94 ± 0.18 vs. 0.95 ± 0.15, p = 0.836) and survival rates were not different (65.4% vs. 51.9% vs. 72.0%, p = 0.148). There was no dose-response association between paclitaxel dosage and death (p = 0.297). The predictors of death were congestive heart failure, stroke, dialysis dependence, neutrophil-lymphocyte ratio (NLR) > 3, age > 71 years, and body mass index (BMI) < 20 kg/m2. Spline model analysis validated the non-linear associations between mortality, age, BMI, and NLR. Conclusions: Repeated PCD exposure for LE-PAD did not result in excess late mortality. Predictors of mortality might change over time, and continuous variables had non-linear relationships with death.

Visual Reassessment with Flux-Interval Plot Configuration after Automatic Classification for Accurate Atrial Fibrillation Detection by Photoplethysmography.

Atrial fibrillation (AFib) is a common type of arrhythmia that is often clinically asymptomatic, which increases the risk of stroke significantly but can be prevented with anticoagulation. The photoplethysmogram (PPG) has recently attracted a lot of attention as a surrogate for electrocardiography (ECG) on atrial fibrillation (AFib) detection, with its out-of-hospital usability for rapid screening or long-term monitoring. Previous studies on AFib detection via PPG signals have achieved good results, but were short of intuitive criteria like ECG p-wave absence or not, especially while using interval randomness to detect AFib suffering from conjunction with premature contractions (PAC/PVC). In this study, we newly developed a PPG flux (pulse amplitude) and interval plots-based methodology, simply comprising an irregularity index threshold of 20 and regression error threshold of 0.06 for the precise automatic detection of AFib. The proposed method with automated detection on AFib shows a combined sensitivity, specificity, accuracy, and precision of 1, 0.995, 0.995, and 0.952 across the 460 samples. Furthermore, the flux-interval plot configuration also acts as a very intuitive tool for visual reassessment to confirm the automatic detection of AFib by its distinctive plot pattern compared to other cardiac rhythms. The study demonstrated that exclusive 2 false-positive cases could be corrected after the reassessment. With the methodology's background theory well established, the detection process automated and visualized, and the PPG sensors already extensively used, this technology is very user-friendly and convincing for promoted to in-house AFib diagnostics.

90% Accuracy for Photoplethysmography-Based Non-Invasive Blood Glucose Prediction by Deep Learning with Cohort Arrangement and Quarterly Measured HbA1c.

Previously published photoplethysmography-(PPG) based non-invasive blood glucose (NIBG) measurements have not yet been validated over 500 subjects. As illustrated in this work, we increased the number subjects recruited to 2538 and found that the prediction accuracy (the ratio in zone A of Clarke's error grid) reduced to undesirable 60.6%. We suspect the low prediction accuracy induced by larger sample size might arise from the physiological diversity of subjects, and one possibility is that the diversity might originate from medication. Therefore, we split the subjects into two cohorts for deep learning: with and without medication (1682 and 856 recruited subjects, respectively). In comparison, the cohort training for subjects without any medication had approximately 30% higher prediction accuracy over the cohort training for those with medication. Furthermore, by adding quarterly (every 3 months) measured glycohemoglobin (HbA1c), we were able to significantly boost the prediction accuracy by approximately 10%. For subjects without medication, the best performing model with quarterly measured HbA1c achieved 94.3% prediction accuracy, RMSE of 12.4 mg/dL, MAE of 8.9 mg/dL, and MAPE of 0.08, which demonstrates a very promising solution for NIBG prediction via deep learning. Regarding subjects with medication, a personalized model could be a viable means of further investigation.

Mechanism of angiotensin receptor-neprilysin inhibitor in suppression of ventricular arrhythmia.

BACKGROUND: The mechanisms underlying angiotensin receptor-neprilysin inhibitor (ARNi) suppression of ventricular arrhythmia (VA) are unclear. This study aimed to investigate the mechanism of ARNi-related suppression of VA in a heart failure (HF) model. METHODS: New Zealand white rabbits (n = 6 per group) were assigned to normal, HF [4 weeks of left ascending artery (LAD) ligation], angiotensin receptor blocker (ARB, valsartan at 27 mg/kg/day for 3 weeks after 1 week of LAD ligation), and ARNi (sacubitril at 34 mg/kg/day and valsartan at 27 mg/kg/day for 3 weeks after 1 week of LAD ligation) groups. Experiments involving echocardiogram, optical mapping, histological of trichrome stain and immunostain, and flow cytometry were performed. RESULTS: HF group had larger left ventricular (LV) internal dimensions in diastole and systole, and lower LV ejection fraction and fractional shortening than normal, ARB, and ARNi groups. HF group had a prolonged action potential duration (APD) and decreased conduction velocity (CV), which was mitigated in ARB and ARNi groups. HF group had a prolonged QRS duration, QT and QTc intervals, which was reversed in ARB and ARNi groups. HF group had a steeper maximum slope of APD restitutions, which was attenuated in normal, ARB, and ARNi groups. HF group had increased number of phase singularities (PSs) and VA inducibility than normal, ARB, and ARNi groups. A higher content of fibrosis was found in HF group than that in normal, ARB, and ARNi groups. Compared to ARB group, ARNi had a lower context of fibrosis. HF group had more peripheral blood CD4+ and CD8+ cells count than normal, ARB, and ARNi group. CONCLUSIONS: In a rabbit model of ischemic HF, ventricular arrhythmogenesis could be suppressed by ARNi treatment. This appears to be mediated by reversing changes in the APD, CV, maximum slope of the APDR, PSs, fibrosis, and inflammation.

Combined corrected QT interval and growth differentiation factor-15 level has synergistic predictive value for long-term outcome of angiographically confirmed coronary artery disease.

BACKGROUND: The corrected QT interval (QTc) predicts prognosis for the general population and patients with coronary artery disease (CAD). Growth differentiation factor-15 (GDF-15) is a biomarker of myocardial fibrosis and left ventricular (LV) remodelling. The interaction between these two parameters is unknown. SUBJECTS AND METHODS: This study included 487 patients with angiographically confirmed CAD. QTc was calculated using the Bazett formula. Multiple biochemistries and GDF-15 levels were measured. The primary endpoint was total mortality, and the secondary endpoints comprised the combination of total mortality, myocardial infarction and hospitalisation for heart failure and stroke. RESULTS: The mean follow-up period was 1029 ± 343 days (5-1692 days), during which 21 patients died and 47 had secondary endpoints. ROC curve analysis for the optimal cut-off value of primary endpoint is 1.12 ng/mL for GDF-15 (AUC = 0.787, P = 9.0 × 10-6 ) and 438.5 msec for QTc (AUC = 0.698, P = .002). Utilising linear regression, QTc has a positive correlation with Log-GDF-15 (r = .216, P = 1.0 × 10-6 ). Utilising Kaplan-Meier analysis, both QTc interval and GDF-15 level are significant predictors for primary end point (P = .000194, P = 2.0 × 10-6 , respectively) and secondary endpoint (P = .00028, P = 6.15 × 10-8 , respectively). When combined these two parameters together, a significant synergistic predictive power was noted for primary and secondary endpoint (P = 2.31 × 10-7 , P = 1.26 × 10-8 , respectively). This combined strategy also showed significant correlation with the severity of CAD (P < .001). CONCLUSION: In Chinese patient with angiographically confirmed CAD, a combined strategy utilising an ECG parameter (QTc) and a circulating biomarker (GDF-15) has good correlation with the severity of CAD, and improves the predictive power for total mortality.

Left Ventricular Electromechanical Remodeling Detected by Acoustic Cardiography in Paroxysmal Atrial Fibrillation.

This study aimed to investigate the electromechanical function detected by acoustic cardiography before and after radiofrequency ablation therapy (RFA) in paroxysmal AF (PAF) patients with preserved left ventricular ejection fraction (LVEF). Seventy-five symptomatic PAF patients and 69 patients without arrhythmia were enrolled. Thirty-seven PAF patients received RFA therapy. Acoustic cardiographic exam was performed to check S3 and S4 heart sound, electromechanical activation time (EMAT), LV systolic time percentage (LVST), and systolic dysfunction index (SDI) in all participants. Furthermore, 37 PAF patients also received follow-up acoustic cardiography postRFA. PAF had impaired electromechanical systolic function compared with health participants (%EMAT 14.69 ± 3.62 vs. 10.84 ± 2.62; %LVST 40.83 ± 5.14 vs. 36.70 ± 3.87; SDI 4.75 ± 1.61 vs. 3.26 ± 0.96 all p < 0.001). RFA can improve electromechanical systolic function. Improvement below 13.1% could predict the recurrent AF postcatheter ablation. Higher degree of improved electromechanical systolic function postRFA contribute to lower recurrence of AF. Graphical Abstract Receiver operating characteristic (ROC) curve analysis for % change of systolic dysfunction index (SDI) postRFA in the detection of recurrent AF.

A Novel and Simple Algorithm Using Surface Electrocardiogram That Localizes Accessory Conduction Pathway in Wolff-Parkinson-White Syndrome in Pediatric Patients.

BACKGROUND: The location of the accessory pathway (AP) can be precisely identified on surface electrocardiography (ECG) in adults with Wolff-Parkinson-White (WPW) syndrome. However, current algorithms to locate the AP in pediatric patients with WPW syndrome are limited. OBJECTIVE: To propose an optimal algorithm that localizes the AP in pediatric patients with WPW syndrome. METHODS: From 1992 to 2016, 180 consecutive patients aged below 18 years with symptomatic WPW syndrome were included. After the exclusion of patients with non-descriptive electrocardiography (ECG), multiple APs, congenital heart diseases, non-inducible tachycardia, and those who received a second ablation, 104 patients were analyzed retrospectively. Surface ECG was obtained before ablation and evaluated by using previously documented algorithms, from which a new pediatric algorithm was developed. RESULTS: Previous algorithms were not highly accurate when used in pediatric patients with WPW syndrome. In the new algorithm, the R/S ratio of V1 and the polarity of the delta wave in lead I could distinguish right from the left side AP with 100% accuracy. The polarity of the delta wave of lead V1 could distinguish free wall AP from septal AP with an accuracy of 100% in left-side AP, compared to 88.6% in leads III and V1 for right-side AP. The overall accuracy was 92.3%. CONCLUSIONS: This simple, novel algorithm could differentiate left from right AP and septal from free wall AP in pediatric patients with WPW syndrome.

Shorter Leukocyte Telomere Length Is Associated With Atrial Remodeling and Predicts Recurrence in Younger Patients With Paroxysmal Atrial Fibrillation After Radiofrequency Ablation.

BACKGROUND: Telomere length is a biologic aging marker. This study investigated leukocyte telomere length (LTL) as a new biomarker to predict recurrence after paroxysmal atrial fibrillation (PAF) ablation.Methods and Results:A total of 131 participants (26 healthy individuals and 105 symptomatic PAF patients) were enrolled. PAF patients (54.1±10.8 years) who received catheter ablation therapy were divided into 2 groups: recurrent AF (n=25) and no recurrent AF after catheter ablation (n=80). Peripheral blood mononuclear cells were collected from all subjects to measure LTL. Under 50 years old, LTL in healthy individuals (n=17) was longer than in PAF patients (n=31; 7.34±0.58 kbp vs. 6.44±0.91 kbp, P=0.01). In PAF patients, LTL was positively correlated with left atrial bipolar voltage (R=0.497, P<0.001), and negatively correlated with biatrial scar area (R=-0.570, P<0.001) and left atrial diameter (R=-0.214, P=0.028). LTL was shorter in the patients with recurrent AF than in those without recurrent AF after catheter ablation (5.68±0.82 kbp vs. 6.66±0.71 kbp; P<0.001). On receiver operating characteristic curve analysis, LTL cut-off <6.14 kbp had a specificity of 0.68 and sensitivity of 0.79 to predict recurrent AF after catheter ablation. CONCLUSIONS: Young PAF patients (≤50 years) had shorter LTL. Shorter LTL was associated with a degenerative atrial substrate and recurrence after catheter ablation in younger PAF patients.

Using a smartwatch with real-time feedback improves the delivery of high-quality cardiopulmonary resuscitation by healthcare professionals.

AIM: Cardiopulmonary resuscitation (CPR) quality affects survival after cardiac arrest. We aimed to investigate if a smartwatch with real-time feedback can improve CPR quality by healthcare professionals. METHODS: An app providing real-time audiovisual feedback was developed for a smartwatch. Emergency Department (ED) professionals were recruited and randomly allocated to either the intervention group wearing a smartwatch with the preinstalled app, or to a control group. All participants were asked to perform a two-minute CPR on a manikin at a 30:2 compression-ventilation ratio. Primary outcomes were the mean CCR and CCD measured on the manikin. A secondary outcome was the percentage of chest compressions meeting both the guideline-recommended rate (100-120 min-1) and depth (50-60 mm) of high-quality CPR during a 2-min period. Differences between groups were evaluated with t-test, Chi-Square test, or Mann-Whitney U test depending on the distribution. RESULTS: Eighty participants were recruited. 40 people were assigned to the intervention and 40 to the control group. The compression rates (mean ± SD, min-1) were significantly faster (but above the guideline recommendation, P < 0.001) in the control (129.1 ± 14.9) than in the intervention group (112.0 ± 3.5). The compression depths (mean ± SD, mm) were significantly deeper (P < 0.001) in the intervention (50.9 ± 6.6) than in the control group (39.0 ± 8.7). The percentage (%) of high-quality CPR was significantly higher (P < 0.001) in the intervention (median 39.4, IQR 27.1-50.1) than in the control group (median 0.0, IQR 0.0-0.0). CONCLUSION: Without real-time feedback, chest compressions tend to be too fast and too shallow. CPR quality can be improved with the assistance of a smartwatch providing real-time feedback.

Wearable-Based Mobile Health App in Gastric Cancer Patients for Postoperative Physical Activity Monitoring: Focus Group Study.

BACKGROUND: Surgical cancer patients often have deteriorated physical activity (PA), which in turn, contributes to poor outcomes and early recurrence of cancer. Mobile health (mHealth) platforms are progressively used for monitoring clinical conditions in medical subjects. Despite prevalent enthusiasm for the use of mHealth, limited studies have applied these platforms to surgical patients who are in much need of care because of acutely significant loss of physical function during the postoperative period. OBJECTIVE: The aim of our study was to determine the feasibility and clinical value of using 1 wearable device connected with the mHealth platform to record PA among patients with gastric cancer (GC) who had undergone gastrectomy. METHODS: We enrolled surgical GC patients during their inpatient stay and trained them to use the app and wearable device, enabling them to automatically monitor their walking steps. The patients continued to transmit data until postoperative day 28. The primary aim of this study was to validate the feasibility of this system, which was defined as the proportion of participants using each element of the system (wearing the device and uploading step counts) for at least 70% of the 28-day study. "Definitely feasible," "possibly feasible," and "not feasible" were defined as ≥70%, 50%-69%, and <50% of participants meeting the criteria, respectively. Moreover, the secondary aim was to evaluate the clinical value of measuring walking steps by examining whether they were associated with early discharge (length of hospital stay <9 days). RESULTS: We enrolled 43 GC inpatients for the analysis. The weekly submission rate at the first, second, third, and fourth week was 100%, 93%, 91%, and 86%, respectively. The overall daily submission rate was 95.5% (1150 days, with 43 subjects submitting data for 28 days). These data showed that this system met the definition of "definitely feasible." Of the 54 missed transmission days, 6 occurred in week 2, 12 occurred in week 3, and 36 occurred in week 4. The primary reason for not sending data was that patients or caregivers forgot to charge the wearable devices (>90%). Furthermore, we used a multivariable-adjusted model to predict early discharge, which demonstrated that every 1000-step increment of walking on postoperative day 5 was associated with early discharge (odds ratio 2.72, 95% CI 1.17-6.32; P=.02). CONCLUSIONS: Incorporating the use of mobile phone apps with wearable devices to record PA in patients of postoperative GC was feasible in patients undergoing gastrectomy in this study. With the support of the mHealth platform, this app offers seamless tracing of patients' recovery with a little extra burden and turns subjective PA into an objective, measurable parameter.

Early detection of electromechanical dysfunction in patients with idiopathic premature ventricular contractions.

BACKGROUND: Premature ventricular contractions (PVCs) induced by subtle cardiac dysfunction are missed by echocardiography. We evaluated acoustic cardiography for detection of early electromechanical dysfunction in patients with idiopathic PVCs and normal left ventricular ejection fraction (LVEF), and investigated the impact of radiofrequency ablation (RFA) in reversing this adverse effect. METHODS: Eighty-six patients with PVCs and 33 normal controls having normal LVEF were studied. Fifty PVC patients were in the ablation group and 36 in the nonablation group. %Electromechanical activation time (%EMAT), %left ventricular systolic time (%LVST), third (S3) and fourth heart sound (S4), and systolic dysfunction index (SDI) during sinus rhythm (SR) were measured by acoustic cardiography (Audicor, Inovise Medical, Inc., Beaverton, OR, USA) pre- and postablation. In 28 patients, acoustic parameters were compared during SR without PVCs, and SR with single PVC, ≥ 2 PVCs, or ventricular tachycardia over 10-second Audicor recording in a single patient at different times. Twenty-four-hour acoustic cardiographic and acoustic cardiographic Holter recording were used to assess the impact of PVC burden on electromechanical function in 41 patients. RESULTS: %EMAT, S3, S4, and SDI showed significant worsening in the PVC versus control group. %EMAT and SDI were worsened with increasing PVC number in a 10-second strip. %EMAT showed significant linear increment with increasing PVC burden. There was a significant improvement in %EMAT, %LVST, S3, S4, and SDI postablation in patients with PVCs. CONCLUSION: Acoustic cardiography can detect PVC-induced minor electromechanical dysfunction in patients with normal LVEF. RFA can reverse this adverse effect.

A novel depth estimation algorithm of chest compression for feedback of high-quality cardiopulmonary resuscitation based on a smartwatch.

INTRODUCTION: High-quality cardiopulmonary resuscitation (CPR) is a key factor affecting cardiac arrest survival. Accurate monitoring and real-time feedback are emphasized to improve CPR quality. The purpose of this study was to develop and validate a novel depth estimation algorithm based on a smartwatch equipped with a built-in accelerometer for feedback instructions during CPR. METHODS: For data collection and model building, researchers wore an Android Wear smartwatch and performed chest compression-only CPR on a Resusci Anne QCPR training manikin. We developed an algorithm based on the assumptions that (1) maximal acceleration measured by the smartwatch accelerometer and the chest compression depth (CCD) are positively correlated and (2) the magnitude of acceleration at a specific time point and interval is correlated with its neighboring points. We defined a statistic value M as a function of time and the magnitude of maximal acceleration. We labeled and processed collected data and determined the relationship between M value, compression rate and CCD. We built a model accordingly, and developed a smartwatch app capable of detecting CCD. For validation, researchers wore a smartwatch with the preinstalled app and performed chest compression-only CPR on the manikin at target sessions. We compared the CCD results given by the smartwatch and the reference using the Wilcoxon Signed Rank Test (WSRT), and used Bland-Altman (BA) analysis to assess the agreement between the two methods. RESULTS: We analyzed a total of 3978 compressions that covered the target rate of 80-140/min and CCD of 4-7 cm. WSRT showed that there was no significant difference between the two methods (P = 0.084). By BA analysis the mean of differences was 0.003 and the bias between the two methods was not significant (95% CI: -0.079 to 0.085). CONCLUSION: Our study indicates that the algorithm developed for estimating CCD based on a smartwatch with a built-in accelerometer is promising. Further studies will be conducted to evaluate its application for CPR training and clinical practice.

Ventricular arrhythmias in nonischemic cardiomyopathy.

Nonischemic cardiomyopathies (NICMs) are composed of variable disease entities, including primary and secondary cardiomyopathies. Determining the etiology of NICM provides pivotal roles of not only the understanding of the individual pathogenesis, but also the clinical management, such as risk stratification, pharmacological treatment, and intervention therapies. Despite the diverse causes of NICM, these cases mostly require clinical attention owing to progressive myocardial injury, resulting in ventricular dysfunction and heart failure. The interaction between the diseased ventricular substrates and systemic/neurophysiological factors contributes to the cornerstones responsible for ventricular arrhythmogenesis and sudden cardiac death (SCD). Prevention of SCD and diminishing ventricular tachyarrhythmias are the important mainstays for the management of NICM patients. Given the understanding of the abnormal ventricular substrates and advancement of navigation systems, radiofrequency catheter ablation (RFCA) has become an adjunctive or alternative strategy for NICM patients who experience drug-refractory ventricular tachycardias (VTs). Successful ablation can frequently be achieved at the expense of an epicardial intervention. A recent study has proven the survival benefits for NICM patients who are free from recurrent VTs after a successful RFCA, regardless of the New York Heart Association (NYHA) functional class status or left ventricular ejection fraction. Additionally, recent evidence has highlighted the better delineation of a diseased myocardium through the incorporation of cardiovascular magnetic resonance imaging (CMRI) and 3D mapping systems, which can facilitate the identification of critical ventricular arrhythmogenic substrates in NICM patients.

Electrocardiographic characteristics for predicting idiopathic right ventricular outflow tract premature ventricular complex-induced cardiomyopathy.

PURPOSE: In spite of several proposed predictors for premature ventricular complex (PVC)-induced cardiomyopathy (PVC-CMP), the specific ECG features of idiopathic right ventricular outflow tract (RVOT) PVC-CMP remain unknown. METHODS: A total of 130 patients (49 males, mean age 44 years) with symptomatic and drug-refractory idiopathic RVOT PVCs undergoing radiofrequency catheter ablation (RFCA) were enrolled. The patients were categorized into two groups, including those with and without RVOT PVC-CMP (left ventricular ejection fraction (LVEF) < 50%, n = 25 and LVEF ≥ 50%, n = 105, respectively). The 12-lead PVC morphologies were assessed. RESULTS: Patients with RVOT PVC-CMP had a lower LVEF (42 ± 5% vs. 60 ± 7%, P < 0.01) and higher PVC burden (24 ± 14% vs. 15 ± 11%, P = 0.02) when compared to patients without RVOT PVC-CMP. The PVC features in those with PVC-CMP displayed a significantly wider QRS duration (143 ± 14 ms vs. 132 ± 17 ms, P < 0.01) and higher peak deflection index (PDI; 0.60 ± 0.07 vs. 0.55 ± 0.08, P < 0.01). A multivariate analysis demonstrated that the QRS duration (odds ratio (OR) 1.130, 95% confidence interval (CI) 1.020-1.253, P = 0.02) and PDI (OR 1.240, 95% CI 1.004-1.532, P = 0.04) were independently associated with RVOT PVC-CMP. Based on the receiver-operating characteristic analysis, a QRS duration > 139 ms and PDI > 0.57 could predict RVOT PVC-CMP (area under the curve (AUC) 0.710 and AUC 0.690, respectively). The elimination and suppression of PVCs by RFCA resulted in the recovery of the LVEF in RVOT PVC-CMP. CONCLUSIONS: The ECG parameters, including a wider QRS duration and higher PDI, could predict the development of RVOT PVC-CMP, which could be effectively treated by RFCA.

Ventricular arrhythmias originating from the cardiac crux and the basal inferior segment of the interventricular septum in the patients with structural heart diseases: characteristics, mapping, and electrophysiological properties.

PURPOSE: There are few reports describing ventricular arrhythmias (VAs) from the crux and the corresponding endocardial site, i.e., the basal inferior segment of the interventricular septum (IVS). We aimed to investigate a distinct clinical group of VAs arising from the endocardium at this area in patients with structural heart diseases (SHD). METHODS: We included 17 patients with SHD and clinically documented VAs. Thirteen patients underwent endocardial mapping only. Three patients underwent both epicardial and endocardial approaches and one had only epicardial mapping. Eighteen VAs were identified, 14 focal and 4 reentrant VAs, confirmed by entrainment. RESULTS: There were 2 VAs from the crux, 5 VAs from the corresponding endocardial site in the right ventricle (RV), and 11 from the site in the left ventricle (LV). Compared with the VAs from RV endocardium, VAs from LV endocardium had a higher R wave in V3 than V2 (V2R/V3R ratio, 1.83 ± 0.84 vs. 0.86 ± 0.38, P = 0.008) and a higher V3 transition ratio percentage (2.16 ± 2.07 vs. 0.58 ± 0.62, P = 0.008). Combining all 16 patients with endocardial mapping, there were also lower bipolar voltages (1.21 ± 1.05 vs. 3.10 ± 2.65 mv, P < 0.0001), lower unipolar voltages (4.05 ± 1.92 vs. 5.75 ± 2.90 mv, P < 0.0001), and longer local electrocardiogram (EGM) lateness (157.6 ± 47.9 vs.140.3 ± 52.5 ms, P = 0.0001) in the dominant chambers. CONCLUSIONS: In VAs from the crux and the corresponding endocardial site, the complete ECG V2R/V3R ratio and V3 transition ratio percentage could differentiate the VAs from the RV or LV endocardium. The lower unipolar, bipolar voltage mapping, and longer EGM lateness are helpful to identify the abnormal substrate in the endocardium in these patients.

Vasovagal responses during cryoballoon pulmonary vein isolation in paroxysmal atrial fibrillation predict favorable mid-term outcomes.

BACKGROUND: Vasovagal responses (VR) encountered during radiofrequency pulmonary vein isolation (PVI) in paroxysmal atrial fibrillation (PAF) suggest ablation of the atrial tissue subjacent to the ganglionic plexi (GP) and confer durability of PVI. OBJECTIVE: We hypothesized that VR during cryoballoon PVI (CB-PVI) in PAF can predict mid-term AF recurrence. METHODS: We enrolled 39 patients who underwent PVI using 2nd generation cryoballoon for PAF from November 2014 to July 2016. We evaluated the long term outcomes for those who had VR during index procedure. RESULTS: A total of 39 patients (76% male, mean age 57 ±â€¯9 years) underwent CB-PVI for PAF and 66.67% (26/39) had VR. VR was frequently observed in the LSPV (100%), followed by RSPV (64%), LIPV (60%), and less frequently, RIPV (28%). Overall, the mean difference in the HR and SBP, and the relative differences in the HR and SBP were observed during CB-PVI in the LSPV (mean difference in HR, p < 0.001; mean difference in SBP, p < 0.001; relative difference in HR, p < 0.001); relative difference in SBP, p < 0.001). After PVI, 22/26 (84.62%) and 5/13 (38.46%) of patients in the VR and NVR group, respectively, maintained SR at 14 ±â€¯6 months follow-up. The Kaplan-Meier analysis showed statistical difference in favor of patients with VR during CB-PVI (log rank p < 0.01) with a better mid-term outcome. CONCLUSION: In a small cohort of patients, VR during CB-PVI in PAF is a surrogate marker for ablation of atrial tissue subjacent to the GP and predicts a favorable mid-term outcome for AF recurrence.

Impact of Renal Denervation on Atrial Arrhythmogenic Substrate in Ischemic Model of Heart Failure.

BACKGROUND: Myocardial infarction increases the risk of heart failure (HF) and atrial fibrillation. Renal denervation (RDN) might suppress the development of atrial remodeling. This study aimed to elucidate the molecular mechanism of RDN in the suppression of atrial fibrillation in a HF model after myocardial infarction. METHODS AND RESULTS: HF rabbits were created 4 weeks after coronary ligation. Rabbits were classified into 3 groups: normal control (n=10), HF (n=10), and HF-RDN (n=6). Surgical and chemical RDN were approached through midabdominal incisions in HF-RDN. Left anterior descending coronary artery in HF and HF-RDN was ligated to create myocardial infarction. After electrophysiological study, the rabbits were euthanized and the left atrial appendage was harvested for real-time polymerase chain reaction analysis and Trichrome stain. Left atrial dimension and left ventricular mass were smaller in HF-RDN by echocardiography compared with HF. Attenuated atrial fibrosis and tyrosine hydroxylase levels were observed in HF-RDN compared with HF. The mRNA expressions of Cav1.2, Nav1.5, Kir2.1, KvLQT1, phosphoinositide 3-kinase, AKT, and endothelial nitric oxide synthase in HF-RDN were significantly higher compared with HF. The effective refractory period and action potential duration of HF-RDN were significantly shorter compared with HF. Decreased atrial fibrillation inducibility was noted in HF-RDN compared with HF (50% versus 100%, P<0.05). CONCLUSIONS: RDN reversed atrial electrical and structural remodeling, and suppressed the atrial fibrillation inducibility in an ischemic HF model. The beneficial effect of RDN may be related to prevention of the downregulation of the phosphoinositide 3-kinase/AKT/endothelial nitric oxide synthase signaling pathway.