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Introduction: The long-QT syndrome (LQTS) is the most common ion channelopathy, typically presenting with a prolonged QT interval and clinical symptoms such as syncope or sudden cardiac death. Patients may present with a concealed phenotype making the diagnosis challenging. Correctly diagnosing at-risk patients is pivotal to starting early preventive treatment. Objective: Identification of congenital and often concealed LQTS by utilizing novel deep learning network architectures, which are specifically designed for multichannel time series and therefore particularly suitable for ECG data. Design and Results: A retrospective artificial intelligence (AI)-based analysis was performed using a 12-lead ECG of genetically confirmed LQTS (n = 124), including 41 patients with a concealed LQTS (33%), and validated against a control cohort (n = 161 of patients) without known LQTS or without QT-prolonging drug treatment but any other cardiovascular disease. The performance of a fully convolutional network (FCN) used in prior studies was compared with a different, novel convolutional neural network model (XceptionTime). We found that the XceptionTime model was able to achieve a higher balanced accuracy score (91.8%) than the associated FCN metric (83.6%), indicating improved prediction possibilities of novel AI architectures. The predictive accuracy prevailed independently of age and QTc parameters. Conclusions: In this study, the XceptionTime model outperformed the FCN model for LQTS patients with even better results than in prior studies. Even when a patient cohort with cardiovascular comorbidities is used. AI-based ECG analysis is a promising step for correct LQTS patient identification, especially if common diagnostic measures might be misleading.

Introduction Supraventricular tachycardias (SVT) are often difficult to document due to their intermittent, short-lasting nature. Smartphone-based one-lead ECG monitors (sECG) were initially developed for the diagnosis of atrial fibrillation. No data have been published regarding their potential role in differentiating inappropiate sinus tachycardia (IST) from regular SVT. If cardiologists could distinguish IST from SVT in sECG, economic health care burden might be significantly reduced. Methods We prospectively recruited 75 consecutive patients with known SVT undergoing an EP study. In all patients, four ECG were recorded: a sECG during SVT and during sinus tachycardia and respective 12-lead ECG. Two experienced electrophysiologists were blinded to the diagnoses and separately evaluated all ECG. Results Three hundred individual ECG were recorded in 75 patients (47 female, age 50 ± 18 years, BMI 26 ± 5 kg/m2, 60 AVNRT, 15 AVRT). The electrophysiologists’ blinded interpretation of sECG recordings showed a sensitivity of 89% and a specificity of 91% for the detection of SVT (interobserver agreement κ = 0.76). In high-quality sECG recordings (68%), sensitivity rose to 95% with a specificity of 92% (interobserver agreement of κ = 0.91). Specificity increased to 96% when both electrophysiologists agreed on the diagnosis. Respective 12-lead ECG had a sensitivity of 100% and specificity of 98% for the detection of SVT. Conclusion A smartphone-based one-lead ECG monitor allows for differentiation of SVT from IST in about 90% of cases. These results should encourage cardiologists to integrate wearables into clinical practice, possibly reducing time to definitive diagnosis of an arrhythmia and unnecessary EP procedures. Graphical abstract A smartphone-based one lead ECG device (panel A) can be used reliably to differentiate supraventricular tachycardia (panel B) from inappropriate sinus tachycardia when compared to a simultaneously conducted gold-standard electrophysiology study (panels C, D).

Background: Different electrocardiogram (ECG) findings are known to be independent predictors of clinical response to cardiac resynchronization therapy (CRT). It remains unknown how these findings influence very long-term prognosis. Methods and Results: A total of 102 consecutive patients (75 males, mean age 65 ± 10 years) referred to our center for CRT implantation had previously been included in this prospective observational study. The same patient group was now re-evaluated for death from all causes over a prolonged median follow-up of 10.3 years (interquartile range 9.4–12.5 years). During follow-up, 55 patients died, and 82% of the clinical non-responders (n = 23) and 44% of the responders (n = 79) were deceased. We screened for univariate associations and found QRS width during biventricular (BIV) pacing (p = 0.02), left ventricular (LV) pacing (p &lt, 0.01), Δ LV paced–right ventricular (RV) paced (p = 0.03), age (p = 0.03), New York Heart Association (NYHA) class (p &lt, 0.01), CHA2DS2-Vasc score (p &lt, 0.01), glomerular filtration rate (p &lt, 0.01), coronary artery disease (p &lt, 0.01), non-ischemic cardiomyopathy (NICM) (p = 0.01), arterial hypertension (p &lt, 0.01), NT-proBNP (p &lt, 0.01), and clinical response to CRT (p &lt, 0.01) to be significantly associated with mortality. In the multivariate analysis, NICM, the lower NYHA class, and smaller QRS width during BIV pacing were independent predictors of better outcomes. Conclusion: Our data show that QRS width duration during biventricular pacing, an ECG parameter easily obtainable during LV lead placement, is an independent predictor of mortality in a long-term follow-up. Our data add further evidence that NICM and lower NYHA class are independent predictors for better outcome after CRT implantation.

Introduction: Multiple studies have shown that left atrial (LA) enlargement is a strong predictor of poor outcome after catheter ablation of atrial fibrillation (AF). LA size is commonly approximated as the diameter in the parasternal long axis. It remains unknown whether more precise echocardiographic measurements of LA size allow for better correlation with outcome after pulmonary vein isolation (PVI). Methods and results: We performed a retrospective study of 131 consecutive patients (43 females, 60% paroxysmal AF, mean CHA2DS2-Vasc score 1.6, mean age 61 ± 12 years) referred for PVI. Measurements of the LA were carried out by a single observer in transthoracic echocardiograms (TTE) performed prior to ablation. We calculated diameter of the LA in the parasternal long axis (PLAX), LA area in the 2- as well as 4-Chamber (CH) view. LA volume was computed using the disc summation technique (LAV) and indexed to body surface area (LAVI). Procedural and follow-up data were gathered from a prospective AF database. Ablation was performed exclusively using the second generation cryoballoon by the same operators. Follow-up visits at 3, 6 and 12 months showed freedom from AF in 76%, 73% and 73% respectively. Mean values of LA calculations were LAPLAX: 37.9 mm ± 6.3 mm, 2CH area: 22.5 cm2 ± 6.7 cm2, 4CH area: 21.4 cm2 ± 5.5 cm2, LAV: 73.7 mL ± 26.1 mL and LAVI: 36.2 mL/m2 ± 12.7 mL/m2, respectively. C statistic revealed the best concordance of LAVI with outcome after 12 months (C = 0.67), LAV also exhibited a satisfactory value (C = 0.61) in comparison to surfaces in 2CH (C = 0.59) and 4CH (C = 0.57). PLAX showed the worst correlation (C = 0.51). Additionally, different binary logistic regression models identified three independent predictors of AF outcome after cryoballoon PVI: gender (OR = 0.95 per year, p = 0.01), LAV (OR = 1.3/10mL, p = 0.02) and LAVI (OR = 1.58/10 mL/m2, p = 0.02). In all models, PLAX and area measurements were not predictive. Conclusions: Our data add further to evidence that LA size lends itself well as a predictor of PVI outcome. LAVI and LAV were independently predictive of rhythm outcome after PVI. This did not hold true for more commonly used measurements, such as PLAX diameter and surfaces of the LA, irrespective of the view chosen.

Background Slow pathway modification (SPM) is the therapy of choice for AV-nodal reentry tachycardia (AVNRT). When AVNRT is not inducible, empirical ablation can be considered, however, the outcome in patients with two AV nodal echo beats (AVNEBs) is unknown. Methods Out of a population of 3003 patients who underwent slow pathway modification at our institution between 1993 and 2013, we retrospectively included 32 patients with a history of symptomatic tachycardia, lack of paroxysmal supraventricular tachycardia (pSVT) inducibility but occurrence of two AVNEBs. Results pSVT documentation by electrocardiography (ECG) was present in 20 patients. The procedural endpoint was inducibility of less than two AVNEBs. This was reached in 31 (97%) patients. Long-term success was assessed by a telephone questionnaire (follow-up time 63 ± 9 months). A total 94% of the patients benefited from the procedure (59% freedom from symptoms; 34% improvement in symptoms). Among those patients in whom ECG documentation was not present, 100% benefited (58% freedom from symptoms, 42% improvement). Conclusion This is the first collective analysis of a group of patients presenting with symptoms of pSVT and inducibility of only two AVNEBs. Procedural success and clinical long-term follow-up were in the range of the reported success rates of slow pathway modification of inducible AVNRT, independent of whether ECG documentation was present. Thus, SPM is a safe and effective therapy in patients with two AVNEBs.

Objective We had the objective to determine the impact of clinical parameters and anticoagulation status on cerebral microembolic signals (MES) during pulmonary vein isolation (PVI) for atrial fibrillation (AF). Background Thromboembolism and stroke are the most feared complications of PVI. MES can help to evaluate embolic burden. It is unknown whether clinical parameters have an impact on embolic risk during PVI. Methods In this retrospective analysis we investigated the impact of clinical parameters, including the CHADS2- and CHA2DS2-VASc-score, pulmonary vein variants and echocardiographic parameters on MES rates in patients that underwent PVI using three different ablation approaches (radiofrequency ablation (iRF), pulmonary vein ablation catheter (PVAC) with deactivated electrode pair 1 or 5 (PVAC-red) or PVAC without deactivation (PVAC-all). Results 118 AF patients (61±12 years) were included between 2011 and 2013 (Median: 489 MES during PVI). Patients were more likely to have more MES (within 4th quartile) with the PVAC-all approach (60.7% vs. 25.0% (iRF) vs. 14.3% (PVAC-red) respectively (p