Arrhythmogenic Effects of Cardiac Memory.

Cardiac memory is the term used to describe an interesting electrocardiographic phenomenon. Whenever a QRS complex is wide and abnormal, such as during ventricular pacing, the T waves will also be abnormal and will point to the opposite direction of the wide QRS. If the QRS then normalizes, such as after cessation of ventricular pacing, the T waves will normalize as well, but at a later stage. The period of cardiac memory is the phase between the sudden normalization of the QRS and the eventual and gradual return of the T waves to their baseline morphology. Cardiac memory is assumed to be an innocent electrocardiographic curiosity. However, during cardiac memory, reduction of repolarizing potassium currents increases left ventricular repolarization gradients. Therefore, when cardiac memory occurs in patients who already have a prolonged QT interval (for whatever reason), it can lead to a frank long QT syndrome with QT-related ventricular arrhythmias (torsades de pointes). These arrhythmogenic effects of cardiac memory are not generally appreciated and are reviewed here for the first time.

Polymorphic Ventricular Tachycardia: Terminology, Mechanism, Diagnosis, and Emergency Therapy.

Polymorphic ventricular tachyarrhythmias are highly lethal arrhythmias. Several types of polymorphic ventricular tachycardia have similar electrocardiographic characteristics but have different modes of therapy. In fact, medications considered the treatment of choice for one form of polymorphic ventricular tachycardia, are contraindicated for the other. Yet confusion about terminology, and thus diagnosis and therapy, continues. We present an in-depth review of the different forms of polymorphic ventricular tachycardia and propose a practical step-by-step approach for distinguishing these malignant arrhythmias.

Outcomes of Patients Undergoing PCI of Ostial Coronary Lesions: A Single-Center Study.

INTRODUCTION: Ostial coronary lesions are a subset of proximal coronary lesions, which are relatively more difficult to treat and were associated with worse clinical outcomes in the early percutaneous coronary intervention (PCI) era. Data regarding the outcomes of ostial lesions' PCI in the contemporary era are lacking. METHODS: We conducted a single-center, all-comer, prospective registry study, enrolling patients undergoing PCI with the use of contemporary drug-eluting stents (DES) between July 2016 and February 2018. Included in the present analysis were only patients treated for proximal lesions. Clinical outcomes were compared between patients undergoing PCI of ostial versus proximal nonostial lesions. The primary endpoint was target vessel revascularization (TVR). Secondary endpoints included target lesion revascularization (TLR) and major cardiovascular adverse events (MACE) at 12 months. RESULTS: A total of 334 (84.7% male, 67.3 ± 10.7 years) patients were included, of which 91 patients were treated for ostial lesions and 243 were treated for proximal nonostial lesions. Baseline and procedural characteristics were similar between the two groups. At 12 months, TVR and TLR were numerically higher among patients undergoing PCI of ostial versus nonostial lesions without reaching statistical significance (5.5% vs. 3.3%; p = 0.35 and 4.4% vs. 2.5%; p = 0.47, respectively). The rate of MACE was similar between the two groups. CONCLUSION: In patients undergoing PCI with the use of contemporary DES, clinical outcomes were similar among patients treated for ostial compared to proximal nonostial lesions. Larger studies are required to further evaluate the performance of contemporary DES in this subset of lesions.

Polymorphic ventricular tachycardia, ischaemic ventricular fibrillation, and torsade de pointes: importance of the QT and the coupling interval in the differential diagnosis.

AIMS: Distinctive types of polymorphic ventricular tachycardia (VT) respond differently to different forms of therapy. We therefore performed the present study to define the electrocardiographic characteristics of different forms of polymorphic VT. METHODS AND RESULTS: We studied 190 patients for whom the onset of 305 polymorphic VT events was available. The study group included 87 patients with coronary artery disease who had spontaneous polymorphic VT triggered by short-coupled extrasystoles in the absence of myocardial ischaemia. This group included 32 patients who had a long QT interval but nevertheless had their polymorphic VT triggered by ectopic beats with short coupling interval, a subcategory termed 'pseudo-torsade de pointes] (TdP). For comparison, we included 50 patients who had ventricular fibrillation (VF) during acute myocardial infarction ('ischaemic VF' group) and 53 patients with drug-induced TdP ('true TdP' group). The QT of patients with pseudo-TdP was (by definition) longer than that of patients with polymorphic VT and normal QT (QTc 491.4 ± 25.2 ms vs. 447.3 ± 55.6 ms, P < 0.001). However, their QT was significantly shorter than that of patients with true TdP (QTc 564.6 ± 75.6 ms, P < 0.001). Importantly, the coupling interval of the ectopic beat triggering the arrhythmia was just as short during pseudo-TdP as during polymorphic VT with normal QT (359.1 ± 38.1 ms vs. 356.6 ± 39.4 ms, P = 0.467) but was much shorter than during true TdP (581.2 ± 95.3 ms, P < 0.001). CONCLUSIONS: The coupling interval helps discriminate between polymorphic VT that occurs despite a long QT interval (pseudo-TdP) and polymorphic arrhythmias striking because of a long QT (true TdP).

Arrhythmic storm from ischemic ventricular fibrillation treated with intravenous quinidine.

We present a case who developed an acute right ventricular infarction. The leads demonstrating ST-segment elevation were different than those expected based on previous publications. We explain why this happened with the aid of 3-dimentional imaging. Our case then developed an arrhythmic storm caused by ischemic ventricular fibrillation (VF). Emergency revascularization failed and the VF-storm failed to respond to sedation, lidocaine and amiodarone but responded to intravenous quinidine.

Pulmonary Vein Isolation With Ablation Index via Single Transseptal Crossing: Critical Role of Carina Isolation.

AIM: Reconnection of the pulmonary veins (PVs) is the most common reason for the recurrence of atrial fibrillation (AF). The ablation index is a marker of ablation lesion quality that achieves high percentages of first-pass isolation and improved AF ablation results. Most operators use a double transseptal approach with confirmation of PV isolation with a circular mapping catheter. In the present study we aimed to show that an ablation index-guided procedure using a single transseptal approach and ablation catheter only would achieve adequate PV isolation while demonstrating the critical role of the carina in PV isolation. METHOD: Sixty-six (66) consecutive patients with paroxysmal AF were included. Thirty-four (34) patients underwent wide antral circumferential ablation (WACA-only) and 32 underwent WACA+ (WACA + empiric carina isolation). All procedures were performed via single transseptal approach. Pulmonary vein isolation was confirmed with the use of a circular mapping catheter in both groups. RESULTS: Compared to WACA-only, WACA+ increased the odds of PV isolation from 65% to 94% (p=0.011). In the WACA-only procedure, ablation of the carina was needed to achieve PV isolation. At the 18-month follow-up (interquartile range 15.2-20.8 months), freedom from AF was 84% for the entire cohort. CONCLUSIONS: Our study confirmed the high success rate of PV isolation using the ablation index and showed that this can be achieved via a single transseptal crossing. Our study confirmed the role of the carina in PV isolation.

Quinidine-Responsive Polymorphic Ventricular Tachycardia in Patients With Coronary Heart Disease.

BACKGROUND: Polymorphic ventricular tachycardia (VT) without QT prolongation is well described in patients without structural heart disease (mainly idiopathic ventricular fibrillation and Brugada syndrome) and in patients with acute ST-elevation myocardial infarction. METHODS: Retrospective study of patients with polymorphic VT related to coronary artery disease, but without evidence of acute myocardial ischemia. RESULTS: The authors identified 43 patients in whom polymorphic VT developed within days of an otherwise uncomplicated myocardial infarction or coronary revascularization procedure. The polymorphic VT events were invariably triggered by extrasystoles with short (364±36 ms) coupling interval. Arrhythmic storms (4-16 events of polymorphic VT deteriorating to ventricular fibrillation) occurred in 23 (53%) patients. These arrhythmic storms were always refractory to conventional antiarrhythmic therapy, including intravenous amiodarone, but invariably responded to quinidine therapy. In-hospital mortality was 17% for patients with arrhythmic storm. Patients treated with quinidine invariably survived to hospital discharge. During long-term follow-up (of 5.6±6 years; range, 1 month to 18 years), 3 (16%) of patients discharged without quinidine developed recurrent polymorphic VT. There were no recurrent arrhythmias during quinidine therapy Conclusions: Arrhythmic storm with recurrent polymorphic VT in patients with coronary disease responds to quinidine therapy when other antiarrhythmic drugs (including intravenous amiodarone) fail.

Soluble ST2 and CXCL-10 may serve as biomarkers of subclinical diastolic dysfunction in SLE and correlate with disease activity and damage.

OBJECTIVE: Subclinical myocardial dysfunction has been reported to occur early in systemic lupus erythematous (SLE). The study aim was to search for biomarkers of subclinical myocardial dysfunction which may correlate with disease activity in SLE patients. METHODS: This is a prospective, controlled, cross-sectional study of 57 consecutive patients with SLE and 18 controls. Serum samples were obtained to determine serum soluble ST2 (sST2), CXCL-10 and high-sensitivity troponin (hs-troponin) levels. All participants underwent an echocardiographic tissue Doppler study. RESULTS: sST2, CXCL-10 and hs-troponin levels were higher in patients with higher SLE disease activity (SLEDAI). sST2 and CXCL-10 levels were higher in patients with more disease damage as measured by the SLE damage index. Measures of diastolic dysfunction, as assessed by echocardiographic tissue Doppler negatively correlated with log CXCL-10: including E/A; E/e'lateral and E/e'septal, while E/e' positively correlated with CXCL-10. Diastolic dysfunction parameters also correlated with log sST2 levels, a negative correlation was seen with E/e'lateral and a positive correlation was seen with E/e'. Systolic dysfunction parameters positively correlated with hs-troponin: LVED, LVES, IVS, LVMASS and LVMASS index. In a multivariate analysis, sST2 and CXCL-10 were found to be significantly different in SLE vs. healthy controls, independent of each other and independent of cardiovascular risk factors. CONCLUSIONS: Soluble ST2 and CXCL-10 are markers of disease activity and accrued damage in SLE and may serve as sensitive biomarkers for detection of subclinical diastolic dysfunction, independent of traditional cardiovascular risk factors.

Quinidine-responsive out-of-hospital polymorphic ventricular tachycardia in patients with coronary heart disease.

AIMS: We recently reported that patients with coronary artery disease (CAD) who develop polymorphic ventricular tachycardia (VT) during the healing phase of an acute coronary event, generally fail to respond to revascularization or standard antiarrhythmic therapy but respond immediately to quinidine therapy. Here, we describe that CAD patients presenting with out-of-hospital polymorphic VT without a recent coronary event or an obvious precipitating factor, also respond uniquely to quinidine therapy. METHODS AND RESULTS: Retrospective study of patients with unheralded, mainly out-of-hospital, polymorphic VT related to CAD but without evidence of acute myocardial ischaemia. We identified 20 patients who developed polymorphic VT without precipitating factors. The polymorphic VT events were triggered by extrasystoles with short (376 ± 49 ms) coupling interval. Arrhythmic storms occurred in 70% patients. These arrhythmic storms were generally refractory to conventional antiarrhythmic therapy but invariably responded to quinidine therapy. Revascularization was antiarrhythmic in 3 patients despite the absent clinical or ECG signs of ischaemia. During long-term follow-up (range 2 months to 11 years), 3 (15%) of patients not receiving quinidine developed recurrent polymorphic VT. There were no recurrent arrhythmias during long-term quinidine therapy. CONCLUSIONS: Patients with CAD may develop polymorphic VT in the absence of obvious acute ischaemia or apparent precipitating factors, presenting as out-of-hospital polymorphic VT with high risk of arrhythmic storms that respond uniquely to quinidine therapy.

Continuous heart rhythm monitoring using mobile photoplethysmography in ambulatory patients.

BACKGROUND: Wearable devices using photo-plethysmography (PPG) can accurately detect heart beats and may be useful for heart rate measurement and diagnosis of arrhythmias such as atrial fibrillation (AF). A previous study of a new portable PPG sensor (CardiacSense) showed high accuracy in heart rate measurement and AF detection in resting patients. We report a trial done to test the same device in active ambulatory patients with diverse characteristics. METHODS: A cohort of 24 ambulatory volunteers, underwent simultaneous PPG recording and continuous electrocardiogram (ECG) recording under different environmental conditions and situations. Per study protocol, the subjects were diverse in age, BMI, hair density and skin tone. Four subjects had AF. Heart rate measurement using the PPG device was compared to measurements by ECG. RESULTS: Of 163,527 recorded ECG-detected beats in the trial, 86,929 (53.2%) were also recorded by the PPG device. Most undetected heart beats were due to motion induced noise. Correlation between ECG and PPG was high (R = 0.94, p < 0.0001), yet in subjects with AF correlation was lower (R = 0.80, p < 0.0001). A Bland-Altman analysis showed the mean difference between measurements was -0.7 ms (95% limit of agreement -93.8 to 92.2). A total of 86,217 (99.9%) of all RR measurements were reliably measured (RR difference within 100 ms). Reliability was sustained (>99.8%) in subjects of all groups including subjects with AF. CONCLUSIONS: This study showed that, in the absence of movement-related noise, the CardiacSense PPG device can reliably detect HR in a variety of situations and subjects' characteristics.

Forced diuresis with matched hydration during transcatheter aortic valve implantation for Reducing Acute Kidney Injury: a randomized, sham-controlled study (REDUCE-AKI).

AIMS: Acute kidney injury (AKI) is a common complication following transcatheter aortic valve implantation (TAVI) and is associated with increased risk for short- and long-term mortality. In patients undergoing percutaneous coronary intervention (PCI), forced diuresis with matched hydration has been shown to reduce the incidence of AKI by ∼50%. The aim of the present study was to evaluate whether forced diuresis with matched intravenous hydration reduces AKI in patients undergoing TAVI. METHODS AND RESULTS: Reducing Acute Kidney Injury (REDUCE-AKI) was a single-centre, prospective, randomized, double-blind sham-controlled clinical trial, designed to examine the effect of an automated matched saline infusion with urine output for the prevention of AKI in patients undergoing TAVI. A total of 136 TAVI patients were randomized, 68 in each group. Mean age was 83.9 ± 5 years and 41.2% were males. There were no differences in baseline characteristics between the two groups. The rate of AKI was not statistically different between the groups (25% in the active group vs. 19.1% in the sham group, P = 0.408). There was a significant increase in long-term mortality in the active group (27.9% vs. 13. 2% HR 3.744, 95% CI 1.51-9.28; P = 0.004). The study was terminated prematurely by the Data Safety Monitoring Board for futility and a possible signal of harm. CONCLUSIONS: Unlike in PCI, forced diuresis with matched hydration does not prevent AKI in patients undergoing TAVI, and might be associated with increased long-term mortality. Future studies should focus on understanding the mechanisms behind these findings. CLINICALTRIALS.GOV REGISTRATION: NCT01866800, 30 April 2013.

Continuous heart rate monitoring for automatic detection of atrial fibrillation with novel bio-sensing technology.

BACKGROUND: Asymptomatic atrial fibrillation [AF] is an important cause of fatal or disabling stroke. A continuous heart-rate monitoring device, comfortable enough to be worn continuously and reliable enough to detect AF, would allow for prompt initiation of anticoagulation therapy to prevent stroke. METHODS: We studied a new custom-made wearable photo-plethysmograph [PPG] wrist-watch sensor, specifically designed for continuous heart rate monitoring and incorporating contact and motion noise-filters. We tested its ability to automatically detect AF in patients undergoing elective cardioversion of AF, using simultaneously recorded electrocardiogram [ECG] as gold standard. RESULTS: A total of 18,608 consecutive R-R-interval measurements were recorded simultaneously with PPG and ECG in 20 patients, including 12,521 [67.3%] R-R-intervals during AF and 6087 [32.7%] R-R intervals during sinus rhythm. Scatter plots and Bland-Altman plots demonstrated that the PPG signals were highly correlated to the simultaneously recorded ECG [R = 0.980, p < 0.001], both during AF and during sinus rhythm. The automatic algorithm distinguished AF from sinus rhythm with a sensitivity of 100% and specificity of 93.1%. CONCLUSIONS: This PPG-based wrist-watch sensor reliably detected AF in non-ambulatory patients.

Long-term flecainide therapy in type 3 long QT syndrome.

Aims: Type 3 long QT syndrome (LQT3) is caused by gain-of-function mutations in the cardiac sodium channel gene (SCN5A). Previous reports on the long-term use of sodium channel blockers in LQT3 are sparse. The objective of the current study was to evaluate the long-term safety and efficacy of flecainide therapy in patients with LQT3 who carry the D1790G SCN5A mutation. Methods and results: The study population comprised 30 D1790G carriers who were treated with flecainide and followed for 1-215 months (mean 145 ± 54 months, median 140 months). The mean baseline (off-drug) QTc was 522 ± 45 ms, and shortened to 469 ± 36 ms with flecainide therapy, a mean decrease of 53 ms [10.1%] (P < 0.01). A QTc longer than 500 ms was evident in 53% of carriers at baseline, and only in 13% on flecainide. All carriers while being compliant with flecainide therapy had no cardiac events during an average follow up of 83 ± 73 months. Twenty carriers stopped flecainide after an average follow up of 40 ± 42 months without symptoms. Six of them (30%) had cardiac events 1-11 months after stopping flecainide. Flecainide induced the appearance of Brugada pattern in six carriers (20%, 5 males), was stopped in three and was not associated with arrhythmia. Sinus-node dysfunction was evident in six carriers (20%) and was fully corrected by flecainide in three. Conclusions: These data suggest that long-term flecainide therapy is relatively safe and effective among LQT3 patients who carry the D1790G SCN5A mutation.

Sex-based differences in prevalence and clinical presentation among pericarditis and myopericarditis patients.

BACKGROUND: Sex differences in heart diseases, including acute coronary syndrome, congestive heart failure, and atrial fibrillation, have been studied extensively. However, data are lacking regarding sex differences in pericarditis and myopericarditis patients. OBJECTIVES: The purpose of the study was to evaluate whether there are sex differences in pericarditis and myopericarditis patients as well. METHODS: We performed a retrospective, single-center observational study that included 200 consecutive patients hospitalized with idiopathic pericarditis or myopericarditis from January 2012 to April 2014. Patients were evaluated for sex differences in prevalence, clinical presentation, laboratory variables, and outcome. We excluded patients with a known cause for pericarditis. RESULTS: Among 200 consecutive patients, 55 (27%) were female. Compared with men, women were significantly older (60±19 years vs 46±19 years, P<.001) and had a higher rate of chronic medical conditions. Myopericarditis was significantly more common among men (51% vs 25%, P=.001). Accordingly, men had significantly higher levels of peak troponin (6.8±17 ng/mL vs 0.9±2.6 ng/mL, P<.001), whereas women presented more frequently with pericardial effusion (68% vs 45%, P=.006). Interestingly, women had a significantly lower rate of hospitalization in the cardiology department (42% vs 63%, P=.015). Overall, there were no significant differences in ejection fraction, type of treatment, complications, or in-hospital mortality. CONCLUSIONS: Most patients admitted with acute idiopathic pericarditis are male. In addition, men have a higher prevalence of myocardial involvement. Significant sex differences exist in laboratory variables and in hospital management; however, the outcome is similar and favorable in both sexes.

Radiofrequency Ablation of Atrial Fibrillation: Nonrandomized Comparison of Circular versus Point-by-Point "Smart" Ablation for Achieving Circumferential Pulmonary Vein Isolation and Curing Arrhythmic Symptoms.

INTRODUCTION: Pulmonary vein isolation (PVI) with radiofrequency (RF) ablation is now standard care for atrial fibrillation (AF). New improvements in PVI techniques include use of catheters that measure contact-force and circular ablation catheters. These techniques have not been compared. METHODS AND RESULTS: We compared the success rate of circumferential pulmonary vein isolation (CPVI) with: (1) "point by point" RF using an irrigated tip ablation catheter with "smart touch" contact-force; (2) irrigated nMARQ circular ablation catheter in 86 patients with AF. The endpoints of the study were acute and long-term success rate of CPVI. The 2 groups had similar characteristics: Smart Touch group with 50 patients, age 62 ± 8 years, 64% male; nMARQ group with 36 patients, 75% male, age 58.7 ± 10 years. The type of AF was similar in the 2 groups: paroxysmal and persistent in 68% and 32% in the Navistar group versus 64% and 36% in the nMARQ group. Follow-up periods were similar (18.4 months vs. 19 months, P = 0.59). All the pulmonary veins were successfully isolated in both groups. However, PVI could not be achieved with the nMARQ in 2.7% of the pulmonary veins ablated and was completed with a Smart Touch. The long-term success rate was comparable in the 2 groups. CONCLUSION: The nMARQ and Smart Touch catheters give similar results in PVI of both paroxysmal and persistent AF. The procedural time was shorter with the nMARQ in paroxysmal AF. Need for crossover from nMARQ to Smart Touch occurred in 2.7% of PVs ablated.

Atopic Predilection among Kawasaki Disease Patients: A Cross-Sectional Study of 1,187,757 Teenagers.

BACKGROUND: Kawasaki disease (KD) is an acute, systemic vasculitis in children, with an etiology that is not completely understood. It is assumed that the development of KD is mediated by an immunologic response. Several reports from East Asia have found a higher prevalence of atopic diseases among patients with KD, but a large-scale study of a non-Asian population regarding this correlation is still lacking. The purpose of this article was to achieve this goal. METHODS: We conducted a cross-sectional, large-scale study to estimate the correlation of KD with allergic diseases. The medical history of 1,187,757 Israeli teenagers (aged 16-20 years during the years 1998-2013) was retrieved. The study population was divided into 3 groups according to a past history of noncomplicated and complicated KD and a control group. The prevalence of allergic diseases among these groups was further investigated. RESULTS: The prevalence of atopic diseases in the 3 study groups was presented (asthma in 11.4, 8.1 and 3.5%, respectively; angioedema/urticaria in 7.1, 0 and 0.46%, respectively; allergic rhinitis in 20, 12.1 and 6.7%, respectively). In noncomplicated KD, a statistically significant link to asthma [odds ratio (OR) 2.4; p = 0.048] and a borderline significant link to allergic rhinitis (OR 1.9; p = 0.06) were found. In KD complicated with cardiac disease, statistically significant links were found for all the allergic conditions, asthma (OR 3.5; p = 0.003), allergic rhinitis (OR 3.5; p < 0.001) and angioedema/urticaria (OR 16.48; p < 0.001). CONCLUSION: KD is associated with allergic diseases. This association increases with the severity of the disease.

Peripheral blood mononuclear cells of HIV-infected patients contain CD8 T cells that form conjugates with and kill HIV-infected autologous CD4 T cells.

Peripheral blood mononuclear cells (PBMC) of untreated, HIV-infected patients contain HIV-specific CD8 T cells as well as their corresponding targets, HIV-infected CD4 T cells. To determine if CD4 T-cell depletion in HIV-infected patients may result from autologous CD8-CD4 T-cell interaction, CD8 and CD4 T cells procured from PBMC of acute and chronic untreated HIV-infected patients were sorted and co-incubated. Formation of CD8-CD4 T-cell conjugates was observed by fluorescence microscopy. Apoptosis of CD4 T cells in conjugation was recorded by digitized images and was further observed and measured by FACS using Annexin staining. Perforin expression in the CD8 T cells was measured using intracellular monoclonal perforin antibody staining. HIV DNA in the conjugated CD4 T cells was detected by in situ PCR. We found that 6·1 ± 0·5% of CD4 T cells from acute HIV-infected patients and 3·0 ± 0·5% from chronic HIV-infected patients formed CD8-CD4 T-cell conjugates. Annexin binding and cell morphology typical of apoptosis were observed in the conjugated CD4 T cells. The majority of CD8 T cells that had conjugated to CD4 T cells expressed perforin. The conjugated CD4 T cells exhibited nuclear HIV DNA. CD8 T cells and HIV-infected CD4 T cells, both procured from the PBMC of untreated HIV-infected patients, form conjugates. Apoptotic lytic activity has been observed in the conjugated CD4 T cells. We propose that CD4 T-cell annihilation in HIV-infected patients results, at least in part, from the interactions of perforin-rich CD8 T cells with autologous, HIV-infected CD4 T cells.

Electromechanical Window and Spontaneous Ventricular Tachyarrhythmias in Takotsubo Syndrome.

QT interval prolongation is common in patients hospitalized with Takotsubo syndrome (TTS), however, only a minority experience ventricular tachyarrhythmias. Our aim was to characterize the electromechanical window (EMW) in patients with TTS and to evaluate its association with ventricular tachyarrhythmias. We preformed aretrospective analysis of 84 patients hospitalized with TTS in the Tel-Aviv Medical Center between 2013 and 2022. All patients underwent a comprehensive echocardiographic evaluation and the EMW was calculated by subtracting the QT interval from the QRS onset to the aortic valve closure obtained from a continuous-wave Doppler for the same beat. Of the 84 patients with TTS, 74 (88%) were female and the mean age was 70 ± 11 years. The mean left ventricular ejection fraction was 42 ± 8%. The EMW was negative in 81 patients (96%), and the mean EMW was -69 ± 50 ms. Ventricular tachyarrhythmias occurred in 7 patients (8%). The EMW of patients who experienced ventricular tachyarrhythmias was more negative than patients who did not (-133 ± 23 ms vs -63 ± 48 ms, p = 0.001). In the univariate analysis, EMW and QT were associated with ventricular tachyarrhythmias (univariate odds ratio [OR]EMW 1.03, 95% confidence interval [CI] 1.01 to 1.05, p = 0.003 and univariate ORQTc 1.02, 95% CI 1.01 to 1.03, p = 0.02); however, only EMW remained significant in the multivariate analysis (OREMW 1.03 95% CI 1.03 to 1.05, p = 0.023). EMW was more effective than corrected QT interval in identifying patients who had ventricular tachyarrhythmias (AUCEMW: 0.89, 95% CI 0.82 to 0.97 vs AUCQTc 0.77, 95% CI 0.61 to 0.93, p = 0.02), and a cut-off value of -108 ms was predictive of ventricular tachyarrhythmias with a sensitivity of 86% and a specificity of 79%. In conclusion, EMW is negative in patients with TTS and is associated with increased risk for ventricular tachyarrhythmias. The role of EMW in the risk stratification of patients with TTS warrants further investigation.

Safety of Sports for Patients with Subcutaneous Implantable Cardioverter Defibrillator (SPORT S-ICD): study rationale and protocol.

Background: Recent studies suggest that participation in recreational and even competitive sports is generally safe for patients with implantable cardioverter-defibrillators (ICDs). However, these studies included only patients with implanted transvenous ICD (TV-ICD). Nowadays, subcutaneous ICD (S-ICD) is a safe and effective alternative and is increasingly implanted in younger ICD candidates. Data on the safety of sport participation for patients with implanted S-ICD systems is urgently needed. Objectives: The goal of the study is to quantify the risks (or determine the safety) of sports participation for athletes with an S-ICD, which will guide shared decision making for athletes requiring an ICD and/or wishing to return to sports after implantation. Methods: The SPORT S-ICD (Sports for Patients with Subcutaneous Implantable Cardioverter Defibrillator) study is an international, multicenter, prospective, noninterventional, observational study, designed specifically to collect data on the safety of sports participation among patients with implanted S-ICD systems who regularly engage in sports activities. Results: A total of 450 patients will undergo baseline assessment including baseline characteristics, indication for S-ICD implantation, arrhythmic history, S-ICD data and programming, and data regarding sports activities. LATITUDE Home Monitoring information will be regularly transferred to the study coordinator for analysis. Conclusion: The results of the study will aid in shaping clinical decision making, and if the tested hypothesis will be proven, it will allow the safe continuation of sports for patients with an implanted S-ICD.