Cardiac implantable electronic devices and bloodstream infections: management and outcomes.

BACKGROUND AND AIMS: Bloodstream infection (BSI) of any cause may lead to device infection in cardiac implantable electronic device (CIED) patients. Aiming for a better understanding of the diagnostic approach, treatment, and outcome, patients with an implantable cardioverter defibrillator (ICD) and cardiac resynchronization therapy and defibrillator (CRT-D) hospitalized with BSI were investigated. METHODS: This is a single-centre, retrospective, cohort analysis including consecutive ICD/CRT-D patients implanted between 2012 and 2021. These patients were screened against a list of all hospitalized patients having positive blood cultures consistent with diagnosed infection in any department of a local public hospital. RESULTS: The total cohort consisted of 515 patients. Over a median follow-up of 59 months (interquartile range 31-87 months), there were 47 BSI episodes in 36 patients. The majority of patients with BSI (92%) was admitted to non-cardiology units, and in 25 episodes (53%), no cardiac imaging was performed. Nearly all patients (85%) were treated with short-term antibiotics, whereas chronic antibiotic suppression therapy (n = 4) and system extraction (n = 3) were less frequent. Patients with BSI had a nearly seven-fold higher rate (hazard ratio 6.7, 95% confidence interval 3.9-11.2; P < .001) of all-cause mortality. CONCLUSIONS: Diagnostic workup of defibrillator patients with BSI admitted to a non-cardiology unit is often insufficient to characterize lead-related endocarditis. The high mortality rate in these patients with BSI may relate to underdiagnosis and consequently late/absence of system removal. Efforts to increase an interdisciplinary approach and greater use of cardiac imaging are necessary for timely diagnosis and adequate treatment.

Fewer Worsening Heart Failure Events With HeartLogic on top of Standard Care: a Propensity-Matched Cohort Analysis.

BACKGROUND: The implantable cardiac defibrillator-based HeartLogic algorithm aims to detect impending fluid retention in patients with heart failure (HF). Studies show that HeartLogic is safe to integrate into clinical practice. The current study investigates whether HeartLogic provides clinical benefit on top of standard care and device telemonitoring in patients with HF. METHODS: A multicenter, retrospective, propensity-matched cohort analysis was performed in patients with HF and implantable cardiac defibrillators, and it compared HeartLogic to conventional telemonitoring. The primary endpoint was the number of worsening HF events. Hospitalizations and ambulatory visits due to HF were also evaluated. RESULTS: Propensity score matching yielded 127 pairs (median age 68 years, 80% male). Worsening HF events occurred more frequently in the control group (2; IQR 0-4) compared to the HeartLogic group (1; IQR 0-3; P = 0.004). The number of HF hospitalization days was higher in controls than in the HeartLogic group (8; IQR 5-12 vs 5; IQR 2-7; P = 0.023), and ambulatory visits for diuretic escalation were more frequent in the control group than in the HeartLogic group (2; IQR 0-3 vs 1; IQR 0-2; P = 0.0001). CONCLUSION: Integrating the HeartLogic algorithm in a well-equipped HF care path on top of standard care is associated with fewer worsening HF events and shorter duration of fluid retention-related hospitalizations.

Electromechanical factors associated with favourable outcome in cardiac resynchronization therapy.

AIMS: Electromechanical coupling in patients receiving cardiac resynchronization therapy (CRT) is not fully understood. Our aim was to determine the best combination of electrical and mechanical substrates associated with effective CRT. METHODS AND RESULTS: Sixty-two patients were prospectively enrolled from two centres. Patients underwent 12-lead electrocardiogram (ECG), cardiovascular magnetic resonance (CMR), echocardiography, and anatomo-electromechanical mapping (AEMM). Remodelling was measured as the end-systolic volume (ΔESV) decrease at 6 months. CRT was defined effective with ΔESV ≤ -15%. QRS duration (QRSd) was measured from ECG. Area strain was obtained from AEMM and used to derive systolic stretch index (SSI) and total left-ventricular mechanical time. Total left-ventricular activation time (TLVAT) and transeptal time (TST) were derived from AEMM and ECG. Scar was measured from CMR. Significant correlations were observed between ΔESV and TST [rho = 0.42; responder: 50 (20-58) vs. non-responder: 33 (8-44) ms], TLVAT [-0.68; 81 (73-97) vs. 112 (96-127) ms], scar [-0.27; 0.0 (0.0-1.2) vs. 8.7 (0.0-19.1)%], and SSI [0.41; 10.7 (7.1-16.8) vs. 4.2 (2.9-5.5)], but not QRSd [-0.13; 155 (140-176) vs. 167 (155-177) ms]. TLVAT and SSI were highly accurate in identifying CRT response [area under the curve (AUC) > 0.80], followed by scar (AUC > 0.70). Total left-ventricular activation time (odds ratio = 0.91), scar (0.94), and SSI (1.29) were independent factors associated with effective CRT. Subjects with SSI >7.9% and TLVAT <91 ms all responded to CRT with a median ΔESV ≈ -50%, while low SSI and prolonged TLVAT were more common in non-responders (ΔESV ≈ -5%). CONCLUSION: Electromechanical measurements are better associated with CRT response than conventional ECG variables. The absence of scar combined with high SSI and low TLVAT ensures effectiveness of CRT.

Role of genetic testing in young patients with idiopathic atrioventricular conduction disease.

AIMS: To investigate the role of genetic testing in patients with idiopathic atrioventricular conduction disease requiring pacemaker (PM) implantation before the age of 50 years. METHODS AND RESULTS: All consecutive PM implantations in Southern Switzerland between 2010 and 2019 were evaluated. Inclusion criteria were: (i) age at the time of PM implantation: < 50 years; (ii) atrioventricular block (AVB) of unknown aetiology. Study population was investigated by ajmaline challenge and echocardiographic assessment over time. Genetic testing was performed using next-generation sequencing panel, containing 174 genes associated to inherited cardiac diseases, and Sanger sequencing confirmation of suspected variants with clinical implication. Of 2510 patients who underwent PM implantation, 15 (0.6%) were young adults (median age: 44 years, male predominance) presenting with advanced AVB of unknown origin. The average incidence of idiopathic AVB computed over the 2010-2019 time window was 0.7 per 100 000 persons per year (95% CI 0.4-1.2). Most of patients (67%) presented with specific genetic findings (pathogenic variant) or variants of uncertain significance (VUS). A pathogenic variant of PKP2 gene was found in one patient (6.7%) with no overt structural cardiac abnormalities. A VUS of TRPM4, MYBPC3, SCN5A, KCNE1, LMNA, GJA5 genes was found in other nine cases (60%). Of these, three unrelated patients (20%) presented the same heterozygous missense variant c.2531G > A p.(Gly844Asp) in TRPM4 gene. Diagnostic re-assessment over time led to a diagnosis of Brugada syndrome and long-QT syndrome in two patients (13%). No cardiac events occurred during a median follow-up of 72 months. CONCLUSION: Idiopathic AVB in adults younger than 50 years is a very rare condition with an incidence of 0.7 per 100 000 persons/year. Systematic investigations, including genetic testing and ajmaline challenge, can lead to the achievement of a specific diagnosis in up to 20% of patients. Heterozygous missense variant c.2531G > A p.(Gly844Asp) in TRPM4 gene was found in an additional 20% of unrelated patients, suggesting possible association of the variant with the disease.

Impact of SMART Pass filter in patients with ajmaline-induced Brugada syndrome and subcutaneous implantable cardioverter-defibrillator eligibility failure: results from a prospective multicentre study.

AIMS: Ajmaline challenge can unmask subcutaneous implantable cardioverter-defibrillator (S-ICD) screening failure in patients with Brugada syndrome (BrS) and non-diagnostic baseline electrocardiogram (ECG). The efficacy of the SMART Pass (SP) filter, a high-pass filter designed to reduce cardiac oversensing (while maintaining an appropriate sensing margin), has not yet been assessed in patients with BrS. The aim of this prospective multicentre study was to investigate the effect of the SP filter on dynamic Brugada ECG changes evoked by ajmaline and to assess its value in reducing S-ICD screening failure in patients with drug-induced Brugada ECGs. METHODS AND RESULTS: The S-ICD screening with conventional automated screening tool (AST) was performed during ajmaline challenge in subjects with suspected BrS. The S-ICD recordings were obtained before, during and after ajmaline administration and evaluated by the means of a simulation model that emulates the AST behaviour with and without SP filter. A patient was considered suitable for S-ICD if at least one sensing vector was acceptable in all tested postures. A sensing vector was considered acceptable in the presence of QRS amplitude >0.5 mV, QRS/T-wave ratio >3.5, and sense vector score >100. Of the 126 subjects (mean age: 42 ± 14 years, males: 61%, sensing vectors: 6786), 46 (36%) presented with an ajmaline-induced Brugada type 1 ECG. Up to 30% of subjects and 40% of vectors failed the screening during the appearance of Brugada type 1 ECG evoked by ajmaline. The S-ICD screening failure rate was not significantly reduced in patients with Brugada ECGs when SP filter was enabled (30% vs. 24%). Similarly, there was only a trend in reduction of vector-failure rate attributable to the SP filter (from 40% to 36%). The most frequent reason for screening failure was low QRS amplitude or low QRS/T-wave ratio. None of these patients was implanted with an S-ICD. CONCLUSION: Patients who pass the sensing screening during ajmaline can be considered good candidates for S-ICD implantation, while those who fail might be susceptible to sensing issues. Although there was a trend towards reduction of vector sensing failure rate when SP filter was enabled, the reduction in S-ICD screening failure in patients with Brugada ECGs did not reach statistical significance. CLINICAL TRIAL REGISTRATION: https://clinicaltrials.gov Unique Identifier NCT04504591.

Reconstruction of three-dimensional biventricular activation based on the 12-lead electrocardiogram via patient-specific modelling.

AIMS: Non-invasive imaging of electrical activation requires high-density body surface potential mapping. The nine electrodes of the 12-lead electrocardiogram (ECG) are insufficient for a reliable reconstruction with standard inverse methods. Patient-specific modelling may offer an alternative route to physiologically constraint the reconstruction. The aim of the study was to assess the feasibility of reconstructing the fully 3D electrical activation map of the ventricles from the 12-lead ECG and cardiovascular magnetic resonance (CMR). METHODS AND RESULTS: Ventricular activation was estimated by iteratively optimizing the parameters (conduction velocity and sites of earliest activation) of a patient-specific model to fit the simulated to the recorded ECG. Chest and cardiac anatomy of 11 patients (QRS duration 126-180 ms, documented scar in two) were segmented from CMR images. Scar presence was assessed by magnetic resonance (MR) contrast enhancement. Activation sequences were modelled with a physiologically based propagation model and ECGs with lead field theory. Validation was performed by comparing reconstructed activation maps with those acquired by invasive electroanatomical mapping of coronary sinus/veins (CS) and right ventricular (RV) and left ventricular (LV) endocardium. The QRS complex was correctly reproduced by the model (Pearson's correlation r = 0.923). Reconstructions accurately located the earliest and latest activated LV regions (median barycentre distance 8.2 mm, IQR 8.8 mm). Correlation of simulated with recorded activation time was very good at LV endocardium (r = 0.83) and good at CS (r = 0.68) and RV endocardium (r = 0.58). CONCLUSION: Non-invasive assessment of biventricular 3D activation using the 12-lead ECG and MR imaging is feasible. Potential applications include patient-specific modelling and pre-/per-procedural evaluation of ventricular activation.

Long-term outcome of catheter ablation for atrial fibrillation in patients with severe left atrial enlargement and reduced left ventricular ejection fraction.

AIMS: Data regarding the efficacy of catheter ablation in heart failure patients with severely dilated left atrium and reduced left ventricular ejection fraction (LVEF) are scanty. We sought to assess the efficacy of catheter ablation in patients with reduced LVEF and severe left atrial (LA) enlargement, and to compare it to those patients with preserved left ventricular function and equally dilated left atrium. METHODS AND RESULTS: Three patient groups with paroxysmal or persistent atrial fibrillation (AF) undergoing a first pulmonary vein isolation (PVI) were considered: Group 1 included patients with normal or mildly abnormal LA volume (≤41 mL/m2) and normal LVEF; Group 2 included patients with severe LA enlargement (>48 mL/m2) and normal LVEF; and Group 3 included patients with severe LA enlargement and reduced LVEF. Time to event analysis was used to investigate AF recurrences. The study cohort includes 439 patients; Group 3 had a higher prevalence of cardiovascular risk factors. LA enlargement was associated with a two-fold in risk of AF recurrence, on the contrary only a smaller non-significant increase of 30% was shown with the further addition of LVEF reduction. CONCLUSIONS: The long-term outcome of patients with severe LA dilatation and reduced LVEF is comparable to those with severe LA enlargement but preserved LVEF. Long-term efficacy of PVI is certainly affected by the enlargement of the left atrium, but less so by the addition of a reduced LVEF. CA remains the best strategy for rhythm control both in paroxysmal and persistent AF in this subgroup of patients.

High-density mapping in patients undergoing ablation of atrial fibrillation with the fourth-generation cryoballoon and the new spiral mapping catheter.

AIMS: To assess the value of high-density mapping (HDM) in revealing undetected incomplete pulmonary vein isolation (PVI) after the fourth-generation cryoballoon (CB4G) ablation compared to the previous cryoballoon's versions. METHODS AND RESULTS: Consecutive patients with paroxysmal or early-persistent atrial fibrillation (AF) undergoing CB ablation as the index procedure, assisted by HDM, were retrospectively included in this study. A total of 68 patients (52 males; mean age: 60 ± 12 years, 58 paroxysmal AF) were included, and a total of 272 veins were mapped. Fourth-generation cryoballoon with the new spiral mapping catheter (SMC) was used in 35 patients (51%). Time to PVI was determined in 102/132 (77%) and in 112/140 (80%) veins during second-generation cryoballoon/third-generation cryoballoon (CB2G/CB3G) and CB4G ablation, respectively (P = 0.66). There was a statistically significant difference in terms of discrepancy rate between the SMC and the mini-basket catheter in PV detection after CB4G and CB2G/CB3G ablation(1.4% vs. 7.6%; P = 0.01). A total of 57 patients (84%) remained free of symptomatic AF during a mean follow-up of 9.8 ± 4.6 months. CONCLUSION: High-density mapping after cryoballoon ablation using CB4G and the new SMC identifies incomplete PVI, not detected by the new SMC, in a significantly lower proportion of veins compared to HDM performed after the other generation CB ablation.

The influence of scar on the spatio-temporal relationship between electrical and mechanical activation in heart failure patients.

AIMS: The aim of this study was to determine the relationship between electrical and mechanical activation in heart failure (HF) patients and whether electromechanical coupling is affected by scar. METHODS AND RESULTS: Seventy HF patients referred for cardiac resynchronization therapy or biological therapy underwent endocardial anatomo-electromechanical mapping (AEMM) and delayed-enhancement magnetic resonance (CMR) scans. Area strain and activation times were derived from AEMM data, allowing to correlate mechanical and electrical activation in time and space with unprecedented accuracy. Special attention was paid to the effect of presence of CMR-evidenced scar. Patients were divided into a scar (n = 43) and a non-scar group (n-27). Correlation between time of electrical and mechanical activation was stronger in the non-scar compared to the scar group [R = 0.84 (0.72-0.89) vs. 0.74 (0.52-0.88), respectively; P = 0.01]. The overlap between latest electrical and mechanical activation areas was larger in the absence than in presence of scar [72% (54-81) vs. 56% (36-73), respectively; P = 0.02], with smaller distance between the centroids of the two regions [10.7 (4.9-17.4) vs. 20.3 (6.9-29.4) % of left ventricular radius, P = 0.02]. CONCLUSION: Scar decreases the association between electrical and mechanical activation, even when scar is remote from late activated regions.

A Bayesian spatiotemporal statistical analysis of out-of-hospital cardiac arrests.

We propose a Bayesian spatiotemporal statistical model for predicting out-of-hospital cardiac arrests (OHCAs). Risk maps for Ticino, adjusted for demographic covariates, are built for explaining and forecasting the spatial distribution of OHCAs and their temporal dynamics. The occurrence intensity of the OHCA event in each area of interest, and the cardiac risk-based clustering of municipalities are efficiently estimated, through a statistical model that decomposes OHCA intensity into overall intensity, demographic fixed effects, spatially structured and unstructured random effects, time polynomial dependence, and spatiotemporal random effect. In the studied geography, time evolution and dependence on demographic features are robust over different categories of OHCAs, but with variability in their spatial and spatiotemporal structure. Two main OHCA incidence-based clusters of municipalities are identified.

Out-of-hospital cardiac arrest due to idiopathic ventricular fibrillation in patients with normal electrocardiograms: results from a multicentre long-term registry.

AIMS: To define the clinical characteristics and long-term clinical outcomes of a large cohort of patients with idiopathic ventricular fibrillation (IVF) and normal 12-lead electrocardiograms (ECGs). METHODS AND RESULTS: Patients with ventricular fibrillation as the presenting rhythm, normal baseline, and follow-up ECGs with no signs of cardiac channelopathy including early repolarization or atrioventricular conduction abnormalities, and without structural heart disease were included in a registry. A total of 245 patients (median age: 38 years; males 59%) were recruited from 25 centres. An implantable cardioverter-defibrillator (ICD) was implanted in 226 patients (92%), while 18 patients (8%) were treated with drug therapy only. Over a median follow-up of 63 months (interquartile range: 25-110 months), 12 patients died (5%); in four of them (1.6%) the lethal event was of cardiac origin. Patients treated with antiarrhythmic drugs only had a higher rate of cardiovascular death compared to patients who received an ICD (16% vs. 0.4%, P = 0.001). Fifty-two patients (21%) experienced an arrhythmic recurrence. Age ≤16 years at the time of the first ventricular arrhythmia was the only predictor of arrhythmic recurrence on multivariable analysis [hazard ratio (HR) 0.41, 95% confidence interval (CI) 0.18-0.92; P = 0.03]. CONCLUSION: Patients with IVF and persistently normal ECGs frequently have arrhythmic recurrences, but a good prognosis when treated with an ICD. Children are a category of IVF patients at higher risk of arrhythmic recurrences.

New onset of phrenic nerve palsy after laser-assisted transvenous lead extraction: a single-centre experience.

Aims: Phrenic nerve palsy (PNP) after mechanical transvenous lead extraction (TLE) was recently described for the first time. We aimed to analyse our TLE database for the presence of PNP. Methods and results: All consecutive patients referred to our institution were included in this study. Every available post-procedural chest X-ray was compared to the routinely performed pre-procedural radiographs. A newly elevated hemidiaphragm ipsilateral to TLE was considered indicative of PNP. Altogether 255 TLE procedures with extraction of 364 leads were performed. Most common TLE indication was lead malfunction (63%). Complete radiographic success rate was 97.3% with an in-hospital procedure-related major complication rate of 2.4%, including one intra-procedural death (0.4%). We identified five cases with PNP (2%), all occurring after laser-assisted TLE. Clinical presentation varied from subtle and aspecific chest pain/discomfort to severe and acute dyspnoea, with time to diagnosis varying from immediate to several weeks after the procedure. In 80% of cases, the explanted lead was a defibrillator electrode and the median lead dwelling time was 70.2 months (29.3; 1084.9). In four cases, the extraction was performed using high-energy laser (pulse repetition rate 80 Hz). Conclusion: The present study reports the incidence of PNP after laser-assisted TLE. We postulate that the thermal energy generated by laser is not dissipated quickly enough in occluded or heavily calcified lesions, injuring the ipsilateral phrenic nerve. Our findings advise to carefully consider to increase pulse repetition rate at the subclavian level. Larger, possibly prospective studies are needed to evaluate the real incidence through systematic radiological assessment after TLE.

Beat-to-beat P-wave morphological variability in patients with paroxysmal atrial fibrillation: an in silico study.

AIMS: P-wave beat-to-beat morphological variability can identify patients prone to paroxysmal atrial fibrillation (AF). To date, no computational study has been carried out to mechanistically explain such finding. The aim of this study was to provide a pathophysiological explanation, by using a computer model of the human atria, of the correlation between P-wave beat-to-beat variability and the risk of AF. METHODS AND RESULTS: A physiological variability in the earliest activation site (EAS), on a beat-to-beat basis, was introduced into a computer model of the human atria by randomizing the EAS location. A methodology for generating multi-scale, spatially-correlated regions of heterogeneous conduction was developed. P-wave variability in the presence of such regions was compared with a control case. Simulations were performed with an eikonal model, for the activation map, and with the lead field approach, for P-wave computation. The methodology was eventually compared with a reference monodomain simulation. A total of 60 P-waves were simulated for each sinus node exit location (12 in total), and for each of the 15 patterns of heterogeneous conduction automatically generated by the model. A P-wave beat-to-beat variability was observed in all cases. Variability was significantly increased in presence of heterogeneous slow conducting regions, up to two-fold the variability in the control case. P-wave variability increased non-linearly with respect to the EAS variability and total area of slow conduction. Distribution of the heterogeneous conduction was more effective in increasing the variability when it surrounded the EAS locations and the fast conducting bundles. P-waves simulated by the eikonal approach compared excellently with the monodomain-based ones. CONCLUSION: P-wave variability in patients with paroxysmal AF could be explained by a variability in sinoatrial node exit location in combination with slow conducting regions.

High rate of subcutaneous implantable cardioverter-defibrillator sensing screening failure in patients with Brugada syndrome: a comparison with other inherited primary arrhythmia syndromes.

Aims: Subcutaneous implantable cardioverter-defibrillator (S-ICD) can avoid important complications associated with transvenous leads in patients with inherited primary arrhythmia syndromes, who do not need pacing therapy. Few data are available on the percentage of patients with inherited arrhythmia syndromes eligible for S-ICD implantation. Aim of this study was to analyse the eligibility for S-ICD in a series of patients with Brugada syndrome (BrS), and to compare it with patients with other channelopathies. Methods and results: Patients presenting with BrS, long-QT syndrome (LQTS), early repolarization syndrome (ERS), and idiopathic ventricular fibrillation (IVF) were considered eligible for this study. ECG screening was performed by analysis of QRS complex and T wave morphology recorded in standing and supine position. Eligibility was defined when ≥1 sense vector was acceptable in both supine and standing position. A total of 100 patients (72 males; mean age: 46 ± 17 years) underwent S-ICD sensing screening. Sixty-one patients presented with BrS, 21 with LQTS, 14 with IVF, and 4 with ERS. Thirty-four patients with BrS (56%) presented with spontaneous type 1 ECG. In the other 27 patients (44%), type 1 ECG was unmasked by ajmaline. Overall, rate of screening failure was 13%. Patients with BrS had a higher rate of inappropriate morphology analysis as compared with other channelopathies (18% vs. 5%, P = 0.07) and had a lower number of suitable sensing vectors (49.6% vs. 84.7% vs. P < 0.001). Ajmaline challenge unmasked sensing failure in 14.8% of drug-induced BrS patients previously considered eligible. In all patients, the reason for sensing inappropriateness was due to the presence of high T wave voltages. Conclusion: S-ICD screening failure occurs in up to 13% of patients with inherited primary arrhythmia syndromes. Patients with BrS present a higher rate of screening failure as compared with other cardiac channelopathies.

A left bundle branch block activation sequence and ventricular pacing influence voltage amplitudes: an in vivo and in silico study.

AIMS: The aim of this study was to investigate the influence of the activation sequence on voltage amplitudes by evaluating regional voltage differences during a left bundle branch block (LBBB) activation sequence vs. a normal synchronous activation sequence and by evaluating pacing-induced voltage differences. METHODS AND RESULTS: Twenty-one patients and three computer models without scar were studied. Regional voltage amplitudes were evaluated in nine LBBB patients who underwent endocardial electro-anatomic mapping (EAM). Pacing-induced voltage differences were evaluated in 12 patients who underwent epicardial EAM during intrinsic rhythm and right ventricular (RV) pacing. Three computer models customized for LBBB patients were created. Changes in voltage amplitudes after an LBBB (intrinsic), a normal synchronous, an RV pacing, and a left ventricular pacing activation sequence were assessed in the computer models. Unipolar voltage amplitudes in patients were approximately 4.5 mV (4.4-4.7 mV, ∼33%) lower in the septum when compared with other segments. A normal synchronous activation sequence in the computer models normalized voltage amplitudes in the septum. Pacing-induced differences were larger in electrograms with higher voltage amplitudes during intrinsic rhythm and furthermore larger and more variable at the epicardium [mean absolute difference: 3.6-6.2 mV, 40-53% of intrinsic value; interquartile range (IQR) differences: 53-63% of intrinsic value] compared to the endocardium (mean absolute difference: 3.3-3.8 mV, 28-30% of intrinsic value; IQR differences: 37-40% of intrinsic value). CONCLUSION: In patients and computer models without scar, lower septal unipolar voltage amplitudes are exclusively associated with an LBBB activation sequence. Pacing substantially affects voltage amplitudes, particularly at the epicardium.

True idiopathic ventricular fibrillation in out-of-hospital cardiac arrest survivors in the Swiss Canton Ticino: prevalence, clinical features, and long-term follow-up.

Aims: Out-of-hospital cardiac arrest (OHCA) in the absence of evident structural heart disease is rare and can be due to subclinical cardiomyopathy and primary electrical disorders, including idiopathic ventricular fibrillation (IVF) with early repolarization (ER) pattern. Aim of this study was to investigate prevalence, clinical features, and long-term prognosis of IVF in OHCA survivors with otherwise normal 12-lead electrocardiograms (ECGs). Methods and Results: Patients with IVF in the absence of ER pattern or atrioventricular conduction abnormalities were considered eligible for this study. A total of 3407 OHCAs occurred in our region from 2000 to 2014. Out-of-hospital cardiac arrests of presumed cardiac origin were 2192; of them, 644 presented with a ventricular arrhythmia (VT/VF) as first shockable rhythm. Among them, a total of 74 implantable cardioverter-defibrillators were implanted for secondary prevention. Ventricular arrhythmia was considered idiopathic in 11 (15%) of these patients. Over a mean follow-up time of 85 ± 47 months (median: 42 months), ECG was found abnormal in three cases. In the remaining eight patients (6 males; median age: 45 years), no ECG or structural abnormalities were detected during the follow-up. Prevalence of IVF in OHCA survivors with first-shockable rhythm was 1.2%. During the long-term follow-up, no patient died or experienced ICD interventions. No new echocardiographic abnormal findings were revealed. Conclusion: Idiopathic ventricular fibrillation is rare occurring in 1.2% of OHCA survivors presenting with a shockable rhythm. The initial diagnosis can change in up to 27% of cases. Patients with IVF and no ER pattern or AV conduction disturbances have a good prognosis during a long-term follow-up.

Changes in P-wave morphology after pulmonary vein isolation: insights from computer simulations.

AIMS: Apparently conflicting clinical measurements of P-wave duration (PWD) pre- vs. post-ablation have been reported. To assist the interpretation of these clinical data, we used a computer model of the atria and torso to simulate P waves before and after pulmonary vein (PV) isolation. METHODS AND RESULTS: Twenty ablation patterns were designed (segmental or ipsilateral ablation; five distances to PV sleeves; addition of a roof line or not). Possible PV reconnections were introduced as gaps in the ablation lines. PWD and area were measured during sinus rhythm in vectorcardiogram (VCG) magnitude signals and on the 16-lead ECG before and after ablation, and after PV reconnection. After PV isolation, biatrial activation time was prolonged by 0-5 ms without and by 48±5 ms with roof line. Yet PWD was shortened in lead V3 and V4 by up to 15 ms. The effect of ablation on P-wave morphology was stronger when larger PV areas were isolated. Segmental and ipsilateral PV isolation led to concordant results. P-wave area increased in V1 and decreased in V6. Changes in PWD and area on the VCG were sensitive to the threshold used for detecting the end of the P wave. The occurrence of PV reconnection was best identified on leads V3, V4, and V9. CONCLUSION: PV isolation and reconnection induced measurable changes on the 16-lead ECG that might be used to improve patient follow-up after ablation.

Better management of out-of-hospital cardiac arrest increases survival rate and improves neurological outcome in the Swiss Canton Ticino.

AIM: To determine the incidence of out-of-hospital cardiac arrest (OHCA) fulfilling Utstein criteria in the Canton Ticino, Switzerland, the survival rate of OHCA patients and their neurological outcome. METHODS AND RESULTS: All OHCAs treated in Canton Ticino between 1 January 2005 and 31 December 2014 were followed until either death or hospital discharge. The survival and neurological outcome of those OHCA fulfilling Utstein criteria are reported. A total of 3367 OHCAs occurred in the Canton Ticino over a 10-year period. Resuscitation was attempted in 2298 patients; of those 1492 (65%) were of presumed cardiac origin, 454 fulfilling the Utstein comparator criteria. About 69% [95% confidence interval (CI), 66.6-71.4%] of the patients had a bystander-witnessed arrest; a dispatched cardiopulmonary resuscitation (CPR) steadily and significantly increased from 2005 to 2014. Out-of-hospital cardiac arrest occurred prevalently home (67%), in men (71%) of a mean age of 71 ± 13 years. There were no statistically significant differences either in demographic characteristics of OHCA victims over these years or in presenting rhythm. There was a progressive increase in the survival at discharge from 15% in 2005 to 55% in 2014; overall 96% (95% CI, 93.3-99.9%) of the survivors had a good neurological outcome. CONCLUSION: The significant increase in Utstein comparator survival rates and improved neurological outcome in OHCA victims in Canton Ticino are the result of an effective OHCA management programme which includes large-scale public education, a coordinated fast EMS response, high density of external defibrillators, and advances in clinical interventions for OHCAs.

An in-silico analysis of the effect of heart position and orientation on the ECG morphology and vectorcardiogram parameters in patients with heart failure and intraventricular conduction defects.

AIM: The aim of this study was to investigate the influence of geometrical factors on the ECG morphology and vectorcardiogram (VCG) parameters. METHODS: Patient-tailored models based on five heart-failure patients with intraventricular conduction defects (IVCDs) were created. The heart was shifted up to 6 cm to the left, right, up, and down and rotated ±30° around the anteroposterior axis. Precordial electrodes were shifted 3 cm down. RESULTS: Geometry modifications strongly altered ECG notching/slurring and intrinsicoid deflection time. Maximum VCG parameter changes were small for QRS duration (-6% to +10%) and QRS-T angle (-6% to +3%), but considerable for QRS amplitude (-36% to +59%), QRS area (-37% to +42%), T-wave amplitude (-41% to +36%), and T-wave area (-42% to +33%). CONCLUSION: The position of the heart with respect to the electrodes is an important factor determining notching/slurring and voltage-dependent parameters and therefore must be considered for accurate diagnosis of IVCDs.

Leadless Pacemaker Implantation, Focusing on Patients With Conduction System Disorders Post-Transcatheter Aortic Valve Replacement: A Retrospective Analysis.

Background: Impairment of the conduction system is a common complication of transcatheter aortic valve replacement (TAVR), which is typically performed in elderly patients. A leadless pacemaker (LP) may be a suitable option in this frail population, but the available scientific data concerning the efficacy and safety of leadless pacing after TAVR are sparse. The purpose of this analysis was to evaluate the efficacy and safety of LP implantation in patients with relevant bradycardias after TAVR, compared to other indications. Methods: Consecutive patients were retrospectively enrolled. Demographics, background heart diseases, interventional parameters, and follow-up data were collected. Results: A total of 257 consecutive patients who underwent LP implantation were included. In 26 patients, the device was implanted due to bradycardias after TAVR (TAVR group), whereas the remaining 231 patients were in the population without previous TAVR (non-TAVR group). The mean implantation duration (56 ± 22 minutes in the TAVR group vs 48 ± 20 minutes in the non-TAVR group; P = not significant [NS]) and the implantation success rate (100% in the TAVR group vs 98.7% in the non-TAVR group; P = NS) were similar in the 2 cohorts. No significant differences occurred in pacing parameters (sensing, impedance, and threshold, respectively) between the 2 groups, either at implantation or during follow-up. A total of 8 major periprocedural complications (3.1% of patients in total; 3.8% in the TAVR group vs 3.0% in the non-TAVR group; P = NS) occurred within 30 days, without significant difference between the 2 groups. Conclusions: LP implantation appears to be safe and effective in patients after TAVR, and therefore, this procedure is a suitable option for this often old and frail population.

Contexte: L'atteinte du système de conduction cardiaque est une complication courante du remplacement valvulaire aortique par cathéter (RVAC), une intervention habituellement pratiquée chez les patients âgés. Un stimulateur cardiaque sans sonde peut être une option convenable pour cette population fragile, mais les données scientifiques actuelles concernant l'efficacité et l'innocuité de la stimulation sans sonde après un RVAC sont fragmentaires. Cette analyse visait à évaluer l'efficacité et l'innocuité de l'implantation d'un stimulateur cardiaque sans sonde chez des patients atteints de bradycardies pertinentes après un RVAC, comparativement à d'autres indications. Méthodologie: Des patients consécutifs ont été recrutés de manière rétrospective. Les données démographiques, les maladies cardiaques sous-jacentes, les paramètres interventionnels et les données de suivi ont été colligés. Résultats: Un total de 257 patients consécutifs qui se sont fait implanter un stimulateur cardiaque sans sonde ont été inclus. Chez 26 patients, le dispositif a été implanté en raison d'une bradycardie après un RVAC (groupe RVAC), alors que les 231 autres patients formaient la population sans RVAC antérieur (groupe sans RVAC). La durée moyenne de l'intervention d'implantation (56 ± 22 minutes dans le groupe RVAC vs 48 ± 20 minutes dans le groupe sans RVAC; p = non significatif [NS]) et le taux de réussite de l'implantation (100 % dans le groupe RVAC vs 98,7 % dans le groupe sans RVAC; p = NS) étaient similaires dans les deux cohortes. Aucune différence significative n'a été observée dans les paramètres de stimulation (sensibilité, impédance et seuil, respectivement) entre les 2 groupes, que ce soit au moment de l'implantation ou pendant le suivi. Un total de 8 complications périopératoires majeures (3,1 % de l'ensemble des patients; 3,8 % dans le groupe RVAC vs 3,0 % dans le groupe sans RVAC; p = NS) sont survenues dans les 30 jours, sans différence notable entre les 2 groupes. Conclusions: L'implantation d'un stimulateur cardiaque sans sonde semble sûre et efficace après un RVAC; par conséquent, cette intervention représente une option convenable pour cette population souvent âgée et fragile.