Impact of different activation wavefronts on ischemic myocardial scar electrophysiological properties during high-density ventricular tachycardia mapping and ablation.

INTRODUCTION: Scar-related ventricular tachycardia (VT) usually results from an underlying reentrant circuit facilitated by anatomical and functional barriers. The later are sensitive to the direction of ventricular activation wavefronts. We aim to evaluate the impact of different ventricular activation wavefronts on the functional electrophysiological properties of myocardial tissue. METHODS: Patients with ischemic heart disease referred for VT ablation underwent high-density mapping using Carto®3 (Biosense Webster). Maps were generated during sinus rhythm, right and left ventricular pacing, and analyzed using a new late potential map software, which allows to assess local conduction velocities and facilitates the delineation of intra-scar conduction corridors (ISCC); and for all stable VTs. RESULTS: In 16 patients, 31 high-resolution substrate maps from different ventricular activation wavefronts and 7 VT activation maps were obtained. Local abnormal ventricular activities (LAVAs) were found in VT isthmus, but also in noncritical areas. The VT isthmus was localized in areas of LAVAs overlapping surface between the different activation wavefronts. The deceleration zone location differed depending on activation wavefronts. Sixty-six percent of ISCCs were similarly identified in all activating wavefronts, but the one acting as VT isthmus was simultaneously identified in all activation wavefronts in all cases. CONCLUSION: Functional based substrate mapping may improve the specificity to localize the most arrhythmogenic regions within the scar, making the use of different activation wavefronts unnecessary in most cases.

Outcome of Temporary Circulatory Support As a Bridge-to-Left Ventricular Assist Device Strategy in Cardiogenic Shock Patients.

OBJECTIVES: Temporary circulatory support (TCS) as a bridge-to-left ventricular assist device (BTL) in cardiogenic shock patients has been increasing, but limited data exists on this BTL strategy. We aimed at analyzing the outcome of BTL patients in a population of cardiogenic shock patients compared with those without TCS at the time of the left ventricular assist device (LVAD) surgery and identify predictors of postoperative mortality in this specific population. DESIGN: A multicenter retrospective observational study conducted in 19 centers from 2006 to 2016. SETTING: Nineteen French centers. PATIENTS: A total of 329 cardiogenic shock patients at the time of LVAD implantation were analyzed. Patients were divided in three groups: those under TCS at the time of LVAD implantation (n = 173), those with TCS removal before LVAD surgery (n = 24), and those who did not undergo a bridging strategy (n = 152). Primary endpoint was 30-day mortality. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Among the BTL group, 68 (39.3%), 18 (10.4%), and 15 (8.7%) patients were under venoarterial extracorporeal membrane oxygenation, Impella, and IABP support alone, and 72 patients (20.6%) were under multiple TCS support. BTL patients presented similar 30 days survival compared with the TCS removal and non-BTL groups. However, BTL group had a significantly longer ICU duration stay, with two-fold duration of mechanical ventilation time, but the three groups experienced similar postoperative complications. Multivariate analysis identified three independent predictors of mortality in the BTL group: combined surgery with LVAD, body mass index (BMI), and heart failure (HF) duration. BTL strategy was not an independent predictor of mortality in cardiogenic shock patients who underwent LVAD. CONCLUSIONS: BTL strategy is not associated with a lower survival among cardiogenic shock patients with LVAD implantation. Predictors of mortality are combined surgery with LVAD, higher BMI, and HF duration.

Brain imaging determinants of functional prognosis after severe endocarditis: a multicenter observational study.

OBJECTIVE: We developed a detailed imaging phenotype of the cerebral complications in critically ill patients with infective endocarditis (IE) and determine whether any specific imaging pattern could impact prognostic information. METHODS: One hundred ninety-two patients admitted to the intensive care units of seven tertiary centers with severe, definite left IE and neurological complications were included. All underwent cerebral imaging few days after admission to define the types of lesions, their volumes, and their locations using voxel-based lesion-symptom mapping (VLSM). We employed uni- and multi-variate logistic regression analyses to explore the associations among imaging features and other prognostic variables and the 6-month modified Rankin Scale (mRS) score. RESULTS: Ischemic lesions were the most common lesions (75%; mean volume, 15.3 ± 33 mL) followed by microbleeds (50%; mean number, 4 ± 7.5), subarachnoidal hemorrhages (20%), hemorrhagic strokes (16%; mean volume, 14.6 ± 21 mL), and hemorrhagic transformations (10%; mean volume, 5.6 ± 11 mL). The volume of hemorrhagic transformations, the severity of leukopathy, and the compromises of certain locations on the motor pathway from the VLSM were associated with a poor 6-month mRS score on univariate analyses. However, upon multivariate analyses, no such specific imaging pattern independently predicted the mRS; this was instead influenced principally by age (OR = 1.03 [1.004-1.06]) and cardiac surgery status (OR = 0.06 [0.02-0.16]) in the entire cohort, and by age (OR = 1.04 [1.01-1.08]) and Staphylococcus aureus status (OR = 2.86 [1.19-6.89]) in operated patients. CONCLUSIONS: In a cohort of severely ill IE patients with neurological complications, no specific imaging pattern could be highlighted as a reliable predictor of prognosis.

Validation of the VT-LVAD score for prediction of late VAs in LVAD recipients.

OBJECTIVES: This study sought to validate the performance of the VT-LVAD risk model in predicting late ventricular arrhythmias (VAs) in patients after left ventricular assist device (LVAD) implantation. BACKGROUND: The need for implantable cardioverter-defibrillator (ICD)-implantation in LVAD recipients is not well studied. A better selection of the patients with high risk for late VAs could lead to a more targeted ICD-implantation or replacement. METHODS: The study evaluated the performance of the VT-LVAD prognostic score (VAs prior LVAD, no ACE-inhibitor in medication, heart failure duration > 12 months, early VAs post-LVAD implantation, atrial fibrillation prior LVAD, idiopathic dilated cardiomyopathy) for the endpoint of the occurrence of late VAs in 357 LVAD patients in Heart Centre of Leipzig. RESULTS: From the initial 460 patients, 357 (age: 58 ± 10 years; left ventricular ejection fraction: 20 ± 6%; HeartWare: 50%; HeartMate III: 42%) were assigned to four risk groups according to their VT-LVAD score varying from low risk to very high risk. After 25 months, late VAs occurred in 130 patients. The VT-LVAD score was an independent predictor of late VAs (multivariate analysis; p = < .001; goodness-of-tip p = .347; odds ratio: 4.8). While there was no statistically significant difference between the low- and intermediate-risk group, risk stratification for patients with high risk and very high risk performed more accurately (pairwise comparison p = .005 and p < .001, respectively). CONCLUSIONS: The VT-LVAD score predicted accurately the occurrence of late VAs in high-risk LVAD recipients in a large external cohort of LVAD recipients supporting its utility for more targeted ICD implantations.

Left ventricular wall thickness assessed by cardiac computed tomography and cardiac resynchronization therapy outcomes.

AIMS: Up to 30% of selected heart failure patients do not benefit clinically from cardiac resynchronization therapy (CRT). Left ventricular (LV) wall thickness (WT) analysed using computed tomography (CT) has rarely been evaluated in response to CRT and mitral regurgitation (MR) improvement. We examined the association of LVWT and the ability to reverse LV remodelling and MR improvement after CRT. METHODS AND RESULTS: Fifty-four patients scheduled for CRT underwent pre-procedural CT. Reduced LVWT was defined as WT <6 mm and quantified as a percentage of total LV area. Endpoints were 6-month clinical and echocardiographic response to CRT [New York Heart Association (NYHA) class, LV ejection fraction (LVEF), LV end-diastolic volume (LVEDV), and LV end-systolic volume (LVESV)], MR improvement and 2-year major adverse cardiac events (MACE). Patients were divided into three groups according to the percentage of LVWT <6 mm area: ≤20%, 20-50%, and ≥50%. At 6 months, 75%, 71%, and 42% of the patients experienced NYHA improvement in the ≤20%, 20-50%, and ≥50% group, respectively. Additionally, ≤20% group presented higher LVEF, LVEDV, and LVESV positive response rate (86%, 59%, and 83%, respectively). Both 20-50% and ≥50% groups exhibited a lower LVEF, LVEDV, and LVESV positive response rate (52% and 42%; 47% and 45%; and 53% and 45%, respectively). Additionally, ≥25% of LVWT <6 mm inclusive of at least one papillary muscle insertion was the only predictor of lack of MR improvement. Lastly, ≥50% group experienced significantly lower 2-year MACE survival free probability. CONCLUSION: WT evaluated using CT could help to stratify the response to CRT and predict MR improvement and outcomes. CLINICAL TRIAL REGISTRATION: NCT01097733.

Implantable cardiac defibrillator leads dysfunction after LVAD implantation.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) lead dysfunction has been reported after left ventricular assist device (LVAD) implantation in limited single-center studies. We aimed at describing and characterizing the incidence of ICD lead parameters dysfunction after LVAD implantation. METHODS: Among the 652 patients enrolled in the ASSIST-ICD study, only patients with an ICD prior to LVAD were included (n = 401). ICD lead parameters dysfunction following LVAD implantation is defined as follows: (a) >50% decrease in sensing threshold, (b) pacing lead impedance increase/decrease by >100Ω, and (c) >50% increase in pacing threshold. RESULTS: One hundred twenty-two patients with an ICD prior to LVAD had available ICD interrogation reports prior and after LVAD. A total of 67 (55%) patients exhibited at least one significant lead dysfunction: 17 (15%) exhibited >50% decrease in right ventricular (RV) sensing, 51 (42%) had >100 Ω increase/decrease in RV pacing impedance, and 24 (20%) experienced >50% increase in RV pacing threshold. A total of 52 patients experienced ventricular arrhythmia during follow-up and all were successfully detected and treated by the device. All lead dysfunction could be managed conservatively. CONCLUSION: More than 50% of LVAD-recipients may experience >1 significant change in lead parameters but none had severe clinical consequences.

CRT-Pacemaker Versus CRT-Defibrillator Who Needs Sudden Cardiac Death Protection?

PURPOSE OF THE REVIEW: Patients with cardiomyopathy and impaired left ventricular (LV) ejection fraction are at risk of sudden cardiac death (SCD). In selected heart failure patients, cardiac resynchronization therapy (CRT) provides LV reverse remodeling and improves the cellular and molecular function leading to a reduced risk of ventricular arrhythmia and SCD. Consequently, some CRT candidates may not need concomitant ICD therapy. This review aimed at focusing on the residual risk of SCD in patients receiving CRT and discussing the requirement of a concomitant ICD therapy in CRT candidates. RECENT FINDINGS: New imaging diagnostic tools may be helpful to accurately predict patient with a residual risk of SCD and who required a CRT-D implantation. Recent data highlighted that cardiac computed tomography (CT) or myocardial scar tissue analysis using contrast-enhanced cardiac magnetic resonance (CMR) was able to predict the occurrence of VA in patients with bi-ventricular pacing. Cardiac imaging and specifically myocardial scar analysis seem promising to evaluate the risk of SCD following bi-ventricular pacing and will probably be of great help in the future to accurately identify those who needs concomitant defibrillator's protection.

Risk factors and prognostic impact of left ventricular assist device-associated infections.

BACKGROUND: Left ventricular assist device (LVAD)-associated infections may be life-threatening and impact patients' outcome. We aimed to identify the characteristics, risk factors, and prognosis of LVAD-associated infections. METHODS: Patients included in the ASSIST-ICD study (19 centers) were enrolled. The main outcome was the occurrence of LVAD-associated infection (driveline infection, pocket infection, or pump/cannula infection) during follow-up. RESULTS: Of the 652 patients enrolled, 201 (30.1%) presented a total of 248 LVAD infections diagnosed 6.5 months after implantation, including 171 (26.2%), 51 (7.8%), and 26 (4.0%) percutaneous driveline infection, pocket infection, or pump/cannula infection, respectively. Patients with infections were aged 58.7 years, and most received HeartMate II (82.1%) or HeartWare (13.4%). Most patients (62%) had implantable cardioverter-defibrillators (ICDs) before LVAD, and 104 (16.0%) had ICD implantation, extraction, or replacement after the LVAD surgery. Main pathogens found among the 248 infections were Staphylococcus aureus (n = 113' 45.4%), Enterobacteriaceae (n = 61; 24.6%), Pseudomonas aeruginosa (n = 34; 13.7%), coagulase-negative staphylococci (n = 13; 5.2%), and Candida species (n = 13; 5.2%). In multivariable analysis, HeartMate II (subhazard ratio, 1.56; 95% CI, 1.03 to 2.36; P = .031) and ICD-related procedures post-LVAD (subhazard ratio, 1.43; 95% CI, 1.03-1.98; P = .031) were significantly associated with LVAD infections. Infections had no detrimental impact on survival. CONCLUSIONS: Left ventricular assist device-associated infections affect one-third of LVAD recipients, mostly related to skin pathogens and gram-negative bacilli, with increased risk with HeartMate II as compared with HeartWare, and in patients who required ICD-related procedures post-LVAD. This is a plea to better select patients needing ICD implantation/replacement after LVAD implantation.

Radiofrequency ablation of right ventricular tachycardia in patients with no femoral access: safety and efficacy of a superior approach.

AIMS: Ventricular tachycardia (VT) ablation has been proven to be effective and safe to avoid arrhythmia recurrences in patients with repaired congenital heart disease (CHD). However, some of these patients may present right ventricular (RV) access issues [agenesia or thrombosis of inferior vena cava (IVC)], making impossible to access the right ventricle through an inferior approach. In such patients, only a superior approach would theoretically be feasible. METHODS AND RESULTS: All VT ablations performed through a jugular or subclavian approach in CHD patients between 2012 and 2017 were included. Among 247 patients scheduled for VT ablation, two patients underwent three VT ablation procedures via a superior approach for due to the inability to access the right ventricle through a conventional IVC access (IVC interruption with azygos continuation in one patient and IVC thrombosis in the other). Ablation was performed using a three-dimensional system through a superior approach, using a subclavian access in both cases. A redo ablation had to be performed in the first patient using a jugular approach. Large curve catheters were used to facilitate RV outflow tract access. Supposed critical isthmuses could be localized and ablated. Patients remained free from arrhythmias during follow-up. CONCLUSION: In patients with repaired CHD and 'no femoral access', ablation of RV tachycardia can be performed using a subclavian or a jugular approach. Mapping may be challenging, requiring large curve catheters. Conventional isthmuses can be mapped and ablated successfully, and such patients should not be denied radiofrequency ablation.

The second generation cryoballoon has improved durable isolation of left but not right pulmonary veins: new insights from a multicentre study.

Aims: Pulmonary vein isolation (PVI) using second-generation cryoballoon (CB2) is associated with improved outcomes compared with first generation (CB1). We aimed at investigating the characteristics of left and right PV reconnections after CB1 and CB2 ablations in patients with clinical recurrences requiring redo ablation. Methods and results: From 2010 to 2016, 776 patients underwent 28-mm cryoballoon PVI for symptomatic paroxysmal atrial fibrillation (AF) in 3 centres, 279 with CB1 and 497 with CB2. Among them, 94 patients (12.1%) had symptomatic AF recurrences requiring a redo ablation [43 (15.4%) CB1 and 51 (10.3%) CB2]. The benefit of CB2 over CB1 was compared for each PV. Durable PVI was confirmed in 7 CB1 (16.3%) and 14 CB2 (27.4%) patients, and 2.7 ± 2.1 and 1.4 ± 1.4 gaps per patient were found, respectively (P = 0.002). Significantly more left superior and left inferior PVs were found to be isolated in CB2 compared with CB1 group (78.4% vs. 48.8%, P = 0.005 and 78.4% vs. 46.5%, P = 0.003, respectively) while the rate of durable right superior and right inferior PVs isolation were similar (68.6% vs. 60.5%, P = 0.542 and 66.7% vs. 55.8%, P = 0.387, respectively). Significantly fewer gaps were found in left PVs in CB2 patients, while there was no significant difference for right PVs. Gaps localization was similar in both groups. Conclusion: Fewer reconnection gaps are observed during redo ablations of paroxysmal AF in patients primarily ablated with CB2. This difference is driven by less reconnection gaps observed in both left PVs, while no difference was observed for right PVs.

Avoiding non-responders to cardiac resynchronization therapy: a practical guide.

Over two decades after the introduction of cardiac resynchronization therapy (CRT) into clinical practice, ∼30% of candidates continue to fail to respond to this highly effective treatment of drug-refractory heart failure (HF). Since the causes of this non-response (NR) are multifactorial, it will require multidisciplinary efforts to overcome. Progress has, thus far, been slowed by several factors, ranging from a lack of consensus regarding the definition of NR and technological limitations to the delivery of therapy. We critically review the various endpoints that have been used in landmark clinical trials of CRT, and the variability in response rates that has been observed as a result of these different investigational designs, different sample populations enrolled and different means of therapy delivered, including new means of multisite and left ventricular endocardial simulation. Precise recommendations are offered regarding the optimal device programming, use of telemonitoring and optimization of management of HF. Potentially reversible causes of NR to CRT are reviewed, with emphasis on loss of biventricular stimulation due to competing arrhythmias. The prevention of NR to CRT is essential to improve the overall performance of this treatment and lower its risk-benefit ratio. These objectives require collaborative efforts by the HF team, the electrophysiologists and the cardiac imaging experts.

Effectiveness of Extracorporeal Life Support for Patients With Cardiogenic Shock Due To Intractable Arrhythmic Storm.

OBJECTIVES: Extracorporeal life support is used for patients with severe heart failure as a bridge to heart transplantation or recovery. We aimed at analyzing the efficacy and safety of extracorporeal life support to treat refractory arrhythmic storm responsible for cardiogenic shock in patients resistant to antiarrhythmic drugs. DESIGN: Retrospective study. SETTING: University Hospital of Rennes, France. PATIENTS: Patients with refractory arrhythmic storm admitted between January 2005 and March 2015. INTERVENTIONS: Patients with intractable refractory arrhythmic storm and cardiogenic shock despite optimal medical therapy were implanted with an extracorporeal life support. Patients' characteristics and outcomes after extracorporeal life support implantation were analyzed. MEASUREMENTS AND MAIN RESULTS: Twenty-six patients (23 men, 52.4 ± 9.2 yr old) were included, most of them having ischemic cardiomyopathy (65.4%). Stable sinus rhythm restoration was immediate in 61.5% of patients and occurred after a median time of 3 hours after extracorporeal life support implantation for the remaining ones. Thirteen patients (50%) eventually died, none of them due to extracorporeal life support-related complications, but mostly due to the occurrence of multiple organ failure, and occurred after a median time of 4 days. The remaining 13 patients (50%) had extracorporeal life support withdrawn after 6.7 ± 3.6 days and were discharged after 34.7 ± 14.7 days after admission. Patients with repetitive ventricular tachycardia/ventricular fibrillation episodes alternating with periods of sinus rhythm at the time of implantation had a better survival than those in refractory ventricular fibrillation (p = 0.017). CONCLUSIONS: This is the largest database of patients temporary implanted with extracorporeal life support for refractory arrhythmic storm responsible for cardiogenic shock resistant to antiarrhythmic drugs. It provides efficient hemodynamic support and survival rate after the implantation is 50%.

Defining nonvalvular atrial fibrillation: A quest for clarification.

Non-vitamin K oral anticoagulants (NOACs) are currently recommended for patients with nonvalvular atrial fibrillation since the publication of the 4 major pivotal trials evaluating the efficacy and safety of factor IIa and factor Xa inhibitors. The definition of nonvalvular atrial fibrillation is unclear, varying from one trial to another and even between North American and European guidelines, which is a source of uncertainties in clinical practice. However, many patients with atrial fibrillation present signs of valvular involvement, and clarification of this term is needed to not deny NOACs to patients based on the wrong perception that they may have valvular atrial fibrillation. The currently unique contraindications to NOACs are patients with mechanical heart valves and those with moderate-to-severe mitral stenosis, as stated by the recent 2015 position paper of the European Heart Rhythm Association. Patients with native heart valve involvement, regardless of their severity, are suitable for NOAC therapy. Patients with bioprosthetic heart valves and mitral valve repair may be suitable for NOACs except for the first 3 and the first 3-6 months postoperatively, respectively. Patients with transaortic valve implantation or percutaneous transluminal aortic valvuloplasty are also considered as being eligible for NOACs, although the bleeding risk has to be carefully considered in this population often requiring a combination with antiplatelet therapy. Future studies are warranted to increase the level of evidence of use of NOACs, particularly in patients with transaortic valve implantation and valvular surgery, and to determine whether they could be used in the future in the only 2 remaining contraindications.

Shear stress triggers insertion of voltage-gated potassium channels from intracellular compartments in atrial myocytes.

Atrial myocytes are continuously exposed to mechanical forces including shear stress. However, in atrial myocytes, the effects of shear stress are poorly understood, particularly with respect to its effect on ion channel function. Here, we report that shear stress activated a large outward current from rat atrial myocytes, with a parallel decrease in action potential duration. The main ion channel underlying the increase in current was found to be Kv1.5, the recruitment of which could be directly observed by total internal reflection fluorescence microscopy, in response to shear stress. The effect was primarily attributable to recruitment of intracellular pools of Kv1.5 to the sarcolemma, as the response was prevented by the SNARE protein inhibitor N-ethylmaleimide and the calcium chelator BAPTA. The process required integrin signaling through focal adhesion kinase and relied on an intact microtubule system. Furthermore, in a rat model of chronic hemodynamic overload, myocytes showed an increase in basal current despite a decrease in Kv1.5 protein expression, with a reduced response to shear stress. Additionally, integrin beta1d expression and focal adhesion kinase activation were increased in this model. This data suggests that, under conditions of chronically increased mechanical stress, the integrin signaling pathway is overactivated, leading to increased functional Kv1.5 at the membrane and reducing the capacity of cells to further respond to mechanical challenge. Thus, pools of Kv1.5 may comprise an inducible reservoir that can facilitate the repolarization of the atrium under conditions of excessive mechanical stress.

Dominant frequency increase rate predicts transition from paroxysmal to long-term persistent atrial fibrillation.

BACKGROUND: Little is known about the mechanisms underlying the transition from paroxysmal to persistent atrial fibrillation (AF). In an ovine model of long-standing persistent AF we tested the hypothesis that the rate of electric and structural remodeling, assessed by dominant frequency (DF) changes, determines the time at which AF becomes persistent. METHODS AND RESULTS: Self-sustained AF was induced by atrial tachypacing. Seven sheep were euthanized 11.5±2.3 days after the transition to persistent AF and without reversal to sinus rhythm; 7 sheep were euthanized after 341.3±16.7 days of long-standing persistent AF. Seven sham-operated animals were in sinus rhythm for 1 year. DF was monitored continuously in each group. Real-time polymerase chain reaction, Western blotting, patch clamping, and histological analyses were used to determine the changes in functional ion channel expression and structural remodeling. Atrial dilatation, mitral valve regurgitation, myocyte hypertrophy, and atrial fibrosis occurred progressively and became statistically significant after the transition to persistent AF, with no evidence for left ventricular dysfunction. DF increased progressively during the paroxysmal-to-persistent AF transition and stabilized when AF became persistent. Importantly, the rate of DF increase correlated strongly with the time to persistent AF. Significant action potential duration abbreviation, secondary to functional ion channel protein expression changes (CaV1.2, NaV1.5, and KV4.2 decrease; Kir2.3 increase), was already present at the transition and persisted for 1 year of follow up. CONCLUSIONS: In the sheep model of long-standing persistent AF, the rate of DF increase predicts the time at which AF stabilizes and becomes persistent, reflecting changes in action potential duration and densities of sodium, L-type calcium, and inward rectifier currents.