Paravalvular regurgitation after transcatheter aortic valve replacement: incidence, quantification, and prognostic impact.

Transcatheter aortic valve replacement (TAVR) is the standard of care in aortic stenosis with results comparable to surgical aortic valve replacement. However, paravalvular regurgitation (PVR) is more common after TAVR. With the alteration of devices and implantation techniques, the incidence of moderate or more PVR has declined. Mild PVR is still common in around 30% of TAVR patients in low-risk trials. Progression of AS causes myocardial hypertrophy and varying degrees of diastolic dysfunction which may cause heart failure even in combination with small volumes of PVR. Any degree of PVR is associated with an increased risk of overall and cardiovascular mortality. Predictors of PVR are annular eccentricity, severe calcification of the aortic valve, bicuspid aortic valves, and type of prosthesis where balloon-expandable devices are associated with less PVR. PVR is diagnosed using echocardiography, aortic angiogram with or without videodensitometry, haemodynamic parameters, or cardiac magnetic resonance. PVR can be treated using post-dilation, interventional treatment using a vascular plug, or implantation of a second device. Successful post-dilation depends on balloon size which should at least be equal to or >95% of the mean annulus diameter. Implantation of a second device to reduce PVR is successful in ∼90% of cases, either through lengthening of the sealing skirt in case of inadequate position or through further expansion of the index device. Implantation of a vascular plug can successfully reduce PVR and reduce mortality.

Upper extremity versus lower extremity for secondary access during transcatheter aortic valve implantation: rationale and design of the randomised TAVI XS trial.

BACKGROUND: During transcatheter aortic valve implantation (TAVI), secondary access is required for angiographic guidance and temporary pacing. The most commonly used secondary access sites are the femoral artery (angiographic guidance) and the femoral vein (temporary pacing). An upper extremity approach using the radial artery and an upper arm vein instead of the lower extremity approach using the femoral artery and femoral vein may reduce clinically relevant secondary access site-related bleeding complications, but robust evidence is lacking. TRIAL DESIGN: The TAVI XS trial is a multicentre, randomised, open-label clinical trial with blinded evaluation of endpoints. A total of 238 patients undergoing transfemoral TAVI will be included. The primary endpoint is the incidence of clinically relevant bleeding (i.e. Bleeding Academic Research Consortium (BARC) type 2, 3 or 5 bleeding) of the randomised secondary access site (either diagnostic or pacemaker access, or both) within 30 days after TAVI. Secondary endpoints include time to mobilisation after TAVI, duration of hospitalisation, any BARC type 2, 3 or 5 bleeding, and early safety at 30 days according to Valve Academic Research Consortium­3 criteria. CONCLUSION: The TAVI XS trial is the first randomised trial comparing an upper extremity approach to a lower extremity approach with regard to clinically relevant secondary access site-related bleeding complications. The results of this trial will provide important insights into the safety and efficacy of an upper extremity approach in patients undergoing transfemoral TAVI.

TransCatheter aortic valve implantation and fractional flow reserve-guided percutaneous coronary intervention versus conventional surgical aortic valve replacement and coronary bypass grafting for treatment of patients with aortic valve stenosis and multivessel or advanced coronary disease: The transcatheter valve and vessels trial (TCW trial): Design and rationale.

BACKGROUND: Patients with severe aortic stenosis (AS) frequently present with concomitant obstructive coronary artery disease (CAD). In those, current guidelines recommend combined coronary artery bypass grafting (CABG) and surgical aortic valve replacement (SAVR) as the preferred treatment option, although this surgical approach is associated with a high rate of clinical events. Combined transcatheter aortic valve implantation (TAVI) and percutaneous coronary intervention (PCI) with or without FFR have evolved as a valid alternative for cardiac surgery in patients with AS and multivessel or advanced CAD. To date, no dedicated trial has prospectively evaluated the outcomes of a percutaneous versus surgical treatment for patients with both severe AS and CAD. AIMS: To investigate whether fractional-flow reserve (FFR)-guided PCI and TAVI is noninferior to combined CABG and SAVR for the treatment of severe AS and multivessel or advanced CAD. METHODS: The Transcatheter Valve and Vessels (TCW) trial (clinicaltrial.gov: NCT03424941) is a prospective, randomized, controlled, open label, international trial. Patients ≥ 70 years with severe AS and multivessel (≥ 2 vessels) or advanced CAD, deemed feasible by the heart team for both; a full percutaneous or surgical treatment, will be randomised in a 1:1 fashion to either FFR-guided PCI followed by TAVI (intervention arm) vs. CABG and SAVR (control arm). The primary endpoint is a patient-oriented composite of all-cause mortality, myocardial infarction, disabling stroke, unscheduled clinically-driven target vessel revascularization, valve reintervention, and life threatening or disabling bleeding at 1 year. The TCW trial is powered for noninferiority, and if met, superiority will be tested. Assuming a primary endpoint rate of 30% in the CABG-SAVR arm, with a significance level α of 5%, a noninferiority limit delta of 15% and a loss to follow-up of 2%, a total of 328 patients are needed to obtain a power of 90%. The primary endpoint analysis is performed on an intention-to-treat basis. SUMMARY: The TCW Trial is the first prospective randomized trial that will study if a less invasive percutaneous treatment for severe AS and concomitant advanced CAD (i.e., FFR-guided PCI-TAVI) is noninferior to the guidelines recommended approach (CABG-SAVR).

Using Upper Arm Vein as Temporary Pacemaker Access Site: A Next Step in Minimizing the Invasiveness of Transcatheter Aortic Valve Replacement.

Background The femoral vein is commonly used as a pacemaker access site during transcatheter aortic valve replacement (TAVR). Using an upper arm vein as an alternative access site potentially causes fewer bleeding complications and shorter time to mobilization. We aimed to assess the safety and efficacy of an upper arm vein as a temporary pacemaker access site during TAVR. Methods We evaluated all patients undergoing TAVR in our center between January 2020 and January 2023. Upper arm, femoral, and jugular vein pacemaker access was used in 255 (45.8%), 191 (34.3%), and 111 (19.9%) patients, respectively. Clinical outcomes were analyzed according to pacemaker access in the overall population and in a propensity-matched population involving 165 upper arm and 165 femoral vein patients. Primary endpoint was Bleeding Academic Research Consortium (BARC) type 2, 3, or 5 pacemaker access site-related bleeding. Results In the overall population, primary endpoint was lowest for upper arm, followed by femoral and jugular vein access (2.4% vs. 5.8% vs. 10.8%, p = 0.003). Time to mobilization was significantly longer (p < 0.001) in the jugular cohort compared with the other cohorts. In the propensity-matched cohort, primary endpoint showed a trend toward lower occurrence in the upper arm compared with the femoral cohort (2.4% vs. 6.1%, p = 0.10). Time to mobilization was significantly shorter (480 vs. 1140 min, p < 0.001) in the upper arm cohort, with a comparable skin-to-skin time (83 vs. 85 min, p = 0.75). Cross-over from upper arm pacemaker access was required in 17 patients (6.3% of attempted cases via an upper arm vein). Conclusions Using an upper arm vein as a temporary pacemaker access site is safe and feasible. Its use might be associated with fewer bleeding complications and shorter time to mobilization compared with the femoral vein.

Diastolic delta best predicts paravalvular regurgitation after transcatheter aortic valve replacement as assessed by cardiac magnetic resonance: the APPOSE trial.

AIMS: Paravalvular regurgitation (PVR) is a common complication after transcatheter aortic valve replacement (TAVR) that poses an increased risk of rehospitalization for heart failure and mortality. The aim of this study was to assess the accuracy of haemodynamic indices to predict relevant PVR. METHODS AND RESULTS: In this prospective single-centre clinical trial, four haemodynamic indices of PVR measured during TAVR were assessed for their correlation with gold standard cardiac magnetic resonance (CMR)-derived regurgitant fraction (CMR-RF) at 1 month follow-up: diastolic delta (DD), heart rate-adjusted diastolic delta (HR-DD), aortic regurgitation index (ARI), and aortic regurgitation index ratio (ARI ratio). These haemodynamic indices were analysed for their ability to predict relevant PVR (defined as CMR-RF > 20%) using receiver operating characteristic (ROC) curves with corresponding area under the ROC curves (AUCs). A total of 77 patients were included and had CMR performed 41 ± 14 days after TAVR. Mean CMR-RF was 12.4 ± 9.3%. Fifteen (19.5%) patients had CMR-RF > 20%. DD had the best correlation with CMR-RF and the highest AUC to predict relevant PVR (0.82; 95% CI, 0.72-0.92), followed by HR-DD (AUC 0.78; 95% CI, 0.67-0.89), ARI (AUC 0.78; 95% CI, 0.66-0.89), and ARI ratio (AUC 0.65; 95% CI, 0.49-0.81). The optimal cut-off value for DD was 32 mmHg, with sensitivity of 69% and specificity of 77% in predicting relevant PVR. CONCLUSION: DD measured during TAVR best predicts relevant PVR. Correction for heart rate (HR-DD) or systolic blood pressure (ARI, ARI ratio) did not improve this predictive value.

Decision Making during the Learning Curve of Minimally Invasive Mitral Valve Surgery: A Focused Review for the Starting Minimally Invasive Surgeon.

Minimally invasive mitral valve surgery is evolving rapidly since the early 1990's and is now increasingly adopted as the standard approach for mitral valve surgery. It has a long and challenging learning curve and there are many considerations regarding technique, planning and patient selection when starting a minimally invasive program. In the current review, we provide an overview of all considerations and the decision-making process during the learning curve.

Aortic Regurgitation Index Ratio Is a Strong Predictor of 1-Year Mortality After Transcatheter Aortic Valve Implantation Using Self-Expanding Devices.

Grading paravalvular leak (PVL) at the time of transcatheter aortic valve implantation (TAVI) deployment is challenging. Per-procedural invasive hemodynamic measurements could serve to optimize PVL grading and predict outcome after TAVI. The aim of this study was to compare hemodynamic measures of paravalvular leak and their prognostic relevance in self-expanding TAVI devices. Between December 2008 and December 2017 consecutive patients treated for severe symptomatic aortic valve stenosis with self-expanding devices were prospectively studied. Peri-procedural hemodynamic measurements, echocardiographic data as well as clinical follow-up according to VARC-2 criteria were prospectively collected. Diastolic delta (DD), heart rate adjusted DD, aortic regurgitation index (ARI) and ARI ratio were calculated and assessed for their association with 1-year mortality. A total of 651 patients were studied. Moderate or severe paravalvular leakage was found in 4.8% of patients. ARI ratio < 0.6 (hazard ratio 1.96 [1.23-3.12], P = 0.005) was the best independent predictor of 1-year mortality. This study confirms the value of hemodynamic measures, specifically ARI ratio, for prognostication, potentially supporting procedural decision-making with regard to PVL.

Transcatheter aortic valve replacement during the COVID-19 pandemic-A Dutch single-center analysis.

BACKGROUND AND AIM OF THE STUDY: The coronavirus disease 2019 (COVID-19) pandemic has put an enormous strain on healthcare systems and intensive care unit (ICU) capacity, leading to suspension of most elective procedures, including transcatheter aortic valve replacement (TAVR). However, deferment of TAVR is associated with significant wait-time mortality in patients with severe aortic valve stenosis. Conversely, there is currently no data available regarding the safety and feasibility of a continued TAVR program during this unprecedented crisis. The aim of this study is to evaluate the safety and feasibility of patients undergoing TAVR during the COVID-19 pandemic in our center, with specific emphasis on COVID-19 related outcomes. METHODS: All patients who underwent TAVR in our center between February 27, 2020, and June 30, 2020, were evaluated. Clinical outcomes were described in terms of Valve Academic Research Consortium 2 definitions. Patient follow-up was done by chart review and telephone survey. RESULTS: A total of 71 patients have undergone TAVR during the study period. Median age was 80 years, 63% were men, and 25% were inpatients. Procedural success was 99%. After TAVR, 30% involved admission to the ICU, and 94% were ultimately discharged to the cardiac care unit on the same day. Two patients (3%) had confirmed COVID-19 a few days after TAVR, and both died of COVID-19 pneumonia within 2 weeks after hospital discharge. CONCLUSIONS: A continued TAVR program during the COVID-19 pandemic is feasible despite limited hospital resources. However, COVID-19 related mortality after TAVR is of concern.

The impact of circulation in a heart-lung machine on function and survival characteristics of red blood cells.

Extracorporeal circulation is accompanied by changes in red blood cell morphology and structural integrity that affect cell function and survival, and thereby may contribute to the various side effects of heart-lung machine-assisted surgery. Our main objectives were to determine the effect of circulation of red blood cells in a stand-alone extracorporeal circuit on several parameters that are known to be affected by, as well as contribute to red blood cell aging. As a source of RBCs, we employed blood bank storage units of different ages. In order to assess the relevance of our in vitro observations for the characterization of extracorporal circulation technology, we compared these changes in those of patients undergoing extracorporeal circulation-assisted cardiac surgery. Our results show that circulation in a heart-lung machine is accompanied by changes in red blood cell volume, an increase in osmotic fragility, changes in deformability and aggregation behavior, and alterations in the exposure of phosphatidylserine and in microvesicle generation. RBCs from 1-week-old concentrates showed the highest similarities with the in vivo situation. These changes in key characteristics of the red blood cell aging process likely increase the susceptibility of red blood cells to the various mechanical, osmotic, and immunological stress conditions encountered during and after surgery in the patient's circulation, and thereby contribute to the side effects of surgery. Thus, aging-related parameters in red blood cell structure and function provide a foundation for the validation and improvement of extracorporeal circulation technology.

Incidence and predictors of vascular complications in transaxillary TAVI.

AIMS: Vascular complications are among the most commonly observed complications after TAVI. Iliofemoral vascular outcome has been described extensively. Little is known about vascular complications in transaxillary TAVI. The aim of the current study was to describe the incidence and predictors of axillary artery complications incorporating computed tomography angiography (CTA) measurements. METHODS AND RESULTS: CT analysis was performed in two hundred patients treated with transaxillary TAVI in our centre between January 2014 and December 2017. Vascular complications occurred in 37 (18.5%) patients. Patient characteristics predicting this outcome were female gender (aOR 3.88 [1.48-10.14], p=0.006) and age (aOR 1.08 [1.01-1.16], p=0.034). The CTA measurement predicting vascular complications was a sheath to artery area ratio (SAAR) equal to or larger than 1.63 (OR 3.95 [1.29-12.12], p=0.016). CONCLUSIONS: The present study describes the incidence of axillary artery complications and identifies patient characteristics associated with this outcome. CTA analysis was shown to be an important screening tool in the assessment of patient (access) eligibility. Axillary artery dimensional screening should be based on vascular luminal area assessment rather than diameter measurement alone.

Delirium After Transcatheter Aortic Valve Implantation Under General Anesthesia: Incidence, Predictors, and Relation to Long-Term Survival.

BACKGROUND/OBJECTIVES: Prospectively collected data on postoperative delirium (POD) after transcatheter aortic valve implantation (TAVI) are scarce. The aim of this study was to report the incidence and risk factors of delirium after TAVI under general anesthesia and to assess the association of POD with clinical outcome and short- and long-term survival. DESIGN: Prospective cohort study. SETTING: Academic medical center. PARTICIPANTS: A total of 703 subsequent patients undergoing TAVI under general anesthesia between 2008 and 2017. MEASUREMENTS: Delirium was assessed according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), criteria. Outcomes were postprocedural clinical outcome and short- and long-term survival (30 days and 5 years, respectively). RESULTS: POD was observed in 16.5% (116/703), was the strongest independent predictor of long-term mortality (hazard ratio = 1.91; 95% confidence interval [CI] = 1.36-2.70), and was associated with impaired 30-day and 5-year survival (92.2% vs 96.8% [P = .025] and 40.0% vs 50.0% [P = .007], respectively). Stroke and new onset of atrial fibrillation were more often observed in delirious patients (6.9% vs 1.9% and 12.1% vs 5.1%, respectively). Strongest independent predictors of POD were prior delirium (odds ratio [OR] = 2.56; 95% CI = 1.52-4.31) and aortic valve area less than 0.75 cm2 (OR = 2.39; 95% CI = 1.53-3.74). CONCLUSION: One in six patients experienced POD after TAVI under general anesthesia. POD was the strongest predictor of long-term mortality and was associated with impaired short- and long-term survival. Prior delirium and a more calcified aortic valve were the strongest independent predictors of POD. J Am Geriatr Soc 67:2325-2330, 2019.

Feasibility and Outcomes of Transcatheter Aortic Valve Implantation Using the Left Axillary Artery as Primary Access Site.

BACKGROUND: The femoral artery is generally used as primary access for transcatheter aortic valve implantation. However, peripheral artery disease often precludes femoral access. The purpose of this study was to describe clinical outcome of transcatheter aortic valve implantation using the left axillary artery (LAA) as primary access site. METHODS: From December 2008 until June 2016, data on all consecutive patients treated with a Medtronic device through the LAA at our hospital were registered, and outcome was prospectively collected according to the updated Valve Academic Research Consortium-2 criteria. Mortality check was performed nationally. RESULTS: In total, 362 patients were included (median age 80 years [range, 76 to 84]; logistic European System for Cardiac Operative Risk Evaluation 17% ± 12%). Successful axillary access was achieved in 99%. Medtronic CoreValve (86%) and Evolut R (14% [Medtronic, Minneapolis, MN]) were implanted. Major vascular complications occurred in 5% of patients, 1% was LAA related. Life-threatening bleeding and major bleeding were observed in 2% and 10%, respectively. Additional complications were new left bundle branch blood (30%), new permanent pacemaker (11%), and stroke (1%). There were 6 procedural deaths (2%) and 19 deaths (5%) within 30 days. One-year mortality rate was 19%. CONCLUSIONS: This is the first study reporting outcome after transcatheter aortic valve implantation using the LAA as default access. We conclude that it is highly feasible and safe with low rates of major vascular complications, bleeding, and stroke.

Intracardiac cement embolism resulting in tricuspid regurgitation.

Bone cement leakage is a common complication after percutaneous kyphoplasty. In rare cases, leakage into the venous system occurs, which can be life-threatening, especially when it embolizes the heart. Here, we present a case of cement embolization of the right ventricle with tricuspid valve involvement. A 69-year-old woman with an asymptomatic severe tricuspid valve regurgitation was referred to our department. She had a history of balloon kyphoplasty because of osteoporotic collapsed vertebrae in 2010. Echocardiography showed a foreign body attached to the right ventricle, prolapsing into the right atrium and causing a severe tricuspid valve regurgitation. The foreign body was surgically removed, and the tricuspid valve was replaced with a biological valve. The foreign body was analysed by scanning electron microscopy and element analysis. Zirconium was identified within the foreign body, which is an additive in bone cement used in orthopaedic surgery. Intracardiac cement embolism following percutaneous kyphoplasty is a rare but life-threatening complication. Here, we present a case of tricuspid valve destruction caused by the long-term presence of an intracardiac foreign body, specifically a cement embolus.

MDCT evaluation of aortic root and aortic valve prior to TAVI. What is the optimal imaging time point in the cardiac cycle?

OBJECTIVES: To determine the optimal imaging time point for transcatheter aortic valve implantation (TAVI) therapy planning by comprehensive evaluation of the aortic root. METHODS: Multidetector-row CT (MDCT) examination with retrospective ECG gating was retrospectively performed in 64 consecutive patients referred for pre-TAVI assessment. Eighteen different parameters of the aortic root were evaluated at 11 different time points in the cardiac cycle. Time points at which maximal (or minimal) sizes were determined, and dimension differences to other time points were evaluated. Theoretical prosthesis sizing based on different measurements was compared. RESULTS: Largest dimensions were found between 10 and 20% of the cardiac cycle for annular short diameter (10%); mean diameter (10%); effective diameter and circumference-derived diameter (20%); distance from the annulus to right coronary artery ostium (10%); aortic root at the left coronary artery level (20%); aortic root at the widest portion of coronary sinuses (20%); and right leaflet length (20%). Prosthesis size selection differed depending on the chosen measurements in 25-75% of cases. CONCLUSION: Significant changes in anatomical structures of the aortic root during the cardiac cycle are crucial for TAVI planning. Imaging in systole is mandatory to obtain maximal dimensions. KEY POINTS: • Most aortic root structures undergo significant dimensional changes throughout the cardiac cycle. • The largest dimensions of aortic parameters should be determined to optimize TAVI. • Circumference-derived diameter showed maximum dimension at 20% of the cardiac cycle.

Frequency and prognosis of new bundle branch block induced by surgical aortic valve replacement.

OBJECTIVES: Recently, transcatheter aortic valve implantation has been introduced, but one of its complications is left bundle branch block (LBBB), a conduction disturbance that has been associated with increased mortality. We investigated the incidence and fate of both right bundle branch block (RBBB) and LBBB after aortic valve replacement (AVR) using a retrospective analysis. We also studied the predictive value of both disorders for all-cause mortality. METHODS: All patients who underwent AVR, with or without concomitant coronary artery bypass grafting surgery, between 2002 and 2010 in our centre were included. All-cause mortality was compared between patients who did and those who did not develop persistent new bundle branch block (BBB) within 7 days postoperatively. Patients were not eligible if one of their electrocardiogram (ECG) recordings prior to AVR showed a BBB or pacemaker activity. A postoperative period of 3-12 months was used to collect follow-up ECGs. RESULTS: Of the 2279 AVR patients, 2033 patients were eligible for analysis. After excluding patients lacking baseline or follow-up ECG (n = 269), 1764 patients remained for analysis. Early LBBB and RBBB occurred in 71 (4.0%) and 92 (5.2%) patients, respectively. At follow-up, LBBB was persistent in 29 patients (1.6%) and RBBB in 74 patients (4.2%). During a median follow-up of 4.5 (2.4-6.5) years, the mortality rate was 16.3% (n = 271) in patients without BBB, 24.1% (n = 7) in patients with persistent LBBB and 18.9% (n = 14) in patients with persistent RBBB (log-rank P = 0.49). Though, in univariate analysis, the hazard ratio for mortality was 1.54 and 1.10 for LBBB and RBBB, respectively, the small numbers precluded identifying AVR-induced LBBB and RBBB as a predictor of mortality. CONCLUSIONS: In the current practice of AVR, persistent postoperative LBBB and RBBB occur infrequently (∼ 5% of cases), a percentage less than half of that in current transcatheter aortic valve implantation procedures. Given the adverse effects of LBBB, the lower prevalence of procedure-induced LBBB in AVR should be taken into account while deciding which valve replacement procedure is chosen for a patient.

Trends in the occurrence of new conduction abnormalities after transcatheter aortic valve implantation.

OBJECTIVES: The aim of the study was to investigate trends over time in the occurrence of left bundle branch block (LBBB) and permanent pacemaker implantation (PPI) after transcatheter aortic valve implantation (TAVI) with the Medtronic CoreValve System (MCS) and Edwards SAPIEN Valve (ESV). BACKGROUND: TAVI-induced conduction abnormalities (TAVI-CAs) such as LBBB and the need for PPI are frequent postoperative complication. New techniques, procedural refinements, and increased awareness are focused on the reduction of these abnormalities. METHODS: Electrocardiograms of 549 patients without preprocedural LBBB and/or pacemaker were assessed to determine the frequency and nature of TAVI-CAs. To study the effect of experience, patients were subdivided per center into tertiles based on the number of procedures. Univariate and multivariate logistic regression was used to study predictors of TAVI-induced LBBB (TAVI-LBBB) and PPI. RESULTS: TAVI-LBBB occurred in 185 patients (33.7%) and significantly decreased over time, from 42.6% to 27.3% (P=0.006). This effect was only significant after implantation of the MCS (59.6% vs. 46.5% vs. 31.1%, P=0.001, ESV: 22.6% vs. 13.1% vs. 24.8%, P=0.11). Between tertiles there was no difference in the frequency of PPI after TAVI (n=73, 13.1% vs. 14.8% vs. 12%, P=0.74). Multivariate analysis revealed that, independent from valve type, depth of implantation was the only significant predictor of TAVI-LBBB (OR [95% C.I.]: 1.16 [1.10-1.24], P<0.001). In case of PPI pre-existing RBBB (OR [95% C.I.]: 7.22 [3.28-15.88], P<0.001) was the only significant predictor. CONCLUSIONS: Over time the frequency of LBBB after TAVI decreased significantly, especially in patients undergoing TAVI with the MCS. Experience and the subsequent reduction in depth of implantation seem responsible for this reduction. Contrary to TAVI-LBBB, the incidence of PPI remained unchanged over time and was not affected by experience. Although experience has led to a decrease in new CAs after TAVI, elucidation of pathophysiologic mechanisms underlying these CAs and subsequent changes in patient stratification, valve design and the procedure are needed to further reduce this complication.

Transcatheter aortic valve implantation-induced left bundle branch block: causes and consequences.

Transcatheter aortic valve implantation (TAVI) is an alternative treatment option for patients with severe aortic valve stenosis who do not qualify for surgical aortic valve replacement (AVR). Besides its proven clinical benefits, one of the complications of TAVI is the creation of conduction abnormalities, like left bundle branch block (LBBB). New LBBB occurs between 7 and 65% of cases, numbers that differ considerably between devices. In this review, we discuss the possible causes and the clinical significance of TAVI-induced LBBB. Several device- and procedural-related factors seem responsible for the development of LBBB, of which depth of implantation and balloon-annulus diameter ratio are the most important ones. TAVI-induced LBBB negatively affects cardiac function and hospitalization, but its impact on mortality is subject of debate. Future research and registries should implement strict diagnostic criteria for LBBB together with recording of its timing and persistence.

Clonal heterogeneity of thymic B cells from early-onset myasthenia gravis patients with antibodies against the acetylcholine receptor.

Myasthenia gravis (MG) with antibodies against the acetylcholine receptor (AChR-MG) is considered as a prototypic autoimmune disease. The thymus is important in the pathophysiology of the disease since thymus hyperplasia is a characteristic of early-onset AChR-MG and patients often improve after thymectomy. We hypothesized that thymic B cell and antibody repertoires of AChR-MG patients differ intrinsically from those of control individuals. Using immortalization with Epstein-Barr Virus and Toll-like receptor 9 activation, we isolated and characterized monoclonal B cell lines from 5 MG patients and 8 controls. Only 2 of 570 immortalized B cell clones from MG patients produced antibodies against the AChR (both clones were from the same patient), suggesting that AChR-specific B cells are not enriched in the thymus. Surprisingly, many B cell lines from both AChR-MG and control thymus samples displayed reactivity against striated muscle proteins. Striational antibodies were produced by 15% of B cell clones from AChR-MG versus 6% in control thymus. The IgVH gene sequence analysis showed remarkable similarities, concerning VH family gene distribution, mutation frequency and CDR3 composition, between B cells of AChR-MG patients and controls. MG patients showed clear evidence of clonal B cell expansion in contrast to controls. In this latter aspect, MG resembles multiple sclerosis and clinically isolated syndrome, but differs from systemic lupus erythematosus. Our results support an antigen driven immune response in the MG thymus, but the paucity of AChR-specific B cells, in combination with the observed polyclonal expansions suggest a more diverse immune response than expected.