Optimal CW-Doppler derived parameter for the diagnosis of iatrogenic mitral stenosis during transcatheter edge-to-edge repair for mitral regurgitation

Introduction

Transcatheter Edge-to-Edge repair (TEER) for mitral regurgitation (MR) is a minimal invasive alternative to surgery for high risk patients. One of the principal disadvantage is the risk of creating a stenosis (MS). The optimal parameter and its cut-off to monitor mitral valve area (MVA) during TEER is currently not defined and usually only the mean transmitral gradient (Gd) is used.

Method

116 patients with complete 3D MVA measurements and CW-Doppler derived mean and maximal diastolic transmitral Gd, and pressure half time (PHT) before the intervention and after each TEER device implantation were included in this study. A clinically significant MS was defined as a 3D MVA <1.5 cm2 according to the ESC guidelines. Because the mean Gd is known to be extremely dependent on the heart rate (HR) this parameter was “normalized” for a frequency of 60/min: norm. mean Gd = (mean Gd/HR) × 60. The accuracy of the different CW-derived parameters to diagnose or predict a MS was evaluated using a ROC analysis.

Results

47% of the patients suffered from a secondary MR, 53% were treated with one device and 47% with two. According to the 3D MVA measurements, after one device 16 and after two devices 12 patients had a clinically significant MS. The ROC analyses for the diagnosis of a significant MS after one device (Figure 1) show a maximal AUC of 0.99 for PHT with an optimal cut-off of 151ms (sensitivity 94%, specificity 95%), followed by norm. mean Gd (AUC 0.96, 3.16mmHg, 100%, 82%), mean Gd (AUC 0.92, 3.6mmHg, 88%, 83%) and max. Gd (AUC 0.92, 8.5mmHg, 94%, 83%). Combining three different cut-offs (PHT 164ms or norm. mean Gd 4.7mmHg or max. Gd 12mmHg) a sensitivity of 100% and a specificity of 98% was achieved. The prognostic value of these same parameters to predict a MS after two devices was much less optimal according to the ROC analyses: PHT, AUC 0.82, 100ms, 83%, 59%; norm. mean Gd AUC 0.73, 2.8mmHg, 67%, 81%; mean Gd AUC 0.70, 2.4mmHg, 83%, 51%; max. Gd AUC 0.69, 8.4mmHg, 50%, 85%. The diagnostic value of the CW-derived parameters measured after the implantation of two devices to detect a MS was better (Figure 2): PHT, AUC 0.92, 142ms, 92%, 78%; norm. mean Gd, AUC 0.87, 3.4mmHg, 92%, 73%; mean Gd, AUC 0.81, 3.9mmHg, 92%, 71%; max. Gd AUC 0.74, 8.6mmHg, 83%, 66%. The cut-offs for PHT without false negative and with the maximal specificity were: 140ms (specificity 86%) to diagnose a MS after one device, 93ms (specificity 56%) to predict a MS after a second device implantation and 133ms (specificity 63%) to detect a MS after two devices.

Conclusion

PHT is the most accurate CW-derived parameter to diagnose or make a prognostic of clinically significant mitral stenosis after TEER. Given the possible disastrous consequence of a iatrogenic stenosis, these parameters should only be used with cut-offs offering a sensitivity of 100% and when a value above these limits is measured, then decisions should be based of 3D MVA measurements.

Funding Acknowledgement

Type of funding sources: None.

Acute impact of transcatheter edge-to-edge repair for mitral regurgitation on left ventricular function

Introduction

Transcatheter Edge-to-Edge repair (TEER) for the therapy of mitral valve regurgitation (MR) is an alternative to surgery for high risk patients. It is a minimal invasive procedure but the acute impact of the pre- and afterload decrease, due to the reduction of both MR and mitral valve area (MVA), on the left ventricle (LV) systolic function was never formally evaluated.

Method

Fifty patients with mixed MR etiologies from our TEER register with complete 3D datasets of the LV before and after TEER were included in this study. LV volumes and function, as evaluate by ejection fraction (LVEF), global longitudinal strain (LV-GLS) and global circumferential strain (LV-GCS), and the MR (3D vena contracta area, 3D VCA) were evaluated before and at the end of the therapy.

Results

The majority of patients suffered from secondary MR (54%), one TEER device was implanted in 64% and two in 36% of the population. TEER leads to a significant reduction of all the LV volume and function parameters excepted for the end-diastolic volume which increased non-significantly (Table 1). The decrease of the LVEF was linked to a decrease of both GLS and GCS in a multivariate analysis (r 0.85), the decrease of GCS having a higher influence (beta −0.606 vs −0.435). In the univariate linear analysis, the reduction of LVEF, GLS and GCS were inverse proportional to the LVEF before TEER and direct proportional to the reduction of the 3D VCA. LVEF decrease was also directly linked to MVA percental reduction. After multivariate evaluation, LVEF reduction kept linked to LVEF before TEER and VCA 3D reduction (r=0.51, p=0.001), GCS decrease only to VCA 3D reduction (r=0.371, P=0.08) and GLS diminution only to LVEF before TEER (r=0.313, p=0.027).

Conclusion

After TEER, left ventricular function reduction seems principally linked to the afterload increase (i.e. the MR reduction); the circumferential function and the left ventricles with the highest ejection fractions being apparently maximally impacted.

Funding Acknowledgement

Type of funding sources: None.

Third generation continuous flow left ventricular assist devices; a comparative outcome analysis by device type

Background

Continuous-flow left ventricular assist devices (CF-LVADs) have become a standard of care in end-stage heart failure (HF). Device-related complications remain high. Limited data exists comparing outcomes of the HeartMate 3 (HM3) and the HeartWare HVAD (HW). We aimed to analyze HM3 and HW devices implanted over the past 10 years with a focus on long-term clinical outcomes of respective patients.

Methods

Investigator-initiated comparative, retrospective observational analysis of all patients who underwent primary implantation of a centrifugal CF-LVAD at our tertiary care academic center between January 2010 and December 2020. Data derived from a prospective registry, and included all patients receiving a HM3 or HW device. Primary endpoint was overall (all-cause) mortality and heart transplantation. Secondary endpoints included device-related major adverse cardiac and cerebrovascular events (MACCE), as well right heart failure (RHF), gastrointestinal (GI) bleeding, driveline infections, and surgical re-interventions.

Results

Out of 106 primary CF-LVAD implantations, 36 (34%) received HM3 and 70 (66%) received HW. Median follow-up time was 1.48 years [interquartile range 0.67, 2.41] and did not differ between devices (p=0.739). HM3 was more often implanted in men (91.7% vs. 72.9%, p=0.024), patients were older (median 61 years [54, 66.5] vs. 52.5 years [43, 60], p<0.001), had a higher body mass index (BMI) (median 26.7 kg/m2 [23.4, 29.0] vs. 24.3 kg/m2 [20.7, 27.4], p=0.013), had more comorbidities and were more likely targeted for destination therapy (DT) (36.1% vs. 14.3%, p=0.010). Death occurred in 33.3% of HM3 patients, compared to 22.9% of HW patients, p=0.247 (probability of survival at 2 years 54.7% vs. 74.1%, p=0.296). After adjustment for confounders, we observed a significant 6-fold risk increase in device malfunctions for HW (hazard ratio (HR) 6.49, 95% CI [1.89, 22.32], p=0.003), but no significant differences between devices in pump thrombosis (p=0.173) or overall survival (p=0.801).

Conclusions

Comparing long-term outcomes between HeartMate 3 and HeartWare HVAD for LVAD support from a prospective registry, HeartWare HVAD patients had a significantly higher risk of device malfunctions. No significant differences were evident between devices in overall survival, and in respect to most clinical outcomes.

Funding Acknowledgement

Type of funding sources: None. KM Plot primary and secondary outcomesRisk analysis on all outcomes

Prospective comparison of noninvasive, bedside ultrasound methods for assessing central venous pressure

PURPOSE

To prospectively evaluate the accuracy of noninvasive central venous pressure (CVP) assessment by compression ultrasound of a forearm vein (CUS), inferior vena cava (IVC-C) and internal jugular vein collapsibility (IJV-C) compared to invasive CVP measurement (invCVP) as the gold standard.

MATERIALS AND METHODS

CUS, IVC-C and IJV-C were performed in a random sequence in 81 consecutive intensive care patients with simultaneous invCVP monitoring. Examiners were blinded to invCVP and previous examinations.

RESULTS

Median invCVP was 12.0 mmHg (range 1 - 23). CUS, IVC-C and IJV-C could be obtained in 89 %, 95 % and 100 % of cases, respectively, within a median time of 188 sec [IQR 125; 270], 133 sec [IQR 100; 211] and 60 sec [IQR 50; 109], respectively. The Spearman correlation coefficient between invCVP and CUS, IVC-C, and IJV-C was 0.485 95 %-CI [0.25; 0.65], -0.186 [-0.42; 0.07], and -0.408 [-0.59; -0.18], respectively. The median absolute difference between CUS and invCVP was 3 mmHg [IQR 2; 6.75]. CVP was categorized as low (< 7 mmHg; collapsibility > 0.6), normal (7 - 12 mmHg; collapsibility 0.6 - 0.2) and high (> 12 mmHg; collapsibility < 0.2) as prespecified. The proportions of identical CVP classifications compared to invCVP were 61.4% 95%-CI [49.3%; 72.4%] with CUS, 48.7% [37.4%; 60%] with IVC-C and 51.3% [40.3%; 62.3%] with IJV-C (p > 0.10 for all pair-wise comparisons).

CONCLUSION

The overall ability of CUS, IVC-C and IJV-C to assess invCVP was only moderate. CUS seems to be the preferable method if absolute CVP values are needed. IJV-C seems to be the fastest and most easily acquirable method, and thus may be especially valuable in emergency rooms.

IgA responses in the intestinal mucosa against pathogenic and non-pathogenic microorganisms

IgA is the most abundant immunoglobulin produced in mammals; most is secreted as a dimer across mucous membranes. This review discusses the different mechanisms of induction of IgA, and its role in protecting mucosal surfaces against pathogenic and non-pathogenic microorganisms.

CD4+ T-cell-epitope escape mutant virus selected in vivo

Mutations in viral genomes that affect T-cell-receptor recognition by CD8+ cytotoxic T lymphocytes have been shown to allow viral evasion from immune surveillance during persistent viral infections. Although CD4+ T-helper cells are crucially involved in the maintenance of effective cytotoxic T-lymphocyte and neutralizing-antibody responses, their role in viral clearance and therefore in imposing similar selective pressures on the virus is unclear. We show here that transgenic virus-specific CD4+ Tcells, transferred into mice persistently infected with lymphocytic choriomeningitis virus, select for T-helper epitope mutant viruses that are not recognized. Together with the observed antigenic variation of the same T-helper epitope during polyclonal CD4+ T-cell responses in infected pore-forming protein-deficient C57BL/6 mice, this finding indicates that viral escape from CD4+ T lymphocytes is a possible mechanism of virus persistence.

Viral escape from the neutralizing antibody response: the lymphocytic choriomeningitis virus model

In addition to CD8+ cytotoxic T lymphocyte (CTL) responses, neutralizing antibodies contribute substantially to the long-term immune control of noncytopathic viruses, as demonstrated during infection with the lymphocytic choriomeningitis virus (LCMV). The high virus load during the initial phase of an infection and the ability of this RNA virus to spontaneously acquire mutations are important prerequisites for escaping an ongoing immune response. In this context, LCMV escape from the humoral response by single point mutations in neutralizing envelope protein determinants may occur, particularly during conditions of CTL deficiency, leading to virus persistence.

Impairment of CD4(+) T cell responses during chronic virus infection prevents neutralizing antibody responses against virus escape mutants

We have shown previously that neutralizing antibodies (nAbs) are important contributors to the long-term immune control of lymphocytic choriomeningitis virus infection, particularly if cytotoxic T cell responses are low or absent. Nevertheless, virus escape from the nAb response due to mutations within the surface glycoprotein gene may subsequently allow the virus to persist. Here we show that most of the antibody-escape viral mutants retain their immunogenicity. We present evidence that the failure of the infected host to mount effective humoral responses against emerging neutralization-escape mutants correlates with the rapid loss of CD4(+) T cell responsiveness during the establishment of viral persistence. Similar mechanisms may contribute to the persistence of some human pathogens such as hepatitis B and C viruses, and human immunodeficiency virus.

Neutralizing antiviral antibody responses

Neutralizing antibodies are evolutionarily important effectors of immunity against viruses. Their evaluation has revealed a number of basic insights into specificity, rules of reactivity (tolerance), and memory—namely, (1) Specificity of neutralizing antibodies is defined by their capacity to distinguish between virus serotypes; (2) B cell reactivity is determined by antigen structure, concentration, and time of availability in secondary lymphoid organs; and (3) B cell memory is provided by elevated protective antibody titers in serum that are depending on antigen stimulation. These perhaps slightly overstated rules are simple, correlate with in vivo evidence as well as clinical observations, and appear to largely demystify many speculations about antibodies and B cell physiology. The chapter also considers successful vaccines and compares them with those infectious diseases where efficient protective vaccines are lacking, it is striking to note that all successful vaccines induce high levels of neutralizing antibodies (nAbs) that are both necessary and sufficient to protect the host from disease. Successful vaccination against infectious diseases such as tuberculosis, leprosy, or HIV would require induction of additional long-lasting T cell responses to control infection.

Viral persistence in vivo through selection of neutralizing antibody-escape variants

Despite initial virus control by CD8(+) cytotoxic T lymphocytes (CTLs), noncytopathic or variably cytopathic viruses (e.g., hepatitis B and C viruses, HIV) are able to establish persistent infections. The role of neutralizing antibodies (nAbs) in controlling disease progression is unclear. Therefore, the phenomenon of viral evasion from the nAb response and its implications for virus persistence remain controversial. Here we demonstrate nAb-mediated viral clearance in CTL-deficient mice infected with the prototypic noncytopathic lymphocytic choriomeningitis virus (strain WE). During prolonged CTL absence, neutralization-resistant virus mutants were selected in individual mice within 70-90 days. In naive animals infected with these virus variants only low nAb responses were induced, resulting in an increased tendency of virus to persist.

Persistence of lymphocytic choriomeningitis virus at very low levels in immune mice

Lymphocytic choriomeningitis virus (LCMV), strain WE, is a non-cytopathic RNA virus that is highly adapted to its natural host, the mouse. Acute infection of adult mice leads to generalized virus spread, followed by cytotoxic T lymphocyte-mediated virus clearance below the detection levels of conventional assays within 2-3 weeks. Indirect evidence had suggested that virus or viral antigen might persist in the immune mouse. Here we demonstrate LCMV-WE persistence at low levels after infection with 10(2) or 10(6) plaque-forming units, shown as viral genome, viral antigen, and replicative virus using sensitive in vitro and in vivo assays. The finding that LCMV-WE persists in the face of apparently intact immune responses resembles the situation in some viral (hepatitis B and C, HIV) and bacterial (tuberculosis, leprosy) infections in humans; the results are relevant to the understanding not only of other murine and human persistent viral infections but also of protective immunological memory by "infection immunity."

Endocarditis due to Aerococcus urinae: diagnostic tests, fatty acid composition and killing kinetics

Two cases of Aerococcus urinae endocarditis are reported. The organism is not included in any database of commercial identification systems at this time. Formation of tetrades and positive reactions for leucine arylamidase and beta-glucuronidase pointed strongly to A. urinae. The cellular fatty acid pattern was similar to that of Aerococcus viridans, with predominantly C16:0, C18:1 omega 9c and C18:0; the presence of C18:1 omega 7t differentiated our isolates from A. viridans and can support the diagnosis of A. urinae. Furthermore, susceptibility to penicillin but resistance to cotrimoxazole represents a pattern opposite to that of A. viridans. Minimal inhibition concentrations of gentamicin and netilmicin were < or = 64 mg/l but those of tobramycin were > or = 256 mg/l. Penicillin combined with either gentamicin or netilmicin showed distinct synergy in killing kinetics. These combinations seem to be the appropriate regimen to treat A. urinae endocarditis.