An Atraumatic Mock Loop for Realistic Hemocompatibility Assessment of Blood Pumps

OBJECTIVE

Conventional mock circulatory loops (MCLs) cannot replicate realistic hemodynamic conditions without inducing blood trauma. This constrains in-vitro hemocompatibility examinations of blood pumps to static test loops that do not mimic clinical scenarios. This study aimed at developing an atraumatic MCL based on a hardware-in-the-loop concept (H-MCL) for realistic hemocompatibility assessment.

METHODS

The H-MCL was designed for 450 ± 50 ml of blood with the polycarbonate reservoirs, the silicone/polyvinyl-chloride tubing, and the blood pump under investigation as the sole blood-contacting components. To account for inherent coupling effects a decoupling pressure control was derived by feedback linearization, whereas the level control was addressed by an optimization task to overcome periodic loss of controllability. The HeartMate 3 was showcased to evaluate the H-MCL's accuracy at typical hemodynamic conditions. To verify the atraumatic properties of the H-MCL, hemolysis (bovine blood, n = 6) was evaluated using the H-MCL in both inactive (static) and active (minor pulsatility) mode, and compared to results achieved in conventional loops.

RESULTS

Typical hemodynamic scenarios were replicated with marginal coupling effects and root mean square error (RMSE) below 1.74 ± 1.37 mmHg while the fluid level remained within ±4% of its target value. The normalized indices of hemolysis (NIH) for the inactive H-MCL showed no significant differences to conventional loops ( ∆NIH = -1.6 mg/100 L). Further, no significant difference was evident between the active and inactive mode in the H-MCL ( ∆NIH = +0.3 mg/100 L).

CONCLUSION AND SIGNIFICANCE

Collectively, these findings indicated the H-MCL's potential for in-vitro hemocompatibility assessment of blood pumps within realistic hemodynamic conditions, eliminating inherent setup-related risks for blood trauma.

Soluble urokinase plasminogen activator receptor predicts survival and hospitalization for heart failure in elective cardiac surgery

Aims

The study investigated the prognostic value of soluble urokinase plasminogen activator receptor (suPAR) patients undergoing cardiac surgery and calculated a simplified biomarker score comprising suPAR, N-terminal pro B-type natriuretic peptide (NT-proBNP) and age.

Methods and results

Biomarkers were assessed in a cohort of 478 patients undergoing elective cardiac surgery. After a median follow-up of 4.2 years a total of 72 (15.1%) patients died. SuPAR, NT-proBNP and age were independent prognosticators of mortality in a multivariable Cox regression model after adjustment for EuroScoreII. We then calculated a simplified biomarker score comprising age, suPAR and NT-proBNP, which had a superior prognostic value compared to EuroScoreII (Harrel's C of 0.76 vs 0.72; P for difference = 0.02). Besides long-term mortality, the biomarker score had an excellent performance predicting one-year mortality and hospitalization due to heart failure.

Conclusion

The biomarker suPAR and NT-proBNP were strongly and independently associated with mortality in patients undergoing cardiac surgery. A simplified biomarker score comprising only 3 variables (age, suPAR and NT-proBNP) performed better than the established EuroScoreII with respect to intermediate and long-term outcome as well as hospitalization due to heart failure. As such, integration of established and upcoming biomarkers in clinical practice may provide improved decision support in cardiac surgery.

Funding Acknowledgement

Type of funding sources: None.

Fibroblast growth factor-23 is an independent predictor of hospitalization for heart failure and major cardiovascular adverse events in patients undergoing cardiac surgery

Background

Fibroblast growth factor 23 (FGF-23) plays a crucial role in regulating phosphate and vitamin D metabolism and was proved to be associated with an increased risk for fatal events in individuals suffering from cardiovascular diseases. Since data on the prognostic potential of FGF-23 in individuals undergoing cardiac valve and/or coronary artery bypass graft (CABG) surgery are scarce, the specific objective of this study was to investigate the impact of FGF-23 on postoperative complications, particularly postoperative atrial fibrillation (POAF), hospitalization for heart failure (HHF) and cardiovascular (CV) death in an unselected patient population after cardiac surgery.

Methods

Within the present investigation, patients undergoing elective cardiac valve and/or CABG surgery were prospectively enrolled at the Department of Cardiac Surgery of a medical university. Blood samples were taken prior to surgery and FGF-23 concentrations were subsequently assessed. Patients were followed prospectively until the primary study endpoint (CV death) was reached.

Results

In total, 462 patients were included in the present analysis and followed over a median of 3.9 years. During follow-up 67 (14.5%) patients died. The patients' median age was 70 years (interquartile range [IQR] 60 to 75) and 133 (28.8%) were female. The median FGF-23 level in the entire study population was 1.9 pmol/L (IQR 1.2 to 3.5). Notably, individuals with POAF showed significantly higher FGF-23 levels than patients without (p<0.001). After stratification into tertiles (T) of FGF-23 patients in the highest FGF-23 tertile showed greater rates of HHF, all-cause and CV death. Furthermore, FGF-23 was consistently associated with POAF development showing an adjusted OR for a 1-unit increase in standardized log-transformed biomarker of 1.28 (95% CI: 1.01 to 1.63), along with an adjusted OR of 2.04 (95% CI 1.33 to 3.13, p=0.001) for the pre-defined high risk cut-off value. A steady risk increase for HHF and CV death among ascending FGF-23 tertiles has been noted. Moreover FGF-23 showed strong discriminatory performance (area under the curve [AUC] 0.69, 95% CI 0.61–0.77). Reclassification analysis indicated that the addition of FGF-23 to NT-proBNP provides a significant improvement in risk discrimination (NRI at the event rate: 0.58, 95% CI 0.34–0.81, p-value <0.001; IDI: 0.03, 95% CI 0.01–0.05, p-value= 0.001).

Conclusion

FGF-23 proved to be a strong and independent predictor for POAF, HHF and CV death in individuals undergoing cardiac surgery. Considering an individualized risk assessment, routine preoperative FGF-23 evaluation may improve detection of patients at risk, who require in-depth clinical attention throughout the peri- and postoperative phase after cardiac surgery.

Funding Acknowledgement

Type of funding sources: None.

The impact of left atrial mechanics on adverse events and clinical outcome after cardiac surgery

Objectives

Post-operative atrial fibrillation (POAF) represents a common complication after cardiac surgery that is associated with unfavorable clinical outcome. Identifying patients at risk for POAF is crucial but challenging.

Purpose

This study aimed to investigate the prognostic potential of speckle tracking echocardiography (STE) on POAF and fatal adverse events from a long-term perspective.

Methods

A total of 124 patients undergoing elective cardiac surgery were prospectively enrolled and underwent pre-operative STE. Patients were followed prospectively for the occurrence of POAF within the entire hospitalization and reaching the secondary endpoints cardiovascular (CV) and all-cause mortality.

Results

Within the study population 43.5% (n=53) of enrolled individuals developed POAF. After a median follow-up of 3.9 years, 25 (20.2%) patients died. We observed that patients presenting with POAF had lower global peak atrial longitudinal strain (PALS) values compared to the non-POAF arm (POAF: 14.8% [95% CI: 10.9–17.8] vs. non-POAF: 19.4% [95% CI: 14.8–23.5], p<0.001). Moreover, global PALS was a strong and independent predictor for POAF (adjusted Odds Ratio per 1-SD: 0.37 [95% CI: 0.22–0.65], p<0.001), and independently associated with mortality (adjusted Hazard Ratio per 1-SD: 0.63 [95% CI: 0.40–0.99], p=0.048). CART analysis revealed a cut-off value of <17% global PALS as high-risk for both POAF and mortality.

Conclusion

Global PALS is associated with the development of POAF following surgery in an unselected patient population undergoing CABG and/or valve surgery. Since patients with global PALS <17% face a poor long-term prognosis, routine assessment of global PALS needs to be considered in terms of proper secondary prevention in the era of personalized medicine.

Funding Acknowledgement

Type of funding sources: None.

Austrian Analysis of the GUARDIAN Registry: Heart Transplant Effects in Europe from the Global Pandemic

Purpose

Methods

Results

Conclusion

Hemolytic Footprint of Rotodynamic Blood Pumps

OBJECTIVE

In preclinical examinations, rotodynamic blood pumps (RBPs) are predominantly evaluated at design-point conditions. In clinical practice, however, they run at diversified modes of operation. This study aimed at extending current preclinical evaluation of hemolytic profiles in RBPs toward broader, clinically relevant ranges of operation.

METHODS

Two implantable RBPs the HeartMate 3 (HM3) and the HeartWare Ventricular Assist Device (HVAD) were analyzed at three pump speeds (HM3: 4300, 5600, 7000rpm; HVAD: 1800, 2760, 3600rpm) with three flow rates (1-9L/min) per speed setting. Hemolysis measurements were performed in heparinized bovine blood. The delta free hemoglobin (dfHb) and the normalized index of hemolysis (NIH) served as hemolytic measures. Statistical analysis was performed by multiple comparison of the 9 operating conditions. Moreover, computational fluid dynamics (CFD) was applied to provide mechanistic insights into the interrelation between hydraulics and hemolysis by correlating numerically computed hydraulic losses with in-vitro hemolytic measures.

RESULTS

In both devices, dfHb increased toward increasing speeds, particularly during low but also during high flow condition. By contrast, in both RBPs magnitudes of NIH were significantly elevated during low flow operation compared to high flow conditions (p<0.0036). Maps of hemolytic metrics revealed morphologically similar trends to in-silico hydraulic losses (r>0.793).

CONCLUSIONS

While off-design operation is associated with increased hemolytic profiles, the setting of different operating conditions render a preclinical prediction of clinical impact with current hemolysis metrics difficult.

SIGNIFICANCE

The identified increase in hemolytic measures during episodes of off-design operation is highlighting the need to consider worst-case operation during preclinical examinations.

Clinical outcomes of pacemaker implantations before and after cancer diagnosis

Background

Cardiotoxicity caused by anticancer treatment affects cardiac conduction. Clinical outcomes of pacemaker patients with newly diagnosed cancer are insufficiently understood.

Purpose

The aim was to investigate the effect of anticancer therapy on pacemaker properties.

Methods

All patients with pacemaker and confirmed cancer diagnosis treated with chemotherapy at our tertiary university hospital were included in this study. The pacemaker database (containing pacemaker related information) was matched with hospital-wide electronic health records (containing cancer types, comorbidities and echo data). Survival data were retrieved from the Statistics Austria Federal Institute. Clinical and pacemaker data of patients with previously diagnosed cancer requiring pacemaker implantation (Group A) were compared to patients with pre-existing pacemaker followed by cancer diagnosis (Group B).

Results

Out of 972 included patients, 295 patients (30.3%) had the pacemaker implantation after their first cancer diagnosis (Group A), and 677 patients (69.7%) had already a pacemaker before their first cancer diagnosis (Group B). Cancer types are displayed in Figure 1. The following cancer types were associated with increased likelihood for pacemaker implantation after cancer diagnosis (Group A): kidney cancer (OR 2.07, 95% CI 1.12 to 3.83, P=0.02), lymphomas (OR 2.27, 95% CI 1.21 to 4.26, P=0.01), and eye cancer (OR 9.29, 95% CI 1.03 to 83.50, P=0.047). Patients in Group A were older at pacemaker implantation (76.0 years [IQR 68.0–82.2] vs. 72.1 years [IQR 64.3–78.0], P&lt;0.001), and single-chamber pacemakers were less frequent (21.8% vs. 32.1%, P=0.001). Pacemaker implantation due to bradycardic atrial fibrillation was less frequent in Group A (15.6% vs. 21.8%, P=0.03), but implantation due to an “unspecified” indication was increased (20.6% vs. 12.7%, P=0.002). Patients in Group A had lower pacing threshold at baseline but had a stronger increase in pacing threshold during the follow-up as indicated in Table 1. No differences regarding left or right ventricular function, left or right end-diastolic diameter, or mitral or tricuspid regurgitation were detected between the groups. Patients in Group A had smaller left atria (59.7±10.7mm vs. 63.9±24.0mm, P=0.02) and smaller right atria (57.9±10.4mm vs. 61.2±11.8mm, P=0.001). Patients with cancer diagnosis requiring pacemaker had worse 10-year survival (31.2% vs. 51.1%, log-rank P&lt;0.001) as shown in Figure 1.

Conclusion

Kidney cancer, lymphoma, and cancer of the eye were associated with increased probability of pacemaker implantation after cancer diagnosis. The significant increase in pacing threshold in patients undergoing chemotherapy could be associated with chemotherapy-induced cardiotoxicity.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union's Horizon 2020 Future and Emerging Technologies Programme Figure 1. Cancer types and survivalTable 1. Baseline characteristics

The prognostic impact of fibroblast growth factor-23 on cardiovascular death after cardiac surgery

Background

Fibroblast growth factor 23 (FGF-23) participates in phosphate and vitamin D metabolism and proved to be associated with an increased risk for fatal events in individuals presenting with cardiovascular disease. In the era of personalized medicine and individualized prognostication, the identification of novel risk markers seems of major importance in terms of state-of-the-art patient care. Since data on the prognostic potential of FGF-23 in individuals undergoing cardiac valve and/or coronary artery bypass graft (CABG) surgery remain scarce, we aimed to investigate the impact of FGF-23 on cardiovascular (CV) death in an unselected patient population after cardiac surgery.

Methods

Within the present investigation, patients undergoing elective cardiac valve and/or CABG surgery were prospectively enrolled at the Department of Cardiac Surgery of our Medical University. Preoperative blood values were assessed immediately before the surgical intervention. FGF-23 concentrations were measured via FGF Quantikine ELISA Kit (R&D Systems, Minneapolis, USA). Patients were followed prospectively until the primary study endpoint (CV death) was reached. Cox regression models were calculated and adjusted for age, sex, diabetes, heart failure, body mass index, prior myocardial infarction, hypertension and coronary artery disease.

Results

In total, 462 patients were included in the present analysis and followed over a median of 3.9 years. During follow-up 67 (14.5%) patients died. The patients' median age was 70 years (interquartile range [IQR] 60 to 75) and 133 (28.8%) were female. The median FGF level in the entire study population was 1.9 pmol/L (IQR 1.2 to 3.5). After stratification into tertiles (T) of FGF-23 (median FGF-23 T1: 0.95 pmol/L [IQR 0.65 to 1.19], T2: 1.93 pmol/L [IQR 1.64 to 2.28] T3: 4.80 pmol/L [IQR 3.54 to 8.09]), patients in the highest FGF-23 tertile had highest rates of CV death (T1: 4.8%, T2: 6.8%, T3: 19.1%; P-logrank &lt;0.001; Figure A). Moreover, there was a strong association between FGF-23 and CV death (Adj. hazard ratio for 1-unit increase in standardized log-transformed biomarker 1.44, 95% CI: 1.19 to 1.75; P-value &lt;0.001). The risk of CV death increased within higher tertiles of FGF-23 (T3: adj. HR 3.59 [95% CI 1.48–8.71], P-value= 0.005) (T1 was chosen as reference). FGF23 also showed good discriminatory performance (area under the curve [AUC] 0.69, 95% CI 0.61–0.77).

Conclusion

FGF-23 proved to be a strong and independent predictor for CV death in individuals undergoing elective cardiac valve and/or CABG surgery. This biomarker may provide improved risk assessment and fosters individualized patient care in this highly vulnerable patient population in the era of personalized medicine.

Funding Acknowledgement

Type of funding sources: None. Figure 1. Kaplan Meier curves

The prognostic potential of growth differentiation factor-15 on bleeding events and patient outcome after cardiac surgery

Background

GDF-15 (growth/differentiation factor 15) is induced by myocardial stretch, volume overload, inflammation and oxidative stress. Its expression is tightly linked with cardiovascular events as well as the risk for major bleeding and all-cause mortality.

Objective

The objective of the present study was to elucidate the prognostic potential of GDF-15 in patients after cardiac surgery.

Methods

504 patients undergoing elective cardiac valve and/or coronary artery bypass graft surgery were prospectively enrolled. GDF-15 levels were measured prior surgery to evaluate the impact on bleeding events, thromboembolic events and mortality.

Results

Preoperative GDF-15 was associated with the primary endpoint of intra- and postoperative red blood cell transfusion (for bleeding risk factors adjusted [adj] OR [odds ratio] per 1-SD [standard deviation] of 1.62 [95% CI: 1.31–2.00]; p&lt;0.001) and postoperative atrial fibrillation (for atrial fibrillation risk factors adj. OR per 1-SD of 1.49 [95% CI: 1.22–1.81]; p&lt;0.001). Higher concentrations of GDF-15 were observed in patients reaching the secondary endpoint of major or clinically relevant minor bleeding (for bleeding risk factors adj. OR per 1-SD of 1.70 [95% CI: 1.05–2.75]; p=0.030) during the 1stpostoperative year, but not for thromboembolic events. GDF-15 was a predictor for cardiovascular mortality (for comorbidities adj. HR [hazard ratio] per 1-SD of 1.67 [95% CI: 1.23–2.27]; p=0.001) and all-cause mortality (for comorbidities adj. HR per 1-SD of 1.55 [95% CI: 1.19–2.01]; p=0.001). A combined risk model of GDF-15 and EuroSCORE II outperformed the EuroSCORE II alone for long-term survival (c-index: 0.75 [95% CI: 0.70–0.80], p=0.046; net reclassification improvement: 33.6%, p&lt;0.001).

Conclusion

Preoperative GDF-15 concentration is an independent predictor for intra- and postoperative major bleeding, major bleeding during the first year and for long-term cardiovascular or all-cause mortality after cardiac surgery.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Medical University of Vienna Central illustration

The prognostic impact of therapeutic anticoagulation after biological aortic valve replacement

Background

Recent guidelines state that in patients with surgical biological aortic valve replacement (AVR), the use of anti-platelet therapy is as a valid alternative to postoperative anticoagulation (AC) in the absence of a further indication for AC. However, the prognostic impact of different anti-thrombotic strategies after biological AVR has not clearly been investigated so far and outcome data remain scare and inconclusive. Moreover, the AC strategy of patients presenting with post-operative atrial fibrillation (POAF), has not been investigated so far. Therefore, we aim to picture the therapeutic AC approach after biological AVR and whether the presence of POAF effects decision making with regard to anti-thrombotic management.

Methods

Within this prospective observational study 515 patients undergoing elective cardiac valve and or coronary artery bypass graft (CABG) surgery were enrolled. All patients were continuously screened for the development of POAF and followed until the primary endpoint (mortality) was reached. Logistic regression analysis was performed to elucidate the effect of AC on outcome.

Results

A total of 200 individuals underwent biological AVR (including 81 [40.3%] combined AVR+CABG surgeries, median age: 77 years [IQR: 71–80 years]; 133 [66.3%] male gender). 97 (48.3%) patients received therapeutic AC at the time of discharge, including 42 (43.4%) on vitamin K antagonists (VKA), 53 (54.6%) on low-dose low-molecular weight heparin (LMWH) and 2 (2.0%) non-vitamin K antagonist oral anticoagulants (NOACs). 103 (51.2%) patients received another anti-thrombotic approach including 23 (22.3%) on dual anti-platelet therapy (DAPT) and 72 (69.9%) with prophylactic LMWH. Interestingly, the fraction of patients that received AC were comparable between POAF (CHA2DS2-Vasc score 4, IQR: 3–5) and non-POAF individuals (51.9% vs. 44.6%; p=0.304). After a median follow-up time of 1069 days (IQR: 673–1475 days) 21 patients (10.4%) died, referring to 9 (8.3%) non-POAF and 12 (13.0%) POAF individuals. We found that a therapeutic AC after surgery showed a strong and inverse association with 3-year mortality with a crude odds ratio (OR) of 0.31 (95% CI 0.12–0.79; p=0.015). The prognostic potential remained stable after adjustment for potential confounders (p=0.029).

Conclusion

Therapeutic AC showed a strong and independent inverse association with 3-year mortality, mirroring a potential benefit on outcome compared to anti-platelet therapy or low-dose LMWH. However, the fraction of patients receiving therapeutic AC was considerably low – especially NOACs were not commonly used. Despite its association with fatal cardiac adverse events, the presence of POAF was not a relevant value for decision making for the initiation of AC. Further prognostic data on both thromboembolic and bleeding events are needed to elucidate a net-benefit of therapeutic AC in patients with surgical biological AVR who have an indication for AC or present with POAF.

Kaplan-Meier Survival plot

Funding Acknowledgement

Type of funding source: None

Pacemaker lead-induced progression of primary vs. secondary tricuspid regurgitation

Background

Currently no data are available whether the implantation of right ventricular (RV) pacemaker (PM) lead worsens preexisting primary or secondary (functional due to RV dilatation, RVD) tricuspid regurgitation (TR).

Purpose

The aim of the present retrospective analysis was to assess TR after PM implantation with a RV lead.

Methods

Patients with PM implantation (n=990) were enrolled if they had routine echocardiography including assessment of TR before first implantation and immediately after. RVD and severity of TR were characterized visually. Based on RVD in baseline echocardiography, patients were divided into 2 groups: with primary TR (without preexisting RVD, n=743) or secondary TR (with preexisting RVD, n=243).

Results

Lead-induced worsening of TR was present in both groups (Table 1). Progression from mild/moderate to severe TR was observed in 6.7% of patients with primary TR, compared to 25.6% of patients with secondary TR (P=0.001). Using an ordinal regression model, the probability to progress to severe TR with primary TR was 14.8% (95% CI 11.0%-19.7%), compared to 41.6% (95% CI 40.3%-42.8%) with secondary TR (P&lt;0.001).

Conclusion

Preexisting secondary TR was associated with higher rates of lead-induced progression to severe TR compared to primary TR. Leadless pacing or tricuspid valve clipping post-PM implantation could be an option for patients with preexisting secondary TR and indication for a PM.

Table 1. Patient characteristics.

Funding Acknowledgement

Type of funding source: Public grant(s) – EU funding. Main funding source(s): This study was supported by the European Union's Horizon 2020 Future and Emerging Technologies Programme [Grant number 732170].

Anticoagulation and outcomes after surgical aortic valve replacement with a biological prosthesis

Background

No strong recommendation exists regarding the use of short-term anticoagulation after surgical aortic valve replacement (SAVR) with a biological prosthesis.

Purpose

Our aim was to analyze outcomes of patients receiving warfarin versus low-molecular weight heparin (LMWH) after isolated SAVR.

Methods

We retrospectively analyzed all adult patients who underwent surgery between 2009 and 2017 at our department (n=598). Exclusion criteria included pre-operative anticoagulation, atrial fibrillation, dialysis, previous aortic valve replacement, or active endocarditis. Patients who were discharged alive were stratified according to the type of anticoagulation (warfarin, n=332, 55.5%; LMWH, n=266, 44.5%). Long-term survival during the follow-up period was analyzed (median follow-up, 5.6 years).

Results

Patients who received warfarin had significantly lower logistic EuroSCORE and were younger (Table 1). Warfarin was more frequently utilized between 2009 and 2014, whereas LMWH was more commonly used between 2015 and 2017. Kaplan-Meier curves in Figure 1 show that patients who received warfarin had significantly superior long-term survival (log-rank test: p=0.002). Multivariable Cox proportional hazards regression analysis confirmed that the use of warfarin was associated with significantly lower risk of long-term mortality when compared with LMWH (hazard ratio [HR] 0.50, 95% confidence interval [CI] 0.34–0.74, p=0.001). Covariables in this model included logistic EuroSCORE, era, and duration of cardiopulmonary bypass.

Conclusions

The present analysis suggests that the use of warfarin is associated with significantly superior survival after SAVR with a biological prosthesis. Our findings require validation in a prospective randomized controlled trial.

Figure 1. Kaplan-Meier survival curves

Funding Acknowledgement

Type of funding source: None

P4736The Prognostic Impact of Volume Substitution on Cardiac Strain and the Development of Postoperative Atrial Fibrillation after Cardiac Surgery

Background

Postoperative atrial fibrillation (POAF) represents a common complication after cardiac valve or coronary artery bypass surgery. Etiologically, multifactorial causes such as the patients' age, weight, comorbidities or local remodeling proved a strong association with this common arrhythmia. While strain of atrial tissue is known to induce atrial fibrillating impulses, less attention has been paid to potentially strain-promoting values during the peri- and post-operative period. Therefore, we aimed to determine the association of peri- and post-operative volume substitution on markers of cardiac strain and subsequently its impact on the promotion and development of POAF.

Methods

In this prospective observational study 271 patients undergoing elective cardiac surgery in our Medical University were enrolled (median age: 69 years [IQR: 60–75 years]; 195 [72%] male gender). Intra- and post-operative data was collected from anesthesiologic and intensive care unit protocols. Multivariate binary logistic regression analysis was used to identify the prognostic value of volume substitution on the development of POAF.

Results

A total of 123 (45.4%) individuals developed POAF. The average intra-operative transfusion volume was significantly elevated in the POAF subgroup (605.6ml [POAF] vs. 227.1ml [non-POAF]; p<0.001). Moreover, the fluid balance within the first 24 hours after surgery was significantly higher in patients developing POAF (+1129.6 ml [POAF] vs. +544.9 ml [non-POAF]; p=0.044). We found that N-terminal pro brain natriuretic peptide (NT-proBNP) values were significantly elevated in patients that received any volume substitution (2860.0 pg/mL [Transfusion] vs. 1486.5 pg/mL [no-Transfusion]; p=0.002). In line with those results, the postoperative fluid balance was also found to have a direct and significant correlation with postoperative NT-ProBNP values (r=0.287, p=0.002). Of note, the amount of substituted volume proved to be a strong and independent predictor for POAF with an adjusted odds-ratio (OR) per one standard deviation (1-SD) of 2.49 (95% CI: 1.25–4.96; p=0.009).

Conclusion

Within the present analysis we were able to demonstrate that substitution of larger transfusion volumes presents a strong and independent predictor for the development of POAF. Via the observed distinct association with NT-proBNP values, it can reasonably be assumed that post-operative atrial fibrillating impulses are triggered via volume-induced cardiac strain.

P1840Mid-term results of bioprosthetic aortic valve replacement with the Trifecta valve: A word of caution

Background

Structural valve deterioration (SVD) with associated bioprosthetic valve dysfunction remains an unsolved problem, exposing patients to the risk of aortic valve re-intervention after surgical aortic valve replacement (SAVR). Several strategies have been proposed to improve prosthesis design for optimal performance. The leaflets of the Trifecta valve are mounted on the outside of the prosthetic stent to achieve a larger orifice area. Although favourable early clinical outcomes have been reported, long-term durability still needs to be assessed.

Purpose

The aim of the current study was to assess the mid-term overall mortality and re-intervention rate in patients who received a Trifecta valve with a follow-up >5 years.

Methods

Patients who underwent SAVR at our centre between 2011 and 2012 were identified in the internal, prospective database. All patients with implantation of a Trifecta valve in aortic position were included. Primary endpoints were freedom from overall mortality and from re-operation at latest follow-up (FU). Additionally, assessment of echocardiographic parameters at baseline and follow-up was performed.

Results

Seventy-six patients (age 77.3±9.5 years, BMI 28.6±5.8, 68% male) were included in the study. EuroScore II was 7.2% (± 7.7) while mean STS-Mortality score was 2.4±1.1%. Of all procedures, 53% were isolated aortic valve replacements, whereas concomitant procedures were performed in 47% of cases (37% CABG, 12% mitral surgery, 8% tricuspid surgery). Baseline echocardiographic assessment showed a mean pressure gradient (MPG) of 51±21 mmHG, a peak pressure gradient (PPG) of 78±36 mmHG and a peak velocity (Vmax) of 4.2±1.1 m/s.

Thirty-day mortality was 7%. Freedom from overall mortality at 1 year and 5 years was 84% and 73%, respectively. Freedom from death and freedom from re-operation at latest FU (6.7±0.5 years) was 68% and 90%, respectively. In a composite endpoint analysis, freedom from death or re-intervention at latest follow up was 60%. A total of 7 patients underwent aortic valve re-interventions (re-replacements n=5, valve-in-valve n=2). Indications for re-interventions were SVD (n=5), NSVD (n=1, pannus ingrowth) and endocarditis (n=1). One case of re-stenosis occurred in a patient who was deemed not feasible for aortic valve re-intervention and died.

Kaplan Meier analysis

Conclusion(s)

To our knowledge, this patient cohort presents with the lowest rate of freedom from re-operation (90%, 6.7±0.5 years) after SAVR with the Trifecta valve. A relatively high number of SVD and NSVD has been observed, which might be attributable to the specific leaflet mounting or the deformable valve frame of the first generation. Current results call for further investigation with prospective echocardiographic follow-up in this patient group.

Acknowledgement/Funding

None

P1891CD8+CD28null T lymphocytes are associated with the development of atrial fibrillation after elective cardiac surgery

Background

Post-operative atrial fibrillation (POAF) is assumed as a complex and multifactorial interaction of different pathogenic factors. Data suggests an inflammatory process as a main trigger of this specific type of atrial fibrillation. CD8+ T lymphocytes that lack the surface protein CD28 were found to be crucially involved in chronic inflammatory processes within the cardiovascular system. Of utmost interest, these so called CD8+CD28null T cells are known to present with auto-aggressive behavior and deleterious cytotoxic effects on human tissue. Therefore, the impact of cellular immunity on the development of POAF was sought to assess.

Methods

To elucidate the impact of cellular immunity on the development of POAF, we prospectively enrolled 129 patients undergoing elective cardiac valve and/or coronary-artery-bypass-graft surgery. Fluorescein-activated cell sorting (FACS) was performed to investigate lymphocyte subsets. Patients were stratified in two subgroups according to patients developing POAF (n=60) and individuals free of POAF (n=69). Binary logistic regression analysis was performed to assess the impact of cellular immunity on the development of POAF.

Results

Comparing patients developing POAF to individuals free of POAF the fraction of CD8+ lymphocytes was significantly higher in individuals developing POAF (30.5% [POAF] vs. 25.7% [non-POAF]; p=0.021) Interestingly, the fraction of CD8+CD28nullT-lymphocytes was significantly higher in the POAF sub-group (66.7% [POAF] vs. 61.6% [non-POAF]; p=0.043). Binary logistic regression further proved that the fraction of CD8+CD28null T cells was a strong prognosticator for the development of POAF with a crude odds ratio per one standard deviation of 3.45 (95% CI 1.11–10.70; p=0.032). The prognostic potential remained stable after adjustment for potential confounders (age, male gender and type of surgery) within the multivariate model with an adjusted odds ratio per one standard deviation of 3.21 (95% CI 1.01–10.18; p=0.048).

Conclusion

We found that cytotoxic CD8+CD28null T lymphocytes proved to be a strong and independent predictor for the development of POAF after elective cardiac surgery. Our results potentially indicate an auto-immune impact of this preexisting, highly cytotoxic T cell subset in the pathogenesis of POAF.

Acknowledgement/Funding

Verein zur Förderung der Forschung – Atherosclerosis Thrombosis and Vascular Biology (Vienna, Austria)

Mechanical Bridge to Transplantation with the Vienna Heart in TAH and LVAD Configuration

The Vienna heart uses a vacuum formed, pellethane pulsatile ventricle and is available in left ventricular assist (LVAD) and total artificial heart (TAH) configurations. This device was used as mechanical support of the failing heart in nine patients intended for heart transplantation. In two patients with cardiomyopathy an orthotopic TAH was implanted; one survived despite severe preoperative ischemic liver damage, and the other died of sepsis.

In seven patients an atrio-aortic LVAD was implanted; six had suffered an acute myocardial infarction with cardiogenic shock, and one could not be weaned off bypass. Three patients survived. These included one 65-year-old with incipient ARDS at operation, and a 40-year-old with preoperative liver and kidney insufficiency who was transplanted in septicemia. In this patient the septic focus, natural and artificial heart, were removed at transplantation.

Four patients died. In one we were unable to establish satisfactory circulation, one died after failure of the transplanted heart, one suffered a lethal cerebral embolism and one developed multi-organ failure after repeated attacks of ventricular fibrillation.

With the Vienna heart sufficient circulatory support could be established with cardiac outputs between 6 and 8 l/min for the TAH and 3.5 to 4.5 I/min for the LVAD. With this type of support an overall survival rate of 44% could be achieved. Mechanical hemolysis was not a clinical problem and no device failure occurred.