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Dive into the research topics where Christian Frerker is active.

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Featured researches published by Christian Frerker.


JAMA | 2014

Comparison of Balloon-Expandable vs Self-expandable Valves in Patients Undergoing Transcatheter Aortic Valve Replacement: The CHOICE Randomized Clinical Trial

Mohamed Abdel-Wahab; Julinda Mehilli; Christian Frerker; Franz-Josef Neumann; Thomas Kurz; Ralph Tölg; Dirk Zachow; Elena Guerra; Steffen Massberg; Ulrich Schäfer; Mohamed El-Mawardy; Gert Richardt

IMPORTANCE Transcatheter aortic valve replacement (TAVR) is an effective treatment option for high-risk patients with severe aortic stenosis. Different from surgery, transcatheter deployment of valves requires either a balloon-expandable or self-expandable system. A randomized comparison of these 2 systems has not been performed. OBJECTIVE To determine whether the balloon-expandable device is associated with a better success rate than the self-expandable device. DESIGN, SETTING, AND PATIENTS The CHOICE study was an investigator-initiated trial in high-risk patients with severe aortic stenosis and an anatomy suitable for the transfemoral TAVR procedure. One hundred twenty-one patients were randomly assigned to receive a balloon-expandable valve (Edwards Sapien XT) and 120 were assigned to receive a self-expandable valve (Medtronic CoreValve). Patients were enrolled between March 2012 and December 2013 at 5 centers in Germany. INTERVENTIONS Transfemoral TAVR with a balloon-expandable or self-expandable device. MAIN OUTCOMES AND MEASURES The primary end point was device success, which is a composite end point including successful vascular access and deployment of the device and retrieval of the delivery system, correct position of the device, intended performance of the heart valve without moderate or severe regurgitation, and only 1 valve implanted in the proper anatomical location. Secondary end points included cardiovascular mortality, bleeding and vascular complications, postprocedural pacemaker placement, and a combined safety end point at 30 days, including all-cause mortality, major stroke, and other serious complications. RESULTS Device success occurred in 116 of 121 patients (95.9%) in the balloon-expandable valve group and 93 of 120 patients (77.5%) in the self-expandable valve group (relative risk [RR], 1.24, 95% CI, 1.12-1.37, P < .001). This was attributed to a significantly lower frequency of residual more-than-mild aortic regurgitation (4.1% vs 18.3%; RR, 0.23; 95% CI, 0.09-0.58; P < .001) and the less frequent need for implanting more than 1 valve (0.8% vs 5.8%, P = .03) in the balloon-expandable valve group. Cardiovascular mortality at 30 days was 4.1% in the balloon-expandable valve group and 4.3% in the self-expandable valve group (RR, 0.97; 95% CI, 0.29-3.25; P = .99). Bleeding and vascular complications were not significantly different, and the combined safety end point occurred in 18.2% of those in the balloon-expandable valve group and 23.1% of the self-expandable valve group (RR, 0.79; 95% CI, 0.48-1.30; P = .42). Placement of a new permanent pacemaker was less frequent in the balloon-expandable valve group (17.3% vs 37.6%, P = .001). CONCLUSIONS AND RELEVANCE Among patients with high-risk aortic stenosis undergoing TAVR, the use of a balloon-expandable valve resulted in a greater rate of device success than use of a self-expandable valve. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01645202.


Jacc-cardiovascular Interventions | 2012

Direct Percutaneous Access Technique for Transaxillary Transcatheter Aortic Valve Implantation: “The Hamburg Sankt Georg Approach”

Ulrich Schäfer; Yen Ho; Christian Frerker; Dimitry Schewel; Damián Sánchez-Quintana; Joachim Schofer; Klaudija Bijuklic; Felix Meincke; Thomas Thielsen; Felix Kreidel; Karl-Heinz Kuck

OBJECTIVES This study questioned whether transaxillary transcatheter aortic valve implantation (TAVI) is feasible as a true percutaneous approach using percutaneous closure devices. BACKGROUND Transaxillary TAVI is gaining increasing acceptance as an alternative to the transfemoral route; however, the access has always been done via surgical cutdown so far. METHODS Between August 2010 and September 2011, a total of 24 high-risk patients with severe aortic valvular stenosis underwent a percutaneous TAVI procedure by direct puncture of the axillary artery without surgical cutdown. For safety reasons and as a target for the puncture, a wire was advanced via the ipsilateral brachial artery. Moreover, a balloon was placed into the subclavian artery via the femoral artery for temporary vessel blockade before percutaneous vessel closure. Vascular closure was performed using either the ProStar XL system (Abbott Vascular Devices, Redwood City, California) or 2 ProGlide systems (Abbott Vascular Devices). RESULTS The true percutaneous approach was successfully completed in all patients (14 left and 8 right axillary artery cases). Overall mortality at 30 days was 8.3%. Acute vascular closure device success was achieved in 17 patients (71%). Vascular closure device success rate was 100% for the ProGlide device and 37% for the ProStar device, respectively. Seven patients (29%) with failing closure devices were treated by endovascular stent graft implantation without the need for surgical repair. For the last 12 treated patients, direct closure was achieved in 11 patients. CONCLUSIONS Direct puncture of the axillary artery for TAVI is feasible and safe if a wire is placed into the subclavian artery via the ipsilateral brachial artery.


Circulation-cardiovascular Interventions | 2016

Transcatheter Replacement of Failed Bioprosthetic Valves: Large Multicenter Assessment of the Effect of Implantation Depth on Hemodynamics After Aortic Valve-in-Valve

Matheus Simonato; John Webb; Ran Kornowski; Alec Vahanian; Christian Frerker; Henrik Nissen; Sabine Bleiziffer; Alison Duncan; Josep Rodés-Cabau; Guilherme F. Attizzani; Eric Horlick; Azeem Latib; Raffi Bekeredjian; Marco Barbanti; Thierry Lefèvre; Alfredo Cerillo; José M. de la Torre Hernández; Giuseppe Bruschi; Konstantinos Spargias; Alessandro Iadanza; Stephen Brecker; José Honório Palma; Ariel Finkelstein; Mohamed Abdel-Wahab; Pedro Lemos; Anna Sonia Petronio; Didier Champagnac; Jan-Malte Sinning; Stefano Salizzoni; Massimo Napodano

Background—Transcatheter valve implantation inside failed bioprosthetic surgical valves (valve-in-valve [ViV]) may offer an advantage over reoperation. Supra-annular transcatheter valve position may be advantageous in achieving better hemodynamics after ViV. Our objective was to define targets for implantation that would improve hemodynamics after ViV. Methods and Results—Cases from the Valve-in-Valve International Data (VIVID) registry were analyzed using centralized core laboratory assessment blinded to clinical events. Multivariate analysis was performed to identify independent predictors of elevated postprocedural gradients (mean ≥20 mm Hg). Optimal implantation depths were defined by receiver operating characteristic curve. A total of 292 consecutive patients (age, 78.9±8.7 years; 60.3% male; 157 CoreValve Evolut and 135 Sapien XT) were evaluated. High implantation was associated with significantly lower rates of elevated gradients in comparison with low implantation (CoreValve Evolut, 15% versus 34.2%; P=0.03 and Sapien XT, 18.5% versus 43.5%; P=0.03, respectively). Optimal implantation depths were defined: CoreValve Evolut, 0 to 5 mm; Sapien XT, 0 to 2 mm (0–10% frame height); sensitivities, 91.3% and 88.5%, respectively. The strongest independent correlate for elevated gradients after ViV was device position (high: odds ratio, 0.22; confidence interval, 0.1–0.52; P=0.001), in addition to type of device used (CoreValve Evolut: odds ratio, 0.5; confidence interval, 0.28–0.88; P=0.02) and surgical valve mechanism of failure (stenosis/mixed baseline failure: odds ratio, 3.12; confidence interval, 1.51–6.45; P=0.002). Conclusions—High implantation inside failed bioprosthetic valves is a strong independent correlate of lower postprocedural gradients in both self- and balloon-expandable transcatheter valves. These clinical evaluations support specific implantation targets to optimize hemodynamics after ViV.


Jacc-cardiovascular Interventions | 2013

Transcatheter Aortic Valve Replacement With a New Self-Expanding Transcatheter Heart Valve and Motorized Delivery System

Ronald K. Binder; Ulrich Schäfer; Karl-Heinz Kuck; David A. Wood; Robert Moss; Jonathon Leipsic; Stefan Toggweiler; Melanie Freeman; Avi J. Ostry; Christian Frerker; Alexander B. Willson; John G. Webb

OBJECTIVES The aim of this study was to demonstrate feasibility and short- and midterm clinical outcomes with a new self-expanding transcatheter heart valve and motorized delivery system. BACKGROUND Refining transcatheter aortic valve replacement with newly designed bioprostheses and delivery systems is anticipated to facilitate the procedure, reduce the risk of complications, improve outcomes, and widen applicability. METHODS The CENTERA valve (Edwards Lifesciences, Irvine, California) was implanted in 15 patients with symptomatic severe aortic stenosis via femoral or axillary arterial percutaneous access. Patients underwent transesophageal echocardiography during and transthoracic echocardiography and multidetector computed tomography before and after valve implantation. Clinical and echocardiographic follow-up was obtained at 30 days and for the initial 10 patients after 1 year. RESULTS All 15 device implants were successful. Aortic valve area increased from 0.7 ± 0.1 cm(2) to 1.6 ± 0.4 cm(2) post-procedure (p < 0.01) and 1.8 ± 0.3 cm(2) at 1 year. Mean transaortic gradient decreased from 36.3 ± 14.2 mm Hg to 10.6 ± 5.4 mm Hg post-procedure (p < 0.001) and 10.8 ± 4.1 mm Hg at 1 year. Paravalvular aortic regurgitation at 30-day follow-up was none/trivial in 3 (23%), mild in 9 (69%), and moderate in 1 (8%) patient. Four patients (27%) received a new permanent pacemaker. Survival was 87% at 30 days and 80% at 1 year. All surviving patients were in New York Heart Association functional class I (25%) or II (75%) at 1 year. CONCLUSIONS Transcatheter aortic valve replacement with the CENTERA transcatheter heart valve and motorized delivery system is feasible and can lead to good short- and midterm clinical and hemodynamic outcomes.


Eurointervention | 2016

Multicentre clinical study evaluating a novel resheathable annular functioning self-expanding transcatheter aortic valve system: safety and performance results at 30 days with the Portico system.

Ganesh Manoharan; Axel Linke; Helge Moellmann; Simon Redwood; Christian Frerker; Jan Kovac; Thomas Walther

AIMS The aim of this study was to evaluate the safety and performance of the resheathable and repositionable St. Jude Medical Portico self-expanding transfemoral TAVI system. METHODS AND RESULTS This prospective, single-arm, multicentre study evaluated the 18 Fr Portico system with either a 23 or a 25 mm valve. Patient follow-up was at 30, 90, 180 days and one year. Results up to 30 days are presented. Adverse events were categorised by VARC definitions and adjudicated by an independent events committee. Echocardiography was evaluated by an independent laboratory and all patients underwent neurological assessment at baseline, post procedure, at 30 days and one year. The primary endpoint was all-cause mortality at 30 days. A total of 102 patients (mean age 84.1±4.8 years; 97% female; median STS score 5.6) were enrolled. The 30-day mortality, disabling stroke and major vascular complications were 2.9%, 2.9% and 5.9%, respectively. Resheathing and repositioning (23.8%) was successful in all instances. Paravalvular leak at 30 days was none/trace in 30.4%, mild in 65.8% and moderate in 3.8%. Mean gradient improved from 45.3±13.8 to 8.9±3.8 mmHg and valve area improved from 0.6±0.2 to 1.7±0.4 cm2. Permanent pacemaker implantation was required in 9.8% of patients. CONCLUSIONS The novel Portico TAVI system is safe and effective at treating high-risk patients with symptomatic severe aortic stenosis, allowing safe repositioning and optimisation of device position.


Eurointervention | 2014

Balloon-expandable valves for degenerated mitral xenografts or failing surgical rings.

Ulrich Schäfer; Ralf Bader; Christian Frerker; Dimitry Schewel; Thomas Thielsen; Michael Schmoeckel; Felix Kreidel; Karl-Heinz Kuck

AIMS Transcatheter mitral valve-in-valve implantation (TMViVI) for the treatment of failing mitral xenografts or recurrent mitral regurgitation after surgical ring implantation is an emerging therapy for patients in need of repeated mitral valve surgery. Despite the fact that these procedures have been shown to be feasible and effective, haemodynamic data after TMViVI are still limited in the literature. METHODS AND RESULTS Twelve patients (logES: 39.2±23.5%) were treated either by transapical (n=7) or transseptal (n=5) TMViVI, as a valve-in-valve (ViV, n=8) or valve-in-ring (ViR, n=4) implantation. Left atrial pressures (LAP), transmitral gradients and right heart haemodynamics (Swan-Ganz catheterisation) were studied before and after TMViVI. Procedural success was 100%, mitral regurgitation after TMViVI was mild in one, trace in five and absent in six patients. Thirty-day mortality was 0%. Left atrial pressures decreased significantly after valve implantation (before LAPmean/v-wave: 24.3/44.1 mmHg; after LAP/v-wave 15.9/22.1 mmHg; p<0.001) and cardiac output increased significantly. Transmitral gradients corresponded to mitral surface areas between 1.7 and 3.5 cm2, and were thus very acceptable in terms of the high surgical risk population. CONCLUSIONS In conclusion, TMViVI with the balloon-expandable SAPIEN XT valve for ViV or ViR implantation is feasible with promising acute transmitral haemodynamic data. Nevertheless, sustained long-term performance remains to be demonstrated in the future.


Eurointervention | 2016

Emergency transcatheter aortic valve replacement in patients with cardiogenic shock due to acutely decompensated aortic stenosis.

Christian Frerker; Jury Schewel; Michael Schlüter; Dimitry Schewel; Hassan Ramadan; Tobias Schmidt; Thomas Thielsen; Felix Kreidel; Friederike Schlingloff; Ralf Bader; Peter Wohlmuth; Ulrich Schäfer; Karl-Heinz Kuck

AIMS To assess outcomes of TAVR as a rescue therapy in patients with cardiogenic shock due to acutely decompensated aortic stenosis. METHODS AND RESULTS Of 771 high-risk patients who underwent TAVR, 27 (3.5%; 78±9 years; 12 men) were treated emergently due to acutely decompensated aortic stenosis with cardiogenic shock. SAPIEN and CoreValve prostheses were implanted in 11 and 16 patients, respectively: the transfemoral access route was used in 25. Three patients died within 72 hours of successful valve deployment, and a further six died within a month, giving a 30-day mortality of 33.3%, which was significantly higher than in electively treated patients (7.7%, p<0.0001). Univariate predictors of 30-day mortality in cardiogenic-shock patients were baseline cardiac output <3.0 l/min, reduced cardiac power index, impaired renal function, and mechanical ventilation, as well as severe acute kidney injury after TAVR. Estimated one-year survival was 59.3% in emergently and 82.7% in electively treated patients (p=0.0009). However, 30-day landmark analysis showed no difference in cumulative survival between TAVR modalities. In cardiogenic-shock patients without concomitant reduced cardiac output and impaired renal function at baseline (n=22), estimated one-year survival was 72.7%. CONCLUSIONS TAVR should be considered a reasonable rescue therapy in patients with cardiogenic shock secondary to decompensated aortic stenosis.


Clinical Research in Cardiology | 2017

In-hospital mortality in propensity-score matched low-risk patients undergoing routine isolated surgical or transfemoral transcatheter aortic valve replacement in 2014 in Germany

Christian Frerker; Kurt Bestehorn; Michael Schlüter; Maike Bestehorn; Christian W. Hamm; Helge Möllmann; Hugo A. Katus; Karl-Heinz Kuck

AimsRecent randomized trials have documented the superiority of TAVR—particularly via transfemoral access—over SAVR in patients with severe aortic stenosis considered to have a high or intermediate operative risk of death. We sought to assess in-hospital outcomes of patients with severe aortic stenosis and a low risk of operative mortality undergoing routine surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR).Methods and resultsWe performed a propensity-score matched comparison of all patients undergoing first-time treatment by SAVR or transfemoral TAVR (TF-TAVR) in 2014 in Germany who had a logistic EuroSCORE (logES) ≤ 10%, considered to reflect low surgical risk. The primary endpoint of our analysis was in-hospital mortality. Of 7624 SAVR and 9969 TF-TAVR procedures, 6844 (89.8%) and 2751 patients (27.6%), respectively, were considered low risk with a logES between 1.505 and 10.0%. Matching yielded 805 TF-TAVR/SAVR patient pairs with identical propensity scores and no difference in pertinent baseline characteristics, except for the logES, which was significantly higher in TF-TAVR patients (6.8 ± 1.7 vs. 4.2 ± 1.3% in SAVR patients, P < 0.001). Observed in-hospital mortalities were 1.7% (95% confidence interval, 1.1–3.0%) in SAVR and 2.0% (1.3–3.3%) in TF-TAVR patients (P = 0.85).ConclusionOur finding of no difference in in-hospital mortality in propensity-score matched low-surgical-risk patients treated by SAVR or TF-TAVR in a routine clinical setting indicates that TF-TAVR can be offered safely to individual patients, despite their operative risk being low. This finding needs to be confirmed in a randomized trial.


Catheterization and Cardiovascular Interventions | 2015

Clinical impact of paravalvular leaks on biomarkers and survival after transcatheter aortic valve implantation

Dimitry Schewel; Christian Frerker; Jury Schewel; Peter Wohlmuth; Felix Meincke; Thomas Thielsen; Felix Kreidel; Karl-Heinz Kuck; Ulrich Schäfer

There is accumulating evidence that up to 20% of the implanted devices after TAVI are associated with a significant degree of paravalvular leaks, which appear to be associated with a negative clinical outcome.


Heart Lung and Circulation | 2014

MitraClip Implantation as a New Treatment Strategy against Systolic Anterior Motion-induced Outflow Tract Obstruction in Hypertrophic Obstructive Cardiomyopathy

Ulrich Schäfer; Felix Kreidel; Christian Frerker

We report on catheter-based treatment of left ventricular outflow tract (LVOT) obstruction targeting primarily a systolic anterior motion of the anterior mitral leaflet in hypertrophic obstructive cardiomyopathy (HOCM). A patient was successfully treated with the MitraClip two years after septal myectomy in conjunction with mitral valve repair. The results prove the concept, that systolic anterior motion (SAM) is clearly involved in gradient formation and is more than an epiphenomenon in HOCM. Thus, SAM-induced subaortic obstruction might be a target for MitraClip implantation.

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Michael Schlüter

Hamburg University of Technology

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Peter Wohlmuth

Royal Stoke University Hospital

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