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Factors Related to Pump Thrombosis at Select Medium to High Volume Centers
Abstracts S131 3( 45)
No Difference in Pump Thrombosis in Heartmate II Patients With Gelatin Sealed and Unsealed Vascular Grafts K.S. Sundareswaran , D.J. Farrar. Research and Scientific Affairs, Thoratec Corporation, Pleasanton, CA.
3( 44) Factors Related to Pump Thrombosis at Select Medium to High Volume Centers C.T. Klodell ,1 H.T. Massey,2 R. Adamson,3 D. Dean,4 D. Horstmanshof,5 J. Ransom,6 C.T. Salerno,7 J. Cowger,7 J. Aranda,8 L. Chen,2 J.W. Long,5 K.S. Sundareswaran,9 D.J. Farrar,9 W. Dembitsky.3 1Division of Thoracic and Cardiovascular Surgery, University of Florida, Gainesville, FL; 2University of Rochester Medical Center, Rochester, NY; 3Sharp Memorial Hospital, San Diego, CA; 4Piedmont Hospital, Atlanta, GA; 5INTEGRIS Baptist Medical Center, Oklahoma City, OK; 6Baptist Health Heart Institute, Little Rock, AR; 7St. Vincent Heart Center of Indiana, Indianapolis, IN; 8Division of Cardiology, University of Florida, Gainesville, FL; 9Research and Scientific Affairs, Thoratec Corporation, Pleasanton, CA. Purpose: Recent reports have suggested that HeartMate II (HMII) thrombosis rates may be higher in implants after 2011 than what was reported in the clinical trial. However, there is wide variability in experiences among centers. We sought to characterize events at high volume HMII centers (> 100 HMII implants) whose device thrombosis rates are lower than those reported by INTERMACs. Methods: 7 centers pooled their clinical data in order to identify common patient (pt) characteristics and clinical strategies that could potentially mitigate the risk of device thrombosis. All centers believed that optimal positioning of the inflow cannula and an appropriately configured pump pocket is critical. Median target INR was 2.25 (range 2.0-2.5), and median target pump speed was 9200 (range: 8600-9600). 530 pts (average: 1.21 ± 0.76 yrs, total: 641 Pt. yrs) were implanted at these centers in 2011 and 2012. Pump thrombus was suspected when there was clinical evidence (e.g. hemolysis, positive ramp test) requiring intervention (e.g. anticoagulation therapy, pump exchange) or patient death. 1 yr survival and stroke rates were also determined. Results: At 6 months, 13 pump exchanges were performed for suspected thrombosis (2.5%), which compares favorably to the rate reported by INTERMACS(5%). Stroke (hemorrhagic: 0.04 events per patient year [eppy] and ischemic: 0.05 eppy]) as well as survival (6 months: 88 ± 2%; 1 yr: 79 ± 2%) were consistent with the national average. 64% (18/28) with suspected thrombosis had at least one risk factor: 10 with sub therapeutic INR (< 1.5) at event, 5 non-compliant with medications, 5 with known hypercoagulable disorder, 7 with recent infection, and 1 with known inflow cannula malposition. In 10 cases (36%), there were no known risk factors. Conclusion: This analysis demonstrates low event rates for thrombus at select medium to large volume centers. Minimization of risk factors by uniform implant techniques, consistent post-op management, and a well aligned team organization can help to reduce the risk of device thrombosis.
Incidence of Device Thrombosis HMII Implants (2011-2012) Freedom from Suspected Thrombosis at 6 months Freedom from Device Exchange for Pump Thrombosis at 6 months
530 94.2 ± 1.1% (28 events) 97.5 ± 0.7% (13 events)
Purpose: INTERMACS data indicates a decrease from 98% to 95% in freedom from pump removal for suspected or confirmed thrombus at 6 months in HeartMate II (HMII) LVAD patients before and after May 2011. This is coincidentally in the same time period as the introduction of sealed vascular grafts in the inflow and outflow conduits of the device. The purpose of the sealed graft design change was to remove the need to pre-clot the grafts prior to implantation, remove the variability in pre-clotting methods, and reduce postoperative bleeding. This analysis was conducted to determine if the design change had any effect on pump thrombus rates. Methods: Thoratec started shipping the HMII with gelatin impregnated polyester grafts for the inflow and outflow conduits in the first half of 2011, as a replacement for conduits with the previous unsealed polyester vascular grafts. We analyzed 2881 pumps implanted that year (1905 with sealed grafts; 976 with un-sealed grafts), and reviewed the Thoratec Corporation Customer Complaint and Device Tracking Databases for suspected pump thrombosis, including the subset of patients requiring pump exchange. Freedom from event analysis was performed with the Kaplan-Meier method and differences determined with the log rank test. Temporal bias was reduced by limiting the analysis to just implants in 2011 when both sealed and unsealed grafts were being utilized. Results: In the first 6 months after implant, there were 120 (6.3%) reports of suspected pump thrombus in 1905 patients with sealed grafts, compared to 57 (5.8%) in 976 patients with un-sealed grafts. There was no difference in freedom from suspected pump thrombus or pump exchange for suspected pump thrombus between the graft types. Conclusion: This analysis indicates no difference in the incidence of device thrombosis in HeartMate II patients with sealed and unsealed grafts.
Incidence of Device Thrombosis
Type of Vascular Grafts Used
N
Un-Sealed Grafts Sealed Grafts
976 1905
Freedom from Suspected Thrombosis at 6 months
Freedom from Pump Exchange for Suspected Thrombosis at 6 months
93.0±0.8% 92.6±0.7% P= NS
96.3±0.7% 96.3±0.5% P= NS
3( 46) LVAD Exchange for Thrombosis Is Associated with Higher Recurrent Rates of Hemolysis, Thrombosis, and Death A.M. Andruska ,1 M. Nassif,1 E. Novak,1 G.A. Ewald,1 S.J. LaRue,1 S.C. Silvestry,2 A. Itoh.2 1Department of Cardiology, Washington University School of Medicine, Saint Louis, MO; 2Department of Cardiothoracic Surgery, Washington University School of Medicine, Saint Louis, MO. Purpose: Morbidity and mortality from device thrombosis of left ventricular assist devices (LVADs), manifesting as hemolysis or pump failure, is profound and often leads to device exchange. Long term outcomes for patients undergoing pump exchange for hemolysis, thrombus, and thrombosis are unknown. Methods: We identified 329 consecutive patients receiving a continuous-flow LVAD and surviving index hospitalization (272 Heartmate II, 36 Heartware devices) at a single institution from 6/01/2005-10/17/2009. 17 patients (8.2%) underwent VAD exchange, 16 due to pump failure with hemolysis/ thrombosis and 1 for persistent hemolysis. 15 of 17 exchanges were performed emergently. The exchange group was compared to a control population of initial VAD implants (291 patients) for the primary outcome of time to hemolysis or thrombosis (defined as pump failure with obstructive thrombus found during exchange or autopsy OR severe hemolysis with LDH > 600 for Heartware or > 875 for Heartmate II). Secondary end points of time to death and a combination of death or thrombosis were also evaluated.
No Difference in Pump Thrombosis in Heartmate II Patients With Gelatin Sealed and Unsealed Vascular Grafts K.S. Sundareswaran , D.J. Farrar. Research and Scientific Affairs, Thoratec Corporation, Pleasanton, CA.
3( 44) Factors Related to Pump Thrombosis at Select Medium to High Volume Centers C.T. Klodell ,1 H.T. Massey,2 R. Adamson,3 D. Dean,4 D. Horstmanshof,5 J. Ransom,6 C.T. Salerno,7 J. Cowger,7 J. Aranda,8 L. Chen,2 J.W. Long,5 K.S. Sundareswaran,9 D.J. Farrar,9 W. Dembitsky.3 1Division of Thoracic and Cardiovascular Surgery, University of Florida, Gainesville, FL; 2University of Rochester Medical Center, Rochester, NY; 3Sharp Memorial Hospital, San Diego, CA; 4Piedmont Hospital, Atlanta, GA; 5INTEGRIS Baptist Medical Center, Oklahoma City, OK; 6Baptist Health Heart Institute, Little Rock, AR; 7St. Vincent Heart Center of Indiana, Indianapolis, IN; 8Division of Cardiology, University of Florida, Gainesville, FL; 9Research and Scientific Affairs, Thoratec Corporation, Pleasanton, CA. Purpose: Recent reports have suggested that HeartMate II (HMII) thrombosis rates may be higher in implants after 2011 than what was reported in the clinical trial. However, there is wide variability in experiences among centers. We sought to characterize events at high volume HMII centers (> 100 HMII implants) whose device thrombosis rates are lower than those reported by INTERMACs. Methods: 7 centers pooled their clinical data in order to identify common patient (pt) characteristics and clinical strategies that could potentially mitigate the risk of device thrombosis. All centers believed that optimal positioning of the inflow cannula and an appropriately configured pump pocket is critical. Median target INR was 2.25 (range 2.0-2.5), and median target pump speed was 9200 (range: 8600-9600). 530 pts (average: 1.21 ± 0.76 yrs, total: 641 Pt. yrs) were implanted at these centers in 2011 and 2012. Pump thrombus was suspected when there was clinical evidence (e.g. hemolysis, positive ramp test) requiring intervention (e.g. anticoagulation therapy, pump exchange) or patient death. 1 yr survival and stroke rates were also determined. Results: At 6 months, 13 pump exchanges were performed for suspected thrombosis (2.5%), which compares favorably to the rate reported by INTERMACS(5%). Stroke (hemorrhagic: 0.04 events per patient year [eppy] and ischemic: 0.05 eppy]) as well as survival (6 months: 88 ± 2%; 1 yr: 79 ± 2%) were consistent with the national average. 64% (18/28) with suspected thrombosis had at least one risk factor: 10 with sub therapeutic INR (< 1.5) at event, 5 non-compliant with medications, 5 with known hypercoagulable disorder, 7 with recent infection, and 1 with known inflow cannula malposition. In 10 cases (36%), there were no known risk factors. Conclusion: This analysis demonstrates low event rates for thrombus at select medium to large volume centers. Minimization of risk factors by uniform implant techniques, consistent post-op management, and a well aligned team organization can help to reduce the risk of device thrombosis.
Incidence of Device Thrombosis HMII Implants (2011-2012) Freedom from Suspected Thrombosis at 6 months Freedom from Device Exchange for Pump Thrombosis at 6 months
530 94.2 ± 1.1% (28 events) 97.5 ± 0.7% (13 events)
Purpose: INTERMACS data indicates a decrease from 98% to 95% in freedom from pump removal for suspected or confirmed thrombus at 6 months in HeartMate II (HMII) LVAD patients before and after May 2011. This is coincidentally in the same time period as the introduction of sealed vascular grafts in the inflow and outflow conduits of the device. The purpose of the sealed graft design change was to remove the need to pre-clot the grafts prior to implantation, remove the variability in pre-clotting methods, and reduce postoperative bleeding. This analysis was conducted to determine if the design change had any effect on pump thrombus rates. Methods: Thoratec started shipping the HMII with gelatin impregnated polyester grafts for the inflow and outflow conduits in the first half of 2011, as a replacement for conduits with the previous unsealed polyester vascular grafts. We analyzed 2881 pumps implanted that year (1905 with sealed grafts; 976 with un-sealed grafts), and reviewed the Thoratec Corporation Customer Complaint and Device Tracking Databases for suspected pump thrombosis, including the subset of patients requiring pump exchange. Freedom from event analysis was performed with the Kaplan-Meier method and differences determined with the log rank test. Temporal bias was reduced by limiting the analysis to just implants in 2011 when both sealed and unsealed grafts were being utilized. Results: In the first 6 months after implant, there were 120 (6.3%) reports of suspected pump thrombus in 1905 patients with sealed grafts, compared to 57 (5.8%) in 976 patients with un-sealed grafts. There was no difference in freedom from suspected pump thrombus or pump exchange for suspected pump thrombus between the graft types. Conclusion: This analysis indicates no difference in the incidence of device thrombosis in HeartMate II patients with sealed and unsealed grafts.
Incidence of Device Thrombosis
Type of Vascular Grafts Used
N
Un-Sealed Grafts Sealed Grafts
976 1905
Freedom from Suspected Thrombosis at 6 months
Freedom from Pump Exchange for Suspected Thrombosis at 6 months
93.0±0.8% 92.6±0.7% P= NS
96.3±0.7% 96.3±0.5% P= NS
3( 46) LVAD Exchange for Thrombosis Is Associated with Higher Recurrent Rates of Hemolysis, Thrombosis, and Death A.M. Andruska ,1 M. Nassif,1 E. Novak,1 G.A. Ewald,1 S.J. LaRue,1 S.C. Silvestry,2 A. Itoh.2 1Department of Cardiology, Washington University School of Medicine, Saint Louis, MO; 2Department of Cardiothoracic Surgery, Washington University School of Medicine, Saint Louis, MO. Purpose: Morbidity and mortality from device thrombosis of left ventricular assist devices (LVADs), manifesting as hemolysis or pump failure, is profound and often leads to device exchange. Long term outcomes for patients undergoing pump exchange for hemolysis, thrombus, and thrombosis are unknown. Methods: We identified 329 consecutive patients receiving a continuous-flow LVAD and surviving index hospitalization (272 Heartmate II, 36 Heartware devices) at a single institution from 6/01/2005-10/17/2009. 17 patients (8.2%) underwent VAD exchange, 16 due to pump failure with hemolysis/ thrombosis and 1 for persistent hemolysis. 15 of 17 exchanges were performed emergently. The exchange group was compared to a control population of initial VAD implants (291 patients) for the primary outcome of time to hemolysis or thrombosis (defined as pump failure with obstructive thrombus found during exchange or autopsy OR severe hemolysis with LDH > 600 for Heartware or > 875 for Heartmate II). Secondary end points of time to death and a combination of death or thrombosis were also evaluated.