Analysis of Pump Thrombosis in the Intermacs Database

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Magdalene Adams
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1 Analysis of Pump Thrombosis in the Intermacs Database Michael Acker William Measey Professor of Surgery Chief of Division of Cardiovascular Surgery Director of Heart and Vascular Center University of Pennsylvania Health System 1

2 Disclosures Consultant for Thoratec and Heartware 2

3 Perceived increase in incidence of HMII pump thrombosis after 2011 by several large VAD centers compared to HMII pivotal trial FDA/NHLBI request Intermacs to investigate 3

4 Figure 1 Overall Survival % Survival Months post implant % Survival 1 95% 3 91% 6 87% 12 80% 24 69% 36 58% 48 46% n=6910, deaths=1772 Event: Death with a device in place (censored at transplant and recovery) Months post implant 4

5 Figure 2 No change in survival by Implant year p(overall) =.63 % Survival Implant Year n Deaths (with a device in place) Totals Event: Death with a device in place (censored at transplant and recovery) Months post implant 5

6 Figure 3 % Freedom from Device Exchange p(overall) <.0001 Implant Year n Events Totals Increase in pump exchange per year Event: Device Exchange (censored at death, transplant and recovery) Months post implant 6

7 Table 1 Device Removal Events n Removed (exchanged) due to a problem 561 Thrombus 288 Elective 94 Emergent 177 Unknown 17 Probable Thrombus 49 Elective 25 Emergent 21 Unknown 3 Infection (Not thrombus) 76 Elective 38 Emergent 11 Unknown 27 Not Thrombus/Unknown Infection 120 Elective 52 Emergent 68 Not Thrombus/Not Infection 28 Unknown 28 Main Event Exchanges or deaths due to thrombus n=382 Device removed due to recovery 133 Death: Device not functionally normally 98 Thrombus 27 Probable Thrombus 18 Not Thrombus 53 Totals 792 7

8 Figure 5 % Freedom from Device Exchange or death due to thrombus % Freedom at Implant Year n Events 6 mos 12 mos 36 mos % 98% 92% % 99% 95% % 97% 90% % 94% % 93% ---- Totals Event: Device Exchange or death due to thrombus* (censored at death, transplant and recovery) Increase in pump exchange/death due to thrombus or death from 1% to 6% p(overall) <.0001 Months post implant *Thrombus events include probable thrombus events 8

9 Table 2 Pump Exchanges due to Thrombus: n=337 Exchange Era Elective Emergent Total (24.3%) 28 (75.7%) 37 (100.0%) * 110 (39.3%) 170 (60.7%) 280 (100.0%) Overall p value =.08 * 2013 includes exchanges from 01/01/2013 through 06/30/2013

10 Figure 4 % Freedom from exchange or death due to thrombus Months % Freedom 6 97% 12 95% 24 92% 48 86% n=6910, events=382 Event: Device exchange or death due to thrombus Hazard Events/Month Months post Implant 10

11 Figure 6 % Freedom from Device Exchange or death due to thrombus % Freedom by implant year p(overall) <.0001 Event: Device Exchange or death due to thrombus* (censored at death, transplant and recovery) Hazard by implant year Events/Month Months post implant *Thrombus events include probable thrombus events 11

12 Occurrence and Incidence of Confirmed Pump Thrombosis Stratified According to Implantation Date. Starling RC et al. N Engl J Med 2014;370:33-40

13 Table 4 Risk Factors for Device Exchange or Death due to Thrombus (Time Zero = 1 Month Post Implant) Risk Factor hazard ratio p-value Implant year (later) 1.46 <.0001 Age (younger) <.0001 White race BMI (larger) LVEF above 20% LDH at 1 month (higher) < Hazard ratio denotes the increased risk for a 60 year compared to a 70 year old patient 2 Hazard ratio denotes the increased risk for a 10 unit increase in BMI 3 Hazard ratio denotes the increased risk for an increase in LDH from 500 to 1000 units BMI, body mass index; LVEF, left ventricular ejection fraction; LDH, lactate dehydrogenase

Figure 13 By LDH Groups % Freedom from Device Exchange or Death due to Thrombus LDH group n Events Missing 4581 223 0-400 1318 52 401-1000 819 66 > 1000 192 41 Totals 6910 382 Event:

14 Figure 13 By LDH Groups % Freedom from Device Exchange or Death due to Thrombus LDH group n Events Missing > Totals Event: Device Exchange due to Thrombus** (censored at death, transplant and recovery) p(overall) <.0001 ** Thrombus events include probable thrombus LDH, lactate dehydrogenase Months post implant 14

15 Figure 8 1 st device, n=6910, deaths=1604 % Survival Exchange due to Thrombus n=337, deaths=80 Exchange due to Infection/Other n=224, deaths=66 p(overall) <.0001 Event: Death with a device in place (censored at transplant and recovery) Months post implant 15

Table 3 Primary Cause of Death within 3 months After Pump Exchange or After Primary Implant* death due to Thrombus Primary Cause of Death n % n % Circulatory Failure 217 34.7% 5 33.

16 Table 3 Primary Cause of Death within 3 months After Pump Exchange or After Primary Implant* death due to Thrombus Primary Cause of Death n % n % Circulatory Failure % % Multisystem Organ Failure % % CNS Event % % Infection % 1 6.7% Respiratory Failure % 1 6.7% Device Malfunction % 0 0.0% * Censored at devices exchange CNS, central nervous system

17 Figure 9 % Freedom from Infection n=6910, events=3206 n=337, events=131 p =.008 Event: Time to first Infection Months post Implant 17

18 Figure 10 n=6910, events=619 % Freedom from CVA n=337, events=37 p <.0001 Event: Time to first CVA Months post Implant CVA, cerebrovascular accident 18

19 Figure Median Visual Analog Scale (VAS) Main Event n=337: Exchanges due to Thrombus Median 1st Operation (prior to exchange) 2 nd Operation (exchanges due to thrombus) p value st Operation (n) nd Operation (n)

20 Figure 14 3 Median INR 1month post implant forward INR st operation Q1-25% Q3-75% INR, International normalized ratio Post Implant Follow-up by Quarter/Year 20

21 Limitations Pump Design/Production Intermacs can not give granular data on subtle differences/changes in clinical practice/patient selection overtime that may affect outcome Implantation techniques ie inflow angles Intensity of anticoagulation; compulsive f/u heparin bridging; Pump speed vs AV opening BP management 22

22 Changes Over Time GI bleeding decrease in anticoagulation goals Elimination of heparin bridging Decrease rpms to allow AV opening Pump Design/Production 2011 changes in outflow graft ; bend relief software changes 2011 Marked ramp up in production 23

23 Summary 6 fold Increase in Pump Exchange or death due to thrombosis in 2011 to 6% from 1% in 2009 Early Hazard of Pump thrombosis in first 3 months after 2011 not seen prior to 2011 Overall survival not changed (I yr 80%) BUT if you have a pump exchanged for thrombosis your survival is decrease (1 yr 70%) and your chance of stroke or infection is increased 24

24 Summary Risk factors for early Pump thrombosis is predominantly Pt year (2011) and early LDH rise after implant; other risk factors younger age; white; large BMI; LVEF > 20% 25

25 Conclusions (personal not intermacs) Most important change post 2011 is not increase rate of thrombosis but new early hazard of thrombosis< 3 months; different than late thrombosis Whatever is happening is happening in the OR or early postop Importance of HMII inflow cannulae ventricular alignment; bridging heparin Early LDH rise not seen prior to 2011 causative or result of early thrombus? Great variations of incidence of thrombosis between sites ( 1% to >20%) Detailed statistical review of different site practices (consortium of high and low incident sites) is needed to determine subtle difference in operative/implantation and pt care practices that may elucidate important risk factors for thrombosis Will allow hypothesis generation to validate in prospective study (PREVENT) Therapeutic window for HMII is more narrow now than prior to 2011 Multifactorial etiology- pump; implantation; pump management (anticoagulation, speed); patient; patient care?anticoagulation goals in high thrombosis incident sites higher now than prior to 2011 Importance of pump flow pass the bearing to dissipate heat rpms > 9000 if possible Continued Thoratec review of manufacturing practices and changes 26 made in pump in 2011

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