Low thromboembolism and pump thrombosis with the HeartMate II left ventricular assist device: analysis of outpatient anti-coagulation.
BACKGROUND
The HeartMate II (Thoratec, Pleasanton, CA) is an effective bridge to transplantation (BTT) but requires anti-coagulation with warfarin and aspirin. We evaluated the risk of thromboembolism and hemorrhage related to the degree of anti-coagulation as reflected by the international normalized ratio (INR).


METHODS
INRs were measured monthly for 6 months in all discharged HeartMate II BTT patients and at an event. Each INR was assigned to ranges of INRs. Adverse events analyzed were ischemic and hemorrhagic stroke, pump thrombosis, and bleeding requiring surgery or transfusion. Events were correlated to the INR during the event and at the start of the month.


RESULTS
In 331 patients discharged on support, 10 had thrombotic events (9 ischemic strokes, 3 pump thromboses), and 58 had hemorrhagic events (7 strokes, 4 hemorrhages requiring surgery, and 102 requiring transfusions). The median INR was 2.1 at discharge and 1.90 at 6 months. Although the incidence of stroke was low, 40% of ischemic strokes occurred in patients with INRs < 1.5 and 33% of hemorrhagic strokes were in patients with INRs > 3.0. The highest incidence of bleeding was at INRs > 2.5.


CONCLUSIONS
The rate of thromboembolism during long-term outpatient support with the HeartMate II is low. The low number of thrombotic events appears to be offset by a greater number of hemorrhagic events. An appropriate target INR is 1.5 to 2.5 in addition to aspirin therapy. In patients having recurrent episodes of bleeding, the risk of lowering the target INR appears to be small.
Boyle
Andrew J
AJ
Division of Cardiology, University of Minnesota, Minneapolis, Minnesota 55455, USA. boyle033@umn.edu
Russell
Stuart D
SD
Teuteberg
Jeffrey J
JJ
Slaughter
Mark S
MS
Moazami
Nader
N
Pagani
Francis D
FD
Frazier
O Howard
OH
Heatley
Gerald
G
Farrar
David J
DJ
John
Ranjit
R
D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use; D000925:Anticoagulants / Q000627:therapeutic use*; D001241:Aspirin / Q000627:therapeutic use; D001803:Blood Transfusion; D004867:Equipment Design; D005260:Female; D016027:Heart Transplantation; D006353:Heart-Assist Devices / Q000009:adverse effects*; D006470:Hemorrhage / Q000453:epidemiology / Q000601:surgery; D006801:Humans; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D010045:Outpatients; D012189:Retrospective Studies; D020521:Stroke / Q000453:epidemiology; D013923:Thromboembolism / Q000453:epidemiology*; D014859:Warfarin / Q000627:therapeutic use; D055815:Young Adult
D000319:Adrenergic beta-Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D000925:Anticoagulants; D014859:Warfarin; D001241:Aspirin