Doppler microembolic load predicts risk of thromboembolic complications in Novacor patients.
OBJECTIVE
Left ventricular assist devices have become an established method to bridge patients with end-stage cardiac failure to heart transplantation. Besides infection and bleeding, thromboembolism represents one of the most serious complications. We evaluated the value of microembolic signals in predicting thromboembolic events for individual patients and distinctive left ventricular assist device periods.


METHODS
Twenty patients (14 male) aged 23-57 years supported with the Novacor N100 left ventricular assist device were enrolled in this study. All patients were on effective anticoagulation, 12 patients additionally received antiplatelet therapy. Unilateral detection of microembolic signals was performed once weekly by insonation of the middle cerebral artery using transcranial Doppler sonography for 30 minutes duration. Evidence of clinically manifest thromboembolic events was based on regular questionnaires, clinical examinations, and results of diagnostic procedures.


RESULTS
During a cumulative follow-up of 3876 left ventricular assist device days, 44 thromboembolic complications occurred (incidence, 1.1%) in 15 out of 20 patients. A total of 360 transcranial Doppler sonography monitorings (range, 5-34 per patient) were performed with an overall microembolic signals prevalence of 35.3% and a microembolic signal mean of 2.3 +/- 9.2 per examination. There was a highly significant correlation between the individual microembolic signal activity and the respective incidence of clinical thromboembolism (r = 0.61-0.9; P <.01). Patients with additional antiplatelet treatment had significantly less thromboembolic complications (0.7%) and lower microembolic signal prevalence (18.3%) than those without (2.8% and 65.4%, respectively). Individual patients and left ventricular assist device months with clinical thromboembolization could be identified using the microembolic signal activity with moderate positive (0.37-0.7) and high negative predictive values (0.82-1.0).


CONCLUSIONS
The amount of microembolic signals, serially detected in patients with the Novacor left ventricular assist device, is significantly associated with their incidence of embolic complications. The high negative predictive value of microembolic signals enables to identify those patients and left ventricular assist device periods with particularly low risk of clinical thromboembolization.
Nabavi
Darius G
DG
Department of Neurology, University of Münster, Germany. nabavi@uni-muenster.de
Stockmann
Joerg
J
Schmid
Christof
C
Schneider
Michael
M
Hammel
Dieter
D
Scheld
Hans H
HH
Ringelstein
E Bernd
EB
D000328:Adult; D000925:Anticoagulants / Q000627:therapeutic use; D002311:Cardiomyopathy, Dilated / Q000401:mortality / Q000601:surgery; D004867:Equipment Design; D005260:Female; D005500:Follow-Up Studies; D006353:Heart-Assist Devices; D006801:Humans; D015994:Incidence; D020766:Intracranial Embolism / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000209:etiology*; D020767:Intracranial Thrombosis / Q000000981:diagnostic imaging* / Q000188:drug therapy / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000401:mortality / Q000601:surgery; D010975:Platelet Aggregation Inhibitors / Q000627:therapeutic use; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology; D011237:Predictive Value of Tests; D012307:Risk Factors; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D016896:Treatment Outcome; D017585:Ultrasonography, Doppler, Transcranial
D000925:Anticoagulants; D010975:Platelet Aggregation Inhibitors