Abstract
Background: Intravenous unfractionated heparin remains a cornerstone of anticoagulation therapy for patients with acute coronary syndromes, but regulation to a target aPTT is challenging. We assessed unfractionated heparin infusion regulation by bedside, whole-blood aPTT testing and computerized, algorithmic infusion adjustment, and further evaluated the relationship of achieving the target aPTT with clinical outcomes.
Methods and Results: We studied 1,275 patients randomized to unfractionated heparin in PARAGON-A, which tested lamifiban with or without unfractionated heparin versus unfractionated heparin. All patients had baseline and 6-hour blinded, bedside aPTTs, then aPTTs per algorithm. A central computer translated encrypted values to algorithmic dose-adjustment commands. We assessed the ability to achieve and maintain aPTTs of 50–70 seconds and associations of 6- and 12-hour aPTTs and time-to-target with 30-day outcomes.
Overall, the median 6-hour aPTT was 50–70 seconds and remained so throughout infusion. Individually, only 33.6% of patients achieved 6-hour target-range aPTTs, and only 40% of all aPTTs were in-range. After achieving target, only 42% of subsequent measures were in-range. Thirty-day death or myocardial infarction (death/MI) increased non-significantly as time-to-target increased (p = 0.08). Thirty-day mortality was similar if target aPTT was reached, regardless of timing. Death/MI trended lower if target aPTT was reached by 8 hours (p = 0.10). The best clinical outcomes were associated with in-range aPTTs.
Conclusions: This study represents the most systematic monitoring and regulation of unfractionated heparin anticoagulation to date. Although average anticoagulation achieved target range, wide inter- and intra-patient variability may have important implications for clinical outcomes.
Abbreviated abstract: Using systematic aPTT testing and computer-directed, algorithmic unfractionated heparin infusion adjustment in 1,275 acute coronary syndrome patients, the overall median aPTT was 50–70 seconds. However, only 33.6% of patients achieved this target 6-hour aPTT range. Only 40% of all aPTTs, and after achieving target, only 42% of subsequent measures, were in this range. Thirty-day death or myocardial infarction increased with increasing time to target aPTT (for trend, p = 0.08). The best outcomes were associated with 6- and 12-hour aPTTs in the target range. Wide inter- and intra-patient variability despite highly systematic, controlled unfractionated heparin infusion regulation has important implications for unfractionated heparin use.
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References
Braunwald E, Antman EM, Beasley JW, et al. ACC/AHA guideline update for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on the Management of Patients with Unstable Angina). 2002. Accessed on April 26, 2002 at: http://www.acc.org/clinical/guidelines/ unstable/unstable.pdf.
Ryan TJ, Antman EM, Brooks NH, et al. 1999 update: ACC/AHA guidelines for the management of patients with acute myocardial infarction: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Management of Acute Myocardial Infarction). J Am Coll Cardiol1999;34: 890–911.
Granger CB, Hirsh J, Califf RM, et al. for the GUSTO-I investigators. Activated partial thromboplastin time and outcome after thrombolytic therapy for acute myocardial infarction: results from the GUSTO-I trial. Circulation1996;93: 870–878.
Becker RC, Cannon CP, Tracy RP, et al. Relation between systemic anticoagulation as determined by activated partial thromboplastin time and heparin measurements and in-hospital clinical events in unstable angina and non-Q wave myocardial infarction. Am Heart J1996;131: 421–423.
Wali A, Hochman JS, Berkowitz S, et al. Failure to achieve optimal anticoagulation with commonly used heparin regimens: a review of GUSTO IIb. J Am Coll Cardiol1998;31: 820 (Abstr).
Hochman JS, Wali AU, Gavrila D, et al. A new regimen for heparin use in acute coronary syndromes. Am Heart J1999;138: 313–318.
The PARAGON A investigators. International, randomized, controlled trial of lamifiban (a platelet glycoprotein IIb/IIIa inhibitor), heparin, or both in unstable angina. Circulation1998;97: 2386–2395.
Cohen M, Demers C, Gurfinkel EP, et al. A comparison of low-molecular-weight heparin with unfractionated heparin for unstable coronary artery disease. N Engl J Med1997;337: 447–452.
Antman EM, McCabe CH, Gurfinkel EP, et al. for the TIMI IIB investigators. Enoxaparin prevents death and cardiac ischemic events in unstable angina/non-Q-wave myocardial infarction: results of the thrombolysis in myocardial infarction (TIMI) 11B trial. Circulation1999:1593–1601.
Becker RC, Ball SP, Eisenberg P, et al. for the Antithrombotic Therapy Consortium Investigators. A randomized, multicenter trial of weight-adjusted intravenous heparin dose titration and point-of-care coagulation monitoring in hospitalized patients with active thromboembolic disease. Am Heart J1999;137: 59–71.
Cannon CP, Dingemanse J, Kleinbloesem CH, Jannett T, Curry KM, Valcke CP. Automated heparin-delivery system to control activated partial thromboplastin time: evaluation in normal volunteers. Circulation1999;99: 751–756.
Kohn LT, Corrigan JM, Donaldson MS. To Err is Human: Building a Safer Health System. Washington: National Academy Press, 1999.
Brown G, Dodek P. An evaluation of empiric vs. nomogram-based dosing of heparin in an intensive care unit. Crit Care Med1997;25: 1534–1538.
Rivey MP, Peterson JP. Pharmacy-managed, weight-based heparin protocol. Am J Hosp Pharm1993;50: 279–284.
Cruickshank MK, Levine MN, Hirsh J, Roberts R, Siguenza M. A standard heparin nomogram for the management of heparin therapy. Arch Intern Med1991;151: 333–337.
Zabel KM, Granger CB, Becker RC, et al. for the GUSTO-I Investigators. Use of bedside activated partial thromboplastin time monitor to adjust heparin dosing after thrombolysis for acute myocardial infarction: results of GUSTO-I. Am Heart J1998;136: 868–887.
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Newby, L.K., Harrington, R.A., Bhapkar, M.V. et al. An Automated Strategy for Bedside aPTT Determination and Unfractionated Heparin Infusion Adjustment in Acute Coronary Syndromes: Insights from PARAGON A. J Thromb Thrombolysis 14, 33–42 (2002). https://doi.org/10.1023/A:1022062204490
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DOI: https://doi.org/10.1023/A:1022062204490