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Incidence of thromboembolic complications in patients with atrial fibrillation or mechanical heart valves with a subtherapeutic international normalized ratio: A prospective multicenter cohort study
Author(s) -
Dentali Francesco,
Pignatelli Pasquale,
Malato Alessandra,
Poli Daniela,
Di Minno Matteo Nicola Dario,
Di Gennaro Leonardo,
Rancan Elena,
Pastori Daniele,
Grifoni Elena,
Squizzato Alessandro,
Siragusa Sergio,
Minno Giovanni di,
Ageno Walter
Publication year - 2012
Publication title -
american journal of hematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.456
H-Index - 105
eISSN - 1096-8652
pISSN - 0361-8609
DOI - 10.1002/ajh.23119
Subject(s) - medicine , atrial fibrillation , prospective cohort study , confidence interval , incidence (geometry) , vitamin k antagonist , population , cohort study , cohort , cardiology , surgery , warfarin , physics , environmental health , optics
Subtherapeutic international normalized ratio (INR) is frequently encountered in clinical practice, and patients with high‐risk atrial fibrillation (AF) and with mechanical heart valve (MHV) with inadequate anticoagulation may be exposed to an increased risk of thromboembolic events (TE). However, there are no prospective data evaluating this risk. Consecutive patients with a history of stable anticoagulation, but with a subtherapeutic INR, were prospectively included. Data on use and dose of low‐molecular weight heparin (LMWH) bridging therapy were collected. The incidence of objectively confirmed TE and of major bleeding events within 90 days after the index INR was assessed. Five hundred and one patients with INR value 0.5–1 INR units below the lower limit of the patient‐specific target INR were included in the study (280 with MHV and 221 with AF and CHADS2 score ≥3). LMWH was prescribed for 64 patients (12.8%). During follow‐up, seven patients had a TE (1.40%; 95% confidence interval 0.68, 2.86%; 5.58 events for 100 patients year). All the events occurred within 14 days after the index INR. When we consider only patients who did not receive bridging therapy, the incidence of TE was 1.14% (5 of 437 patients; 95% confidence interval 0.49, 2.64%; 4.58 events for 100 patients year). There were no major bleeding events. The risk of TE in this population was not negligible. Given the frequent observation of subtherapeutic INR levels when monitoring vitamin K antagonists, this finding warrants additional investigation to improve the management of these patients. Am. J. Hematol. 2012. © 2012 Wiley Periodicals, Inc.