Incidence of thromboembolic complications in patients with mechanical heart valves with a subtherapeutic international normalized ratio.
OBJECTIVE
Subtherapeutic international normalized ratios are frequently encountered in clinical practice, and patients with mechanical heart valves with inadequate anticoagulation may be exposed to an increased risk of thromboembolic events. There are no data on thromboembolic event risk for these patients.


METHODS
We assessed the current practice patterns in the management of patients with mechanical heart valves with subtherapeutic international normalized ratios and assessed the risk of thromboembolic complications in this setting. The charts of patients with mechanical heart valves followed up in two anticoagulation clinics were reviewed. Patients with a history of stable, therapeutic anticoagulation but with a subtherapeutic international normalized ratio were included. Patients who underwent invasive procedures requiring temporary suspension of antithrombotic therapy were excluded. Data on use and dose of low-molecular weight heparin bridging therapy were collected.


RESULTS
The incidence of objectively confirmed thromboembolic events within 90 days after obtaining the index international normalized ratio was assessed. Two hundred ninety-four patients with mechanical heart valves were included (mean age 63.3 years, 47.3% male). Low-molecular weight heparin was prescribed in 14 cases (4.8%). At 90 days, 1 patient had a thromboembolic complication (0.3%, 95% confidence interval 0%-1.9%).


CONCLUSIONS
Patients with previously stable, therapeutic anticoagulation with a subtherapeutic international normalized ratio have a low risk of thromboembolic events. Withholding low-molecular weight heparin bridging therapy is a reasonable therapeutic option in these cases.
Dentali
Francesco
F
Department of Clinical Medicine, University of Insubria, Varese, Italy. fdentali@libero.it
Riva
Nicoletta
N
Malato
Alessandra
A
Saccullo
Giorgia
G
Siragusa
Sergio
S
Ageno
Walter
W
D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D006350:Heart Valve Prosthesis / Q000009:adverse effects*; D006801:Humans; D015994:Incidence; D019934:International Normalized Ratio; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D012189:Retrospective Studies; D018570:Risk Assessment; D013923:Thromboembolism / Q000453:epidemiology* / Q000209:etiology*; D055815:Young Adult