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07-07-2010 | Cardiology | Article

Low INR target suitable for AVR patients


Free abstract

MedWire News: Results from the LOWERING-IT trial support the use of a moderate oral anticoagulation regimen in low risk patients following mechanical aortic valve replacement (AVR).

The study compared the outcome of warfarin-treated patients set a low International Normalized Ratio (INR) target of 1.5-2.5 with those using the conventional INR target of 2.0-3.0.

This trial "established that the proposed LOW-INR target is safe and feasible in low-risk patients after bileaflet aortic mechanical valve replacement," report Michele Torella (Second University of Naples, Italy) and co-authors.

"It results in similar thrombotic events and in a significant reduction of bleeding occurrence when compared to the conventional anticoagulation regimen."

The team examined the impact of a low INR target in low-risk warfarin-naive patients, defined as those with a single AVR, in normal sinus rhythm, with a valve prosthesis dimension of at least 21 mm, a normal ejection fraction, and a left atrium diameter of less than 47 mm.

Overall, 197 patients were randomly allocated to the low INR target, while 199 were given the conventional INR target. None of the patients were given aspirin. The patients were followed-up for a median of 5.6 years.

The low- and conventional-INR treated patients achieved an average INR of 1.94 and 2.61, respectively.

Overall, thromboembolic events occurred in one low-INR patient and three conventional-INR patients. The difference was non-significant and met the primary study measure of non-inferiority for prevention of thromboembolism.

In addition, bleeding was significantly less common among low-INR patients than conventionally treated patients, affecting six and 16 patients, respectively.

"Because the proportion of patients who are at low risk of thromboembolic events is considerable in relation to the total number of recipients of mechanical heart valves, the data of the LOWERING-IT trial are important… because they begin to fill a void in the context of the other studies available so far," Torella et al write in the American Heart Journal.

"Yet, larger randomized controlled trials are needed to establish the effectiveness of the lower anticoagulation strategy over the current recommended antithrombotic management for these patients," they say.

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2010

By Lynda Williams

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