Se ha publicado en el Journal of the American College of Cardiology (17 Diciembre 2003. Volumen 42. Articulo 12. Paginas 2042 a 2048. el siguiente Metanalisis.

The optimal intensity of vitamin k antagonists in patients with mechanical heart valves: A meta-analysis *

Roel Vink * *, Roderik A. Kraaijenhagen †, Barbara A. Hutten ‡, Renee B. A. van den Brink †, Bas A. de Mol §, Harry R. Büller * and Marcel Levi *
Received: 2/27/2003. Revised: 7/7/2003. Accepted: 7/21/2003.

Abstract

Objectives

The purpose of this study was to compare two different intensities of vitamin K antagonists (VKA) among patients with mechanical heart valves using meta-analytic techniques.

Background

Patients with mechanical heart valves are at increased risk for valve thrombosis and systemic embolism, which can be reduced by VKA. The range of optimal intensity of VKA is still a matter of debate.

Methods

A computerized search in the PubMed database was made for relevant articles. A meta-analysis was performed of all eligible studies with data on the incidences of thromboembolic and bleeding complications in patients with mechanical heart valve prostheses during different intensities of VKA therapy. The studies were classified into low-intensity VKA therapy (mean target international normalized ratio [INR] of 3.0 or lower) or high-intensity VKA therapy (mean target INR above 3.0).

Results

Thirty-five eligible studies were identified, including in total 23,145 patients, who were studied for 108,792 patient-years. For patients with an aortic valve, high intensity resulted in a lower incidence of thromboembolic events (risk ratio [RR] = 0.73, p < 0.0001); however, the incidence of bleeding was increased (RR = 1.23, p < 0.0001). In the mitral valve group, the incidence rate for thromboembolism was lower in the high-intensity group (RR = 0.74, p < 0.0001), without a significantly increased bleeding incidence (RR = 1.08, P = 0.0524). The total number of thromboembolic and bleeding events was decreased in the high-intensity group compared with low-intensity VKA therapy for both aortic and mitral valve prostheses (RR = 0.94 [p = 0.0067] and 0.84 [p < 0.0001]), respectively.

Conclusions

This meta-analysis shows that both aortic and mitral valves will benefit from a treatment strategy with a target INR higher than 3.0.

Comentario: Los pacientes con válvulas mecánicas presentan un riesgo mayor de procesos tromboembolicos, tanto sobre la propia válvula como embolismos sistémicos.

El conseguir una anticoagulacion adecuada disminuyendo el riesgo de hemorragias es un objetivo deseable.
La realización del metanalisis sobre diversos estudios se hizo comparando dos intensidades de anticoagulacion. Menor de 3 de INR o bien mayor de 3 de INR.

El análisis se realizo sobre un total de 25 estudios con un total de 23.145 pacientes se observo un beneficio en la tasa de tromboembolismo y hemorragias mas favorable al grupo de INR superior a 3, tanto en Aorticas como en Mítrales aunque hay que mencionar que el grupo de Valvulopatia Aortica el índice de hemorragias fue mayor que en los de INR inferior a 3.

¿Cuál seria entonces la tasa ideal?

A la vista de este metanalisis se podría recomendar una tasa de anticoagulacion de INR= 3-3,5. tanto en Valvulopatias mítrales como Aorticas con prótesis metálicas.