Relación entre el efecto antiagregante de la aspirina y el recuento plaquetario. Posibles implicaciones en la dosificación;
The Association of Antiplatelet Aggregation Effect of Aspirin and Platelet Count. Possible Dosage Implications

IntroducciónEl 30% de los pacientes presentan antiagregación plaquetaria inadecuada con 100 mg/día de aspirina (AAS) luego de la cirugía de revascularización miocárdica (CRM), que podría deberse a una acción inhibitoria menor de esta dosificación de AAS a la mayor activación plaquetaria y al aumento del recambio plaquetario que ocurren en el posoperatorio.ObjetivosEvaluar la relación entre el recuento plaquetario y el menor efecto antiagregante y determinar si dosis fragmentadas de AAS mejoran la antiagregación. Material y métodosLuego de la CRM con bypass cardiopulmonar (2,95 bypass en promedio), se aleatorizaron prospectivamente 50 pacientes a tres grupos: 18 pacientes (G100) a 100 mg/día, 14 (G300) a 300 mg/día y 18 (G100×3) a 100 mg 3 veces por día de AAS. En el preoperatorio todos recibieron 100 mg/día. La reactividad plaquetaria se midió mediante agregación en sangre entera con ácido araquidónico antes de la cirugía (T0), al primero (T1), tercero (T2) y séptimo días (T3) y al mes (T4) pos-CRM.resumen completo en pdf

BackgroundThirty percent of patients do not achieve an adequate antiplateleteffect despite therapy with aspirin (ASA) 100 mg/dafter coronary artery bypass-graft surgery (CABGS), probablydue to reduced inhibitory effect of ASA, increased plateletactivation and increased platelet turnover secondary to thesurgical procedure.ObjectivesTo evaluate the relation between platelet count and lowerantiplatelet effect and to determine if antiaggregation improvesby dividing the dose of ASA.Material and MethodsA total of 50 patients undergoing CABGS (with an averageof 2.95 grafts per surgery) were randomly assigned to threegroups depending on the dose of ASA indicated: G100 (100mg/d, n=18 patients), G300 (300 mg/d, n=14) and G100×3(100 mg TID, n=18). All the patients received 100 mg/d beforesurgery. Platelet reactivity was assessed by whole bloodimpedance using arachidonic acid before surgery (T0), 24 h(T1), 72 h (T2), 7 days (T3), and one month post-CABG (T4).ResultsBefore surgery, all patients had optimal values of antiaggregation(0 W). During the postoperative period, antiaggregationvalues were better in patients from G100×3 (p <0.05). Nopatients in G100×3 had values ≥ W, which correspond tothose of healthy subjects who do not receive ASA. This value was observed in 5 patients (28%) from G100 and 4 patients(29%) from G300. The association between antiaggregationand platelet turnover was statistically significant (R2=0.57;p=0.001). A daily turnover >20% was related with values ofplatelet aggregation ≥6 W; OR=2.1 (CI 1.8-4.21; p=0.0028).ConclusionsIn patients undergoing CABGS, the lowest antiplatelet effectof ASA was associated with the highest platelet turnover. Abetter antiaggregation might be achieved by dividing therapyin low dose of ASA.