The Effect of Restrictive vs Liberal Blood Transfusion Strategy on Subsequent Myocardial Infarction Type.

BACKGROUND

Data on the differential impact of interventions on subsequent myocardial infarction (MI) type are limited.

OBJECTIVES

This post-hoc analysis was done to evaluate the 30-day rate of subsequent MI by type (ie, type 1 and 2) among patients enrolled in the MINT (Myocardial Ischemia and Transfusion; NCT02981407) trial.

METHODS

Subdistribution HRs and cumulative incidences of subsequent MI types were computed using Fine-Gray subdistribution models that accounted for the competing risk of death and other MI types, if applicable. Effect modification of treatment strategy by index MI type was tested using log-binomial regression models.

RESULTS

Among 3,504 MINT trial patients, 275 (7.8%) had a 30-day subsequent MI, of which 118 (43%) were type 2 MI, 79 (28%) were uncertain MI type, 40 (15%) were type 4 MI, and 38 (14%) were type 1 MI. The rate of subsequent type 2 MI in patients randomized to the restrictive vs liberal transfusion was 3.5% (n = 61) vs 3.2% (n = 57) (HR: 1.07; 95% CI: 0.74-1.53) as compared with a subsequent type 1 MI rate of 1.3% (n = 23) vs 0.9% (n = 15) (HR: 1.53; 95% CI: 0.80-2.94).

CONCLUSIONS

Among patients with MI and anemia, subsequent MI occurred within 30 days in 7.8% of patients, with type 2 MI occurring 3 times more often than type 1 MI. A differential effect of the restrictive vs liberal transfusion strategy on the type of subsequent MI (eg, type 1 vs type 2) was not observed.