Dobutamine versus milrinone for inferior ST-segment elevation myocardial infarction with right ventricular involvement: a retrospective cohort study.

BACKGROUND

Inferior ST-segment elevation myocardial infarction (STEMI) complicated by right ventricular involvement (RVMI) leads to right-heart-dominant failure and a higher incidence of cardiogenic shock (CS). Evidence guiding the choice between inotropic agents in this specific phenotype remains limited.

METHODS

This single-center retrospective cohort study included 211 patients with inferior STEMI and suspected RVMI treated with either dobutamine (n = 55) or milrinone (n = 156) between June 2009 and June 2025. The primary outcome was 30-day mortality. Secondary outcomes included duration of inotropic support and hospital length of stay. Confounding and missing data were addressed using multiple imputation, multivariable Cox regression, inverse probability of treatment weighting, and sensitivity analyses.

RESULTS

The dobutamine group had more severe hemodynamic and electrical instability, while the milrinone group exhibited greater left ventricular dysfunction. The 30-day mortality rates were 25.5% for dobutamine and 29.5% for milrinone. No significant difference was found in unadjusted (HR 0.863; 95% CI 0.475-1.570; P = 0.632) or multivariable-adjusted Cox analysis (HR 0.612; 95% CI 0.316-1.187; P = 0.153), with results remaining consistent across multiple sensitivity and propensity-based analyses. Notably, among survivors, the duration of inotropic support was significantly shorter in the dobutamine group (3.1 vs. 5.0 days; adjusted β = -1.805; 95% CI -3.147 to -0.463; P = 0.009).

CONCLUSION

In patients with inferior STEMI and suspected RVMI, no statistically significant difference in 30-day mortality was detected between dobutamine and milrinone, though the study was underpowered to establish equivalence. Dobutamine was associated with a shorter duration of support among survivors despite its application in more unstable patients. Inotrope selection should therefore be individualized based on the patient's hemodynamic phenotypes.