Clinical characteristics and in-hospital mortality among insulin pump users with acute coronary syndrome in the predominantly open-loop era: A UK-wide MINAP registry analysis.

BACKGROUND

We compared characteristics of adults with insulin-treated diabetes using continuous subcutaneous insulin infusion (CSII) versus multiple daily insulin injections (MDI) during admission with acute coronary syndrome (ACS) and identified factors associated with in-hospital mortality among CSII users.

METHODS

This retrospective cohort study used the Myocardial Ischaemia National Audit Project, a registry of ACS admissions in England and Wales. Adults aged ≥18 years with confirmed ACS and insulin-treated diabetes were classified as CSII or MDI users. Baseline characteristics were compared. Gradient boosting machine (GBM) modelling and multivariable logistic regression evaluated mortality predictors among CSII users.

RESULTS

The cohort included 3321 CSII users and 30,593 MDI users. In-hospital mortality was higher among CSII users (11.4% vs. 5.1%; p < 0.001). CSII users had higher rates of cardiogenic shock (4.8% vs. 1.3%), pulmonary oedema (12.1% vs. 8.3%), poor left ventricular systolic function (23.5% vs. 19.7%), and STEMI (32.2% vs. 20.5%). Cardiogenic shock was the strongest predictor of mortality (adjusted OR 10.46, 95% CI 6.95-15.81), followed by poor left ventricular function (OR 4.15, 95% CI 2.69-6.53), basal crepitations (OR 1.94, 95% CI 1.40-2.67) and pulmonary oedema (OR 1.56, 95% CI 1.05-2.28). Higher systolic blood pressure was associated with lower mortality (OR 0.86 per 10 mmHg, 95% CI 0.82-0.90). The GBM model achieved an AUC of 0.85 and a Brier score of 0.088.

CONCLUSIONS

CSII users admitted with ACS represented a more complex group with haemodynamic compromise and higher unadjusted mortality. Findings predominantly reflect the open-loop CSII era and may not generalise to contemporary hybrid closed-loop systems.