Influence of bedside blood insulin measurement on acute coronary syndrome pathways

Acute insulin resistance in ST-segment elevation myocardial infarction in non-diabetic patients is associated with incomplete myocardial reperfusion and impaired coronary microcirculatory function

Background

Insulin resistance (IR) assessed by the Homeostatic Model Assessment (HOMA) index in the acute phase of myocardial infarction in non-diabetic patients was recently established as an independent predictor of intrahospital mortality. In this study we postulated that acute IR is a dynamic phenomenon associated with the development of myocardial and microvascular injury and larger final infarct size in patients with ST-segment elevation myocardial infarction (STEMI) treated by primary percutaneous coronary intervention (pPCI).

Methods

In 104 consecutive patients with the first anterior STEMI without diabetes, the HOMA index was determined on the 2^nd and 7^th day after pPCI. Worst-lead residual ST-segment elevation (ST-E) on postprocedural ECG, coronary flow reserve (CFR) determined by transthoracic Doppler echocardiography on the 2^nd day after pPCI and fixed perfusion defect on single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) determined six weeks after pPCI were analyzed according to HOMA indices.

Results

IR was present in 55 % and 58 % of patients on day 2 and day 7, respectively. Incomplete post-procedural ST-E resolution was more frequent in patients with IR compared to patients without IR, both on day 2 (p = 0.001) and day 7 (p < 0.001). The HOMA index on day 7 correlated with SPECT-MPI perfusion defect (r = 0.331), whereas both HOMA indices correlated well with CFR (r = -0.331 to -0.386) (p < 0.01 for all). In multivariable backward logistic regression analysis adjusted for significant univariate predictors and potential confounding variables, IR on day 2 was an independent predictor of residual ST-E ≥ 2 mm (OR 11.70, 95% CI 2.46-55.51, p = 0.002) and CFR < 2 (OR = 5.98, 95% CI 1.88-19.03, p = 0.002), whereas IR on day 7 was an independent predictor of SPECT-MPI perfusion defect > 20% (OR 11.37, 95% CI 1.34-96.21, p = 0.026).

Conclusion

IR assessed by the HOMA index during the acute phase of the first anterior STEMI in patients without diabetes treated by pPCI is independently associated with poorer myocardial reperfusion, impaired coronary microcirculatory function and potentially with larger final infarct size.

Acute insulin resistance assessed by the homeostatic model assessment in acute coronary syndromes without previously known diabetes

We assessed the incidence and the prognostic role for early death of acute insulin resistance (by means of homeostatic model assessment [HOMA] index) in 1350 patients with acute coronary syndrome (ACS) consecutively admitted to our intensive cardiac care unit (ICCU). The incidence of HOMA positivity was 5% (68 of 1350), with the highest percentage of HOMA positivity among ST-segment elevation myocardial infarction (STEMI). Patients with HOMA positivity showed a higher body mass index (P = .003), lower values of admission and discharge left-ventricular ejection fraction (LVEF; P < .001 and P = .003, respectively), and higher levels of peak troponin I (Tn I; P < .001). The HOMA index was an independent predictor of early death (odds ratio 1.724, 95% confidence interval 1.252-2.375, P = .001). In patients with ACS and without previously known diabetes, acute insulin resistance (HOMA index) is associated with a larger myocardial damage (ie, higher values of peak Tn I and lower LVEF) and a greater inflammatory activation (indicated by correlation with leukocyte count). The HOMA positivity was an independent predictor of in-ICCU mortality.