Doenças Cardiovasculares e Diagnóstico

The Significance of Dynamics of ST Segment Changes when Assessing the Effectiveness of Mechanical Reperfusion of the Myocardium in Hyperglycaemic Patients with Acute Myocardial Infarction with Persistent ST-Segment Elevation

Abstract

Andres M

Background: The coexistence of coronary heart disease and consequently acute myocardial infarction with persistent ST-segment elevation (STEMI) and glucose metabolism disorders is well known. Still, glucose metabolism disorders in the STEMI population are not fully understood. We know that diabetes mellitus (DM) is a factor disabling the function of microcirculation, which in turn may affect the outcome of a coronary intervention.

Aim: To evaluate the dynamics of ST-segment changes in ECG (electrocardiogram) in STEMI (ST-segment elevation myocardial infarction) patients with co-existing hyperglycaemia compared to those with normoglycaemia treated with percutaneous coronary intervention (PCI), as well as to determine this parameter in the assessment of reperfusion effectiveness.

Method: The study included 92 patients with the diagnosis of STEMI enrolled in the PCI treatment and was divided into groups based on the glucose levels on admission (reactive hyperglycaemia): a group with higher glucose levels on admission (Glc ≥ 7.8 mmol/L, n=46), a group with lower glucose levels on admission (Glc <7.8 mmol/L, n=46) and into groups based on the concentration of HbA1c : a group with a lower HbA1c level (<6.5% (48 mmol/mol), n=71) and a group with a higher level (≥ 6.5%, n=21).

Results: On admission there were no significant differences in terms of clinical characteristics between the groups of patients with normoglycemia and reactive hyperglycaemia. After PCI the patients with normoglycemia had significantly higher (p=0.021) dynamics of changes in the resolution of ST-segment elevation in ECG expressed in an indicator of sum STR (resolution of ST elevation). A degree of resolution of ST elevation in ECG was significantly (p=0.021) dependent on the level of blood glucose - the higher the blood glucose level, the weaker resolution. The patients with the glucose levels ≥ 7.8 mmol/L had significantly higher levels of CK and CK-MB during the first 48 hours of hospitalization. There was a statistically significant difference in the mean length of hospitalization between individuals from the group with lower and higher blood glucose levels on admission (p=0.028). A 4-month follow-up revealed no significant difference in the incidence of MACE in the study groups (p=0.063). A 4-year follow-up of patients with higher levels of blood glucose on admission showed a higher incidence of MACE (p=0.01). The patients with HbA1c ≥ 6.5% were older (p=0.004), had a greater BMI >30 kg/m2 (p=0.019) and the lower ejection fraction of the left ventricle (p=0.003) compared to those with the HbA1c levels <6.5%. The incidence of MACE in 4- month and 4-year follow-up was comparable in the study population.

Conclusion: Myocardial reperfusion after primary angioplasty in acute myocardial infarction, which is determined by the degree of resolution of ST elevation in ECG, depends on the state of the glucose metabolism. The dynamics of changes in the ST-segment in ECG, taken immediately after PCI, is lower in patients with reactive hyperglycaemia.