Prognostic value of early in-hospital glycemic excursion in elderly patients with acute myocardial infarction

Abstract

Background: Acute phase hyperglycemia has been associated with increased mortality in patients with acute myocardial infarction (AMI). However, the predictive value of glycemic excursion for adverse outcome in elderly AMI patients is not clear. The aim of this study is to investigate the prognostic value of early in-hospital glycemic excursion and hemoglobin A1c (HbA1c) for one-year major adverse cardiac event (MACE) in elderly patients with AMI.

Methods: We studied 186 elderly AMI patients, whose clinical data were collected and the Global Registry of Acute Coronary Events (GRACE) risk score were calculated on admission. The fluctuations of blood glucose in patients were measured by a continuous glucose monitoring system (CGMS) for 72 hours. Participants were grouped into tertiles of mean amplitude of glycemic excursions (MAGE) and grouped into HbA1c levels (as ≥6.5% or <6.5%). The MACE of patients, including new-onset myocardial infarction, acute heart failure and cardiac death, was documented during one year follow-up. The relationship of MAGE and HbA1c to the incidence of MACE in elderly AMI patients was analyzed.

Results: In all participants, a higher MAGE level was associated with the higher GRACE score (r = 0.335, p < 0.001). The rate of MACE by MAGE tertiles (>3.94 mmol/L, 2.55-3.94 mmol/L or <2.55 mmol/L) was 30.2% vs. 14.8% vs. 8.1%, respectively (p = 0.004); by HbA1c category (≥6.5% vs. <6.5%) was 22.7% vs. 14.4%, respectively (p = 0.148). Elderly AMI patients with a higher MAGE level had a significantly higher cardiac mortality. In multivariable analysis, high MAGE level was significantly associated with incidence of MACE (HR 3.107, 95% CI 1.190-8.117, p = 0.021) even after adjusting for GRACE risk score, but HbA1c was not.

Conclusions: The early in-hospital intraday glycemic excursion may be an important predictor of mortality and MACE even stronger than HbA1c in elderly patients after AMI.

Figure 1

Incidence of MACE after 1-year follow-up in relation to MAGE levels. Elderly AMI patients with a higher MAGE level had significantly higher cardiac mortality and incidence of all MACE

Figure 2

Incidence of MACE after 1-year follow-up in relation to HbA_1c levels. There are no significant differences of adverse cardiovascular events rates between different HbA_1c level groups (all p > 0.05)

Figure 3

Kaplan-Meier event-free survival curves for freedom from MACE in three patient groups by MAGE levels. The event-free survival rate was significantly lower in the high MAGE level group (log-rank test, p = 0.003)

Figure 4

Kaplan-Meier event-free survival curves for freedom from MACE in two patient groups by HbA_1c levels. There is not significant lower event-free survival rate in high HbA_1c level patients (log-rank test, p = 0.107)